summaryrefslogtreecommitdiff
path: root/kernel/bpf/btf.c
blob: 1095bbe2985930f486010f955d96ee7b57d0a8a1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018 Facebook */

#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/bpf_lsm.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <linux/bsearch.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>

#include <net/netfilter/nf_bpf_link.h>

#include <net/sock.h>
#include <net/xdp.h>
#include "../tools/lib/bpf/relo_core.h"

/* BTF (BPF Type Format) is the meta data format which describes
 * the data types of BPF program/map.  Hence, it basically focus
 * on the C programming language which the modern BPF is primary
 * using.
 *
 * ELF Section:
 * ~~~~~~~~~~~
 * The BTF data is stored under the ".BTF" ELF section
 *
 * struct btf_type:
 * ~~~~~~~~~~~~~~~
 * Each 'struct btf_type' object describes a C data type.
 * Depending on the type it is describing, a 'struct btf_type'
 * object may be followed by more data.  F.e.
 * To describe an array, 'struct btf_type' is followed by
 * 'struct btf_array'.
 *
 * 'struct btf_type' and any extra data following it are
 * 4 bytes aligned.
 *
 * Type section:
 * ~~~~~~~~~~~~~
 * The BTF type section contains a list of 'struct btf_type' objects.
 * Each one describes a C type.  Recall from the above section
 * that a 'struct btf_type' object could be immediately followed by extra
 * data in order to describe some particular C types.
 *
 * type_id:
 * ~~~~~~~
 * Each btf_type object is identified by a type_id.  The type_id
 * is implicitly implied by the location of the btf_type object in
 * the BTF type section.  The first one has type_id 1.  The second
 * one has type_id 2...etc.  Hence, an earlier btf_type has
 * a smaller type_id.
 *
 * A btf_type object may refer to another btf_type object by using
 * type_id (i.e. the "type" in the "struct btf_type").
 *
 * NOTE that we cannot assume any reference-order.
 * A btf_type object can refer to an earlier btf_type object
 * but it can also refer to a later btf_type object.
 *
 * For example, to describe "const void *".  A btf_type
 * object describing "const" may refer to another btf_type
 * object describing "void *".  This type-reference is done
 * by specifying type_id:
 *
 * [1] CONST (anon) type_id=2
 * [2] PTR (anon) type_id=0
 *
 * The above is the btf_verifier debug log:
 *   - Each line started with "[?]" is a btf_type object
 *   - [?] is the type_id of the btf_type object.
 *   - CONST/PTR is the BTF_KIND_XXX
 *   - "(anon)" is the name of the type.  It just
 *     happens that CONST and PTR has no name.
 *   - type_id=XXX is the 'u32 type' in btf_type
 *
 * NOTE: "void" has type_id 0
 *
 * String section:
 * ~~~~~~~~~~~~~~
 * The BTF string section contains the names used by the type section.
 * Each string is referred by an "offset" from the beginning of the
 * string section.
 *
 * Each string is '\0' terminated.
 *
 * The first character in the string section must be '\0'
 * which is used to mean 'anonymous'. Some btf_type may not
 * have a name.
 */

/* BTF verification:
 *
 * To verify BTF data, two passes are needed.
 *
 * Pass #1
 * ~~~~~~~
 * The first pass is to collect all btf_type objects to
 * an array: "btf->types".
 *
 * Depending on the C type that a btf_type is describing,
 * a btf_type may be followed by extra data.  We don't know
 * how many btf_type is there, and more importantly we don't
 * know where each btf_type is located in the type section.
 *
 * Without knowing the location of each type_id, most verifications
 * cannot be done.  e.g. an earlier btf_type may refer to a later
 * btf_type (recall the "const void *" above), so we cannot
 * check this type-reference in the first pass.
 *
 * In the first pass, it still does some verifications (e.g.
 * checking the name is a valid offset to the string section).
 *
 * Pass #2
 * ~~~~~~~
 * The main focus is to resolve a btf_type that is referring
 * to another type.
 *
 * We have to ensure the referring type:
 * 1) does exist in the BTF (i.e. in btf->types[])
 * 2) does not cause a loop:
 *	struct A {
 *		struct B b;
 *	};
 *
 *	struct B {
 *		struct A a;
 *	};
 *
 * btf_type_needs_resolve() decides if a btf_type needs
 * to be resolved.
 *
 * The needs_resolve type implements the "resolve()" ops which
 * essentially does a DFS and detects backedge.
 *
 * During resolve (or DFS), different C types have different
 * "RESOLVED" conditions.
 *
 * When resolving a BTF_KIND_STRUCT, we need to resolve all its
 * members because a member is always referring to another
 * type.  A struct's member can be treated as "RESOLVED" if
 * it is referring to a BTF_KIND_PTR.  Otherwise, the
 * following valid C struct would be rejected:
 *
 *	struct A {
 *		int m;
 *		struct A *a;
 *	};
 *
 * When resolving a BTF_KIND_PTR, it needs to keep resolving if
 * it is referring to another BTF_KIND_PTR.  Otherwise, we cannot
 * detect a pointer loop, e.g.:
 * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
 *                        ^                                         |
 *                        +-----------------------------------------+
 *
 */

#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) \
	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))

#define BTF_INFO_MASK 0x9f00ffff
#define BTF_INT_MASK 0x0fffffff
#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)

/* 16MB for 64k structs and each has 16 members and
 * a few MB spaces for the string section.
 * The hard limit is S32_MAX.
 */
#define BTF_MAX_SIZE (16 * 1024 * 1024)

#define for_each_member_from(i, from, struct_type, member)		\
	for (i = from, member = btf_type_member(struct_type) + from;	\
	     i < btf_type_vlen(struct_type);				\
	     i++, member++)

#define for_each_vsi_from(i, from, struct_type, member)				\
	for (i = from, member = btf_type_var_secinfo(struct_type) + from;	\
	     i < btf_type_vlen(struct_type);					\
	     i++, member++)

DEFINE_IDR(btf_idr);
DEFINE_SPINLOCK(btf_idr_lock);

enum btf_kfunc_hook {
	BTF_KFUNC_HOOK_COMMON,
	BTF_KFUNC_HOOK_XDP,
	BTF_KFUNC_HOOK_TC,
	BTF_KFUNC_HOOK_STRUCT_OPS,
	BTF_KFUNC_HOOK_TRACING,
	BTF_KFUNC_HOOK_SYSCALL,
	BTF_KFUNC_HOOK_FMODRET,
	BTF_KFUNC_HOOK_CGROUP_SKB,
	BTF_KFUNC_HOOK_SCHED_ACT,
	BTF_KFUNC_HOOK_SK_SKB,
	BTF_KFUNC_HOOK_SOCKET_FILTER,
	BTF_KFUNC_HOOK_LWT,
	BTF_KFUNC_HOOK_NETFILTER,
	BTF_KFUNC_HOOK_MAX,
};

enum {
	BTF_KFUNC_SET_MAX_CNT = 256,
	BTF_DTOR_KFUNC_MAX_CNT = 256,
	BTF_KFUNC_FILTER_MAX_CNT = 16,
};

struct btf_kfunc_hook_filter {
	btf_kfunc_filter_t filters[BTF_KFUNC_FILTER_MAX_CNT];
	u32 nr_filters;
};

struct btf_kfunc_set_tab {
	struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
	struct btf_kfunc_hook_filter hook_filters[BTF_KFUNC_HOOK_MAX];
};

struct btf_id_dtor_kfunc_tab {
	u32 cnt;
	struct btf_id_dtor_kfunc dtors[];
};

struct btf {
	void *data;
	struct btf_type **types;
	u32 *resolved_ids;
	u32 *resolved_sizes;
	const char *strings;
	void *nohdr_data;
	struct btf_header hdr;
	u32 nr_types; /* includes VOID for base BTF */
	u32 types_size;
	u32 data_size;
	refcount_t refcnt;
	u32 id;
	struct rcu_head rcu;
	struct btf_kfunc_set_tab *kfunc_set_tab;
	struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;
	struct btf_struct_metas *struct_meta_tab;

	/* split BTF support */
	struct btf *base_btf;
	u32 start_id; /* first type ID in this BTF (0 for base BTF) */
	u32 start_str_off; /* first string offset (0 for base BTF) */
	char name[MODULE_NAME_LEN];
	bool kernel_btf;
};

enum verifier_phase {
	CHECK_META,
	CHECK_TYPE,
};

struct resolve_vertex {
	const struct btf_type *t;
	u32 type_id;
	u16 next_member;
};

enum visit_state {
	NOT_VISITED,
	VISITED,
	RESOLVED,
};

enum resolve_mode {
	RESOLVE_TBD,	/* To Be Determined */
	RESOLVE_PTR,	/* Resolving for Pointer */
	RESOLVE_STRUCT_OR_ARRAY,	/* Resolving for struct/union
					 * or array
					 */
};

#define MAX_RESOLVE_DEPTH 32

struct btf_sec_info {
	u32 off;
	u32 len;
};

struct btf_verifier_env {
	struct btf *btf;
	u8 *visit_states;
	struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
	struct bpf_verifier_log log;
	u32 log_type_id;
	u32 top_stack;
	enum verifier_phase phase;
	enum resolve_mode resolve_mode;
};

static const char * const btf_kind_str[NR_BTF_KINDS] = {
	[BTF_KIND_UNKN]		= "UNKNOWN",
	[BTF_KIND_INT]		= "INT",
	[BTF_KIND_PTR]		= "PTR",
	[BTF_KIND_ARRAY]	= "ARRAY",
	[BTF_KIND_STRUCT]	= "STRUCT",
	[BTF_KIND_UNION]	= "UNION",
	[BTF_KIND_ENUM]		= "ENUM",
	[BTF_KIND_FWD]		= "FWD",
	[BTF_KIND_TYPEDEF]	= "TYPEDEF",
	[BTF_KIND_VOLATILE]	= "VOLATILE",
	[BTF_KIND_CONST]	= "CONST",
	[BTF_KIND_RESTRICT]	= "RESTRICT",
	[BTF_KIND_FUNC]		= "FUNC",
	[BTF_KIND_FUNC_PROTO]	= "FUNC_PROTO",
	[BTF_KIND_VAR]		= "VAR",
	[BTF_KIND_DATASEC]	= "DATASEC",
	[BTF_KIND_FLOAT]	= "FLOAT",
	[BTF_KIND_DECL_TAG]	= "DECL_TAG",
	[BTF_KIND_TYPE_TAG]	= "TYPE_TAG",
	[BTF_KIND_ENUM64]	= "ENUM64",
};

const char *btf_type_str(const struct btf_type *t)
{
	return btf_kind_str[BTF_INFO_KIND(t->info)];
}

/* Chunk size we use in safe copy of data to be shown. */
#define BTF_SHOW_OBJ_SAFE_SIZE		32

/*
 * This is the maximum size of a base type value (equivalent to a
 * 128-bit int); if we are at the end of our safe buffer and have
 * less than 16 bytes space we can't be assured of being able
 * to copy the next type safely, so in such cases we will initiate
 * a new copy.
 */
#define BTF_SHOW_OBJ_BASE_TYPE_SIZE	16

/* Type name size */
#define BTF_SHOW_NAME_SIZE		80

/*
 * The suffix of a type that indicates it cannot alias another type when
 * comparing BTF IDs for kfunc invocations.
 */
#define NOCAST_ALIAS_SUFFIX		"___init"

/*
 * Common data to all BTF show operations. Private show functions can add
 * their own data to a structure containing a struct btf_show and consult it
 * in the show callback.  See btf_type_show() below.
 *
 * One challenge with showing nested data is we want to skip 0-valued
 * data, but in order to figure out whether a nested object is all zeros
 * we need to walk through it.  As a result, we need to make two passes
 * when handling structs, unions and arrays; the first path simply looks
 * for nonzero data, while the second actually does the display.  The first
 * pass is signalled by show->state.depth_check being set, and if we
 * encounter a non-zero value we set show->state.depth_to_show to
 * the depth at which we encountered it.  When we have completed the
 * first pass, we will know if anything needs to be displayed if
 * depth_to_show > depth.  See btf_[struct,array]_show() for the
 * implementation of this.
 *
 * Another problem is we want to ensure the data for display is safe to
 * access.  To support this, the anonymous "struct {} obj" tracks the data
 * object and our safe copy of it.  We copy portions of the data needed
 * to the object "copy" buffer, but because its size is limited to
 * BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
 * traverse larger objects for display.
 *
 * The various data type show functions all start with a call to
 * btf_show_start_type() which returns a pointer to the safe copy
 * of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
 * raw data itself).  btf_show_obj_safe() is responsible for
 * using copy_from_kernel_nofault() to update the safe data if necessary
 * as we traverse the object's data.  skbuff-like semantics are
 * used:
 *
 * - obj.head points to the start of the toplevel object for display
 * - obj.size is the size of the toplevel object
 * - obj.data points to the current point in the original data at
 *   which our safe data starts.  obj.data will advance as we copy
 *   portions of the data.
 *
 * In most cases a single copy will suffice, but larger data structures
 * such as "struct task_struct" will require many copies.  The logic in
 * btf_show_obj_safe() handles the logic that determines if a new
 * copy_from_kernel_nofault() is needed.
 */
struct btf_show {
	u64 flags;
	void *target;	/* target of show operation (seq file, buffer) */
	void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
	const struct btf *btf;
	/* below are used during iteration */
	struct {
		u8 depth;
		u8 depth_to_show;
		u8 depth_check;
		u8 array_member:1,
		   array_terminated:1;
		u16 array_encoding;
		u32 type_id;
		int status;			/* non-zero for error */
		const struct btf_type *type;
		const struct btf_member *member;
		char name[BTF_SHOW_NAME_SIZE];	/* space for member name/type */
	} state;
	struct {
		u32 size;
		void *head;
		void *data;
		u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
	} obj;
};

struct btf_kind_operations {
	s32 (*check_meta)(struct btf_verifier_env *env,
			  const struct btf_type *t,
			  u32 meta_left);
	int (*resolve)(struct btf_verifier_env *env,
		       const struct resolve_vertex *v);
	int (*check_member)(struct btf_verifier_env *env,
			    const struct btf_type *struct_type,
			    const struct btf_member *member,
			    const struct btf_type *member_type);
	int (*check_kflag_member)(struct btf_verifier_env *env,
				  const struct btf_type *struct_type,
				  const struct btf_member *member,
				  const struct btf_type *member_type);
	void (*log_details)(struct btf_verifier_env *env,
			    const struct btf_type *t);
	void (*show)(const struct btf *btf, const struct btf_type *t,
			 u32 type_id, void *data, u8 bits_offsets,
			 struct btf_show *show);
};

static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
static struct btf_type btf_void;

static int btf_resolve(struct btf_verifier_env *env,
		       const struct btf_type *t, u32 type_id);

static int btf_func_check(struct btf_verifier_env *env,
			  const struct btf_type *t);

static bool btf_type_is_modifier(const struct btf_type *t)
{
	/* Some of them is not strictly a C modifier
	 * but they are grouped into the same bucket
	 * for BTF concern:
	 *   A type (t) that refers to another
	 *   type through t->type AND its size cannot
	 *   be determined without following the t->type.
	 *
	 * ptr does not fall into this bucket
	 * because its size is always sizeof(void *).
	 */
	switch (BTF_INFO_KIND(t->info)) {
	case BTF_KIND_TYPEDEF:
	case BTF_KIND_VOLATILE:
	case BTF_KIND_CONST:
	case BTF_KIND_RESTRICT:
	case BTF_KIND_TYPE_TAG:
		return true;
	}

	return false;
}

bool btf_type_is_void(const struct btf_type *t)
{
	return t == &btf_void;
}

static bool btf_type_is_fwd(const struct btf_type *t)
{
	return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}

static bool btf_type_is_datasec(const struct btf_type *t)
{
	return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
}

static bool btf_type_is_decl_tag(const struct btf_type *t)
{
	return BTF_INFO_KIND(t->info) == BTF_KIND_DECL_TAG;
}

static bool btf_type_nosize(const struct btf_type *t)
{
	return btf_type_is_void(t) || btf_type_is_fwd(t) ||
	       btf_type_is_func(t) || btf_type_is_func_proto(t) ||
	       btf_type_is_decl_tag(t);
}

static bool btf_type_nosize_or_null(const struct btf_type *t)
{
	return !t || btf_type_nosize(t);
}

static bool btf_type_is_decl_tag_target(const struct btf_type *t)
{
	return btf_type_is_func(t) || btf_type_is_struct(t) ||
	       btf_type_is_var(t) || btf_type_is_typedef(t);
}

u32 btf_nr_types(const struct btf *btf)
{
	u32 total = 0;

	while (btf) {
		total += btf->nr_types;
		btf = btf->base_btf;
	}

	return total;
}

s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
{
	const struct btf_type *t;
	const char *tname;
	u32 i, total;

	total = btf_nr_types(btf);
	for (i = 1; i < total; i++) {
		t = btf_type_by_id(btf, i);
		if (BTF_INFO_KIND(t->info) != kind)
			continue;

		tname = btf_name_by_offset(btf, t->name_off);
		if (!strcmp(tname, name))
			return i;
	}

	return -ENOENT;
}

s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
{
	struct btf *btf;
	s32 ret;
	int id;

	btf = bpf_get_btf_vmlinux();
	if (IS_ERR(btf))
		return PTR_ERR(btf);
	if (!btf)
		return -EINVAL;

	ret = btf_find_by_name_kind(btf, name, kind);
	/* ret is never zero, since btf_find_by_name_kind returns
	 * positive btf_id or negative error.
	 */
	if (ret > 0) {
		btf_get(btf);
		*btf_p = btf;
		return ret;
	}

	/* If name is not found in vmlinux's BTF then search in module's BTFs */
	spin_lock_bh(&btf_idr_lock);
	idr_for_each_entry(&btf_idr, btf, id) {
		if (!btf_is_module(btf))
			continue;
		/* linear search could be slow hence unlock/lock
		 * the IDR to avoiding holding it for too long
		 */
		btf_get(btf);
		spin_unlock_bh(&btf_idr_lock);
		ret = btf_find_by_name_kind(btf, name, kind);
		if (ret > 0) {
			*btf_p = btf;
			return ret;
		}
		btf_put(btf);
		spin_lock_bh(&btf_idr_lock);
	}
	spin_unlock_bh(&btf_idr_lock);
	return ret;
}

const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
					       u32 id, u32 *res_id)
{
	const struct btf_type *t = btf_type_by_id(btf, id);

	while (btf_type_is_modifier(t)) {
		id = t->type;
		t = btf_type_by_id(btf, t->type);
	}

	if (res_id)
		*res_id = id;

	return t;
}

const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
					    u32 id, u32 *res_id)
{
	const struct btf_type *t;

	t = btf_type_skip_modifiers(btf, id, NULL);
	if (!btf_type_is_ptr(t))
		return NULL;

	return btf_type_skip_modifiers(btf, t->type, res_id);
}

const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
						 u32 id, u32 *res_id)
{
	const struct btf_type *ptype;

	ptype = btf_type_resolve_ptr(btf, id, res_id);
	if (ptype && btf_type_is_func_proto(ptype))
		return ptype;

	return NULL;
}

/* Types that act only as a source, not sink or intermediate
 * type when resolving.
 */
static bool btf_type_is_resolve_source_only(const struct btf_type *t)
{
	return btf_type_is_var(t) ||
	       btf_type_is_decl_tag(t) ||
	       btf_type_is_datasec(t);
}

/* What types need to be resolved?
 *
 * btf_type_is_modifier() is an obvious one.
 *
 * btf_type_is_struct() because its member refers to
 * another type (through member->type).
 *
 * btf_type_is_var() because the variable refers to
 * another type. btf_type_is_datasec() holds multiple
 * btf_type_is_var() types that need resolving.
 *
 * btf_type_is_array() because its element (array->type)
 * refers to another type.  Array can be thought of a
 * special case of struct while array just has the same
 * member-type repeated by array->nelems of times.
 */
static bool btf_type_needs_resolve(const struct btf_type *t)
{
	return btf_type_is_modifier(t) ||
	       btf_type_is_ptr(t) ||
	       btf_type_is_struct(t) ||
	       btf_type_is_array(t) ||
	       btf_type_is_var(t) ||
	       btf_type_is_func(t) ||
	       btf_type_is_decl_tag(t) ||
	       btf_type_is_datasec(t);
}

/* t->size can be used */
static bool btf_type_has_size(const struct btf_type *t)
{
	switch (BTF_INFO_KIND(t->info)) {
	case BTF_KIND_INT:
	case BTF_KIND_STRUCT:
	case BTF_KIND_UNION:
	case BTF_KIND_ENUM:
	case BTF_KIND_DATASEC:
	case BTF_KIND_FLOAT:
	case BTF_KIND_ENUM64:
		return true;
	}

	return false;
}

static const char *btf_int_encoding_str(u8 encoding)
{
	if (encoding == 0)
		return "(none)";
	else if (encoding == BTF_INT_SIGNED)
		return "SIGNED";
	else if (encoding == BTF_INT_CHAR)
		return "CHAR";
	else if (encoding == BTF_INT_BOOL)
		return "BOOL";
	else
		return "UNKN";
}

static u32 btf_type_int(const struct btf_type *t)
{
	return *(u32 *)(t + 1);
}

static const struct btf_array *btf_type_array(const struct btf_type *t)
{
	return (const struct btf_array *)(t + 1);
}

static const struct btf_enum *btf_type_enum(const struct btf_type *t)
{
	return (const struct btf_enum *)(t + 1);
}

static const struct btf_var *btf_type_var(const struct btf_type *t)
{
	return (const struct btf_var *)(t + 1);
}

static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t)
{
	return (const struct btf_decl_tag *)(t + 1);
}

static const struct btf_enum64 *btf_type_enum64(const struct btf_type *t)
{
	return (const struct btf_enum64 *)(t + 1);
}

static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
{
	return kind_ops[BTF_INFO_KIND(t->info)];
}

static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
{
	if (!BTF_STR_OFFSET_VALID(offset))
		return false;

	while (offset < btf->start_str_off)
		btf = btf->base_btf;

	offset -= btf->start_str_off;
	return offset < btf->hdr.str_len;
}

static bool __btf_name_char_ok(char c, bool first)
{
	if ((first ? !isalpha(c) :
		     !isalnum(c)) &&
	    c != '_' &&
	    c != '.')
		return false;
	return true;
}

static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
{
	while (offset < btf->start_str_off)
		btf = btf->base_btf;

	offset -= btf->start_str_off;
	if (offset < btf->hdr.str_len)
		return &btf->strings[offset];

	return NULL;
}

static bool __btf_name_valid(const struct btf *btf, u32 offset)
{
	/* offset must be valid */
	const char *src = btf_str_by_offset(btf, offset);
	const char *src_limit;

	if (!__btf_name_char_ok(*src, true))
		return false;

	/* set a limit on identifier length */
	src_limit = src + KSYM_NAME_LEN;
	src++;
	while (*src && src < src_limit) {
		if (!__btf_name_char_ok(*src, false))
			return false;
		src++;
	}

	return !*src;
}

static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
	return __btf_name_valid(btf, offset);
}

static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
	return __btf_name_valid(btf, offset);
}

static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
{
	const char *name;

	if (!offset)
		return "(anon)";

	name = btf_str_by_offset(btf, offset);
	return name ?: "(invalid-name-offset)";
}

const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
	return btf_str_by_offset(btf, offset);
}

const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
{
	while (type_id < btf->start_id)
		btf = btf->base_btf;

	type_id -= btf->start_id;
	if (type_id >= btf->nr_types)
		return NULL;
	return btf->types[type_id];
}
EXPORT_SYMBOL_GPL(btf_type_by_id);

/*
 * Regular int is not a bit field and it must be either
 * u8/u16/u32/u64 or __int128.
 */
static bool btf_type_int_is_regular(const struct btf_type *t)
{
	u8 nr_bits, nr_bytes;
	u32 int_data;

	int_data = btf_type_int(t);
	nr_bits = BTF_INT_BITS(int_data);
	nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
	if (BITS_PER_BYTE_MASKED(nr_bits) ||
	    BTF_INT_OFFSET(int_data) ||
	    (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
	     nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
	     nr_bytes != (2 * sizeof(u64)))) {
		return false;
	}

	return true;
}

/*
 * Check that given struct member is a regular int with expected
 * offset and size.
 */
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
			   const struct btf_member *m,
			   u32 expected_offset, u32 expected_size)
{
	const struct btf_type *t;
	u32 id, int_data;
	u8 nr_bits;

	id = m->type;
	t = btf_type_id_size(btf, &id, NULL);
	if (!t || !btf_type_is_int(t))
		return false;

	int_data = btf_type_int(t);
	nr_bits = BTF_INT_BITS(int_data);
	if (btf_type_kflag(s)) {
		u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
		u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);

		/* if kflag set, int should be a regular int and
		 * bit offset should be at byte boundary.
		 */
		return !bitfield_size &&
		       BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
		       BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
	}

	if (BTF_INT_OFFSET(int_data) ||
	    BITS_PER_BYTE_MASKED(m->offset) ||
	    BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
	    BITS_PER_BYTE_MASKED(nr_bits) ||
	    BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
		return false;

	return true;
}

/* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
						       u32 id)
{
	const struct btf_type *t = btf_type_by_id(btf, id);

	while (btf_type_is_modifier(t) &&
	       BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
		t = btf_type_by_id(btf, t->type);
	}

	return t;
}

#define BTF_SHOW_MAX_ITER	10

#define BTF_KIND_BIT(kind)	(1ULL << kind)

/*
 * Populate show->state.name with type name information.
 * Format of type name is
 *
 * [.member_name = ] (type_name)
 */
static const char *btf_show_name(struct btf_show *show)
{
	/* BTF_MAX_ITER array suffixes "[]" */
	const char *array_suffixes = "[][][][][][][][][][]";
	const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
	/* BTF_MAX_ITER pointer suffixes "*" */
	const char *ptr_suffixes = "**********";
	const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
	const char *name = NULL, *prefix = "", *parens = "";
	const struct btf_member *m = show->state.member;
	const struct btf_type *t;
	const struct btf_array *array;
	u32 id = show->state.type_id;
	const char *member = NULL;
	bool show_member = false;
	u64 kinds = 0;
	int i;

	show->state.name[0] = '\0';

	/*
	 * Don't show type name if we're showing an array member;
	 * in that case we show the array type so don't need to repeat
	 * ourselves for each member.
	 */
	if (show->state.array_member)
		return "";

	/* Retrieve member name, if any. */
	if (m) {
		member = btf_name_by_offset(show->btf, m->name_off);
		show_member = strlen(member) > 0;
		id = m->type;
	}

	/*
	 * Start with type_id, as we have resolved the struct btf_type *
	 * via btf_modifier_show() past the parent typedef to the child
	 * struct, int etc it is defined as.  In such cases, the type_id
	 * still represents the starting type while the struct btf_type *
	 * in our show->state points at the resolved type of the typedef.
	 */
	t = btf_type_by_id(show->btf, id);
	if (!t)
		return "";

	/*
	 * The goal here is to build up the right number of pointer and
	 * array suffixes while ensuring the type name for a typedef
	 * is represented.  Along the way we accumulate a list of
	 * BTF kinds we have encountered, since these will inform later
	 * display; for example, pointer types will not require an
	 * opening "{" for struct, we will just display the pointer value.
	 *
	 * We also want to accumulate the right number of pointer or array
	 * indices in the format string while iterating until we get to
	 * the typedef/pointee/array member target type.
	 *
	 * We start by pointing at the end of pointer and array suffix
	 * strings; as we accumulate pointers and arrays we move the pointer
	 * or array string backwards so it will show the expected number of
	 * '*' or '[]' for the type.  BTF_SHOW_MAX_ITER of nesting of pointers
	 * and/or arrays and typedefs are supported as a precaution.
	 *
	 * We also want to get typedef name while proceeding to resolve
	 * type it points to so that we can add parentheses if it is a
	 * "typedef struct" etc.
	 */
	for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {

		switch (BTF_INFO_KIND(t->info)) {
		case BTF_KIND_TYPEDEF:
			if (!name)
				name = btf_name_by_offset(show->btf,
							       t->name_off);
			kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
			id = t->type;
			break;
		case BTF_KIND_ARRAY:
			kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
			parens = "[";
			if (!t)
				return "";
			array = btf_type_array(t);
			if (array_suffix > array_suffixes)
				array_suffix -= 2;
			id = array->type;
			break;
		case BTF_KIND_PTR:
			kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
			if (ptr_suffix > ptr_suffixes)
				ptr_suffix -= 1;
			id = t->type;
			break;
		default:
			id = 0;
			break;
		}
		if (!id)
			break;
		t = btf_type_skip_qualifiers(show->btf, id);
	}
	/* We may not be able to represent this type; bail to be safe */
	if (i == BTF_SHOW_MAX_ITER)
		return "";

	if (!name)
		name = btf_name_by_offset(show->btf, t->name_off);

	switch (BTF_INFO_KIND(t->info)) {
	case BTF_KIND_STRUCT:
	case BTF_KIND_UNION:
		prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
			 "struct" : "union";
		/* if it's an array of struct/union, parens is already set */
		if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
			parens = "{";
		break;
	case BTF_KIND_ENUM:
	case BTF_KIND_ENUM64:
		prefix = "enum";
		break;
	default:
		break;
	}

	/* pointer does not require parens */
	if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
		parens = "";
	/* typedef does not require struct/union/enum prefix */
	if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
		prefix = "";

	if (!name)
		name = "";

	/* Even if we don't want type name info, we want parentheses etc */
	if (show->flags & BTF_SHOW_NONAME)
		snprintf(show->state.name, sizeof(show->state.name), "%s",
			 parens);
	else
		snprintf(show->state.name, sizeof(show->state.name),
			 "%s%s%s(%s%s%s%s%s%s)%s",
			 /* first 3 strings comprise ".member = " */
			 show_member ? "." : "",
			 show_member ? member : "",
			 show_member ? " = " : "",
			 /* ...next is our prefix (struct, enum, etc) */
			 prefix,
			 strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
			 /* ...this is the type name itself */
			 name,
			 /* ...suffixed by the appropriate '*', '[]' suffixes */
			 strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
			 array_suffix, parens);

	return show->state.name;
}

static const char *__btf_show_indent(struct btf_show *show)
{
	const char *indents = "                                ";
	const char *indent = &indents[strlen(indents)];

	if ((indent - show->state.depth) >= indents)
		return indent - show->state.depth;
	return indents;
}

static const char *btf_show_indent(struct btf_show *show)
{
	return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
}

static const char *btf_show_newline(struct btf_show *show)
{
	return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
}

static const char *btf_show_delim(struct btf_show *show)
{
	if (show->state.depth == 0)
		return "";

	if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
		BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
		return "|";

	return ",";
}

__printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
{
	va_list args;

	if (!show->state.depth_check) {
		va_start(args, fmt);
		show->showfn(show, fmt, args);
		va_end(args);
	}
}

/* Macros are used here as btf_show_type_value[s]() prepends and appends
 * format specifiers to the format specifier passed in; these do the work of
 * adding indentation, delimiters etc while the caller simply has to specify
 * the type value(s) in the format specifier + value(s).
 */
#define btf_show_type_value(show, fmt, value)				       \
	do {								       \
		if ((value) != (__typeof__(value))0 ||			       \
		    (show->flags & BTF_SHOW_ZERO) ||			       \
		    show->state.depth == 0) {				       \
			btf_show(show, "%s%s" fmt "%s%s",		       \
				 btf_show_indent(show),			       \
				 btf_show_name(show),			       \
				 value, btf_show_delim(show),		       \
				 btf_show_newline(show));		       \
			if (show->state.depth > show->state.depth_to_show)     \
				show->state.depth_to_show = show->state.depth; \
		}							       \
	} while (0)

#define btf_show_type_values(show, fmt, ...)				       \
	do {								       \
		btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show),       \
			 btf_show_name(show),				       \
			 __VA_ARGS__, btf_show_delim(show),		       \
			 btf_show_newline(show));			       \
		if (show->state.depth > show->state.depth_to_show)	       \
			show->state.depth_to_show = show->state.depth;	       \
	} while (0)

/* How much is left to copy to safe buffer after @data? */
static int btf_show_obj_size_left(struct btf_show *show, void *data)
{
	return show->obj.head + show->obj.size - data;
}

/* Is object pointed to by @data of @size already copied to our safe buffer? */
static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
{
	return data >= show->obj.data &&
	       (data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
}

/*
 * If object pointed to by @data of @size falls within our safe buffer, return
 * the equivalent pointer to the same safe data.  Assumes
 * copy_from_kernel_nofault() has already happened and our safe buffer is
 * populated.
 */
static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
{
	if (btf_show_obj_is_safe(show, data, size))
		return show->obj.safe + (data - show->obj.data);
	return NULL;
}

/*
 * Return a safe-to-access version of data pointed to by @data.
 * We do this by copying the relevant amount of information
 * to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
 *
 * If BTF_SHOW_UNSAFE is specified, just return data as-is; no
 * safe copy is needed.
 *
 * Otherwise we need to determine if we have the required amount
 * of data (determined by the @data pointer and the size of the
 * largest base type we can encounter (represented by
 * BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
 * that we will be able to print some of the current object,
 * and if more is needed a copy will be triggered.
 * Some objects such as structs will not fit into the buffer;
 * in such cases additional copies when we iterate over their
 * members may be needed.
 *
 * btf_show_obj_safe() is used to return a safe buffer for
 * btf_show_start_type(); this ensures that as we recurse into
 * nested types we always have safe data for the given type.
 * This approach is somewhat wasteful; it's possible for example
 * that when iterating over a large union we'll end up copying the
 * same data repeatedly, but the goal is safety not performance.
 * We use stack data as opposed to per-CPU buffers because the
 * iteration over a type can take some time, and preemption handling
 * would greatly complicate use of the safe buffer.
 */
static void *btf_show_obj_safe(struct btf_show *show,
			       const struct btf_type *t,
			       void *data)
{
	const struct btf_type *rt;
	int size_left, size;
	void *safe = NULL;

	if (show->flags & BTF_SHOW_UNSAFE)
		return data;

	rt = btf_resolve_size(show->btf, t, &size);
	if (IS_ERR(rt)) {
		show->state.status = PTR_ERR(rt);
		return NULL;
	}

	/*
	 * Is this toplevel object? If so, set total object size and
	 * initialize pointers.  Otherwise check if we still fall within
	 * our safe object data.
	 */
	if (show->state.depth == 0) {
		show->obj.size = size;
		show->obj.head = data;
	} else {
		/*
		 * If the size of the current object is > our remaining
		 * safe buffer we _may_ need to do a new copy.  However
		 * consider the case of a nested struct; it's size pushes
		 * us over the safe buffer limit, but showing any individual
		 * struct members does not.  In such cases, we don't need
		 * to initiate a fresh copy yet; however we definitely need
		 * at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
		 * in our buffer, regardless of the current object size.
		 * The logic here is that as we resolve types we will
		 * hit a base type at some point, and we need to be sure
		 * the next chunk of data is safely available to display
		 * that type info safely.  We cannot rely on the size of
		 * the current object here because it may be much larger
		 * than our current buffer (e.g. task_struct is 8k).
		 * All we want to do here is ensure that we can print the
		 * next basic type, which we can if either
		 * - the current type size is within the safe buffer; or
		 * - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
		 *   the safe buffer.
		 */
		safe = __btf_show_obj_safe(show, data,
					   min(size,
					       BTF_SHOW_OBJ_BASE_TYPE_SIZE));
	}

	/*
	 * We need a new copy to our safe object, either because we haven't
	 * yet copied and are initializing safe data, or because the data
	 * we want falls outside the boundaries of the safe object.
	 */
	if (!safe) {
		size_left = btf_show_obj_size_left(show, data);
		if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
			size_left = BTF_SHOW_OBJ_SAFE_SIZE;
		show->state.status = copy_from_kernel_nofault(show->obj.safe,
							      data, size_left);
		if (!show->state.status) {
			show->obj.data = data;
			safe = show->obj.safe;
		}
	}

	return safe;
}

/*
 * Set the type we are starting to show and return a safe data pointer
 * to be used for showing the associated data.
 */
static void *btf_show_start_type(struct btf_show *show,
				 const struct btf_type *t,
				 u32 type_id, void *data)
{
	show->state.type = t;
	show->state.type_id = type_id;
	show->state.name[0] = '\0';

	return btf_show_obj_safe(show, t, data);
}

static void btf_show_end_type(struct btf_show *show)
{
	show->state.type = NULL;
	show->state.type_id = 0;
	show->state.name[0] = '\0';
}

static void *btf_show_start_aggr_type(struct btf_show *show,
				      const struct btf_type *t,
				      u32 type_id, void *data)
{
	void *safe_data = btf_show_start_type(show, t, type_id, data);

	if (!safe_data)
		return safe_data;

	btf_show(show, "%s%s%s", btf_show_indent(show),
		 btf_show_name(show),
		 btf_show_newline(show));
	show->state.depth++;
	return safe_data;
}

static void btf_show_end_aggr_type(struct btf_show *show,
				   const char *suffix)
{
	show->state.depth--;
	btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
		 btf_show_delim(show), btf_show_newline(show));
	btf_show_end_type(show);
}

static void btf_show_start_member(struct btf_show *show,
				  const struct btf_member *m)
{
	show->state.member = m;
}

static void btf_show_start_array_member(struct btf_show *show)
{
	show->state.array_member = 1;
	btf_show_start_member(show, NULL);
}

static void btf_show_end_member(struct btf_show *show)
{
	show->state.member = NULL;
}

static void btf_show_end_array_member(struct btf_show *show)
{
	show->state.array_member = 0;
	btf_show_end_member(show);
}

static void *btf_show_start_array_type(struct btf_show *show,
				       const struct btf_type *t,
				       u32 type_id,
				       u16 array_encoding,
				       void *data)
{
	show->state.array_encoding = array_encoding;
	show->state.array_terminated = 0;
	return btf_show_start_aggr_type(show, t, type_id, data);
}

static void btf_show_end_array_type(struct btf_show *show)
{
	show->state.array_encoding = 0;
	show->state.array_terminated = 0;
	btf_show_end_aggr_type(show, "]");
}

static void *btf_show_start_struct_type(struct btf_show *show,
					const struct btf_type *t,
					u32 type_id,
					void *data)
{
	return btf_show_start_aggr_type(show, t, type_id, data);
}

static void btf_show_end_struct_type(struct btf_show *show)
{
	btf_show_end_aggr_type(show, "}");
}

__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
					      const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	bpf_verifier_vlog(log, fmt, args);
	va_end(args);
}

__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
					    const char *fmt, ...)
{
	struct bpf_verifier_log *log = &env->log;
	va_list args;

	if (!bpf_verifier_log_needed(log))
		return;

	va_start(args, fmt);
	bpf_verifier_vlog(log, fmt, args);
	va_end(args);
}

__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
						   const struct btf_type *t,
						   bool log_details,
						   const char *fmt, ...)
{
	struct bpf_verifier_log *log = &env->log;
	struct btf *btf = env->btf;
	va_list args;

	if (!bpf_verifier_log_needed(log))
		return;

	if (log->level == BPF_LOG_KERNEL) {
		/* btf verifier prints all types it is processing via
		 * btf_verifier_log_type(..., fmt = NULL).
		 * Skip those prints for in-kernel BTF verification.
		 */
		if (!fmt)
			return;

		/* Skip logging when loading module BTF with mismatches permitted */
		if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
			return;
	}

	__btf_verifier_log(log, "[%u] %s %s%s",
			   env->log_type_id,
			   btf_type_str(t),
			   __btf_name_by_offset(btf, t->name_off),
			   log_details ? " " : "");

	if (log_details)
		btf_type_ops(t)->log_details(env, t);

	if (fmt && *fmt) {
		__btf_verifier_log(log, " ");
		va_start(args, fmt);
		bpf_verifier_vlog(log, fmt, args);
		va_end(args);
	}

	__btf_verifier_log(log, "\n");
}

#define btf_verifier_log_type(env, t, ...) \
	__btf_verifier_log_type((env), (t), true, __VA_ARGS__)
#define btf_verifier_log_basic(env, t, ...) \
	__btf_verifier_log_type((env), (t), false, __VA_ARGS__)

__printf(4, 5)
static void btf_verifier_log_member(struct btf_verifier_env *env,
				    const struct btf_type *struct_type,
				    const struct btf_member *member,
				    const char *fmt, ...)
{
	struct bpf_verifier_log *log = &env->log;
	struct btf *btf = env->btf;
	va_list args;

	if (!bpf_verifier_log_needed(log))
		return;

	if (log->level == BPF_LOG_KERNEL) {
		if (!fmt)
			return;

		/* Skip logging when loading module BTF with mismatches permitted */
		if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
			return;
	}

	/* The CHECK_META phase already did a btf dump.
	 *
	 * If member is logged again, it must hit an error in
	 * parsing this member.  It is useful to print out which
	 * struct this member belongs to.
	 */
	if (env->phase != CHECK_META)
		btf_verifier_log_type(env, struct_type, NULL);

	if (btf_type_kflag(struct_type))
		__btf_verifier_log(log,
				   "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
				   __btf_name_by_offset(btf, member->name_off),
				   member->type,
				   BTF_MEMBER_BITFIELD_SIZE(member->offset),
				   BTF_MEMBER_BIT_OFFSET(member->offset));
	else
		__btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
				   __btf_name_by_offset(btf, member->name_off),
				   member->type, member->offset);

	if (fmt && *fmt) {
		__btf_verifier_log(log, " ");
		va_start(args, fmt);
		bpf_verifier_vlog(log, fmt, args);
		va_end(args);
	}

	__btf_verifier_log(log, "\n");
}

__printf(4, 5)
static void btf_verifier_log_vsi(struct btf_verifier_env *env,
				 const struct btf_type *datasec_type,
				 const struct btf_var_secinfo *vsi,
				 const char *fmt, ...)
{
	struct bpf_verifier_log *log = &env->log;
	va_list args;

	if (!bpf_verifier_log_needed(log))
		return;
	if (log->level == BPF_LOG_KERNEL && !fmt)
		return;
	if (env->phase != CHECK_META)
		btf_verifier_log_type(env, datasec_type, NULL);

	__btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
			   vsi->type, vsi->offset, vsi->size);
	if (fmt && *fmt) {
		__btf_verifier_log(log, " ");
		va_start(args, fmt);
		bpf_verifier_vlog(log, fmt, args);
		va_end(args);
	}

	__btf_verifier_log(log, "\n");
}

static void btf_verifier_log_hdr(struct btf_verifier_env *env,
				 u32 btf_data_size)
{
	struct bpf_verifier_log *log = &env->log;
	const struct btf *btf = env->btf;
	const struct btf_header *hdr;

	if (!bpf_verifier_log_needed(log))
		return;

	if (log->level == BPF_LOG_KERNEL)
		return;
	hdr = &btf->hdr;
	__btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
	__btf_verifier_log(log, "version: %u\n", hdr->version);
	__btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
	__btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
	__btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
	__btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
	__btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
	__btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
	__btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
}

static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
{
	struct btf *btf = env->btf;

	if (btf->types_size == btf->nr_types) {
		/* Expand 'types' array */

		struct btf_type **new_types;
		u32 expand_by, new_size;

		if (btf->start_id + btf->types_size == BTF_MAX_TYPE) {
			btf_verifier_log(env, "Exceeded max num of types");
			return -E2BIG;
		}

		expand_by = max_t(u32, btf->types_size >> 2, 16);
		new_size = min_t(u32, BTF_MAX_TYPE,
				 btf->types_size + expand_by);

		new_types = kvcalloc(new_size, sizeof(*new_types),
				     GFP_KERNEL | __GFP_NOWARN);
		if (!new_types)
			return -ENOMEM;

		if (btf->nr_types == 0) {
			if (!btf->base_btf) {
				/* lazily init VOID type */
				new_types[0] = &btf_void;
				btf->nr_types++;
			}
		} else {
			memcpy(new_types, btf->types,
			       sizeof(*btf->types) * btf->nr_types);
		}

		kvfree(btf->types);
		btf->types = new_types;
		btf->types_size = new_size;
	}

	btf->types[btf->nr_types++] = t;

	return 0;
}

static int btf_alloc_id(struct btf *btf)
{
	int id;

	idr_preload(GFP_KERNEL);
	spin_lock_bh(&btf_idr_lock);
	id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
	if (id > 0)
		btf->id = id;
	spin_unlock_bh(&btf_idr_lock);
	idr_preload_end();

	if (WARN_ON_ONCE(!id))
		return -ENOSPC;

	return id > 0 ? 0 : id;
}

static void btf_free_id(struct btf *btf)
{
	unsigned long flags;

	/*
	 * In map-in-map, calling map_delete_elem() on outer
	 * map will call bpf_map_put on the inner map.
	 * It will then eventually call btf_free_id()
	 * on the inner map.  Some of the map_delete_elem()
	 * implementation may have irq disabled, so
	 * we need to use the _irqsave() version instead
	 * of the _bh() version.
	 */
	spin_lock_irqsave(&btf_idr_lock, flags);
	idr_remove(&btf_idr, btf->id);
	spin_unlock_irqrestore(&btf_idr_lock, flags);
}

static void btf_free_kfunc_set_tab(struct btf *btf)
{
	struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
	int hook;

	if (!tab)
		return;
	/* For module BTF, we directly assign the sets being registered, so
	 * there is nothing to free except kfunc_set_tab.
	 */
	if (btf_is_module(btf))
		goto free_tab;
	for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++)
		kfree(tab->sets[hook]);
free_tab:
	kfree(tab);
	btf->kfunc_set_tab = NULL;
}

static void btf_free_dtor_kfunc_tab(struct btf *btf)
{
	struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;

	if (!tab)
		return;
	kfree(tab);
	btf->dtor_kfunc_tab = NULL;
}

static void btf_struct_metas_free(struct btf_struct_metas *tab)
{
	int i;

	if (!tab)
		return;
	for (i = 0; i < tab->cnt; i++)
		btf_record_free(tab->types[i].record);
	kfree(tab);
}

static void btf_free_struct_meta_tab(struct btf *btf)
{
	struct btf_struct_metas *tab = btf->struct_meta_tab;

	btf_struct_metas_free(tab);
	btf->struct_meta_tab = NULL;
}

static void btf_free(struct btf *btf)
{
	btf_free_struct_meta_tab(btf);
	btf_free_dtor_kfunc_tab(btf);
	btf_free_kfunc_set_tab(btf);
	kvfree(btf->types);
	kvfree(btf->resolved_sizes);
	kvfree(btf->resolved_ids);
	kvfree(btf->data);
	kfree(btf);
}

static void btf_free_rcu(struct rcu_head *rcu)
{
	struct btf *btf = container_of(rcu, struct btf, rcu);

	btf_free(btf);
}

void btf_get(struct btf *btf)
{
	refcount_inc(&btf->refcnt);
}

void btf_put(struct btf *btf)
{
	if (btf && refcount_dec_and_test(&btf->refcnt)) {
		btf_free_id(btf);
		call_rcu(&btf->rcu, btf_free_rcu);
	}
}

static int env_resolve_init(struct btf_verifier_env *env)
{
	struct btf *btf = env->btf;
	u32 nr_types = btf->nr_types;
	u32 *resolved_sizes = NULL;
	u32 *resolved_ids = NULL;
	u8 *visit_states = NULL;

	resolved_sizes = kvcalloc(nr_types, sizeof(*resolved_sizes),
				  GFP_KERNEL | __GFP_NOWARN);
	if (!resolved_sizes)
		goto nomem;

	resolved_ids = kvcalloc(nr_types, sizeof(*resolved_ids),
				GFP_KERNEL | __GFP_NOWARN);
	if (!resolved_ids)
		goto nomem;

	visit_states = kvcalloc(nr_types, sizeof(*visit_states),
				GFP_KERNEL | __GFP_NOWARN);
	if (!visit_states)
		goto nomem;

	btf->resolved_sizes = resolved_sizes;
	btf->resolved_ids = resolved_ids;
	env->visit_states = visit_states;

	return 0;

nomem:
	kvfree(resolved_sizes);
	kvfree(resolved_ids);
	kvfree(visit_states);
	return -ENOMEM;
}

static void btf_verifier_env_free(struct btf_verifier_env *env)
{
	kvfree(env->visit_states);
	kfree(env);
}

static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
				     const struct btf_type *next_type)
{
	switch (env->resolve_mode) {
	case RESOLVE_TBD:
		/* int, enum or void is a sink */
		return !btf_type_needs_resolve(next_type);
	case RESOLVE_PTR:
		/* int, enum, void, struct, array, func or func_proto is a sink
		 * for ptr
		 */
		return !btf_type_is_modifier(next_type) &&
			!btf_type_is_ptr(next_type);
	case RESOLVE_STRUCT_OR_ARRAY:
		/* int, enum, void, ptr, func or func_proto is a sink
		 * for struct and array
		 */
		return !btf_type_is_modifier(next_type) &&
			!btf_type_is_array(next_type) &&
			!btf_type_is_struct(next_type);
	default:
		BUG();
	}
}

static bool env_type_is_resolved(const struct btf_verifier_env *env,
				 u32 type_id)
{
	/* base BTF types should be resolved by now */
	if (type_id < env->btf->start_id)
		return true;

	return env->visit_states[type_id - env->btf->start_id] == RESOLVED;
}

static int env_stack_push(struct btf_verifier_env *env,
			  const struct btf_type *t, u32 type_id)
{
	const struct btf *btf = env->btf;
	struct resolve_vertex *v;

	if (env->top_stack == MAX_RESOLVE_DEPTH)
		return -E2BIG;

	if (type_id < btf->start_id
	    || env->visit_states[type_id - btf->start_id] != NOT_VISITED)
		return -EEXIST;

	env->visit_states[type_id - btf->start_id] = VISITED;

	v = &env->stack[env->top_stack++];
	v->t = t;
	v->type_id = type_id;
	v->next_member = 0;

	if (env->resolve_mode == RESOLVE_TBD) {
		if (btf_type_is_ptr(t))
			env->resolve_mode = RESOLVE_PTR;
		else if (btf_type_is_struct(t) || btf_type_is_array(t))
			env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
	}

	return 0;
}

static void env_stack_set_next_member(struct btf_verifier_env *env,
				      u16 next_member)
{
	env->stack[env->top_stack - 1].next_member = next_member;
}

static void env_stack_pop_resolved(struct btf_verifier_env *env,
				   u32 resolved_type_id,
				   u32 resolved_size)
{
	u32 type_id = env->stack[--(env->top_stack)].type_id;
	struct btf *btf = env->btf;

	type_id -= btf->start_id; /* adjust to local type id */
	btf->resolved_sizes[type_id] = resolved_size;
	btf->resolved_ids[type_id] = resolved_type_id;
	env->visit_states[type_id] = RESOLVED;
}

static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
{
	return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
}

/* Resolve the size of a passed-in "type"
 *
 * type: is an array (e.g. u32 array[x][y])
 * return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
 * *type_size: (x * y * sizeof(u32)).  Hence, *type_size always
 *             corresponds to the return type.
 * *elem_type: u32
 * *elem_id: id of u32
 * *total_nelems: (x * y).  Hence, individual elem size is
 *                (*type_size / *total_nelems)
 * *type_id: id of type if it's changed within the function, 0 if not
 *
 * type: is not an array (e.g. const struct X)
 * return type: type "struct X"
 * *type_size: sizeof(struct X)
 * *elem_type: same as return type ("struct X")
 * *elem_id: 0
 * *total_nelems: 1
 * *type_id: id of type if it's changed within the function, 0 if not
 */
static const struct btf_type *
__btf_resolve_size(const struct btf *btf, const struct btf_type *type,
		   u32 *type_size, const struct btf_type **elem_type,
		   u32 *elem_id, u32 *total_nelems, u32 *type_id)
{
	const struct btf_type *array_type = NULL;
	const struct btf_array *array = NULL;
	u32 i, size, nelems = 1, id = 0;

	for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
		switch (BTF_INFO_KIND(type->info)) {
		/* type->size can be used */
		case BTF_KIND_INT:
		case BTF_KIND_STRUCT:
		case BTF_KIND_UNION:
		case BTF_KIND_ENUM:
		case BTF_KIND_FLOAT:
		case BTF_KIND_ENUM64:
			size = type->size;
			goto resolved;

		case BTF_KIND_PTR:
			size = sizeof(void *);
			goto resolved;

		/* Modifiers */
		case BTF_KIND_TYPEDEF:
		case BTF_KIND_VOLATILE:
		case BTF_KIND_CONST:
		case BTF_KIND_RESTRICT:
		case BTF_KIND_TYPE_TAG:
			id = type->type;
			type = btf_type_by_id(btf, type->type);
			break;

		case BTF_KIND_ARRAY:
			if (!array_type)
				array_type = type;
			array = btf_type_array(type);
			if (nelems && array->nelems > U32_MAX / nelems)
				return ERR_PTR(-EINVAL);
			nelems *= array->nelems;
			type = btf_type_by_id(btf, array->type);
			break;

		/* type without size */
		default:
			return ERR_PTR(-EINVAL);
		}
	}

	return ERR_PTR(-EINVAL);

resolved:
	if (nelems && size > U32_MAX / nelems)
		return ERR_PTR(-EINVAL);

	*type_size = nelems * size;
	if (total_nelems)
		*total_nelems = nelems;
	if (elem_type)
		*elem_type = type;
	if (elem_id)
		*elem_id = array ? array->type : 0;
	if (type_id && id)
		*type_id = id;

	return array_type ? : type;
}

const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
		 u32 *type_size)
{
	return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
}

static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
{
	while (type_id < btf->start_id)
		btf = btf->base_btf;

	return btf->resolved_ids[type_id - btf->start_id];
}

/* The input param "type_id" must point to a needs_resolve type */
static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
						  u32 *type_id)
{
	*type_id = btf_resolved_type_id(btf, *type_id);
	return btf_type_by_id(btf, *type_id);
}

static u32 btf_resolved_type_size(const struct btf *btf, u32 type_id)
{
	while (type_id < btf->start_id)
		btf = btf->base_btf;

	return btf->resolved_sizes[type_id - btf->start_id];
}

const struct btf_type *btf_type_id_size(const struct btf *btf,
					u32 *type_id, u32 *ret_size)
{
	const struct btf_type *size_type;
	u32 size_type_id = *type_id;
	u32 size = 0;

	size_type = btf_type_by_id(btf, size_type_id);
	if (btf_type_nosize_or_null(size_type))
		return NULL;

	if (btf_type_has_size(size_type)) {
		size = size_type->size;
	} else if (btf_type_is_array(size_type)) {
		size = btf_resolved_type_size(btf, size_type_id);
	} else if (btf_type_is_ptr(size_type)) {
		size = sizeof(void *);
	} else {
		if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
				 !btf_type_is_var(size_type)))
			return NULL;

		size_type_id = btf_resolved_type_id(btf, size_type_id);
		size_type = btf_type_by_id(btf, size_type_id);
		if (btf_type_nosize_or_null(size_type))
			return NULL;
		else if (btf_type_has_size(size_type))
			size = size_type->size;
		else if (btf_type_is_array(size_type))
			size = btf_resolved_type_size(btf, size_type_id);
		else if (btf_type_is_ptr(size_type))
			size = sizeof(void *);
		else
			return NULL;
	}

	*type_id = size_type_id;
	if (ret_size)
		*ret_size = size;

	return size_type;
}

static int btf_df_check_member(struct btf_verifier_env *env,
			       const struct btf_type *struct_type,
			       const struct btf_member *member,
			       const struct btf_type *member_type)
{
	btf_verifier_log_basic(env, struct_type,
			       "Unsupported check_member");
	return -EINVAL;
}

static int btf_df_check_kflag_member(struct btf_verifier_env *env,
				     const struct btf_type *struct_type,
				     const struct btf_member *member,
				     const struct btf_type *member_type)
{
	btf_verifier_log_basic(env, struct_type,
			       "Unsupported check_kflag_member");
	return -EINVAL;
}

/* Used for ptr, array struct/union and float type members.
 * int, enum and modifier types have their specific callback functions.
 */
static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
					  const struct btf_type *struct_type,
					  const struct btf_member *member,
					  const struct btf_type *member_type)
{
	if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member bitfield_size");
		return -EINVAL;
	}

	/* bitfield size is 0, so member->offset represents bit offset only.
	 * It is safe to call non kflag check_member variants.
	 */
	return btf_type_ops(member_type)->check_member(env, struct_type,
						       member,
						       member_type);
}

static int btf_df_resolve(struct btf_verifier_env *env,
			  const struct resolve_vertex *v)
{
	btf_verifier_log_basic(env, v->t, "Unsupported resolve");
	return -EINVAL;
}

static void btf_df_show(const struct btf *btf, const struct btf_type *t,
			u32 type_id, void *data, u8 bits_offsets,
			struct btf_show *show)
{
	btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
}

static int btf_int_check_member(struct btf_verifier_env *env,
				const struct btf_type *struct_type,
				const struct btf_member *member,
				const struct btf_type *member_type)
{
	u32 int_data = btf_type_int(member_type);
	u32 struct_bits_off = member->offset;
	u32 struct_size = struct_type->size;
	u32 nr_copy_bits;
	u32 bytes_offset;

	if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
		btf_verifier_log_member(env, struct_type, member,
					"bits_offset exceeds U32_MAX");
		return -EINVAL;
	}

	struct_bits_off += BTF_INT_OFFSET(int_data);
	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
	nr_copy_bits = BTF_INT_BITS(int_data) +
		BITS_PER_BYTE_MASKED(struct_bits_off);

	if (nr_copy_bits > BITS_PER_U128) {
		btf_verifier_log_member(env, struct_type, member,
					"nr_copy_bits exceeds 128");
		return -EINVAL;
	}

	if (struct_size < bytes_offset ||
	    struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static int btf_int_check_kflag_member(struct btf_verifier_env *env,
				      const struct btf_type *struct_type,
				      const struct btf_member *member,
				      const struct btf_type *member_type)
{
	u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
	u32 int_data = btf_type_int(member_type);
	u32 struct_size = struct_type->size;
	u32 nr_copy_bits;

	/* a regular int type is required for the kflag int member */
	if (!btf_type_int_is_regular(member_type)) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member base type");
		return -EINVAL;
	}

	/* check sanity of bitfield size */
	nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
	struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
	nr_int_data_bits = BTF_INT_BITS(int_data);
	if (!nr_bits) {
		/* Not a bitfield member, member offset must be at byte
		 * boundary.
		 */
		if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
			btf_verifier_log_member(env, struct_type, member,
						"Invalid member offset");
			return -EINVAL;
		}

		nr_bits = nr_int_data_bits;
	} else if (nr_bits > nr_int_data_bits) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member bitfield_size");
		return -EINVAL;
	}

	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
	nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
	if (nr_copy_bits > BITS_PER_U128) {
		btf_verifier_log_member(env, struct_type, member,
					"nr_copy_bits exceeds 128");
		return -EINVAL;
	}

	if (struct_size < bytes_offset ||
	    struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static s32 btf_int_check_meta(struct btf_verifier_env *env,
			      const struct btf_type *t,
			      u32 meta_left)
{
	u32 int_data, nr_bits, meta_needed = sizeof(int_data);
	u16 encoding;

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	int_data = btf_type_int(t);
	if (int_data & ~BTF_INT_MASK) {
		btf_verifier_log_basic(env, t, "Invalid int_data:%x",
				       int_data);
		return -EINVAL;
	}

	nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);

	if (nr_bits > BITS_PER_U128) {
		btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
				      BITS_PER_U128);
		return -EINVAL;
	}

	if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
		btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
		return -EINVAL;
	}

	/*
	 * Only one of the encoding bits is allowed and it
	 * should be sufficient for the pretty print purpose (i.e. decoding).
	 * Multiple bits can be allowed later if it is found
	 * to be insufficient.
	 */
	encoding = BTF_INT_ENCODING(int_data);
	if (encoding &&
	    encoding != BTF_INT_SIGNED &&
	    encoding != BTF_INT_CHAR &&
	    encoding != BTF_INT_BOOL) {
		btf_verifier_log_type(env, t, "Unsupported encoding");
		return -ENOTSUPP;
	}

	btf_verifier_log_type(env, t, NULL);

	return meta_needed;
}

static void btf_int_log(struct btf_verifier_env *env,
			const struct btf_type *t)
{
	int int_data = btf_type_int(t);

	btf_verifier_log(env,
			 "size=%u bits_offset=%u nr_bits=%u encoding=%s",
			 t->size, BTF_INT_OFFSET(int_data),
			 BTF_INT_BITS(int_data),
			 btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
}

static void btf_int128_print(struct btf_show *show, void *data)
{
	/* data points to a __int128 number.
	 * Suppose
	 *     int128_num = *(__int128 *)data;
	 * The below formulas shows what upper_num and lower_num represents:
	 *     upper_num = int128_num >> 64;
	 *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
	 */
	u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
	upper_num = *(u64 *)data;
	lower_num = *(u64 *)(data + 8);
#else
	upper_num = *(u64 *)(data + 8);
	lower_num = *(u64 *)data;
#endif
	if (upper_num == 0)
		btf_show_type_value(show, "0x%llx", lower_num);
	else
		btf_show_type_values(show, "0x%llx%016llx", upper_num,
				     lower_num);
}

static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
			     u16 right_shift_bits)
{
	u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
	upper_num = print_num[0];
	lower_num = print_num[1];
#else
	upper_num = print_num[1];
	lower_num = print_num[0];
#endif

	/* shake out un-needed bits by shift/or operations */
	if (left_shift_bits >= 64) {
		upper_num = lower_num << (left_shift_bits - 64);
		lower_num = 0;
	} else {
		upper_num = (upper_num << left_shift_bits) |
			    (lower_num >> (64 - left_shift_bits));
		lower_num = lower_num << left_shift_bits;
	}

	if (right_shift_bits >= 64) {
		lower_num = upper_num >> (right_shift_bits - 64);
		upper_num = 0;
	} else {
		lower_num = (lower_num >> right_shift_bits) |
			    (upper_num << (64 - right_shift_bits));
		upper_num = upper_num >> right_shift_bits;
	}

#ifdef __BIG_ENDIAN_BITFIELD
	print_num[0] = upper_num;
	print_num[1] = lower_num;
#else
	print_num[0] = lower_num;
	print_num[1] = upper_num;
#endif
}

static void btf_bitfield_show(void *data, u8 bits_offset,
			      u8 nr_bits, struct btf_show *show)
{
	u16 left_shift_bits, right_shift_bits;
	u8 nr_copy_bytes;
	u8 nr_copy_bits;
	u64 print_num[2] = {};

	nr_copy_bits = nr_bits + bits_offset;
	nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);

	memcpy(print_num, data, nr_copy_bytes);

#ifdef __BIG_ENDIAN_BITFIELD
	left_shift_bits = bits_offset;
#else
	left_shift_bits = BITS_PER_U128 - nr_copy_bits;
#endif
	right_shift_bits = BITS_PER_U128 - nr_bits;

	btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
	btf_int128_print(show, print_num);
}


static void btf_int_bits_show(const struct btf *btf,
			      const struct btf_type *t,
			      void *data, u8 bits_offset,
			      struct btf_show *show)
{
	u32 int_data = btf_type_int(t);
	u8 nr_bits = BTF_INT_BITS(int_data);
	u8 total_bits_offset;

	/*
	 * bits_offset is at most 7.
	 * BTF_INT_OFFSET() cannot exceed 128 bits.
	 */
	total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
	data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
	bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
	btf_bitfield_show(data, bits_offset, nr_bits, show);
}

static void btf_int_show(const struct btf *btf, const struct btf_type *t,
			 u32 type_id, void *data, u8 bits_offset,
			 struct btf_show *show)
{
	u32 int_data = btf_type_int(t);
	u8 encoding = BTF_INT_ENCODING(int_data);
	bool sign = encoding & BTF_INT_SIGNED;
	u8 nr_bits = BTF_INT_BITS(int_data);
	void *safe_data;

	safe_data = btf_show_start_type(show, t, type_id, data);
	if (!safe_data)
		return;

	if (bits_offset || BTF_INT_OFFSET(int_data) ||
	    BITS_PER_BYTE_MASKED(nr_bits)) {
		btf_int_bits_show(btf, t, safe_data, bits_offset, show);
		goto out;
	}

	switch (nr_bits) {
	case 128:
		btf_int128_print(show, safe_data);
		break;
	case 64:
		if (sign)
			btf_show_type_value(show, "%lld", *(s64 *)safe_data);
		else
			btf_show_type_value(show, "%llu", *(u64 *)safe_data);
		break;
	case 32:
		if (sign)
			btf_show_type_value(show, "%d", *(s32 *)safe_data);
		else
			btf_show_type_value(show, "%u", *(u32 *)safe_data);
		break;
	case 16:
		if (sign)
			btf_show_type_value(show, "%d", *(s16 *)safe_data);
		else
			btf_show_type_value(show, "%u", *(u16 *)safe_data);
		break;
	case 8:
		if (show->state.array_encoding == BTF_INT_CHAR) {
			/* check for null terminator */
			if (show->state.array_terminated)
				break;
			if (*(char *)data == '\0') {
				show->state.array_terminated = 1;
				break;
			}
			if (isprint(*(char *)data)) {
				btf_show_type_value(show, "'%c'",
						    *(char *)safe_data);
				break;
			}
		}
		if (sign)
			btf_show_type_value(show, "%d", *(s8 *)safe_data);
		else
			btf_show_type_value(show, "%u", *(u8 *)safe_data);
		break;
	default:
		btf_int_bits_show(btf, t, safe_data, bits_offset, show);
		break;
	}
out:
	btf_show_end_type(show);
}

static const struct btf_kind_operations int_ops = {
	.check_meta = btf_int_check_meta,
	.resolve = btf_df_resolve,
	.check_member = btf_int_check_member,
	.check_kflag_member = btf_int_check_kflag_member,
	.log_details = btf_int_log,
	.show = btf_int_show,
};

static int btf_modifier_check_member(struct btf_verifier_env *env,
				     const struct btf_type *struct_type,
				     const struct btf_member *member,
				     const struct btf_type *member_type)
{
	const struct btf_type *resolved_type;
	u32 resolved_type_id = member->type;
	struct btf_member resolved_member;
	struct btf *btf = env->btf;

	resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
	if (!resolved_type) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member");
		return -EINVAL;
	}

	resolved_member = *member;
	resolved_member.type = resolved_type_id;

	return btf_type_ops(resolved_type)->check_member(env, struct_type,
							 &resolved_member,
							 resolved_type);
}

static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
					   const struct btf_type *struct_type,
					   const struct btf_member *member,
					   const struct btf_type *member_type)
{
	const struct btf_type *resolved_type;
	u32 resolved_type_id = member->type;
	struct btf_member resolved_member;
	struct btf *btf = env->btf;

	resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
	if (!resolved_type) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member");
		return -EINVAL;
	}

	resolved_member = *member;
	resolved_member.type = resolved_type_id;

	return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
							       &resolved_member,
							       resolved_type);
}

static int btf_ptr_check_member(struct btf_verifier_env *env,
				const struct btf_type *struct_type,
				const struct btf_member *member,
				const struct btf_type *member_type)
{
	u32 struct_size, struct_bits_off, bytes_offset;

	struct_size = struct_type->size;
	struct_bits_off = member->offset;
	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);

	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member is not byte aligned");
		return -EINVAL;
	}

	if (struct_size - bytes_offset < sizeof(void *)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static int btf_ref_type_check_meta(struct btf_verifier_env *env,
				   const struct btf_type *t,
				   u32 meta_left)
{
	const char *value;

	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	if (!BTF_TYPE_ID_VALID(t->type)) {
		btf_verifier_log_type(env, t, "Invalid type_id");
		return -EINVAL;
	}

	/* typedef/type_tag type must have a valid name, and other ref types,
	 * volatile, const, restrict, should have a null name.
	 */
	if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
		if (!t->name_off ||
		    !btf_name_valid_identifier(env->btf, t->name_off)) {
			btf_verifier_log_type(env, t, "Invalid name");
			return -EINVAL;
		}
	} else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
		value = btf_name_by_offset(env->btf, t->name_off);
		if (!value || !value[0]) {
			btf_verifier_log_type(env, t, "Invalid name");
			return -EINVAL;
		}
	} else {
		if (t->name_off) {
			btf_verifier_log_type(env, t, "Invalid name");
			return -EINVAL;
		}
	}

	btf_verifier_log_type(env, t, NULL);

	return 0;
}

static int btf_modifier_resolve(struct btf_verifier_env *env,
				const struct resolve_vertex *v)
{
	const struct btf_type *t = v->t;
	const struct btf_type *next_type;
	u32 next_type_id = t->type;
	struct btf *btf = env->btf;

	next_type = btf_type_by_id(btf, next_type_id);
	if (!next_type || btf_type_is_resolve_source_only(next_type)) {
		btf_verifier_log_type(env, v->t, "Invalid type_id");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, next_type) &&
	    !env_type_is_resolved(env, next_type_id))
		return env_stack_push(env, next_type, next_type_id);

	/* Figure out the resolved next_type_id with size.
	 * They will be stored in the current modifier's
	 * resolved_ids and resolved_sizes such that it can
	 * save us a few type-following when we use it later (e.g. in
	 * pretty print).
	 */
	if (!btf_type_id_size(btf, &next_type_id, NULL)) {
		if (env_type_is_resolved(env, next_type_id))
			next_type = btf_type_id_resolve(btf, &next_type_id);

		/* "typedef void new_void", "const void"...etc */
		if (!btf_type_is_void(next_type) &&
		    !btf_type_is_fwd(next_type) &&
		    !btf_type_is_func_proto(next_type)) {
			btf_verifier_log_type(env, v->t, "Invalid type_id");
			return -EINVAL;
		}
	}

	env_stack_pop_resolved(env, next_type_id, 0);

	return 0;
}

static int btf_var_resolve(struct btf_verifier_env *env,
			   const struct resolve_vertex *v)
{
	const struct btf_type *next_type;
	const struct btf_type *t = v->t;
	u32 next_type_id = t->type;
	struct btf *btf = env->btf;

	next_type = btf_type_by_id(btf, next_type_id);
	if (!next_type || btf_type_is_resolve_source_only(next_type)) {
		btf_verifier_log_type(env, v->t, "Invalid type_id");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, next_type) &&
	    !env_type_is_resolved(env, next_type_id))
		return env_stack_push(env, next_type, next_type_id);

	if (btf_type_is_modifier(next_type)) {
		const struct btf_type *resolved_type;
		u32 resolved_type_id;

		resolved_type_id = next_type_id;
		resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

		if (btf_type_is_ptr(resolved_type) &&
		    !env_type_is_resolve_sink(env, resolved_type) &&
		    !env_type_is_resolved(env, resolved_type_id))
			return env_stack_push(env, resolved_type,
					      resolved_type_id);
	}

	/* We must resolve to something concrete at this point, no
	 * forward types or similar that would resolve to size of
	 * zero is allowed.
	 */
	if (!btf_type_id_size(btf, &next_type_id, NULL)) {
		btf_verifier_log_type(env, v->t, "Invalid type_id");
		return -EINVAL;
	}

	env_stack_pop_resolved(env, next_type_id, 0);

	return 0;
}

static int btf_ptr_resolve(struct btf_verifier_env *env,
			   const struct resolve_vertex *v)
{
	const struct btf_type *next_type;
	const struct btf_type *t = v->t;
	u32 next_type_id = t->type;
	struct btf *btf = env->btf;

	next_type = btf_type_by_id(btf, next_type_id);
	if (!next_type || btf_type_is_resolve_source_only(next_type)) {
		btf_verifier_log_type(env, v->t, "Invalid type_id");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, next_type) &&
	    !env_type_is_resolved(env, next_type_id))
		return env_stack_push(env, next_type, next_type_id);

	/* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
	 * the modifier may have stopped resolving when it was resolved
	 * to a ptr (last-resolved-ptr).
	 *
	 * We now need to continue from the last-resolved-ptr to
	 * ensure the last-resolved-ptr will not referring back to
	 * the current ptr (t).
	 */
	if (btf_type_is_modifier(next_type)) {
		const struct btf_type *resolved_type;
		u32 resolved_type_id;

		resolved_type_id = next_type_id;
		resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

		if (btf_type_is_ptr(resolved_type) &&
		    !env_type_is_resolve_sink(env, resolved_type) &&
		    !env_type_is_resolved(env, resolved_type_id))
			return env_stack_push(env, resolved_type,
					      resolved_type_id);
	}

	if (!btf_type_id_size(btf, &next_type_id, NULL)) {
		if (env_type_is_resolved(env, next_type_id))
			next_type = btf_type_id_resolve(btf, &next_type_id);

		if (!btf_type_is_void(next_type) &&
		    !btf_type_is_fwd(next_type) &&
		    !btf_type_is_func_proto(next_type)) {
			btf_verifier_log_type(env, v->t, "Invalid type_id");
			return -EINVAL;
		}
	}

	env_stack_pop_resolved(env, next_type_id, 0);

	return 0;
}

static void btf_modifier_show(const struct btf *btf,
			      const struct btf_type *t,
			      u32 type_id, void *data,
			      u8 bits_offset, struct btf_show *show)
{
	if (btf->resolved_ids)
		t = btf_type_id_resolve(btf, &type_id);
	else
		t = btf_type_skip_modifiers(btf, type_id, NULL);

	btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}

static void btf_var_show(const struct btf *btf, const struct btf_type *t,
			 u32 type_id, void *data, u8 bits_offset,
			 struct btf_show *show)
{
	t = btf_type_id_resolve(btf, &type_id);

	btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}

static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
			 u32 type_id, void *data, u8 bits_offset,
			 struct btf_show *show)
{
	void *safe_data;

	safe_data = btf_show_start_type(show, t, type_id, data);
	if (!safe_data)
		return;

	/* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
	if (show->flags & BTF_SHOW_PTR_RAW)
		btf_show_type_value(show, "0x%px", *(void **)safe_data);
	else
		btf_show_type_value(show, "0x%p", *(void **)safe_data);
	btf_show_end_type(show);
}

static void btf_ref_type_log(struct btf_verifier_env *env,
			     const struct btf_type *t)
{
	btf_verifier_log(env, "type_id=%u", t->type);
}

static struct btf_kind_operations modifier_ops = {
	.check_meta = btf_ref_type_check_meta,
	.resolve = btf_modifier_resolve,
	.check_member = btf_modifier_check_member,
	.check_kflag_member = btf_modifier_check_kflag_member,
	.log_details = btf_ref_type_log,
	.show = btf_modifier_show,
};

static struct btf_kind_operations ptr_ops = {
	.check_meta = btf_ref_type_check_meta,
	.resolve = btf_ptr_resolve,
	.check_member = btf_ptr_check_member,
	.check_kflag_member = btf_generic_check_kflag_member,
	.log_details = btf_ref_type_log,
	.show = btf_ptr_show,
};

static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
			      const struct btf_type *t,
			      u32 meta_left)
{
	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (t->type) {
		btf_verifier_log_type(env, t, "type != 0");
		return -EINVAL;
	}

	/* fwd type must have a valid name */
	if (!t->name_off ||
	    !btf_name_valid_identifier(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return 0;
}

static void btf_fwd_type_log(struct btf_verifier_env *env,
			     const struct btf_type *t)
{
	btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}

static struct btf_kind_operations fwd_ops = {
	.check_meta = btf_fwd_check_meta,
	.resolve = btf_df_resolve,
	.check_member = btf_df_check_member,
	.check_kflag_member = btf_df_check_kflag_member,
	.log_details = btf_fwd_type_log,
	.show = btf_df_show,
};

static int btf_array_check_member(struct btf_verifier_env *env,
				  const struct btf_type *struct_type,
				  const struct btf_member *member,
				  const struct btf_type *member_type)
{
	u32 struct_bits_off = member->offset;
	u32 struct_size, bytes_offset;
	u32 array_type_id, array_size;
	struct btf *btf = env->btf;

	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member is not byte aligned");
		return -EINVAL;
	}

	array_type_id = member->type;
	btf_type_id_size(btf, &array_type_id, &array_size);
	struct_size = struct_type->size;
	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
	if (struct_size - bytes_offset < array_size) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static s32 btf_array_check_meta(struct btf_verifier_env *env,
				const struct btf_type *t,
				u32 meta_left)
{
	const struct btf_array *array = btf_type_array(t);
	u32 meta_needed = sizeof(*array);

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	/* array type should not have a name */
	if (t->name_off) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	if (t->size) {
		btf_verifier_log_type(env, t, "size != 0");
		return -EINVAL;
	}

	/* Array elem type and index type cannot be in type void,
	 * so !array->type and !array->index_type are not allowed.
	 */
	if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
		btf_verifier_log_type(env, t, "Invalid elem");
		return -EINVAL;
	}

	if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
		btf_verifier_log_type(env, t, "Invalid index");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return meta_needed;
}

static int btf_array_resolve(struct btf_verifier_env *env,
			     const struct resolve_vertex *v)
{
	const struct btf_array *array = btf_type_array(v->t);
	const struct btf_type *elem_type, *index_type;
	u32 elem_type_id, index_type_id;
	struct btf *btf = env->btf;
	u32 elem_size;

	/* Check array->index_type */
	index_type_id = array->index_type;
	index_type = btf_type_by_id(btf, index_type_id);
	if (btf_type_nosize_or_null(index_type) ||
	    btf_type_is_resolve_source_only(index_type)) {
		btf_verifier_log_type(env, v->t, "Invalid index");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, index_type) &&
	    !env_type_is_resolved(env, index_type_id))
		return env_stack_push(env, index_type, index_type_id);

	index_type = btf_type_id_size(btf, &index_type_id, NULL);
	if (!index_type || !btf_type_is_int(index_type) ||
	    !btf_type_int_is_regular(index_type)) {
		btf_verifier_log_type(env, v->t, "Invalid index");
		return -EINVAL;
	}

	/* Check array->type */
	elem_type_id = array->type;
	elem_type = btf_type_by_id(btf, elem_type_id);
	if (btf_type_nosize_or_null(elem_type) ||
	    btf_type_is_resolve_source_only(elem_type)) {
		btf_verifier_log_type(env, v->t,
				      "Invalid elem");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, elem_type) &&
	    !env_type_is_resolved(env, elem_type_id))
		return env_stack_push(env, elem_type, elem_type_id);

	elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
	if (!elem_type) {
		btf_verifier_log_type(env, v->t, "Invalid elem");
		return -EINVAL;
	}

	if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
		btf_verifier_log_type(env, v->t, "Invalid array of int");
		return -EINVAL;
	}

	if (array->nelems && elem_size > U32_MAX / array->nelems) {
		btf_verifier_log_type(env, v->t,
				      "Array size overflows U32_MAX");
		return -EINVAL;
	}

	env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);

	return 0;
}

static void btf_array_log(struct btf_verifier_env *env,
			  const struct btf_type *t)
{
	const struct btf_array *array = btf_type_array(t);

	btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
			 array->type, array->index_type, array->nelems);
}

static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
			     u32 type_id, void *data, u8 bits_offset,
			     struct btf_show *show)
{
	const struct btf_array *array = btf_type_array(t);
	const struct btf_kind_operations *elem_ops;
	const struct btf_type *elem_type;
	u32 i, elem_size = 0, elem_type_id;
	u16 encoding = 0;

	elem_type_id = array->type;
	elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
	if (elem_type && btf_type_has_size(elem_type))
		elem_size = elem_type->size;

	if (elem_type && btf_type_is_int(elem_type)) {
		u32 int_type = btf_type_int(elem_type);

		encoding = BTF_INT_ENCODING(int_type);

		/*
		 * BTF_INT_CHAR encoding never seems to be set for
		 * char arrays, so if size is 1 and element is
		 * printable as a char, we'll do that.
		 */
		if (elem_size == 1)
			encoding = BTF_INT_CHAR;
	}

	if (!btf_show_start_array_type(show, t, type_id, encoding, data))
		return;

	if (!elem_type)
		goto out;
	elem_ops = btf_type_ops(elem_type);

	for (i = 0; i < array->nelems; i++) {

		btf_show_start_array_member(show);

		elem_ops->show(btf, elem_type, elem_type_id, data,
			       bits_offset, show);
		data += elem_size;

		btf_show_end_array_member(show);

		if (show->state.array_terminated)
			break;
	}
out:
	btf_show_end_array_type(show);
}

static void btf_array_show(const struct btf *btf, const struct btf_type *t,
			   u32 type_id, void *data, u8 bits_offset,
			   struct btf_show *show)
{
	const struct btf_member *m = show->state.member;

	/*
	 * First check if any members would be shown (are non-zero).
	 * See comments above "struct btf_show" definition for more
	 * details on how this works at a high-level.
	 */
	if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
		if (!show->state.depth_check) {
			show->state.depth_check = show->state.depth + 1;
			show->state.depth_to_show = 0;
		}
		__btf_array_show(btf, t, type_id, data, bits_offset, show);
		show->state.member = m;

		if (show->state.depth_check != show->state.depth + 1)
			return;
		show->state.depth_check = 0;

		if (show->state.depth_to_show <= show->state.depth)
			return;
		/*
		 * Reaching here indicates we have recursed and found
		 * non-zero array member(s).
		 */
	}
	__btf_array_show(btf, t, type_id, data, bits_offset, show);
}

static struct btf_kind_operations array_ops = {
	.check_meta = btf_array_check_meta,
	.resolve = btf_array_resolve,
	.check_member = btf_array_check_member,
	.check_kflag_member = btf_generic_check_kflag_member,
	.log_details = btf_array_log,
	.show = btf_array_show,
};

static int btf_struct_check_member(struct btf_verifier_env *env,
				   const struct btf_type *struct_type,
				   const struct btf_member *member,
				   const struct btf_type *member_type)
{
	u32 struct_bits_off = member->offset;
	u32 struct_size, bytes_offset;

	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member is not byte aligned");
		return -EINVAL;
	}

	struct_size = struct_type->size;
	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
	if (struct_size - bytes_offset < member_type->size) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static s32 btf_struct_check_meta(struct btf_verifier_env *env,
				 const struct btf_type *t,
				 u32 meta_left)
{
	bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
	const struct btf_member *member;
	u32 meta_needed, last_offset;
	struct btf *btf = env->btf;
	u32 struct_size = t->size;
	u32 offset;
	u16 i;

	meta_needed = btf_type_vlen(t) * sizeof(*member);
	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	/* struct type either no name or a valid one */
	if (t->name_off &&
	    !btf_name_valid_identifier(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	last_offset = 0;
	for_each_member(i, t, member) {
		if (!btf_name_offset_valid(btf, member->name_off)) {
			btf_verifier_log_member(env, t, member,
						"Invalid member name_offset:%u",
						member->name_off);
			return -EINVAL;
		}

		/* struct member either no name or a valid one */
		if (member->name_off &&
		    !btf_name_valid_identifier(btf, member->name_off)) {
			btf_verifier_log_member(env, t, member, "Invalid name");
			return -EINVAL;
		}
		/* A member cannot be in type void */
		if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
			btf_verifier_log_member(env, t, member,
						"Invalid type_id");
			return -EINVAL;
		}

		offset = __btf_member_bit_offset(t, member);
		if (is_union && offset) {
			btf_verifier_log_member(env, t, member,
						"Invalid member bits_offset");
			return -EINVAL;
		}

		/*
		 * ">" instead of ">=" because the last member could be
		 * "char a[0];"
		 */
		if (last_offset > offset) {
			btf_verifier_log_member(env, t, member,
						"Invalid member bits_offset");
			return -EINVAL;
		}

		if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
			btf_verifier_log_member(env, t, member,
						"Member bits_offset exceeds its struct size");
			return -EINVAL;
		}

		btf_verifier_log_member(env, t, member, NULL);
		last_offset = offset;
	}

	return meta_needed;
}

static int btf_struct_resolve(struct btf_verifier_env *env,
			      const struct resolve_vertex *v)
{
	const struct btf_member *member;
	int err;
	u16 i;

	/* Before continue resolving the next_member,
	 * ensure the last member is indeed resolved to a
	 * type with size info.
	 */
	if (v->next_member) {
		const struct btf_type *last_member_type;
		const struct btf_member *last_member;
		u32 last_member_type_id;

		last_member = btf_type_member(v->t) + v->next_member - 1;
		last_member_type_id = last_member->type;
		if (WARN_ON_ONCE(!env_type_is_resolved(env,
						       last_member_type_id)))
			return -EINVAL;

		last_member_type = btf_type_by_id(env->btf,
						  last_member_type_id);
		if (btf_type_kflag(v->t))
			err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
								last_member,
								last_member_type);
		else
			err = btf_type_ops(last_member_type)->check_member(env, v->t,
								last_member,
								last_member_type);
		if (err)
			return err;
	}

	for_each_member_from(i, v->next_member, v->t, member) {
		u32 member_type_id = member->type;
		const struct btf_type *member_type = btf_type_by_id(env->btf,
								member_type_id);

		if (btf_type_nosize_or_null(member_type) ||
		    btf_type_is_resolve_source_only(member_type)) {
			btf_verifier_log_member(env, v->t, member,
						"Invalid member");
			return -EINVAL;
		}

		if (!env_type_is_resolve_sink(env, member_type) &&
		    !env_type_is_resolved(env, member_type_id)) {
			env_stack_set_next_member(env, i + 1);
			return env_stack_push(env, member_type, member_type_id);
		}

		if (btf_type_kflag(v->t))
			err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
									    member,
									    member_type);
		else
			err = btf_type_ops(member_type)->check_member(env, v->t,
								      member,
								      member_type);
		if (err)
			return err;
	}

	env_stack_pop_resolved(env, 0, 0);

	return 0;
}

static void btf_struct_log(struct btf_verifier_env *env,
			   const struct btf_type *t)
{
	btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

enum {
	BTF_FIELD_IGNORE = 0,
	BTF_FIELD_FOUND  = 1,
};

struct btf_field_info {
	enum btf_field_type type;
	u32 off;
	union {
		struct {
			u32 type_id;
		} kptr;
		struct {
			const char *node_name;
			u32 value_btf_id;
		} graph_root;
	};
};

static int btf_find_struct(const struct btf *btf, const struct btf_type *t,
			   u32 off, int sz, enum btf_field_type field_type,
			   struct btf_field_info *info)
{
	if (!__btf_type_is_struct(t))
		return BTF_FIELD_IGNORE;
	if (t->size != sz)
		return BTF_FIELD_IGNORE;
	info->type = field_type;
	info->off = off;
	return BTF_FIELD_FOUND;
}

static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
			 u32 off, int sz, struct btf_field_info *info)
{
	enum btf_field_type type;
	u32 res_id;

	/* Permit modifiers on the pointer itself */
	if (btf_type_is_volatile(t))
		t = btf_type_by_id(btf, t->type);
	/* For PTR, sz is always == 8 */
	if (!btf_type_is_ptr(t))
		return BTF_FIELD_IGNORE;
	t = btf_type_by_id(btf, t->type);

	if (!btf_type_is_type_tag(t))
		return BTF_FIELD_IGNORE;
	/* Reject extra tags */
	if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
		return -EINVAL;
	if (!strcmp("kptr_untrusted", __btf_name_by_offset(btf, t->name_off)))
		type = BPF_KPTR_UNREF;
	else if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
		type = BPF_KPTR_REF;
	else
		return -EINVAL;

	/* Get the base type */
	t = btf_type_skip_modifiers(btf, t->type, &res_id);
	/* Only pointer to struct is allowed */
	if (!__btf_type_is_struct(t))
		return -EINVAL;

	info->type = type;
	info->off = off;
	info->kptr.type_id = res_id;
	return BTF_FIELD_FOUND;
}

static const char *btf_find_decl_tag_value(const struct btf *btf,
					   const struct btf_type *pt,
					   int comp_idx, const char *tag_key)
{
	int i;

	for (i = 1; i < btf_nr_types(btf); i++) {
		const struct btf_type *t = btf_type_by_id(btf, i);
		int len = strlen(tag_key);

		if (!btf_type_is_decl_tag(t))
			continue;
		if (pt != btf_type_by_id(btf, t->type) ||
		    btf_type_decl_tag(t)->component_idx != comp_idx)
			continue;
		if (strncmp(__btf_name_by_offset(btf, t->name_off), tag_key, len))
			continue;
		return __btf_name_by_offset(btf, t->name_off) + len;
	}
	return NULL;
}

static int
btf_find_graph_root(const struct btf *btf, const struct btf_type *pt,
		    const struct btf_type *t, int comp_idx, u32 off,
		    int sz, struct btf_field_info *info,
		    enum btf_field_type head_type)
{
	const char *node_field_name;
	const char *value_type;
	s32 id;

	if (!__btf_type_is_struct(t))
		return BTF_FIELD_IGNORE;
	if (t->size != sz)
		return BTF_FIELD_IGNORE;
	value_type = btf_find_decl_tag_value(btf, pt, comp_idx, "contains:");
	if (!value_type)
		return -EINVAL;
	node_field_name = strstr(value_type, ":");
	if (!node_field_name)
		return -EINVAL;
	value_type = kstrndup(value_type, node_field_name - value_type, GFP_KERNEL | __GFP_NOWARN);
	if (!value_type)
		return -ENOMEM;
	id = btf_find_by_name_kind(btf, value_type, BTF_KIND_STRUCT);
	kfree(value_type);
	if (id < 0)
		return id;
	node_field_name++;
	if (str_is_empty(node_field_name))
		return -EINVAL;
	info->type = head_type;
	info->off = off;
	info->graph_root.value_btf_id = id;
	info->graph_root.node_name = node_field_name;
	return BTF_FIELD_FOUND;
}

#define field_mask_test_name(field_type, field_type_str) \
	if (field_mask & field_type && !strcmp(name, field_type_str)) { \
		type = field_type;					\
		goto end;						\
	}

static int btf_get_field_type(const char *name, u32 field_mask, u32 *seen_mask,
			      int *align, int *sz)
{
	int type = 0;

	if (field_mask & BPF_SPIN_LOCK) {
		if (!strcmp(name, "bpf_spin_lock")) {
			if (*seen_mask & BPF_SPIN_LOCK)
				return -E2BIG;
			*seen_mask |= BPF_SPIN_LOCK;
			type = BPF_SPIN_LOCK;
			goto end;
		}
	}
	if (field_mask & BPF_TIMER) {
		if (!strcmp(name, "bpf_timer")) {
			if (*seen_mask & BPF_TIMER)
				return -E2BIG;
			*seen_mask |= BPF_TIMER;
			type = BPF_TIMER;
			goto end;
		}
	}
	field_mask_test_name(BPF_LIST_HEAD, "bpf_list_head");
	field_mask_test_name(BPF_LIST_NODE, "bpf_list_node");
	field_mask_test_name(BPF_RB_ROOT,   "bpf_rb_root");
	field_mask_test_name(BPF_RB_NODE,   "bpf_rb_node");
	field_mask_test_name(BPF_REFCOUNT,  "bpf_refcount");

	/* Only return BPF_KPTR when all other types with matchable names fail */
	if (field_mask & BPF_KPTR) {
		type = BPF_KPTR_REF;
		goto end;
	}
	return 0;
end:
	*sz = btf_field_type_size(type);
	*align = btf_field_type_align(type);
	return type;
}

#undef field_mask_test_name

static int btf_find_struct_field(const struct btf *btf,
				 const struct btf_type *t, u32 field_mask,
				 struct btf_field_info *info, int info_cnt)
{
	int ret, idx = 0, align, sz, field_type;
	const struct btf_member *member;
	struct btf_field_info tmp;
	u32 i, off, seen_mask = 0;

	for_each_member(i, t, member) {
		const struct btf_type *member_type = btf_type_by_id(btf,
								    member->type);

		field_type = btf_get_field_type(__btf_name_by_offset(btf, member_type->name_off),
						field_mask, &seen_mask, &align, &sz);
		if (field_type == 0)
			continue;
		if (field_type < 0)
			return field_type;

		off = __btf_member_bit_offset(t, member);
		if (off % 8)
			/* valid C code cannot generate such BTF */
			return -EINVAL;
		off /= 8;
		if (off % align)
			continue;

		switch (field_type) {
		case BPF_SPIN_LOCK:
		case BPF_TIMER:
		case BPF_LIST_NODE:
		case BPF_RB_NODE:
		case BPF_REFCOUNT:
			ret = btf_find_struct(btf, member_type, off, sz, field_type,
					      idx < info_cnt ? &info[idx] : &tmp);
			if (ret < 0)
				return ret;
			break;
		case BPF_KPTR_UNREF:
		case BPF_KPTR_REF:
			ret = btf_find_kptr(btf, member_type, off, sz,
					    idx < info_cnt ? &info[idx] : &tmp);
			if (ret < 0)
				return ret;
			break;
		case BPF_LIST_HEAD:
		case BPF_RB_ROOT:
			ret = btf_find_graph_root(btf, t, member_type,
						  i, off, sz,
						  idx < info_cnt ? &info[idx] : &tmp,
						  field_type);
			if (ret < 0)
				return ret;
			break;
		default:
			return -EFAULT;
		}

		if (ret == BTF_FIELD_IGNORE)
			continue;
		if (idx >= info_cnt)
			return -E2BIG;
		++idx;
	}
	return idx;
}

static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
				u32 field_mask, struct btf_field_info *info,
				int info_cnt)
{
	int ret, idx = 0, align, sz, field_type;
	const struct btf_var_secinfo *vsi;
	struct btf_field_info tmp;
	u32 i, off, seen_mask = 0;

	for_each_vsi(i, t, vsi) {
		const struct btf_type *var = btf_type_by_id(btf, vsi->type);
		const struct btf_type *var_type = btf_type_by_id(btf, var->type);

		field_type = btf_get_field_type(__btf_name_by_offset(btf, var_type->name_off),
						field_mask, &seen_mask, &align, &sz);
		if (field_type == 0)
			continue;
		if (field_type < 0)
			return field_type;

		off = vsi->offset;
		if (vsi->size != sz)
			continue;
		if (off % align)
			continue;

		switch (field_type) {
		case BPF_SPIN_LOCK:
		case BPF_TIMER:
		case BPF_LIST_NODE:
		case BPF_RB_NODE:
		case BPF_REFCOUNT:
			ret = btf_find_struct(btf, var_type, off, sz, field_type,
					      idx < info_cnt ? &info[idx] : &tmp);
			if (ret < 0)
				return ret;
			break;
		case BPF_KPTR_UNREF:
		case BPF_KPTR_REF:
			ret = btf_find_kptr(btf, var_type, off, sz,
					    idx < info_cnt ? &info[idx] : &tmp);
			if (ret < 0)
				return ret;
			break;
		case BPF_LIST_HEAD:
		case BPF_RB_ROOT:
			ret = btf_find_graph_root(btf, var, var_type,
						  -1, off, sz,
						  idx < info_cnt ? &info[idx] : &tmp,
						  field_type);
			if (ret < 0)
				return ret;
			break;
		default:
			return -EFAULT;
		}

		if (ret == BTF_FIELD_IGNORE)
			continue;
		if (idx >= info_cnt)
			return -E2BIG;
		++idx;
	}
	return idx;
}

static int btf_find_field(const struct btf *btf, const struct btf_type *t,
			  u32 field_mask, struct btf_field_info *info,
			  int info_cnt)
{
	if (__btf_type_is_struct(t))
		return btf_find_struct_field(btf, t, field_mask, info, info_cnt);
	else if (btf_type_is_datasec(t))
		return btf_find_datasec_var(btf, t, field_mask, info, info_cnt);
	return -EINVAL;
}

static int btf_parse_kptr(const struct btf *btf, struct btf_field *field,
			  struct btf_field_info *info)
{
	struct module *mod = NULL;
	const struct btf_type *t;
	/* If a matching btf type is found in kernel or module BTFs, kptr_ref
	 * is that BTF, otherwise it's program BTF
	 */
	struct btf *kptr_btf;
	int ret;
	s32 id;

	/* Find type in map BTF, and use it to look up the matching type
	 * in vmlinux or module BTFs, by name and kind.
	 */
	t = btf_type_by_id(btf, info->kptr.type_id);
	id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info),
			     &kptr_btf);
	if (id == -ENOENT) {
		/* btf_parse_kptr should only be called w/ btf = program BTF */
		WARN_ON_ONCE(btf_is_kernel(btf));

		/* Type exists only in program BTF. Assume that it's a MEM_ALLOC
		 * kptr allocated via bpf_obj_new
		 */
		field->kptr.dtor = NULL;
		id = info->kptr.type_id;
		kptr_btf = (struct btf *)btf;
		btf_get(kptr_btf);
		goto found_dtor;
	}
	if (id < 0)
		return id;

	/* Find and stash the function pointer for the destruction function that
	 * needs to be eventually invoked from the map free path.
	 */
	if (info->type == BPF_KPTR_REF) {
		const struct btf_type *dtor_func;
		const char *dtor_func_name;
		unsigned long addr;
		s32 dtor_btf_id;

		/* This call also serves as a whitelist of allowed objects that
		 * can be used as a referenced pointer and be stored in a map at
		 * the same time.
		 */
		dtor_btf_id = btf_find_dtor_kfunc(kptr_btf, id);
		if (dtor_btf_id < 0) {
			ret = dtor_btf_id;
			goto end_btf;
		}

		dtor_func = btf_type_by_id(kptr_btf, dtor_btf_id);
		if (!dtor_func) {
			ret = -ENOENT;
			goto end_btf;
		}

		if (btf_is_module(kptr_btf)) {
			mod = btf_try_get_module(kptr_btf);
			if (!mod) {
				ret = -ENXIO;
				goto end_btf;
			}
		}

		/* We already verified dtor_func to be btf_type_is_func
		 * in register_btf_id_dtor_kfuncs.
		 */
		dtor_func_name = __btf_name_by_offset(kptr_btf, dtor_func->name_off);
		addr = kallsyms_lookup_name(dtor_func_name);
		if (!addr) {
			ret = -EINVAL;
			goto end_mod;
		}
		field->kptr.dtor = (void *)addr;
	}

found_dtor:
	field->kptr.btf_id = id;
	field->kptr.btf = kptr_btf;
	field->kptr.module = mod;
	return 0;
end_mod:
	module_put(mod);
end_btf:
	btf_put(kptr_btf);
	return ret;
}

static int btf_parse_graph_root(const struct btf *btf,
				struct btf_field *field,
				struct btf_field_info *info,
				const char *node_type_name,
				size_t node_type_align)
{
	const struct btf_type *t, *n = NULL;
	const struct btf_member *member;
	u32 offset;
	int i;

	t = btf_type_by_id(btf, info->graph_root.value_btf_id);
	/* We've already checked that value_btf_id is a struct type. We
	 * just need to figure out the offset of the list_node, and
	 * verify its type.
	 */
	for_each_member(i, t, member) {
		if (strcmp(info->graph_root.node_name,
			   __btf_name_by_offset(btf, member->name_off)))
			continue;
		/* Invalid BTF, two members with same name */
		if (n)
			return -EINVAL;
		n = btf_type_by_id(btf, member->type);
		if (!__btf_type_is_struct(n))
			return -EINVAL;
		if (strcmp(node_type_name, __btf_name_by_offset(btf, n->name_off)))
			return -EINVAL;
		offset = __btf_member_bit_offset(n, member);
		if (offset % 8)
			return -EINVAL;
		offset /= 8;
		if (offset % node_type_align)
			return -EINVAL;

		field->graph_root.btf = (struct btf *)btf;
		field->graph_root.value_btf_id = info->graph_root.value_btf_id;
		field->graph_root.node_offset = offset;
	}
	if (!n)
		return -ENOENT;
	return 0;
}

static int btf_parse_list_head(const struct btf *btf, struct btf_field *field,
			       struct btf_field_info *info)
{
	return btf_parse_graph_root(btf, field, info, "bpf_list_node",
					    __alignof__(struct bpf_list_node));
}

static int btf_parse_rb_root(const struct btf *btf, struct btf_field *field,
			     struct btf_field_info *info)
{
	return btf_parse_graph_root(btf, field, info, "bpf_rb_node",
					    __alignof__(struct bpf_rb_node));
}

static int btf_field_cmp(const void *_a, const void *_b, const void *priv)
{
	const struct btf_field *a = (const struct btf_field *)_a;
	const struct btf_field *b = (const struct btf_field *)_b;

	if (a->offset < b->offset)
		return -1;
	else if (a->offset > b->offset)
		return 1;
	return 0;
}

struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
				    u32 field_mask, u32 value_size)
{
	struct btf_field_info info_arr[BTF_FIELDS_MAX];
	u32 next_off = 0, field_type_size;
	struct btf_record *rec;
	int ret, i, cnt;

	ret = btf_find_field(btf, t, field_mask, info_arr, ARRAY_SIZE(info_arr));
	if (ret < 0)
		return ERR_PTR(ret);
	if (!ret)
		return NULL;

	cnt = ret;
	/* This needs to be kzalloc to zero out padding and unused fields, see
	 * comment in btf_record_equal.
	 */
	rec = kzalloc(offsetof(struct btf_record, fields[cnt]), GFP_KERNEL | __GFP_NOWARN);
	if (!rec)
		return ERR_PTR(-ENOMEM);

	rec->spin_lock_off = -EINVAL;
	rec->timer_off = -EINVAL;
	rec->refcount_off = -EINVAL;
	for (i = 0; i < cnt; i++) {
		field_type_size = btf_field_type_size(info_arr[i].type);
		if (info_arr[i].off + field_type_size > value_size) {
			WARN_ONCE(1, "verifier bug off %d size %d", info_arr[i].off, value_size);
			ret = -EFAULT;
			goto end;
		}
		if (info_arr[i].off < next_off) {
			ret = -EEXIST;
			goto end;
		}
		next_off = info_arr[i].off + field_type_size;

		rec->field_mask |= info_arr[i].type;
		rec->fields[i].offset = info_arr[i].off;
		rec->fields[i].type = info_arr[i].type;
		rec->fields[i].size = field_type_size;

		switch (info_arr[i].type) {
		case BPF_SPIN_LOCK:
			WARN_ON_ONCE(rec->spin_lock_off >= 0);
			/* Cache offset for faster lookup at runtime */
			rec->spin_lock_off = rec->fields[i].offset;
			break;
		case BPF_TIMER:
			WARN_ON_ONCE(rec->timer_off >= 0);
			/* Cache offset for faster lookup at runtime */
			rec->timer_off = rec->fields[i].offset;
			break;
		case BPF_REFCOUNT:
			WARN_ON_ONCE(rec->refcount_off >= 0);
			/* Cache offset for faster lookup at runtime */
			rec->refcount_off = rec->fields[i].offset;
			break;
		case BPF_KPTR_UNREF:
		case BPF_KPTR_REF:
			ret = btf_parse_kptr(btf, &rec->fields[i], &info_arr[i]);
			if (ret < 0)
				goto end;
			break;
		case BPF_LIST_HEAD:
			ret = btf_parse_list_head(btf, &rec->fields[i], &info_arr[i]);
			if (ret < 0)
				goto end;
			break;
		case BPF_RB_ROOT:
			ret = btf_parse_rb_root(btf, &rec->fields[i], &info_arr[i]);
			if (ret < 0)
				goto end;
			break;
		case BPF_LIST_NODE:
		case BPF_RB_NODE:
			break;
		default:
			ret = -EFAULT;
			goto end;
		}
		rec->cnt++;
	}

	/* bpf_{list_head, rb_node} require bpf_spin_lock */
	if ((btf_record_has_field(rec, BPF_LIST_HEAD) ||
	     btf_record_has_field(rec, BPF_RB_ROOT)) && rec->spin_lock_off < 0) {
		ret = -EINVAL;
		goto end;
	}

	if (rec->refcount_off < 0 &&
	    btf_record_has_field(rec, BPF_LIST_NODE) &&
	    btf_record_has_field(rec, BPF_RB_NODE)) {
		ret = -EINVAL;
		goto end;
	}

	sort_r(rec->fields, rec->cnt, sizeof(struct btf_field), btf_field_cmp,
	       NULL, rec);

	return rec;
end:
	btf_record_free(rec);
	return ERR_PTR(ret);
}

#define GRAPH_ROOT_MASK (BPF_LIST_HEAD | BPF_RB_ROOT)
#define GRAPH_NODE_MASK (BPF_LIST_NODE | BPF_RB_NODE)

int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec)
{
	int i;

	/* There are three types that signify ownership of some other type:
	 *  kptr_ref, bpf_list_head, bpf_rb_root.
	 * kptr_ref only supports storing kernel types, which can't store
	 * references to program allocated local types.
	 *
	 * Hence we only need to ensure that bpf_{list_head,rb_root} ownership
	 * does not form cycles.
	 */
	if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & GRAPH_ROOT_MASK))
		return 0;
	for (i = 0; i < rec->cnt; i++) {
		struct btf_struct_meta *meta;
		u32 btf_id;

		if (!(rec->fields[i].type & GRAPH_ROOT_MASK))
			continue;
		btf_id = rec->fields[i].graph_root.value_btf_id;
		meta = btf_find_struct_meta(btf, btf_id);
		if (!meta)
			return -EFAULT;
		rec->fields[i].graph_root.value_rec = meta->record;

		/* We need to set value_rec for all root types, but no need
		 * to check ownership cycle for a type unless it's also a
		 * node type.
		 */
		if (!(rec->field_mask & GRAPH_NODE_MASK))
			continue;

		/* We need to ensure ownership acyclicity among all types. The
		 * proper way to do it would be to topologically sort all BTF
		 * IDs based on the ownership edges, since there can be multiple
		 * bpf_{list_head,rb_node} in a type. Instead, we use the
		 * following resaoning:
		 *
		 * - A type can only be owned by another type in user BTF if it
		 *   has a bpf_{list,rb}_node. Let's call these node types.
		 * - A type can only _own_ another type in user BTF if it has a
		 *   bpf_{list_head,rb_root}. Let's call these root types.
		 *
		 * We ensure that if a type is both a root and node, its
		 * element types cannot be root types.
		 *
		 * To ensure acyclicity:
		 *
		 * When A is an root type but not a node, its ownership
		 * chain can be:
		 *	A -> B -> C
		 * Where:
		 * - A is an root, e.g. has bpf_rb_root.
		 * - B is both a root and node, e.g. has bpf_rb_node and
		 *   bpf_list_head.
		 * - C is only an root, e.g. has bpf_list_node
		 *
		 * When A is both a root and node, some other type already
		 * owns it in the BTF domain, hence it can not own
		 * another root type through any of the ownership edges.
		 *	A -> B
		 * Where:
		 * - A is both an root and node.
		 * - B is only an node.
		 */
		if (meta->record->field_mask & GRAPH_ROOT_MASK)
			return -ELOOP;
	}
	return 0;
}

static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
			      u32 type_id, void *data, u8 bits_offset,
			      struct btf_show *show)
{
	const struct btf_member *member;
	void *safe_data;
	u32 i;

	safe_data = btf_show_start_struct_type(show, t, type_id, data);
	if (!safe_data)
		return;

	for_each_member(i, t, member) {
		const struct btf_type *member_type = btf_type_by_id(btf,
								member->type);
		const struct btf_kind_operations *ops;
		u32 member_offset, bitfield_size;
		u32 bytes_offset;
		u8 bits8_offset;

		btf_show_start_member(show, member);

		member_offset = __btf_member_bit_offset(t, member);
		bitfield_size = __btf_member_bitfield_size(t, member);
		bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
		bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
		if (bitfield_size) {
			safe_data = btf_show_start_type(show, member_type,
							member->type,
							data + bytes_offset);
			if (safe_data)
				btf_bitfield_show(safe_data,
						  bits8_offset,
						  bitfield_size, show);
			btf_show_end_type(show);
		} else {
			ops = btf_type_ops(member_type);
			ops->show(btf, member_type, member->type,
				  data + bytes_offset, bits8_offset, show);
		}

		btf_show_end_member(show);
	}

	btf_show_end_struct_type(show);
}

static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
			    u32 type_id, void *data, u8 bits_offset,
			    struct btf_show *show)
{
	const struct btf_member *m = show->state.member;

	/*
	 * First check if any members would be shown (are non-zero).
	 * See comments above "struct btf_show" definition for more
	 * details on how this works at a high-level.
	 */
	if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
		if (!show->state.depth_check) {
			show->state.depth_check = show->state.depth + 1;
			show->state.depth_to_show = 0;
		}
		__btf_struct_show(btf, t, type_id, data, bits_offset, show);
		/* Restore saved member data here */
		show->state.member = m;
		if (show->state.depth_check != show->state.depth + 1)
			return;
		show->state.depth_check = 0;

		if (show->state.depth_to_show <= show->state.depth)
			return;
		/*
		 * Reaching here indicates we have recursed and found
		 * non-zero child values.
		 */
	}

	__btf_struct_show(btf, t, type_id, data, bits_offset, show);
}

static struct btf_kind_operations struct_ops = {
	.check_meta = btf_struct_check_meta,
	.resolve = btf_struct_resolve,
	.check_member = btf_struct_check_member,
	.check_kflag_member = btf_generic_check_kflag_member,
	.log_details = btf_struct_log,
	.show = btf_struct_show,
};

static int btf_enum_check_member(struct btf_verifier_env *env,
				 const struct btf_type *struct_type,
				 const struct btf_member *member,
				 const struct btf_type *member_type)
{
	u32 struct_bits_off = member->offset;
	u32 struct_size, bytes_offset;

	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
		btf_verifier_log_member(env, struct_type, member,
					"Member is not byte aligned");
		return -EINVAL;
	}

	struct_size = struct_type->size;
	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
	if (struct_size - bytes_offset < member_type->size) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
				       const struct btf_type *struct_type,
				       const struct btf_member *member,
				       const struct btf_type *member_type)
{
	u32 struct_bits_off, nr_bits, bytes_end, struct_size;
	u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;

	struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
	nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
	if (!nr_bits) {
		if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
			btf_verifier_log_member(env, struct_type, member,
						"Member is not byte aligned");
			return -EINVAL;
		}

		nr_bits = int_bitsize;
	} else if (nr_bits > int_bitsize) {
		btf_verifier_log_member(env, struct_type, member,
					"Invalid member bitfield_size");
		return -EINVAL;
	}

	struct_size = struct_type->size;
	bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
	if (struct_size < bytes_end) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static s32 btf_enum_check_meta(struct btf_verifier_env *env,
			       const struct btf_type *t,
			       u32 meta_left)
{
	const struct btf_enum *enums = btf_type_enum(t);
	struct btf *btf = env->btf;
	const char *fmt_str;
	u16 i, nr_enums;
	u32 meta_needed;

	nr_enums = btf_type_vlen(t);
	meta_needed = nr_enums * sizeof(*enums);

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (t->size > 8 || !is_power_of_2(t->size)) {
		btf_verifier_log_type(env, t, "Unexpected size");
		return -EINVAL;
	}

	/* enum type either no name or a valid one */
	if (t->name_off &&
	    !btf_name_valid_identifier(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	for (i = 0; i < nr_enums; i++) {
		if (!btf_name_offset_valid(btf, enums[i].name_off)) {
			btf_verifier_log(env, "\tInvalid name_offset:%u",
					 enums[i].name_off);
			return -EINVAL;
		}

		/* enum member must have a valid name */
		if (!enums[i].name_off ||
		    !btf_name_valid_identifier(btf, enums[i].name_off)) {
			btf_verifier_log_type(env, t, "Invalid name");
			return -EINVAL;
		}

		if (env->log.level == BPF_LOG_KERNEL)
			continue;
		fmt_str = btf_type_kflag(t) ? "\t%s val=%d\n" : "\t%s val=%u\n";
		btf_verifier_log(env, fmt_str,
				 __btf_name_by_offset(btf, enums[i].name_off),
				 enums[i].val);
	}

	return meta_needed;
}

static void btf_enum_log(struct btf_verifier_env *env,
			 const struct btf_type *t)
{
	btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
			  u32 type_id, void *data, u8 bits_offset,
			  struct btf_show *show)
{
	const struct btf_enum *enums = btf_type_enum(t);
	u32 i, nr_enums = btf_type_vlen(t);
	void *safe_data;
	int v;

	safe_data = btf_show_start_type(show, t, type_id, data);
	if (!safe_data)
		return;

	v = *(int *)safe_data;

	for (i = 0; i < nr_enums; i++) {
		if (v != enums[i].val)
			continue;

		btf_show_type_value(show, "%s",
				    __btf_name_by_offset(btf,
							 enums[i].name_off));

		btf_show_end_type(show);
		return;
	}

	if (btf_type_kflag(t))
		btf_show_type_value(show, "%d", v);
	else
		btf_show_type_value(show, "%u", v);
	btf_show_end_type(show);
}

static struct btf_kind_operations enum_ops = {
	.check_meta = btf_enum_check_meta,
	.resolve = btf_df_resolve,
	.check_member = btf_enum_check_member,
	.check_kflag_member = btf_enum_check_kflag_member,
	.log_details = btf_enum_log,
	.show = btf_enum_show,
};

static s32 btf_enum64_check_meta(struct btf_verifier_env *env,
				 const struct btf_type *t,
				 u32 meta_left)
{
	const struct btf_enum64 *enums = btf_type_enum64(t);
	struct btf *btf = env->btf;
	const char *fmt_str;
	u16 i, nr_enums;
	u32 meta_needed;

	nr_enums = btf_type_vlen(t);
	meta_needed = nr_enums * sizeof(*enums);

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (t->size > 8 || !is_power_of_2(t->size)) {
		btf_verifier_log_type(env, t, "Unexpected size");
		return -EINVAL;
	}

	/* enum type either no name or a valid one */
	if (t->name_off &&
	    !btf_name_valid_identifier(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	for (i = 0; i < nr_enums; i++) {
		if (!btf_name_offset_valid(btf, enums[i].name_off)) {
			btf_verifier_log(env, "\tInvalid name_offset:%u",
					 enums[i].name_off);
			return -EINVAL;
		}

		/* enum member must have a valid name */
		if (!enums[i].name_off ||
		    !btf_name_valid_identifier(btf, enums[i].name_off)) {
			btf_verifier_log_type(env, t, "Invalid name");
			return -EINVAL;
		}

		if (env->log.level == BPF_LOG_KERNEL)
			continue;

		fmt_str = btf_type_kflag(t) ? "\t%s val=%lld\n" : "\t%s val=%llu\n";
		btf_verifier_log(env, fmt_str,
				 __btf_name_by_offset(btf, enums[i].name_off),
				 btf_enum64_value(enums + i));
	}

	return meta_needed;
}

static void btf_enum64_show(const struct btf *btf, const struct btf_type *t,
			    u32 type_id, void *data, u8 bits_offset,
			    struct btf_show *show)
{
	const struct btf_enum64 *enums = btf_type_enum64(t);
	u32 i, nr_enums = btf_type_vlen(t);
	void *safe_data;
	s64 v;

	safe_data = btf_show_start_type(show, t, type_id, data);
	if (!safe_data)
		return;

	v = *(u64 *)safe_data;

	for (i = 0; i < nr_enums; i++) {
		if (v != btf_enum64_value(enums + i))
			continue;

		btf_show_type_value(show, "%s",
				    __btf_name_by_offset(btf,
							 enums[i].name_off));

		btf_show_end_type(show);
		return;
	}

	if (btf_type_kflag(t))
		btf_show_type_value(show, "%lld", v);
	else
		btf_show_type_value(show, "%llu", v);
	btf_show_end_type(show);
}

static struct btf_kind_operations enum64_ops = {
	.check_meta = btf_enum64_check_meta,
	.resolve = btf_df_resolve,
	.check_member = btf_enum_check_member,
	.check_kflag_member = btf_enum_check_kflag_member,
	.log_details = btf_enum_log,
	.show = btf_enum64_show,
};

static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
				     const struct btf_type *t,
				     u32 meta_left)
{
	u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (t->name_off) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return meta_needed;
}

static void btf_func_proto_log(struct btf_verifier_env *env,
			       const struct btf_type *t)
{
	const struct btf_param *args = (const struct btf_param *)(t + 1);
	u16 nr_args = btf_type_vlen(t), i;

	btf_verifier_log(env, "return=%u args=(", t->type);
	if (!nr_args) {
		btf_verifier_log(env, "void");
		goto done;
	}

	if (nr_args == 1 && !args[0].type) {
		/* Only one vararg */
		btf_verifier_log(env, "vararg");
		goto done;
	}

	btf_verifier_log(env, "%u %s", args[0].type,
			 __btf_name_by_offset(env->btf,
					      args[0].name_off));
	for (i = 1; i < nr_args - 1; i++)
		btf_verifier_log(env, ", %u %s", args[i].type,
				 __btf_name_by_offset(env->btf,
						      args[i].name_off));

	if (nr_args > 1) {
		const struct btf_param *last_arg = &args[nr_args - 1];

		if (last_arg->type)
			btf_verifier_log(env, ", %u %s", last_arg->type,
					 __btf_name_by_offset(env->btf,
							      last_arg->name_off));
		else
			btf_verifier_log(env, ", vararg");
	}

done:
	btf_verifier_log(env, ")");
}

static struct btf_kind_operations func_proto_ops = {
	.check_meta = btf_func_proto_check_meta,
	.resolve = btf_df_resolve,
	/*
	 * BTF_KIND_FUNC_PROTO cannot be directly referred by
	 * a struct's member.
	 *
	 * It should be a function pointer instead.
	 * (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
	 *
	 * Hence, there is no btf_func_check_member().
	 */
	.check_member = btf_df_check_member,
	.check_kflag_member = btf_df_check_kflag_member,
	.log_details = btf_func_proto_log,
	.show = btf_df_show,
};

static s32 btf_func_check_meta(struct btf_verifier_env *env,
			       const struct btf_type *t,
			       u32 meta_left)
{
	if (!t->name_off ||
	    !btf_name_valid_identifier(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
		btf_verifier_log_type(env, t, "Invalid func linkage");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return 0;
}

static int btf_func_resolve(struct btf_verifier_env *env,
			    const struct resolve_vertex *v)
{
	const struct btf_type *t = v->t;
	u32 next_type_id = t->type;
	int err;

	err = btf_func_check(env, t);
	if (err)
		return err;

	env_stack_pop_resolved(env, next_type_id, 0);
	return 0;
}

static struct btf_kind_operations func_ops = {
	.check_meta = btf_func_check_meta,
	.resolve = btf_func_resolve,
	.check_member = btf_df_check_member,
	.check_kflag_member = btf_df_check_kflag_member,
	.log_details = btf_ref_type_log,
	.show = btf_df_show,
};

static s32 btf_var_check_meta(struct btf_verifier_env *env,
			      const struct btf_type *t,
			      u32 meta_left)
{
	const struct btf_var *var;
	u32 meta_needed = sizeof(*var);

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	if (!t->name_off ||
	    !__btf_name_valid(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	/* A var cannot be in type void */
	if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
		btf_verifier_log_type(env, t, "Invalid type_id");
		return -EINVAL;
	}

	var = btf_type_var(t);
	if (var->linkage != BTF_VAR_STATIC &&
	    var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
		btf_verifier_log_type(env, t, "Linkage not supported");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return meta_needed;
}

static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
{
	const struct btf_var *var = btf_type_var(t);

	btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
}

static const struct btf_kind_operations var_ops = {
	.check_meta		= btf_var_check_meta,
	.resolve		= btf_var_resolve,
	.check_member		= btf_df_check_member,
	.check_kflag_member	= btf_df_check_kflag_member,
	.log_details		= btf_var_log,
	.show			= btf_var_show,
};

static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
				  const struct btf_type *t,
				  u32 meta_left)
{
	const struct btf_var_secinfo *vsi;
	u64 last_vsi_end_off = 0, sum = 0;
	u32 i, meta_needed;

	meta_needed = btf_type_vlen(t) * sizeof(*vsi);
	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	if (!t->size) {
		btf_verifier_log_type(env, t, "size == 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	if (!t->name_off ||
	    !btf_name_valid_section(env->btf, t->name_off)) {
		btf_verifier_log_type(env, t, "Invalid name");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	for_each_vsi(i, t, vsi) {
		/* A var cannot be in type void */
		if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
			btf_verifier_log_vsi(env, t, vsi,
					     "Invalid type_id");
			return -EINVAL;
		}

		if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
			btf_verifier_log_vsi(env, t, vsi,
					     "Invalid offset");
			return -EINVAL;
		}

		if (!vsi->size || vsi->size > t->size) {
			btf_verifier_log_vsi(env, t, vsi,
					     "Invalid size");
			return -EINVAL;
		}

		last_vsi_end_off = vsi->offset + vsi->size;
		if (last_vsi_end_off > t->size) {
			btf_verifier_log_vsi(env, t, vsi,
					     "Invalid offset+size");
			return -EINVAL;
		}

		btf_verifier_log_vsi(env, t, vsi, NULL);
		sum += vsi->size;
	}

	if (t->size < sum) {
		btf_verifier_log_type(env, t, "Invalid btf_info size");
		return -EINVAL;
	}

	return meta_needed;
}

static int btf_datasec_resolve(struct btf_verifier_env *env,
			       const struct resolve_vertex *v)
{
	const struct btf_var_secinfo *vsi;
	struct btf *btf = env->btf;
	u16 i;

	env->resolve_mode = RESOLVE_TBD;
	for_each_vsi_from(i, v->next_member, v->t, vsi) {
		u32 var_type_id = vsi->type, type_id, type_size = 0;
		const struct btf_type *var_type = btf_type_by_id(env->btf,
								 var_type_id);
		if (!var_type || !btf_type_is_var(var_type)) {
			btf_verifier_log_vsi(env, v->t, vsi,
					     "Not a VAR kind member");
			return -EINVAL;
		}

		if (!env_type_is_resolve_sink(env, var_type) &&
		    !env_type_is_resolved(env, var_type_id)) {
			env_stack_set_next_member(env, i + 1);
			return env_stack_push(env, var_type, var_type_id);
		}

		type_id = var_type->type;
		if (!btf_type_id_size(btf, &type_id, &type_size)) {
			btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
			return -EINVAL;
		}

		if (vsi->size < type_size) {
			btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
			return -EINVAL;
		}
	}

	env_stack_pop_resolved(env, 0, 0);
	return 0;
}

static void btf_datasec_log(struct btf_verifier_env *env,
			    const struct btf_type *t)
{
	btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

static void btf_datasec_show(const struct btf *btf,
			     const struct btf_type *t, u32 type_id,
			     void *data, u8 bits_offset,
			     struct btf_show *show)
{
	const struct btf_var_secinfo *vsi;
	const struct btf_type *var;
	u32 i;

	if (!btf_show_start_type(show, t, type_id, data))
		return;

	btf_show_type_value(show, "section (\"%s\") = {",
			    __btf_name_by_offset(btf, t->name_off));
	for_each_vsi(i, t, vsi) {
		var = btf_type_by_id(btf, vsi->type);
		if (i)
			btf_show(show, ",");
		btf_type_ops(var)->show(btf, var, vsi->type,
					data + vsi->offset, bits_offset, show);
	}
	btf_show_end_type(show);
}

static const struct btf_kind_operations datasec_ops = {
	.check_meta		= btf_datasec_check_meta,
	.resolve		= btf_datasec_resolve,
	.check_member		= btf_df_check_member,
	.check_kflag_member	= btf_df_check_kflag_member,
	.log_details		= btf_datasec_log,
	.show			= btf_datasec_show,
};

static s32 btf_float_check_meta(struct btf_verifier_env *env,
				const struct btf_type *t,
				u32 meta_left)
{
	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
	    t->size != 16) {
		btf_verifier_log_type(env, t, "Invalid type_size");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return 0;
}

static int btf_float_check_member(struct btf_verifier_env *env,
				  const struct btf_type *struct_type,
				  const struct btf_member *member,
				  const struct btf_type *member_type)
{
	u64 start_offset_bytes;
	u64 end_offset_bytes;
	u64 misalign_bits;
	u64 align_bytes;
	u64 align_bits;

	/* Different architectures have different alignment requirements, so
	 * here we check only for the reasonable minimum. This way we ensure
	 * that types after CO-RE can pass the kernel BTF verifier.
	 */
	align_bytes = min_t(u64, sizeof(void *), member_type->size);
	align_bits = align_bytes * BITS_PER_BYTE;
	div64_u64_rem(member->offset, align_bits, &misalign_bits);
	if (misalign_bits) {
		btf_verifier_log_member(env, struct_type, member,
					"Member is not properly aligned");
		return -EINVAL;
	}

	start_offset_bytes = member->offset / BITS_PER_BYTE;
	end_offset_bytes = start_offset_bytes + member_type->size;
	if (end_offset_bytes > struct_type->size) {
		btf_verifier_log_member(env, struct_type, member,
					"Member exceeds struct_size");
		return -EINVAL;
	}

	return 0;
}

static void btf_float_log(struct btf_verifier_env *env,
			  const struct btf_type *t)
{
	btf_verifier_log(env, "size=%u", t->size);
}

static const struct btf_kind_operations float_ops = {
	.check_meta = btf_float_check_meta,
	.resolve = btf_df_resolve,
	.check_member = btf_float_check_member,
	.check_kflag_member = btf_generic_check_kflag_member,
	.log_details = btf_float_log,
	.show = btf_df_show,
};

static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
			      const struct btf_type *t,
			      u32 meta_left)
{
	const struct btf_decl_tag *tag;
	u32 meta_needed = sizeof(*tag);
	s32 component_idx;
	const char *value;

	if (meta_left < meta_needed) {
		btf_verifier_log_basic(env, t,
				       "meta_left:%u meta_needed:%u",
				       meta_left, meta_needed);
		return -EINVAL;
	}

	value = btf_name_by_offset(env->btf, t->name_off);
	if (!value || !value[0]) {
		btf_verifier_log_type(env, t, "Invalid value");
		return -EINVAL;
	}

	if (btf_type_vlen(t)) {
		btf_verifier_log_type(env, t, "vlen != 0");
		return -EINVAL;
	}

	if (btf_type_kflag(t)) {
		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
		return -EINVAL;
	}

	component_idx = btf_type_decl_tag(t)->component_idx;
	if (component_idx < -1) {
		btf_verifier_log_type(env, t, "Invalid component_idx");
		return -EINVAL;
	}

	btf_verifier_log_type(env, t, NULL);

	return meta_needed;
}

static int btf_decl_tag_resolve(struct btf_verifier_env *env,
			   const struct resolve_vertex *v)
{
	const struct btf_type *next_type;
	const struct btf_type *t = v->t;
	u32 next_type_id = t->type;
	struct btf *btf = env->btf;
	s32 component_idx;
	u32 vlen;

	next_type = btf_type_by_id(btf, next_type_id);
	if (!next_type || !btf_type_is_decl_tag_target(next_type)) {
		btf_verifier_log_type(env, v->t, "Invalid type_id");
		return -EINVAL;
	}

	if (!env_type_is_resolve_sink(env, next_type) &&
	    !env_type_is_resolved(env, next_type_id))
		return env_stack_push(env, next_type, next_type_id);

	component_idx = btf_type_decl_tag(t)->component_idx;
	if (component_idx != -1) {
		if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
			btf_verifier_log_type(env, v->t, "Invalid component_idx");
			return -EINVAL;
		}

		if (btf_type_is_struct(next_type)) {
			vlen = btf_type_vlen(next_type);
		} else {
			/* next_type should be a function */
			next_type = btf_type_by_id(btf, next_type->type);
			vlen = btf_type_vlen(next_type);
		}

		if ((u32)component_idx >= vlen) {
			btf_verifier_log_type(env, v->t, "Invalid component_idx");
			return -EINVAL;
		}
	}

	env_stack_pop_resolved(env, next_type_id, 0);

	return 0;
}

static void btf_decl_tag_log(struct btf_verifier_env *env, const struct btf_type *t)
{
	btf_verifier_log(env, "type=%u component_idx=%d", t->type,
			 btf_type_decl_tag(t)->component_idx);
}

static const struct btf_kind_operations decl_tag_ops = {
	.check_meta = btf_decl_tag_check_meta,
	.resolve = btf_decl_tag_resolve,
	.check_member = btf_df_check_member,
	.check_kflag_member = btf_df_check_kflag_member,
	.log_details = btf_decl_tag_log,
	.show = btf_df_show,
};

static int btf_func_proto_check(struct btf_verifier_env *env,
				const struct btf_type *t)
{
	const struct btf_type *ret_type;
	const struct btf_param *args;
	const struct btf *btf;
	u16 nr_args, i;
	int err;

	btf = env->btf;
	args = (const struct btf_param *)(t + 1);
	nr_args = btf_type_vlen(t);

	/* Check func return type which could be "void" (t->type == 0) */
	if (t->type) {
		u32 ret_type_id = t->type;

		ret_type = btf_type_by_id(btf, ret_type_id);
		if (!ret_type) {
			btf_verifier_log_type(env, t, "Invalid return type");
			return -EINVAL;
		}

		if (btf_type_is_resolve_source_only(ret_type)) {
			btf_verifier_log_type(env, t, "Invalid return type");
			return -EINVAL;
		}

		if (btf_type_needs_resolve(ret_type) &&
		    !env_type_is_resolved(env, ret_type_id)) {
			err = btf_resolve(env, ret_type, ret_type_id);
			if (err)
				return err;
		}

		/* Ensure the return type is a type that has a size */
		if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
			btf_verifier_log_type(env, t, "Invalid return type");
			return -EINVAL;
		}
	}

	if (!nr_args)
		return 0;

	/* Last func arg type_id could be 0 if it is a vararg */
	if (!args[nr_args - 1].type) {
		if (args[nr_args - 1].name_off) {
			btf_verifier_log_type(env, t, "Invalid arg#%u",
					      nr_args);
			return -EINVAL;
		}
		nr_args--;
	}

	for (i = 0; i < nr_args; i++) {
		const struct btf_type *arg_type;
		u32 arg_type_id;

		arg_type_id = args[i].type;
		arg_type = btf_type_by_id(btf, arg_type_id);
		if (!arg_type) {
			btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
			return -EINVAL;
		}

		if (btf_type_is_resolve_source_only(arg_type)) {
			btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
			return -EINVAL;
		}

		if (args[i].name_off &&
		    (!btf_name_offset_valid(btf, args[i].name_off) ||
		     !btf_name_valid_identifier(btf, args[i].name_off))) {
			btf_verifier_log_type(env, t,
					      "Invalid arg#%u", i + 1);
			return -EINVAL;
		}

		if (btf_type_needs_resolve(arg_type) &&
		    !env_type_is_resolved(env, arg_type_id)) {
			err = btf_resolve(env, arg_type, arg_type_id);
			if (err)
				return err;
		}

		if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
			btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
			return -EINVAL;
		}
	}

	return 0;
}

static int btf_func_check(struct btf_verifier_env *env,
			  const struct btf_type *t)
{
	const struct btf_type *proto_type;
	const struct btf_param *args;
	const struct btf *btf;
	u16 nr_args, i;

	btf = env->btf;
	proto_type = btf_type_by_id(btf, t->type);

	if (!proto_type || !btf_type_is_func_proto(proto_type)) {
		btf_verifier_log_type(env, t, "Invalid type_id");
		return -EINVAL;
	}

	args = (const struct btf_param *)(proto_type + 1);
	nr_args = btf_type_vlen(proto_type);
	for (i = 0; i < nr_args; i++) {
		if (!args[i].name_off && args[i].type) {
			btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
			return -EINVAL;
		}
	}

	return 0;
}

static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
	[BTF_KIND_INT] = &int_ops,
	[BTF_KIND_PTR] = &ptr_ops,
	[BTF_KIND_ARRAY] = &array_ops,
	[BTF_KIND_STRUCT] = &struct_ops,
	[BTF_KIND_UNION] = &struct_ops,
	[BTF_KIND_ENUM] = &enum_ops,
	[BTF_KIND_FWD] = &fwd_ops,
	[BTF_KIND_TYPEDEF] = &modifier_ops,
	[BTF_KIND_VOLATILE] = &modifier_ops,
	[BTF_KIND_CONST] = &modifier_ops,
	[BTF_KIND_RESTRICT] = &modifier_ops,
	[BTF_KIND_FUNC] = &func_ops,
	[BTF_KIND_FUNC_PROTO] = &func_proto_ops,
	[BTF_KIND_VAR] = &var_ops,
	[BTF_KIND_DATASEC] = &datasec_ops,
	[BTF_KIND_FLOAT] = &float_ops,
	[BTF_KIND_DECL_TAG] = &decl_tag_ops,
	[BTF_KIND_TYPE_TAG] = &modifier_ops,
	[BTF_KIND_ENUM64] = &enum64_ops,
};

static s32 btf_check_meta(struct btf_verifier_env *env,
			  const struct btf_type *t,
			  u32 meta_left)
{
	u32 saved_meta_left = meta_left;
	s32 var_meta_size;

	if (meta_left < sizeof(*t)) {
		btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
				 env->log_type_id, meta_left, sizeof(*t));
		return -EINVAL;
	}
	meta_left -= sizeof(*t);

	if (t->info & ~BTF_INFO_MASK) {
		btf_verifier_log(env, "[%u] Invalid btf_info:%x",
				 env->log_type_id, t->info);
		return -EINVAL;
	}

	if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
	    BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
		btf_verifier_log(env, "[%u] Invalid kind:%u",
				 env->log_type_id, BTF_INFO_KIND(t->info));
		return -EINVAL;
	}

	if (!btf_name_offset_valid(env->btf, t->name_off)) {
		btf_verifier_log(env, "[%u] Invalid name_offset:%u",
				 env->log_type_id, t->name_off);
		return -EINVAL;
	}

	var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
	if (var_meta_size < 0)
		return var_meta_size;

	meta_left -= var_meta_size;

	return saved_meta_left - meta_left;
}

static int btf_check_all_metas(struct btf_verifier_env *env)
{
	struct btf *btf = env->btf;
	struct btf_header *hdr;
	void *cur, *end;

	hdr = &btf->hdr;
	cur = btf->nohdr_data + hdr->type_off;
	end = cur + hdr->type_len;

	env->log_type_id = btf->base_btf ? btf->start_id : 1;
	while (cur < end) {
		struct btf_type *t = cur;
		s32 meta_size;

		meta_size = btf_check_meta(env, t, end - cur);
		if (meta_size < 0)
			return meta_size;

		btf_add_type(env, t);
		cur += meta_size;
		env->log_type_id++;
	}

	return 0;
}

static bool btf_resolve_valid(struct btf_verifier_env *env,
			      const struct btf_type *t,
			      u32 type_id)
{
	struct btf *btf = env->btf;

	if (!env_type_is_resolved(env, type_id))
		return false;

	if (btf_type_is_struct(t) || btf_type_is_datasec(t))
		return !btf_resolved_type_id(btf, type_id) &&
		       !btf_resolved_type_size(btf, type_id);

	if (btf_type_is_decl_tag(t) || btf_type_is_func(t))
		return btf_resolved_type_id(btf, type_id) &&
		       !btf_resolved_type_size(btf, type_id);

	if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
	    btf_type_is_var(t)) {
		t = btf_type_id_resolve(btf, &type_id);
		return t &&
		       !btf_type_is_modifier(t) &&
		       !btf_type_is_var(t) &&
		       !btf_type_is_datasec(t);
	}

	if (btf_type_is_array(t)) {
		const struct btf_array *array = btf_type_array(t);
		const struct btf_type *elem_type;
		u32 elem_type_id = array->type;
		u32 elem_size;

		elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
		return elem_type && !btf_type_is_modifier(elem_type) &&
			(array->nelems * elem_size ==
			 btf_resolved_type_size(btf, type_id));
	}

	return false;
}

static int btf_resolve(struct btf_verifier_env *env,
		       const struct btf_type *t, u32 type_id)
{
	u32 save_log_type_id = env->log_type_id;
	const struct resolve_vertex *v;
	int err = 0;

	env->resolve_mode = RESOLVE_TBD;
	env_stack_push(env, t, type_id);
	while (!err && (v = env_stack_peak(env))) {
		env->log_type_id = v->type_id;
		err = btf_type_ops(v->t)->resolve(env, v);
	}

	env->log_type_id = type_id;
	if (err == -E2BIG) {
		btf_verifier_log_type(env, t,
				      "Exceeded max resolving depth:%u",
				      MAX_RESOLVE_DEPTH);
	} else if (err == -EEXIST) {
		btf_verifier_log_type(env, t, "Loop detected");
	}

	/* Final sanity check */
	if (!err && !btf_resolve_valid(env, t, type_id)) {
		btf_verifier_log_type(env, t, "Invalid resolve state");
		err = -EINVAL;
	}

	env->log_type_id = save_log_type_id;
	return err;
}

static int btf_check_all_types(struct btf_verifier_env *env)
{
	struct btf *btf = env->btf;
	const struct btf_type *t;
	u32 type_id, i;
	int err;

	err = env_resolve_init(env);
	if (err)
		return err;

	env->phase++;
	for (i = btf->base_btf ? 0 : 1; i < btf->nr_types; i++) {
		type_id = btf->start_id + i;
		t = btf_type_by_id(btf, type_id);

		env->log_type_id = type_id;
		if (btf_type_needs_resolve(t) &&
		    !env_type_is_resolved(env, type_id)) {
			err = btf_resolve(env, t, type_id);
			if (err)
				return err;
		}

		if (btf_type_is_func_proto(t)) {
			err = btf_func_proto_check(env, t);
			if (err)
				return err;
		}
	}

	return 0;
}

static int btf_parse_type_sec(struct btf_verifier_env *env)
{
	const struct btf_header *hdr = &env->btf->hdr;
	int err;

	/* Type section must align to 4 bytes */
	if (hdr->type_off & (sizeof(u32) - 1)) {
		btf_verifier_log(env, "Unaligned type_off");
		return -EINVAL;
	}

	if (!env->btf->base_btf && !hdr->type_len) {
		btf_verifier_log(env, "No type found");
		return -EINVAL;
	}

	err = btf_check_all_metas(env);
	if (err)
		return err;

	return btf_check_all_types(env);
}

static int btf_parse_str_sec(struct btf_verifier_env *env)
{
	const struct btf_header *hdr;
	struct btf *btf = env->btf;
	const char *start, *end;

	hdr = &btf->hdr;
	start = btf->nohdr_data + hdr->str_off;
	end = start + hdr->str_len;

	if (end != btf->data + btf->data_size) {
		btf_verifier_log(env, "String section is not at the end");
		return -EINVAL;
	}

	btf->strings = start;

	if (btf->base_btf && !hdr->str_len)
		return 0;
	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET || end[-1]) {
		btf_verifier_log(env, "Invalid string section");
		return -EINVAL;
	}
	if (!btf->base_btf && start[0]) {
		btf_verifier_log(env, "Invalid string section");
		return -EINVAL;
	}

	return 0;
}

static const size_t btf_sec_info_offset[] = {
	offsetof(struct btf_header, type_off),
	offsetof(struct btf_header, str_off),
};

static int btf_sec_info_cmp(const void *a, const void *b)
{
	const struct btf_sec_info *x = a;
	const struct btf_sec_info *y = b;

	return (int)(x->off - y->off) ? : (int)(x->len - y->len);
}

static int btf_check_sec_info(struct btf_verifier_env *env,
			      u32 btf_data_size)
{
	struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
	u32 total, expected_total, i;
	const struct btf_header *hdr;
	const struct btf *btf;

	btf = env->btf;
	hdr = &btf->hdr;

	/* Populate the secs from hdr */
	for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
		secs[i] = *(struct btf_sec_info *)((void *)hdr +
						   btf_sec_info_offset[i]);

	sort(secs, ARRAY_SIZE(btf_sec_info_offset),
	     sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);

	/* Check for gaps and overlap among sections */
	total = 0;
	expected_total = btf_data_size - hdr->hdr_len;
	for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
		if (expected_total < secs[i].off) {
			btf_verifier_log(env, "Invalid section offset");
			return -EINVAL;
		}
		if (total < secs[i].off) {
			/* gap */
			btf_verifier_log(env, "Unsupported section found");
			return -EINVAL;
		}
		if (total > secs[i].off) {
			btf_verifier_log(env, "Section overlap found");
			return -EINVAL;
		}
		if (expected_total - total < secs[i].len) {
			btf_verifier_log(env,
					 "Total section length too long");
			return -EINVAL;
		}
		total += secs[i].len;
	}

	/* There is data other than hdr and known sections */
	if (expected_total != total) {
		btf_verifier_log(env, "Unsupported section found");
		return -EINVAL;
	}

	return 0;
}

static int btf_parse_hdr(struct btf_verifier_env *env)
{
	u32 hdr_len, hdr_copy, btf_data_size;
	const struct btf_header *hdr;
	struct btf *btf;

	btf = env->btf;
	btf_data_size = btf->data_size;

	if (btf_data_size < offsetofend(struct btf_header, hdr_len)) {
		btf_verifier_log(env, "hdr_len not found");
		return -EINVAL;
	}

	hdr = btf->data;
	hdr_len = hdr->hdr_len;
	if (btf_data_size < hdr_len) {
		btf_verifier_log(env, "btf_header not found");
		return -EINVAL;
	}

	/* Ensure the unsupported header fields are zero */
	if (hdr_len > sizeof(btf->hdr)) {
		u8 *expected_zero = btf->data + sizeof(btf->hdr);
		u8 *end = btf->data + hdr_len;

		for (; expected_zero < end; expected_zero++) {
			if (*expected_zero) {
				btf_verifier_log(env, "Unsupported btf_header");
				return -E2BIG;
			}
		}
	}

	hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
	memcpy(&btf->hdr, btf->data, hdr_copy);

	hdr = &btf->hdr;

	btf_verifier_log_hdr(env, btf_data_size);

	if (hdr->magic != BTF_MAGIC) {
		btf_verifier_log(env, "Invalid magic");
		return -EINVAL;
	}

	if (hdr->version != BTF_VERSION) {
		btf_verifier_log(env, "Unsupported version");
		return -ENOTSUPP;
	}

	if (hdr->flags) {
		btf_verifier_log(env, "Unsupported flags");
		return -ENOTSUPP;
	}

	if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
		btf_verifier_log(env, "No data");
		return -EINVAL;
	}

	return btf_check_sec_info(env, btf_data_size);
}

static const char *alloc_obj_fields[] = {
	"bpf_spin_lock",
	"bpf_list_head",
	"bpf_list_node",
	"bpf_rb_root",
	"bpf_rb_node",
	"bpf_refcount",
};

static struct btf_struct_metas *
btf_parse_struct_metas(struct bpf_verifier_log *log, struct btf *btf)
{
	union {
		struct btf_id_set set;
		struct {
			u32 _cnt;
			u32 _ids[ARRAY_SIZE(alloc_obj_fields)];
		} _arr;
	} aof;
	struct btf_struct_metas *tab = NULL;
	int i, n, id, ret;

	BUILD_BUG_ON(offsetof(struct btf_id_set, cnt) != 0);
	BUILD_BUG_ON(sizeof(struct btf_id_set) != sizeof(u32));

	memset(&aof, 0, sizeof(aof));
	for (i = 0; i < ARRAY_SIZE(alloc_obj_fields); i++) {
		/* Try to find whether this special type exists in user BTF, and
		 * if so remember its ID so we can easily find it among members
		 * of structs that we iterate in the next loop.
		 */
		id = btf_find_by_name_kind(btf, alloc_obj_fields[i], BTF_KIND_STRUCT);
		if (id < 0)
			continue;
		aof.set.ids[aof.set.cnt++] = id;
	}

	if (!aof.set.cnt)
		return NULL;
	sort(&aof.set.ids, aof.set.cnt, sizeof(aof.set.ids[0]), btf_id_cmp_func, NULL);

	n = btf_nr_types(btf);
	for (i = 1; i < n; i++) {
		struct btf_struct_metas *new_tab;
		const struct btf_member *member;
		struct btf_struct_meta *type;
		struct btf_record *record;
		const struct btf_type *t;
		int j, tab_cnt;

		t = btf_type_by_id(btf, i);
		if (!t) {
			ret = -EINVAL;
			goto free;
		}
		if (!__btf_type_is_struct(t))
			continue;

		cond_resched();

		for_each_member(j, t, member) {
			if (btf_id_set_contains(&aof.set, member->type))
				goto parse;
		}
		continue;
	parse:
		tab_cnt = tab ? tab->cnt : 0;
		new_tab = krealloc(tab, offsetof(struct btf_struct_metas, types[tab_cnt + 1]),
				   GFP_KERNEL | __GFP_NOWARN);
		if (!new_tab) {
			ret = -ENOMEM;
			goto free;
		}
		if (!tab)
			new_tab->cnt = 0;
		tab = new_tab;

		type = &tab->types[tab->cnt];
		type->btf_id = i;
		record = btf_parse_fields(btf, t, BPF_SPIN_LOCK | BPF_LIST_HEAD | BPF_LIST_NODE |
						  BPF_RB_ROOT | BPF_RB_NODE | BPF_REFCOUNT, t->size);
		/* The record cannot be unset, treat it as an error if so */
		if (IS_ERR_OR_NULL(record)) {
			ret = PTR_ERR_OR_ZERO(record) ?: -EFAULT;
			goto free;
		}
		type->record = record;
		tab->cnt++;
	}
	return tab;
free:
	btf_struct_metas_free(tab);
	return ERR_PTR(ret);
}

struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
{
	struct btf_struct_metas *tab;

	BUILD_BUG_ON(offsetof(struct btf_struct_meta, btf_id) != 0);
	tab = btf->struct_meta_tab;
	if (!tab)
		return NULL;
	return bsearch(&btf_id, tab->types, tab->cnt, sizeof(tab->types[0]), btf_id_cmp_func);
}

static int btf_check_type_tags(struct btf_verifier_env *env,
			       struct btf *btf, int start_id)
{
	int i, n, good_id = start_id - 1;
	bool in_tags;

	n = btf_nr_types(btf);
	for (i = start_id; i < n; i++) {
		const struct btf_type *t;
		int chain_limit = 32;
		u32 cur_id = i;

		t = btf_type_by_id(btf, i);
		if (!t)
			return -EINVAL;
		if (!btf_type_is_modifier(t))
			continue;

		cond_resched();

		in_tags = btf_type_is_type_tag(t);
		while (btf_type_is_modifier(t)) {
			if (!chain_limit--) {
				btf_verifier_log(env, "Max chain length or cycle detected");
				return -ELOOP;
			}
			if (btf_type_is_type_tag(t)) {
				if (!in_tags) {
					btf_verifier_log(env, "Type tags don't precede modifiers");
					return -EINVAL;
				}
			} else if (in_tags) {
				in_tags = false;
			}
			if (cur_id <= good_id)
				break;
			/* Move to next type */
			cur_id = t->type;
			t = btf_type_by_id(btf, cur_id);
			if (!t)
				return -EINVAL;
		}
		good_id = i;
	}
	return 0;
}

static int finalize_log(struct bpf_verifier_log *log, bpfptr_t uattr, u32 uattr_size)
{
	u32 log_true_size;
	int err;

	err = bpf_vlog_finalize(log, &log_true_size);

	if (uattr_size >= offsetofend(union bpf_attr, btf_log_true_size) &&
	    copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, btf_log_true_size),
				  &log_true_size, sizeof(log_true_size)))
		err = -EFAULT;

	return err;
}

static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
{
	bpfptr_t btf_data = make_bpfptr(attr->btf, uattr.is_kernel);
	char __user *log_ubuf = u64_to_user_ptr(attr->btf_log_buf);
	struct btf_struct_metas *struct_meta_tab;
	struct btf_verifier_env *env = NULL;
	struct btf *btf = NULL;
	u8 *data;
	int err, ret;

	if (attr->btf_size > BTF_MAX_SIZE)
		return ERR_PTR(-E2BIG);

	env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
	if (!env)
		return ERR_PTR(-ENOMEM);

	/* user could have requested verbose verifier output
	 * and supplied buffer to store the verification trace
	 */
	err = bpf_vlog_init(&env->log, attr->btf_log_level,
			    log_ubuf, attr->btf_log_size);
	if (err)
		goto errout_free;

	btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
	if (!btf) {
		err = -ENOMEM;
		goto errout;
	}
	env->btf = btf;

	data = kvmalloc(attr->btf_size, GFP_KERNEL | __GFP_NOWARN);
	if (!data) {
		err = -ENOMEM;
		goto errout;
	}

	btf->data = data;
	btf->data_size = attr->btf_size;

	if (copy_from_bpfptr(data, btf_data, attr->btf_size)) {
		err = -EFAULT;
		goto errout;
	}

	err = btf_parse_hdr(env);
	if (err)
		goto errout;

	btf->nohdr_data = btf->data + btf->hdr.hdr_len;

	err = btf_parse_str_sec(env);
	if (err)
		goto errout;

	err = btf_parse_type_sec(env);
	if (err)
		goto errout;

	err = btf_check_type_tags(env, btf, 1);
	if (err)
		goto errout;

	struct_meta_tab = btf_parse_struct_metas(&env->log, btf);
	if (IS_ERR(struct_meta_tab)) {
		err = PTR_ERR(struct_meta_tab);
		goto errout;
	}
	btf->struct_meta_tab = struct_meta_tab;

	if (struct_meta_tab) {
		int i;

		for (i = 0; i < struct_meta_tab->cnt; i++) {
			err = btf_check_and_fixup_fields(btf, struct_meta_tab->types[i].record);
			if (err < 0)
				goto errout_meta;
		}
	}

	err = finalize_log(&env->log, uattr, uattr_size);
	if (err)
		goto errout_free;

	btf_verifier_env_free(env);
	refcount_set(&btf->refcnt, 1);
	return btf;

errout_meta:
	btf_free_struct_meta_tab(btf);
errout:
	/* overwrite err with -ENOSPC or -EFAULT */
	ret = finalize_log(&env->log, uattr, uattr_size);
	if (ret)
		err = ret;
errout_free:
	btf_verifier_env_free(env);
	if (btf)
		btf_free(btf);
	return ERR_PTR(err);
}

extern char __weak __start_BTF[];
extern char __weak __stop_BTF[];
extern struct btf *btf_vmlinux;

#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
static union {
	struct bpf_ctx_convert {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
	prog_ctx_type _id##_prog; \
	kern_ctx_type _id##_kern;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
	} *__t;
	/* 't' is written once under lock. Read many times. */
	const struct btf_type *t;
} bpf_ctx_convert;
enum {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
	__ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
	__ctx_convert_unused, /* to avoid empty enum in extreme .config */
};
static u8 bpf_ctx_convert_map[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
	[_id] = __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
	0, /* avoid empty array */
};
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE

const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
		      const struct btf_type *t, enum bpf_prog_type prog_type,
		      int arg)
{
	const struct btf_type *conv_struct;
	const struct btf_type *ctx_struct;
	const struct btf_member *ctx_type;
	const char *tname, *ctx_tname;

	conv_struct = bpf_ctx_convert.t;
	if (!conv_struct) {
		bpf_log(log, "btf_vmlinux is malformed\n");
		return NULL;
	}
	t = btf_type_by_id(btf, t->type);
	while (btf_type_is_modifier(t))
		t = btf_type_by_id(btf, t->type);
	if (!btf_type_is_struct(t)) {
		/* Only pointer to struct is supported for now.
		 * That means that BPF_PROG_TYPE_TRACEPOINT with BTF
		 * is not supported yet.
		 * BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
		 */
		return NULL;
	}
	tname = btf_name_by_offset(btf, t->name_off);
	if (!tname) {
		bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
		return NULL;
	}
	/* prog_type is valid bpf program type. No need for bounds check. */
	ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
	/* ctx_struct is a pointer to prog_ctx_type in vmlinux.
	 * Like 'struct __sk_buff'
	 */
	ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type);
	if (!ctx_struct)
		/* should not happen */
		return NULL;
again:
	ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off);
	if (!ctx_tname) {
		/* should not happen */
		bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
		return NULL;
	}
	/* only compare that prog's ctx type name is the same as
	 * kernel expects. No need to compare field by field.
	 * It's ok for bpf prog to do:
	 * struct __sk_buff {};
	 * int socket_filter_bpf_prog(struct __sk_buff *skb)
	 * { // no fields of skb are ever used }
	 */
	if (strcmp(ctx_tname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0)
		return ctx_type;
	if (strcmp(ctx_tname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0)
		return ctx_type;
	if (strcmp(ctx_tname, tname)) {
		/* bpf_user_pt_regs_t is a typedef, so resolve it to
		 * underlying struct and check name again
		 */
		if (!btf_type_is_modifier(ctx_struct))
			return NULL;
		while (btf_type_is_modifier(ctx_struct))
			ctx_struct = btf_type_by_id(btf_vmlinux, ctx_struct->type);
		goto again;
	}
	return ctx_type;
}

static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
				     struct btf *btf,
				     const struct btf_type *t,
				     enum bpf_prog_type prog_type,
				     int arg)
{
	const struct btf_member *prog_ctx_type, *kern_ctx_type;

	prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg);
	if (!prog_ctx_type)
		return -ENOENT;
	kern_ctx_type = prog_ctx_type + 1;
	return kern_ctx_type->type;
}

int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type)
{
	const struct btf_member *kctx_member;
	const struct btf_type *conv_struct;
	const struct btf_type *kctx_type;
	u32 kctx_type_id;

	conv_struct = bpf_ctx_convert.t;
	/* get member for kernel ctx type */
	kctx_member = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1;
	kctx_type_id = kctx_member->type;
	kctx_type = btf_type_by_id(btf_vmlinux, kctx_type_id);
	if (!btf_type_is_struct(kctx_type)) {
		bpf_log(log, "kern ctx type id %u is not a struct\n", kctx_type_id);
		return -EINVAL;
	}

	return kctx_type_id;
}

BTF_ID_LIST(bpf_ctx_convert_btf_id)
BTF_ID(struct, bpf_ctx_convert)

struct btf *btf_parse_vmlinux(void)
{
	struct btf_verifier_env *env = NULL;
	struct bpf_verifier_log *log;
	struct btf *btf = NULL;
	int err;

	env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
	if (!env)
		return ERR_PTR(-ENOMEM);

	log = &env->log;
	log->level = BPF_LOG_KERNEL;

	btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
	if (!btf) {
		err = -ENOMEM;
		goto errout;
	}
	env->btf = btf;

	btf->data = __start_BTF;
	btf->data_size = __stop_BTF - __start_BTF;
	btf->kernel_btf = true;
	snprintf(btf->name, sizeof(btf->name), "vmlinux");

	err = btf_parse_hdr(env);
	if (err)
		goto errout;

	btf->nohdr_data = btf->data + btf->hdr.hdr_len;

	err = btf_parse_str_sec(env);
	if (err)
		goto errout;

	err = btf_check_all_metas(env);
	if (err)
		goto errout;

	err = btf_check_type_tags(env, btf, 1);
	if (err)
		goto errout;

	/* btf_parse_vmlinux() runs under bpf_verifier_lock */
	bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);

	bpf_struct_ops_init(btf, log);

	refcount_set(&btf->refcnt, 1);

	err = btf_alloc_id(btf);
	if (err)
		goto errout;

	btf_verifier_env_free(env);
	return btf;

errout:
	btf_verifier_env_free(env);
	if (btf) {
		kvfree(btf->types);
		kfree(btf);
	}
	return ERR_PTR(err);
}

#ifdef CONFIG_DEBUG_INFO_BTF_MODULES

static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size)
{
	struct btf_verifier_env *env = NULL;
	struct bpf_verifier_log *log;
	struct btf *btf = NULL, *base_btf;
	int err;

	base_btf = bpf_get_btf_vmlinux();
	if (IS_ERR(base_btf))
		return base_btf;
	if (!base_btf)
		return ERR_PTR(-EINVAL);

	env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
	if (!env)
		return ERR_PTR(-ENOMEM);

	log = &env->log;
	log->level = BPF_LOG_KERNEL;

	btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
	if (!btf) {
		err = -ENOMEM;
		goto errout;
	}
	env->btf = btf;

	btf->base_btf = base_btf;
	btf->start_id = base_btf->nr_types;
	btf->start_str_off = base_btf->hdr.str_len;
	btf->kernel_btf = true;
	snprintf(btf->name, sizeof(btf->name), "%s", module_name);

	btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN);
	if (!btf->data) {
		err = -ENOMEM;
		goto errout;
	}
	memcpy(btf->data, data, data_size);
	btf->data_size = data_size;

	err = btf_parse_hdr(env);
	if (err)
		goto errout;

	btf->nohdr_data = btf->data + btf->hdr.hdr_len;

	err = btf_parse_str_sec(env);
	if (err)
		goto errout;

	err = btf_check_all_metas(env);
	if (err)
		goto errout;

	err = btf_check_type_tags(env, btf, btf_nr_types(base_btf));
	if (err)
		goto errout;

	btf_verifier_env_free(env);
	refcount_set(&btf->refcnt, 1);
	return btf;

errout:
	btf_verifier_env_free(env);
	if (btf) {
		kvfree(btf->data);
		kvfree(btf->types);
		kfree(btf);
	}
	return ERR_PTR(err);
}

#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */

struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
{
	struct bpf_prog *tgt_prog = prog->aux->dst_prog;

	if (tgt_prog)
		return tgt_prog->aux->btf;
	else
		return prog->aux->attach_btf;
}

static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
{
	/* skip modifiers */
	t = btf_type_skip_modifiers(btf, t->type, NULL);

	return btf_type_is_int(t);
}

static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto,
			   int off)
{
	const struct btf_param *args;
	const struct btf_type *t;
	u32 offset = 0, nr_args;
	int i;

	if (!func_proto)
		return off / 8;

	nr_args = btf_type_vlen(func_proto);
	args = (const struct btf_param *)(func_proto + 1);
	for (i = 0; i < nr_args; i++) {
		t = btf_type_skip_modifiers(btf, args[i].type, NULL);
		offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
		if (off < offset)
			return i;
	}

	t = btf_type_skip_modifiers(btf, func_proto->type, NULL);
	offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
	if (off < offset)
		return nr_args;

	return nr_args + 1;
}

static bool prog_args_trusted(const struct bpf_prog *prog)
{
	enum bpf_attach_type atype = prog->expected_attach_type;

	switch (prog->type) {
	case BPF_PROG_TYPE_TRACING:
		return atype == BPF_TRACE_RAW_TP || atype == BPF_TRACE_ITER;
	case BPF_PROG_TYPE_LSM:
		return bpf_lsm_is_trusted(prog);
	case BPF_PROG_TYPE_STRUCT_OPS:
		return true;
	default:
		return false;
	}
}

bool btf_ctx_access(int off, int size, enum bpf_access_type type,
		    const struct bpf_prog *prog,
		    struct bpf_insn_access_aux *info)
{
	const struct btf_type *t = prog->aux->attach_func_proto;
	struct bpf_prog *tgt_prog = prog->aux->dst_prog;
	struct btf *btf = bpf_prog_get_target_btf(prog);
	const char *tname = prog->aux->attach_func_name;
	struct bpf_verifier_log *log = info->log;
	const struct btf_param *args;
	const char *tag_value;
	u32 nr_args, arg;
	int i, ret;

	if (off % 8) {
		bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
			tname, off);
		return false;
	}
	arg = get_ctx_arg_idx(btf, t, off);
	args = (const struct btf_param *)(t + 1);
	/* if (t == NULL) Fall back to default BPF prog with
	 * MAX_BPF_FUNC_REG_ARGS u64 arguments.
	 */
	nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
	if (prog->aux->attach_btf_trace) {
		/* skip first 'void *__data' argument in btf_trace_##name typedef */
		args++;
		nr_args--;
	}

	if (arg > nr_args) {
		bpf_log(log, "func '%s' doesn't have %d-th argument\n",
			tname, arg + 1);
		return false;
	}

	if (arg == nr_args) {
		switch (prog->expected_attach_type) {
		case BPF_LSM_CGROUP:
		case BPF_LSM_MAC:
		case BPF_TRACE_FEXIT:
			/* When LSM programs are attached to void LSM hooks
			 * they use FEXIT trampolines and when attached to
			 * int LSM hooks, they use MODIFY_RETURN trampolines.
			 *
			 * While the LSM programs are BPF_MODIFY_RETURN-like
			 * the check:
			 *
			 *	if (ret_type != 'int')
			 *		return -EINVAL;
			 *
			 * is _not_ done here. This is still safe as LSM hooks
			 * have only void and int return types.
			 */
			if (!t)
				return true;
			t = btf_type_by_id(btf, t->type);
			break;
		case BPF_MODIFY_RETURN:
			/* For now the BPF_MODIFY_RETURN can only be attached to
			 * functions that return an int.
			 */
			if (!t)
				return false;

			t = btf_type_skip_modifiers(btf, t->type, NULL);
			if (!btf_type_is_small_int(t)) {
				bpf_log(log,
					"ret type %s not allowed for fmod_ret\n",
					btf_type_str(t));
				return false;
			}
			break;
		default:
			bpf_log(log, "func '%s' doesn't have %d-th argument\n",
				tname, arg + 1);
			return false;
		}
	} else {
		if (!t)
			/* Default prog with MAX_BPF_FUNC_REG_ARGS args */
			return true;
		t = btf_type_by_id(btf, args[arg].type);
	}

	/* skip modifiers */
	while (btf_type_is_modifier(t))
		t = btf_type_by_id(btf, t->type);
	if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
		/* accessing a scalar */
		return true;
	if (!btf_type_is_ptr(t)) {
		bpf_log(log,
			"func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
			tname, arg,
			__btf_name_by_offset(btf, t->name_off),
			btf_type_str(t));
		return false;
	}

	/* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
	for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
		const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
		u32 type, flag;

		type = base_type(ctx_arg_info->reg_type);
		flag = type_flag(ctx_arg_info->reg_type);
		if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
		    (flag & PTR_MAYBE_NULL)) {
			info->reg_type = ctx_arg_info->reg_type;
			return true;
		}
	}

	if (t->type == 0)
		/* This is a pointer to void.
		 * It is the same as scalar from the verifier safety pov.
		 * No further pointer walking is allowed.
		 */
		return true;

	if (is_int_ptr(btf, t))
		return true;

	/* this is a pointer to another type */
	for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
		const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];

		if (ctx_arg_info->offset == off) {
			if (!ctx_arg_info->btf_id) {
				bpf_log(log,"invalid btf_id for context argument offset %u\n", off);
				return false;
			}

			info->reg_type = ctx_arg_info->reg_type;
			info->btf = btf_vmlinux;
			info->btf_id = ctx_arg_info->btf_id;
			return true;
		}
	}

	info->reg_type = PTR_TO_BTF_ID;
	if (prog_args_trusted(prog))
		info->reg_type |= PTR_TRUSTED;

	if (tgt_prog) {
		enum bpf_prog_type tgt_type;

		if (tgt_prog->type == BPF_PROG_TYPE_EXT)
			tgt_type = tgt_prog->aux->saved_dst_prog_type;
		else
			tgt_type = tgt_prog->type;

		ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg);
		if (ret > 0) {
			info->btf = btf_vmlinux;
			info->btf_id = ret;
			return true;
		} else {
			return false;
		}
	}

	info->btf = btf;
	info->btf_id = t->type;
	t = btf_type_by_id(btf, t->type);

	if (btf_type_is_type_tag(t)) {
		tag_value = __btf_name_by_offset(btf, t->name_off);
		if (strcmp(tag_value, "user") == 0)
			info->reg_type |= MEM_USER;
		if (strcmp(tag_value, "percpu") == 0)
			info->reg_type |= MEM_PERCPU;
	}

	/* skip modifiers */
	while (btf_type_is_modifier(t)) {
		info->btf_id = t->type;
		t = btf_type_by_id(btf, t->type);
	}
	if (!btf_type_is_struct(t)) {
		bpf_log(log,
			"func '%s' arg%d type %s is not a struct\n",
			tname, arg, btf_type_str(t));
		return false;
	}
	bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
		tname, arg, info->btf_id, btf_type_str(t),
		__btf_name_by_offset(btf, t->name_off));
	return true;
}

enum bpf_struct_walk_result {
	/* < 0 error */
	WALK_SCALAR = 0,
	WALK_PTR,
	WALK_STRUCT,
};

static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
			   const struct btf_type *t, int off, int size,
			   u32 *next_btf_id, enum bpf_type_flag *flag,
			   const char **field_name)
{
	u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
	const struct btf_type *mtype, *elem_type = NULL;
	const struct btf_member *member;
	const char *tname, *mname, *tag_value;
	u32 vlen, elem_id, mid;

again:
	if (btf_type_is_modifier(t))
		t = btf_type_skip_modifiers(btf, t->type, NULL);
	tname = __btf_name_by_offset(btf, t->name_off);
	if (!btf_type_is_struct(t)) {
		bpf_log(log, "Type '%s' is not a struct\n", tname);
		return -EINVAL;
	}

	vlen = btf_type_vlen(t);
	if (BTF_INFO_KIND(t->info) == BTF_KIND_UNION && vlen != 1 && !(*flag & PTR_UNTRUSTED))
		/*
		 * walking unions yields untrusted pointers
		 * with exception of __bpf_md_ptr and other
		 * unions with a single member
		 */
		*flag |= PTR_UNTRUSTED;

	if (off + size > t->size) {
		/* If the last element is a variable size array, we may
		 * need to relax the rule.
		 */
		struct btf_array *array_elem;

		if (vlen == 0)
			goto error;

		member = btf_type_member(t) + vlen - 1;
		mtype = btf_type_skip_modifiers(btf, member->type,
						NULL);
		if (!btf_type_is_array(mtype))
			goto error;

		array_elem = (struct btf_array *)(mtype + 1);
		if (array_elem->nelems != 0)
			goto error;

		moff = __btf_member_bit_offset(t, member) / 8;
		if (off < moff)
			goto error;

		/* allow structure and integer */
		t = btf_type_skip_modifiers(btf, array_elem->type,
					    NULL);

		if (btf_type_is_int(t))
			return WALK_SCALAR;

		if (!btf_type_is_struct(t))
			goto error;

		off = (off - moff) % t->size;
		goto again;

error:
		bpf_log(log, "access beyond struct %s at off %u size %u\n",
			tname, off, size);
		return -EACCES;
	}

	for_each_member(i, t, member) {
		/* offset of the field in bytes */
		moff = __btf_member_bit_offset(t, member) / 8;
		if (off + size <= moff)
			/* won't find anything, field is already too far */
			break;

		if (__btf_member_bitfield_size(t, member)) {
			u32 end_bit = __btf_member_bit_offset(t, member) +
				__btf_member_bitfield_size(t, member);

			/* off <= moff instead of off == moff because clang
			 * does not generate a BTF member for anonymous
			 * bitfield like the ":16" here:
			 * struct {
			 *	int :16;
			 *	int x:8;
			 * };
			 */
			if (off <= moff &&
			    BITS_ROUNDUP_BYTES(end_bit) <= off + size)
				return WALK_SCALAR;

			/* off may be accessing a following member
			 *
			 * or
			 *
			 * Doing partial access at either end of this
			 * bitfield.  Continue on this case also to
			 * treat it as not accessing this bitfield
			 * and eventually error out as field not
			 * found to keep it simple.
			 * It could be relaxed if there was a legit
			 * partial access case later.
			 */
			continue;
		}

		/* In case of "off" is pointing to holes of a struct */
		if (off < moff)
			break;

		/* type of the field */
		mid = member->type;
		mtype = btf_type_by_id(btf, member->type);
		mname = __btf_name_by_offset(btf, member->name_off);

		mtype = __btf_resolve_size(btf, mtype, &msize,
					   &elem_type, &elem_id, &total_nelems,
					   &mid);
		if (IS_ERR(mtype)) {
			bpf_log(log, "field %s doesn't have size\n", mname);
			return -EFAULT;
		}

		mtrue_end = moff + msize;
		if (off >= mtrue_end)
			/* no overlap with member, keep iterating */
			continue;

		if (btf_type_is_array(mtype)) {
			u32 elem_idx;

			/* __btf_resolve_size() above helps to
			 * linearize a multi-dimensional array.
			 *
			 * The logic here is treating an array
			 * in a struct as the following way:
			 *
			 * struct outer {
			 *	struct inner array[2][2];
			 * };
			 *
			 * looks like:
			 *
			 * struct outer {
			 *	struct inner array_elem0;
			 *	struct inner array_elem1;
			 *	struct inner array_elem2;
			 *	struct inner array_elem3;
			 * };
			 *
			 * When accessing outer->array[1][0], it moves
			 * moff to "array_elem2", set mtype to
			 * "struct inner", and msize also becomes
			 * sizeof(struct inner).  Then most of the
			 * remaining logic will fall through without
			 * caring the current member is an array or
			 * not.
			 *
			 * Unlike mtype/msize/moff, mtrue_end does not
			 * change.  The naming difference ("_true") tells
			 * that it is not always corresponding to
			 * the current mtype/msize/moff.
			 * It is the true end of the current
			 * member (i.e. array in this case).  That
			 * will allow an int array to be accessed like
			 * a scratch space,
			 * i.e. allow access beyond the size of
			 *      the array's element as long as it is
			 *      within the mtrue_end boundary.
			 */

			/* skip empty array */
			if (moff == mtrue_end)
				continue;

			msize /= total_nelems;
			elem_idx = (off - moff) / msize;
			moff += elem_idx * msize;
			mtype = elem_type;
			mid = elem_id;
		}

		/* the 'off' we're looking for is either equal to start
		 * of this field or inside of this struct
		 */
		if (btf_type_is_struct(mtype)) {
			/* our field must be inside that union or struct */
			t = mtype;

			/* return if the offset matches the member offset */
			if (off == moff) {
				*next_btf_id = mid;
				return WALK_STRUCT;
			}

			/* adjust offset we're looking for */
			off -= moff;
			goto again;
		}

		if (btf_type_is_ptr(mtype)) {
			const struct btf_type *stype, *t;
			enum bpf_type_flag tmp_flag = 0;
			u32 id;

			if (msize != size || off != moff) {
				bpf_log(log,
					"cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
					mname, moff, tname, off, size);
				return -EACCES;
			}

			/* check type tag */
			t = btf_type_by_id(btf, mtype->type);
			if (btf_type_is_type_tag(t)) {
				tag_value = __btf_name_by_offset(btf, t->name_off);
				/* check __user tag */
				if (strcmp(tag_value, "user") == 0)
					tmp_flag = MEM_USER;
				/* check __percpu tag */
				if (strcmp(tag_value, "percpu") == 0)
					tmp_flag = MEM_PERCPU;
				/* check __rcu tag */
				if (strcmp(tag_value, "rcu") == 0)
					tmp_flag = MEM_RCU;
			}

			stype = btf_type_skip_modifiers(btf, mtype->type, &id);
			if (btf_type_is_struct(stype)) {
				*next_btf_id = id;
				*flag |= tmp_flag;
				if (field_name)
					*field_name = mname;
				return WALK_PTR;
			}
		}

		/* Allow more flexible access within an int as long as
		 * it is within mtrue_end.
		 * Since mtrue_end could be the end of an array,
		 * that also allows using an array of int as a scratch
		 * space. e.g. skb->cb[].
		 */
		if (off + size > mtrue_end && !(*flag & PTR_UNTRUSTED)) {
			bpf_log(log,
				"access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
				mname, mtrue_end, tname, off, size);
			return -EACCES;
		}

		return WALK_SCALAR;
	}
	bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
	return -EINVAL;
}

int btf_struct_access(struct bpf_verifier_log *log,
		      const struct bpf_reg_state *reg,
		      int off, int size, enum bpf_access_type atype __maybe_unused,
		      u32 *next_btf_id, enum bpf_type_flag *flag,
		      const char **field_name)
{
	const struct btf *btf = reg->btf;
	enum bpf_type_flag tmp_flag = 0;
	const struct btf_type *t;
	u32 id = reg->btf_id;
	int err;

	while (type_is_alloc(reg->type)) {
		struct btf_struct_meta *meta;
		struct btf_record *rec;
		int i;

		meta = btf_find_struct_meta(btf, id);
		if (!meta)
			break;
		rec = meta->record;
		for (i = 0; i < rec->cnt; i++) {
			struct btf_field *field = &rec->fields[i];
			u32 offset = field->offset;
			if (off < offset + btf_field_type_size(field->type) && offset < off + size) {
				bpf_log(log,
					"direct access to %s is disallowed\n",
					btf_field_type_name(field->type));
				return -EACCES;
			}
		}
		break;
	}

	t = btf_type_by_id(btf, id);
	do {
		err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag, field_name);

		switch (err) {
		case WALK_PTR:
			/* For local types, the destination register cannot
			 * become a pointer again.
			 */
			if (type_is_alloc(reg->type))
				return SCALAR_VALUE;
			/* If we found the pointer or scalar on t+off,
			 * we're done.
			 */
			*next_btf_id = id;
			*flag = tmp_flag;
			return PTR_TO_BTF_ID;
		case WALK_SCALAR:
			return SCALAR_VALUE;
		case WALK_STRUCT:
			/* We found nested struct, so continue the search
			 * by diving in it. At this point the offset is
			 * aligned with the new type, so set it to 0.
			 */
			t = btf_type_by_id(btf, id);
			off = 0;
			break;
		default:
			/* It's either error or unknown return value..
			 * scream and leave.
			 */
			if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
				return -EINVAL;
			return err;
		}
	} while (t);

	return -EINVAL;
}

/* Check that two BTF types, each specified as an BTF object + id, are exactly
 * the same. Trivial ID check is not enough due to module BTFs, because we can
 * end up with two different module BTFs, but IDs point to the common type in
 * vmlinux BTF.
 */
bool btf_types_are_same(const struct btf *btf1, u32 id1,
			const struct btf *btf2, u32 id2)
{
	if (id1 != id2)
		return false;
	if (btf1 == btf2)
		return true;
	return btf_type_by_id(btf1, id1) == btf_type_by_id(btf2, id2);
}

bool btf_struct_ids_match(struct bpf_verifier_log *log,
			  const struct btf *btf, u32 id, int off,
			  const struct btf *need_btf, u32 need_type_id,
			  bool strict)
{
	const struct btf_type *type;
	enum bpf_type_flag flag = 0;
	int err;

	/* Are we already done? */
	if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id))
		return true;
	/* In case of strict type match, we do not walk struct, the top level
	 * type match must succeed. When strict is true, off should have already
	 * been 0.
	 */
	if (strict)
		return false;
again:
	type = btf_type_by_id(btf, id);
	if (!type)
		return false;
	err = btf_struct_walk(log, btf, type, off, 1, &id, &flag, NULL);
	if (err != WALK_STRUCT)
		return false;

	/* We found nested struct object. If it matches
	 * the requested ID, we're done. Otherwise let's
	 * continue the search with offset 0 in the new
	 * type.
	 */
	if (!btf_types_are_same(btf, id, need_btf, need_type_id)) {
		off = 0;
		goto again;
	}

	return true;
}

static int __get_type_size(struct btf *btf, u32 btf_id,
			   const struct btf_type **ret_type)
{
	const struct btf_type *t;

	*ret_type = btf_type_by_id(btf, 0);
	if (!btf_id)
		/* void */
		return 0;
	t = btf_type_by_id(btf, btf_id);
	while (t && btf_type_is_modifier(t))
		t = btf_type_by_id(btf, t->type);
	if (!t)
		return -EINVAL;
	*ret_type = t;
	if (btf_type_is_ptr(t))
		/* kernel size of pointer. Not BPF's size of pointer*/
		return sizeof(void *);
	if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
		return t->size;
	return -EINVAL;
}

static u8 __get_type_fmodel_flags(const struct btf_type *t)
{
	u8 flags = 0;

	if (__btf_type_is_struct(t))
		flags |= BTF_FMODEL_STRUCT_ARG;
	if (btf_type_is_signed_int(t))
		flags |= BTF_FMODEL_SIGNED_ARG;

	return flags;
}

int btf_distill_func_proto(struct bpf_verifier_log *log,
			   struct btf *btf,
			   const struct btf_type *func,
			   const char *tname,
			   struct btf_func_model *m)
{
	const struct btf_param *args;
	const struct btf_type *t;
	u32 i, nargs;
	int ret;

	if (!func) {
		/* BTF function prototype doesn't match the verifier types.
		 * Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
		 */
		for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
			m->arg_size[i] = 8;
			m->arg_flags[i] = 0;
		}
		m->ret_size = 8;
		m->ret_flags = 0;
		m->nr_args = MAX_BPF_FUNC_REG_ARGS;
		return 0;
	}
	args = (const struct btf_param *)(func + 1);
	nargs = btf_type_vlen(func);
	if (nargs > MAX_BPF_FUNC_ARGS) {
		bpf_log(log,
			"The function %s has %d arguments. Too many.\n",
			tname, nargs);
		return -EINVAL;
	}
	ret = __get_type_size(btf, func->type, &t);
	if (ret < 0 || __btf_type_is_struct(t)) {
		bpf_log(log,
			"The function %s return type %s is unsupported.\n",
			tname, btf_type_str(t));
		return -EINVAL;
	}
	m->ret_size = ret;
	m->ret_flags = __get_type_fmodel_flags(t);

	for (i = 0; i < nargs; i++) {
		if (i == nargs - 1 && args[i].type == 0) {
			bpf_log(log,
				"The function %s with variable args is unsupported.\n",
				tname);
			return -EINVAL;
		}
		ret = __get_type_size(btf, args[i].type, &t);

		/* No support of struct argument size greater than 16 bytes */
		if (ret < 0 || ret > 16) {
			bpf_log(log,
				"The function %s arg%d type %s is unsupported.\n",
				tname, i, btf_type_str(t));
			return -EINVAL;
		}
		if (ret == 0) {
			bpf_log(log,
				"The function %s has malformed void argument.\n",
				tname);
			return -EINVAL;
		}
		m->arg_size[i] = ret;
		m->arg_flags[i] = __get_type_fmodel_flags(t);
	}
	m->nr_args = nargs;
	return 0;
}

/* Compare BTFs of two functions assuming only scalars and pointers to context.
 * t1 points to BTF_KIND_FUNC in btf1
 * t2 points to BTF_KIND_FUNC in btf2
 * Returns:
 * EINVAL - function prototype mismatch
 * EFAULT - verifier bug
 * 0 - 99% match. The last 1% is validated by the verifier.
 */
static int btf_check_func_type_match(struct bpf_verifier_log *log,
				     struct btf *btf1, const struct btf_type *t1,
				     struct btf *btf2, const struct btf_type *t2)
{
	const struct btf_param *args1, *args2;
	const char *fn1, *fn2, *s1, *s2;
	u32 nargs1, nargs2, i;

	fn1 = btf_name_by_offset(btf1, t1->name_off);
	fn2 = btf_name_by_offset(btf2, t2->name_off);

	if (btf_func_linkage(t1) != BTF_FUNC_GLOBAL) {
		bpf_log(log, "%s() is not a global function\n", fn1);
		return -EINVAL;
	}
	if (btf_func_linkage(t2) != BTF_FUNC_GLOBAL) {
		bpf_log(log, "%s() is not a global function\n", fn2);
		return -EINVAL;
	}

	t1 = btf_type_by_id(btf1, t1->type);
	if (!t1 || !btf_type_is_func_proto(t1))
		return -EFAULT;
	t2 = btf_type_by_id(btf2, t2->type);
	if (!t2 || !btf_type_is_func_proto(t2))
		return -EFAULT;

	args1 = (const struct btf_param *)(t1 + 1);
	nargs1 = btf_type_vlen(t1);
	args2 = (const struct btf_param *)(t2 + 1);
	nargs2 = btf_type_vlen(t2);

	if (nargs1 != nargs2) {
		bpf_log(log, "%s() has %d args while %s() has %d args\n",
			fn1, nargs1, fn2, nargs2);
		return -EINVAL;
	}

	t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
	t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
	if (t1->info != t2->info) {
		bpf_log(log,
			"Return type %s of %s() doesn't match type %s of %s()\n",
			btf_type_str(t1), fn1,
			btf_type_str(t2), fn2);
		return -EINVAL;
	}

	for (i = 0; i < nargs1; i++) {
		t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
		t2 = btf_type_skip_modifiers(btf2, args2[i].type, NULL);

		if (t1->info != t2->info) {
			bpf_log(log, "arg%d in %s() is %s while %s() has %s\n",
				i, fn1, btf_type_str(t1),
				fn2, btf_type_str(t2));
			return -EINVAL;
		}
		if (btf_type_has_size(t1) && t1->size != t2->size) {
			bpf_log(log,
				"arg%d in %s() has size %d while %s() has %d\n",
				i, fn1, t1->size,
				fn2, t2->size);
			return -EINVAL;
		}

		/* global functions are validated with scalars and pointers
		 * to context only. And only global functions can be replaced.
		 * Hence type check only those types.
		 */
		if (btf_type_is_int(t1) || btf_is_any_enum(t1))
			continue;
		if (!btf_type_is_ptr(t1)) {
			bpf_log(log,
				"arg%d in %s() has unrecognized type\n",
				i, fn1);
			return -EINVAL;
		}
		t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
		t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
		if (!btf_type_is_struct(t1)) {
			bpf_log(log,
				"arg%d in %s() is not a pointer to context\n",
				i, fn1);
			return -EINVAL;
		}
		if (!btf_type_is_struct(t2)) {
			bpf_log(log,
				"arg%d in %s() is not a pointer to context\n",
				i, fn2);
			return -EINVAL;
		}
		/* This is an optional check to make program writing easier.
		 * Compare names of structs and report an error to the user.
		 * btf_prepare_func_args() already checked that t2 struct
		 * is a context type. btf_prepare_func_args() will check
		 * later that t1 struct is a context type as well.
		 */
		s1 = btf_name_by_offset(btf1, t1->name_off);
		s2 = btf_name_by_offset(btf2, t2->name_off);
		if (strcmp(s1, s2)) {
			bpf_log(log,
				"arg%d %s(struct %s *) doesn't match %s(struct %s *)\n",
				i, fn1, s1, fn2, s2);
			return -EINVAL;
		}
	}
	return 0;
}

/* Compare BTFs of given program with BTF of target program */
int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
			 struct btf *btf2, const struct btf_type *t2)
{
	struct btf *btf1 = prog->aux->btf;
	const struct btf_type *t1;
	u32 btf_id = 0;

	if (!prog->aux->func_info) {
		bpf_log(log, "Program extension requires BTF\n");
		return -EINVAL;
	}

	btf_id = prog->aux->func_info[0].type_id;
	if (!btf_id)
		return -EFAULT;

	t1 = btf_type_by_id(btf1, btf_id);
	if (!t1 || !btf_type_is_func(t1))
		return -EFAULT;

	return btf_check_func_type_match(log, btf1, t1, btf2, t2);
}

static int btf_check_func_arg_match(struct bpf_verifier_env *env,
				    const struct btf *btf, u32 func_id,
				    struct bpf_reg_state *regs,
				    bool ptr_to_mem_ok,
				    bool processing_call)
{
	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
	struct bpf_verifier_log *log = &env->log;
	const char *func_name, *ref_tname;
	const struct btf_type *t, *ref_t;
	const struct btf_param *args;
	u32 i, nargs, ref_id;
	int ret;

	t = btf_type_by_id(btf, func_id);
	if (!t || !btf_type_is_func(t)) {
		/* These checks were already done by the verifier while loading
		 * struct bpf_func_info or in add_kfunc_call().
		 */
		bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
			func_id);
		return -EFAULT;
	}
	func_name = btf_name_by_offset(btf, t->name_off);

	t = btf_type_by_id(btf, t->type);
	if (!t || !btf_type_is_func_proto(t)) {
		bpf_log(log, "Invalid BTF of func %s\n", func_name);
		return -EFAULT;
	}
	args = (const struct btf_param *)(t + 1);
	nargs = btf_type_vlen(t);
	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
		bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
			MAX_BPF_FUNC_REG_ARGS);
		return -EINVAL;
	}

	/* check that BTF function arguments match actual types that the
	 * verifier sees.
	 */
	for (i = 0; i < nargs; i++) {
		enum bpf_arg_type arg_type = ARG_DONTCARE;
		u32 regno = i + 1;
		struct bpf_reg_state *reg = &regs[regno];

		t = btf_type_skip_modifiers(btf, args[i].type, NULL);
		if (btf_type_is_scalar(t)) {
			if (reg->type == SCALAR_VALUE)
				continue;
			bpf_log(log, "R%d is not a scalar\n", regno);
			return -EINVAL;
		}

		if (!btf_type_is_ptr(t)) {
			bpf_log(log, "Unrecognized arg#%d type %s\n",
				i, btf_type_str(t));
			return -EINVAL;
		}

		ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
		ref_tname = btf_name_by_offset(btf, ref_t->name_off);

		ret = check_func_arg_reg_off(env, reg, regno, arg_type);
		if (ret < 0)
			return ret;

		if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
			/* If function expects ctx type in BTF check that caller
			 * is passing PTR_TO_CTX.
			 */
			if (reg->type != PTR_TO_CTX) {
				bpf_log(log,
					"arg#%d expected pointer to ctx, but got %s\n",
					i, btf_type_str(t));
				return -EINVAL;
			}
		} else if (ptr_to_mem_ok && processing_call) {
			const struct btf_type *resolve_ret;
			u32 type_size;

			resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
			if (IS_ERR(resolve_ret)) {
				bpf_log(log,
					"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
					i, btf_type_str(ref_t), ref_tname,
					PTR_ERR(resolve_ret));
				return -EINVAL;
			}

			if (check_mem_reg(env, reg, regno, type_size))
				return -EINVAL;
		} else {
			bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i,
				func_name, func_id);
			return -EINVAL;
		}
	}

	return 0;
}

/* Compare BTF of a function declaration with given bpf_reg_state.
 * Returns:
 * EFAULT - there is a verifier bug. Abort verification.
 * EINVAL - there is a type mismatch or BTF is not available.
 * 0 - BTF matches with what bpf_reg_state expects.
 * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
 */
int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog,
				struct bpf_reg_state *regs)
{
	struct bpf_prog *prog = env->prog;
	struct btf *btf = prog->aux->btf;
	bool is_global;
	u32 btf_id;
	int err;

	if (!prog->aux->func_info)
		return -EINVAL;

	btf_id = prog->aux->func_info[subprog].type_id;
	if (!btf_id)
		return -EFAULT;

	if (prog->aux->func_info_aux[subprog].unreliable)
		return -EINVAL;

	is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
	err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, false);

	/* Compiler optimizations can remove arguments from static functions
	 * or mismatched type can be passed into a global function.
	 * In such cases mark the function as unreliable from BTF point of view.
	 */
	if (err)
		prog->aux->func_info_aux[subprog].unreliable = true;
	return err;
}

/* Compare BTF of a function call with given bpf_reg_state.
 * Returns:
 * EFAULT - there is a verifier bug. Abort verification.
 * EINVAL - there is a type mismatch or BTF is not available.
 * 0 - BTF matches with what bpf_reg_state expects.
 * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
 *
 * NOTE: the code is duplicated from btf_check_subprog_arg_match()
 * because btf_check_func_arg_match() is still doing both. Once that
 * function is split in 2, we can call from here btf_check_subprog_arg_match()
 * first, and then treat the calling part in a new code path.
 */
int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
			   struct bpf_reg_state *regs)
{
	struct bpf_prog *prog = env->prog;
	struct btf *btf = prog->aux->btf;
	bool is_global;
	u32 btf_id;
	int err;

	if (!prog->aux->func_info)
		return -EINVAL;

	btf_id = prog->aux->func_info[subprog].type_id;
	if (!btf_id)
		return -EFAULT;

	if (prog->aux->func_info_aux[subprog].unreliable)
		return -EINVAL;

	is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
	err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, true);

	/* Compiler optimizations can remove arguments from static functions
	 * or mismatched type can be passed into a global function.
	 * In such cases mark the function as unreliable from BTF point of view.
	 */
	if (err)
		prog->aux->func_info_aux[subprog].unreliable = true;
	return err;
}

/* Convert BTF of a function into bpf_reg_state if possible
 * Returns:
 * EFAULT - there is a verifier bug. Abort verification.
 * EINVAL - cannot convert BTF.
 * 0 - Successfully converted BTF into bpf_reg_state
 * (either PTR_TO_CTX or SCALAR_VALUE).
 */
int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
			  struct bpf_reg_state *regs)
{
	struct bpf_verifier_log *log = &env->log;
	struct bpf_prog *prog = env->prog;
	enum bpf_prog_type prog_type = prog->type;
	struct btf *btf = prog->aux->btf;
	const struct btf_param *args;
	const struct btf_type *t, *ref_t;
	u32 i, nargs, btf_id;
	const char *tname;

	if (!prog->aux->func_info ||
	    prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) {
		bpf_log(log, "Verifier bug\n");
		return -EFAULT;
	}

	btf_id = prog->aux->func_info[subprog].type_id;
	if (!btf_id) {
		bpf_log(log, "Global functions need valid BTF\n");
		return -EFAULT;
	}

	t = btf_type_by_id(btf, btf_id);
	if (!t || !btf_type_is_func(t)) {
		/* These checks were already done by the verifier while loading
		 * struct bpf_func_info
		 */
		bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
			subprog);
		return -EFAULT;
	}
	tname = btf_name_by_offset(btf, t->name_off);

	if (log->level & BPF_LOG_LEVEL)
		bpf_log(log, "Validating %s() func#%d...\n",
			tname, subprog);

	if (prog->aux->func_info_aux[subprog].unreliable) {
		bpf_log(log, "Verifier bug in function %s()\n", tname);
		return -EFAULT;
	}
	if (prog_type == BPF_PROG_TYPE_EXT)
		prog_type = prog->aux->dst_prog->type;

	t = btf_type_by_id(btf, t->type);
	if (!t || !btf_type_is_func_proto(t)) {
		bpf_log(log, "Invalid type of function %s()\n", tname);
		return -EFAULT;
	}
	args = (const struct btf_param *)(t + 1);
	nargs = btf_type_vlen(t);
	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
		bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
			tname, nargs, MAX_BPF_FUNC_REG_ARGS);
		return -EINVAL;
	}
	/* check that function returns int */
	t = btf_type_by_id(btf, t->type);
	while (btf_type_is_modifier(t))
		t = btf_type_by_id(btf, t->type);
	if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
		bpf_log(log,
			"Global function %s() doesn't return scalar. Only those are supported.\n",
			tname);
		return -EINVAL;
	}
	/* Convert BTF function arguments into verifier types.
	 * Only PTR_TO_CTX and SCALAR are supported atm.
	 */
	for (i = 0; i < nargs; i++) {
		struct bpf_reg_state *reg = &regs[i + 1];

		t = btf_type_by_id(btf, args[i].type);
		while (btf_type_is_modifier(t))
			t = btf_type_by_id(btf, t->type);
		if (btf_type_is_int(t) || btf_is_any_enum(t)) {
			reg->type = SCALAR_VALUE;
			continue;
		}
		if (btf_type_is_ptr(t)) {
			if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
				reg->type = PTR_TO_CTX;
				continue;
			}

			t = btf_type_skip_modifiers(btf, t->type, NULL);

			ref_t = btf_resolve_size(btf, t, &reg->mem_size);
			if (IS_ERR(ref_t)) {
				bpf_log(log,
				    "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
				    i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
					PTR_ERR(ref_t));
				return -EINVAL;
			}

			reg->type = PTR_TO_MEM | PTR_MAYBE_NULL;
			reg->id = ++env->id_gen;

			continue;
		}
		bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
			i, btf_type_str(t), tname);
		return -EINVAL;
	}
	return 0;
}

static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
			  struct btf_show *show)
{
	const struct btf_type *t = btf_type_by_id(btf, type_id);

	show->btf = btf;
	memset(&show->state, 0, sizeof(show->state));
	memset(&show->obj, 0, sizeof(show->obj));

	btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
}

static void btf_seq_show(struct btf_show *show, const char *fmt,
			 va_list args)
{
	seq_vprintf((struct seq_file *)show->target, fmt, args);
}

int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
			    void *obj, struct seq_file *m, u64 flags)
{
	struct btf_show sseq;

	sseq.target = m;
	sseq.showfn = btf_seq_show;
	sseq.flags = flags;

	btf_type_show(btf, type_id, obj, &sseq);

	return sseq.state.status;
}

void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
		       struct seq_file *m)
{
	(void) btf_type_seq_show_flags(btf, type_id, obj, m,
				       BTF_SHOW_NONAME | BTF_SHOW_COMPACT |
				       BTF_SHOW_ZERO | BTF_SHOW_UNSAFE);
}

struct btf_show_snprintf {
	struct btf_show show;
	int len_left;		/* space left in string */
	int len;		/* length we would have written */
};

static void btf_snprintf_show(struct btf_show *show, const char *fmt,
			      va_list args)
{
	struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
	int len;

	len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);

	if (len < 0) {
		ssnprintf->len_left = 0;
		ssnprintf->len = len;
	} else if (len >= ssnprintf->len_left) {
		/* no space, drive on to get length we would have written */
		ssnprintf->len_left = 0;
		ssnprintf->len += len;
	} else {
		ssnprintf->len_left -= len;
		ssnprintf->len += len;
		show->target += len;
	}
}

int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
			   char *buf, int len, u64 flags)
{
	struct btf_show_snprintf ssnprintf;

	ssnprintf.show.target = buf;
	ssnprintf.show.flags = flags;
	ssnprintf.show.showfn = btf_snprintf_show;
	ssnprintf.len_left = len;
	ssnprintf.len = 0;

	btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf);

	/* If we encountered an error, return it. */
	if (ssnprintf.show.state.status)
		return ssnprintf.show.state.status;

	/* Otherwise return length we would have written */
	return ssnprintf.len;
}

#ifdef CONFIG_PROC_FS
static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
{
	const struct btf *btf = filp->private_data;

	seq_printf(m, "btf_id:\t%u\n", btf->id);
}
#endif

static int btf_release(struct inode *inode, struct file *filp)
{
	btf_put(filp->private_data);
	return 0;
}

const struct file_operations btf_fops = {
#ifdef CONFIG_PROC_FS
	.show_fdinfo	= bpf_btf_show_fdinfo,
#endif
	.release	= btf_release,
};

static int __btf_new_fd(struct btf *btf)
{
	return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
}

int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
{
	struct btf *btf;
	int ret;

	btf = btf_parse(attr, uattr, uattr_size);
	if (IS_ERR(btf))
		return PTR_ERR(btf);

	ret = btf_alloc_id(btf);
	if (ret) {
		btf_free(btf);
		return ret;
	}

	/*
	 * The BTF ID is published to the userspace.
	 * All BTF free must go through call_rcu() from
	 * now on (i.e. free by calling btf_put()).
	 */

	ret = __btf_new_fd(btf);
	if (ret < 0)
		btf_put(btf);

	return ret;
}

struct btf *btf_get_by_fd(int fd)
{
	struct btf *btf;
	struct fd f;

	f = fdget(fd);

	if (!f.file)
		return ERR_PTR(-EBADF);

	if (f.file->f_op != &btf_fops) {
		fdput(f);
		return ERR_PTR(-EINVAL);
	}

	btf = f.file->private_data;
	refcount_inc(&btf->refcnt);
	fdput(f);

	return btf;
}

int btf_get_info_by_fd(const struct btf *btf,
		       const union bpf_attr *attr,
		       union bpf_attr __user *uattr)
{
	struct bpf_btf_info __user *uinfo;
	struct bpf_btf_info info;
	u32 info_copy, btf_copy;
	void __user *ubtf;
	char __user *uname;
	u32 uinfo_len, uname_len, name_len;
	int ret = 0;

	uinfo = u64_to_user_ptr(attr->info.info);
	uinfo_len = attr->info.info_len;

	info_copy = min_t(u32, uinfo_len, sizeof(info));
	memset(&info, 0, sizeof(info));
	if (copy_from_user(&info, uinfo, info_copy))
		return -EFAULT;

	info.id = btf->id;
	ubtf = u64_to_user_ptr(info.btf);
	btf_copy = min_t(u32, btf->data_size, info.btf_size);
	if (copy_to_user(ubtf, btf->data, btf_copy))
		return -EFAULT;
	info.btf_size = btf->data_size;

	info.kernel_btf = btf->kernel_btf;

	uname = u64_to_user_ptr(info.name);
	uname_len = info.name_len;
	if (!uname ^ !uname_len)
		return -EINVAL;

	name_len = strlen(btf->name);
	info.name_len = name_len;

	if (uname) {
		if (uname_len >= name_len + 1) {
			if (copy_to_user(uname, btf->name, name_len + 1))
				return -EFAULT;
		} else {
			char zero = '\0';

			if (copy_to_user(uname, btf->name, uname_len - 1))
				return -EFAULT;
			if (put_user(zero, uname + uname_len - 1))
				return -EFAULT;
			/* let user-space know about too short buffer */
			ret = -ENOSPC;
		}
	}

	if (copy_to_user(uinfo, &info, info_copy) ||
	    put_user(info_copy, &uattr->info.info_len))
		return -EFAULT;

	return ret;
}

int btf_get_fd_by_id(u32 id)
{
	struct btf *btf;
	int fd;

	rcu_read_lock();
	btf = idr_find(&btf_idr, id);
	if (!btf || !refcount_inc_not_zero(&btf->refcnt))
		btf = ERR_PTR(-ENOENT);
	rcu_read_unlock();

	if (IS_ERR(btf))
		return PTR_ERR(btf);

	fd = __btf_new_fd(btf);
	if (fd < 0)
		btf_put(btf);

	return fd;
}

u32 btf_obj_id(const struct btf *btf)
{
	return btf->id;
}

bool btf_is_kernel(const struct btf *btf)
{
	return btf->kernel_btf;
}

bool btf_is_module(const struct btf *btf)
{
	return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0;
}

enum {
	BTF_MODULE_F_LIVE = (1 << 0),
};

#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module {
	struct list_head list;
	struct module *module;
	struct btf *btf;
	struct bin_attribute *sysfs_attr;
	int flags;
};

static LIST_HEAD(btf_modules);
static DEFINE_MUTEX(btf_module_mutex);

static ssize_t
btf_module_read(struct file *file, struct kobject *kobj,
		struct bin_attribute *bin_attr,
		char *buf, loff_t off, size_t len)
{
	const struct btf *btf = bin_attr->private;

	memcpy(buf, btf->data + off, len);
	return len;
}

static void purge_cand_cache(struct btf *btf);

static int btf_module_notify(struct notifier_block *nb, unsigned long op,
			     void *module)
{
	struct btf_module *btf_mod, *tmp;
	struct module *mod = module;
	struct btf *btf;
	int err = 0;

	if (mod->btf_data_size == 0 ||
	    (op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE &&
	     op != MODULE_STATE_GOING))
		goto out;

	switch (op) {
	case MODULE_STATE_COMING:
		btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL);
		if (!btf_mod) {
			err = -ENOMEM;
			goto out;
		}
		btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size);
		if (IS_ERR(btf)) {
			kfree(btf_mod);
			if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
				pr_warn("failed to validate module [%s] BTF: %ld\n",
					mod->name, PTR_ERR(btf));
				err = PTR_ERR(btf);
			} else {
				pr_warn_once("Kernel module BTF mismatch detected, BTF debug info may be unavailable for some modules\n");
			}
			goto out;
		}
		err = btf_alloc_id(btf);
		if (err) {
			btf_free(btf);
			kfree(btf_mod);
			goto out;
		}

		purge_cand_cache(NULL);
		mutex_lock(&btf_module_mutex);
		btf_mod->module = module;
		btf_mod->btf = btf;
		list_add(&btf_mod->list, &btf_modules);
		mutex_unlock(&btf_module_mutex);

		if (IS_ENABLED(CONFIG_SYSFS)) {
			struct bin_attribute *attr;

			attr = kzalloc(sizeof(*attr), GFP_KERNEL);
			if (!attr)
				goto out;

			sysfs_bin_attr_init(attr);
			attr->attr.name = btf->name;
			attr->attr.mode = 0444;
			attr->size = btf->data_size;
			attr->private = btf;
			attr->read = btf_module_read;

			err = sysfs_create_bin_file(btf_kobj, attr);
			if (err) {
				pr_warn("failed to register module [%s] BTF in sysfs: %d\n",
					mod->name, err);
				kfree(attr);
				err = 0;
				goto out;
			}

			btf_mod->sysfs_attr = attr;
		}

		break;
	case MODULE_STATE_LIVE:
		mutex_lock(&btf_module_mutex);
		list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
			if (btf_mod->module != module)
				continue;

			btf_mod->flags |= BTF_MODULE_F_LIVE;
			break;
		}
		mutex_unlock(&btf_module_mutex);
		break;
	case MODULE_STATE_GOING:
		mutex_lock(&btf_module_mutex);
		list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
			if (btf_mod->module != module)
				continue;

			list_del(&btf_mod->list);
			if (btf_mod->sysfs_attr)
				sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
			purge_cand_cache(btf_mod->btf);
			btf_put(btf_mod->btf);
			kfree(btf_mod->sysfs_attr);
			kfree(btf_mod);
			break;
		}
		mutex_unlock(&btf_module_mutex);
		break;
	}
out:
	return notifier_from_errno(err);
}

static struct notifier_block btf_module_nb = {
	.notifier_call = btf_module_notify,
};

static int __init btf_module_init(void)
{
	register_module_notifier(&btf_module_nb);
	return 0;
}

fs_initcall(btf_module_init);
#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */

struct module *btf_try_get_module(const struct btf *btf)
{
	struct module *res = NULL;
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
	struct btf_module *btf_mod, *tmp;

	mutex_lock(&btf_module_mutex);
	list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
		if (btf_mod->btf != btf)
			continue;

		/* We must only consider module whose __init routine has
		 * finished, hence we must check for BTF_MODULE_F_LIVE flag,
		 * which is set from the notifier callback for
		 * MODULE_STATE_LIVE.
		 */
		if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module))
			res = btf_mod->module;

		break;
	}
	mutex_unlock(&btf_module_mutex);
#endif

	return res;
}

/* Returns struct btf corresponding to the struct module.
 * This function can return NULL or ERR_PTR.
 */
static struct btf *btf_get_module_btf(const struct module *module)
{
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
	struct btf_module *btf_mod, *tmp;
#endif
	struct btf *btf = NULL;

	if (!module) {
		btf = bpf_get_btf_vmlinux();
		if (!IS_ERR_OR_NULL(btf))
			btf_get(btf);
		return btf;
	}

#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
	mutex_lock(&btf_module_mutex);
	list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
		if (btf_mod->module != module)
			continue;

		btf_get(btf_mod->btf);
		btf = btf_mod->btf;
		break;
	}
	mutex_unlock(&btf_module_mutex);
#endif

	return btf;
}

BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
{
	struct btf *btf = NULL;
	int btf_obj_fd = 0;
	long ret;

	if (flags)
		return -EINVAL;

	if (name_sz <= 1 || name[name_sz - 1])
		return -EINVAL;

	ret = bpf_find_btf_id(name, kind, &btf);
	if (ret > 0 && btf_is_module(btf)) {
		btf_obj_fd = __btf_new_fd(btf);
		if (btf_obj_fd < 0) {
			btf_put(btf);
			return btf_obj_fd;
		}
		return ret | (((u64)btf_obj_fd) << 32);
	}
	if (ret > 0)
		btf_put(btf);
	return ret;
}

const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
	.func		= bpf_btf_find_by_name_kind,
	.gpl_only	= false,
	.ret_type	= RET_INTEGER,
	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
	.arg2_type	= ARG_CONST_SIZE,
	.arg3_type	= ARG_ANYTHING,
	.arg4_type	= ARG_ANYTHING,
};

BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE)
#define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type)
BTF_TRACING_TYPE_xxx
#undef BTF_TRACING_TYPE

static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name,
				 const struct btf_type *func, u32 func_flags)
{
	u32 flags = func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
	const char *name, *sfx, *iter_name;
	const struct btf_param *arg;
	const struct btf_type *t;
	char exp_name[128];
	u32 nr_args;

	/* exactly one of KF_ITER_{NEW,NEXT,DESTROY} can be set */
	if (!flags || (flags & (flags - 1)))
		return -EINVAL;

	/* any BPF iter kfunc should have `struct bpf_iter_<type> *` first arg */
	nr_args = btf_type_vlen(func);
	if (nr_args < 1)
		return -EINVAL;

	arg = &btf_params(func)[0];
	t = btf_type_skip_modifiers(btf, arg->type, NULL);
	if (!t || !btf_type_is_ptr(t))
		return -EINVAL;
	t = btf_type_skip_modifiers(btf, t->type, NULL);
	if (!t || !__btf_type_is_struct(t))
		return -EINVAL;

	name = btf_name_by_offset(btf, t->name_off);
	if (!name || strncmp(name, ITER_PREFIX, sizeof(ITER_PREFIX) - 1))
		return -EINVAL;

	/* sizeof(struct bpf_iter_<type>) should be a multiple of 8 to
	 * fit nicely in stack slots
	 */
	if (t->size == 0 || (t->size % 8))
		return -EINVAL;

	/* validate bpf_iter_<type>_{new,next,destroy}(struct bpf_iter_<type> *)
	 * naming pattern
	 */
	iter_name = name + sizeof(ITER_PREFIX) - 1;
	if (flags & KF_ITER_NEW)
		sfx = "new";
	else if (flags & KF_ITER_NEXT)
		sfx = "next";
	else /* (flags & KF_ITER_DESTROY) */
		sfx = "destroy";

	snprintf(exp_name, sizeof(exp_name), "bpf_iter_%s_%s", iter_name, sfx);
	if (strcmp(func_name, exp_name))
		return -EINVAL;

	/* only iter constructor should have extra arguments */
	if (!(flags & KF_ITER_NEW) && nr_args != 1)
		return -EINVAL;

	if (flags & KF_ITER_NEXT) {
		/* bpf_iter_<type>_next() should return pointer */
		t = btf_type_skip_modifiers(btf, func->type, NULL);
		if (!t || !btf_type_is_ptr(t))
			return -EINVAL;
	}

	if (flags & KF_ITER_DESTROY) {
		/* bpf_iter_<type>_destroy() should return void */
		t = btf_type_by_id(btf, func->type);
		if (!t || !btf_type_is_void(t))
			return -EINVAL;
	}

	return 0;
}

static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
{
	const struct btf_type *func;
	const char *func_name;
	int err;

	/* any kfunc should be FUNC -> FUNC_PROTO */
	func = btf_type_by_id(btf, func_id);
	if (!func || !btf_type_is_func(func))
		return -EINVAL;

	/* sanity check kfunc name */
	func_name = btf_name_by_offset(btf, func->name_off);
	if (!func_name || !func_name[0])
		return -EINVAL;

	func = btf_type_by_id(btf, func->type);
	if (!func || !btf_type_is_func_proto(func))
		return -EINVAL;

	if (func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY)) {
		err = btf_check_iter_kfuncs(btf, func_name, func, func_flags);
		if (err)
			return err;
	}

	return 0;
}

/* Kernel Function (kfunc) BTF ID set registration API */

static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
				  const struct btf_kfunc_id_set *kset)
{
	struct btf_kfunc_hook_filter *hook_filter;
	struct btf_id_set8 *add_set = kset->set;
	bool vmlinux_set = !btf_is_module(btf);
	bool add_filter = !!kset->filter;
	struct btf_kfunc_set_tab *tab;
	struct btf_id_set8 *set;
	u32 set_cnt;
	int ret;

	if (hook >= BTF_KFUNC_HOOK_MAX) {
		ret = -EINVAL;
		goto end;
	}

	if (!add_set->cnt)
		return 0;

	tab = btf->kfunc_set_tab;

	if (tab && add_filter) {
		u32 i;

		hook_filter = &tab->hook_filters[hook];
		for (i = 0; i < hook_filter->nr_filters; i++) {
			if (hook_filter->filters[i] == kset->filter) {
				add_filter = false;
				break;
			}
		}

		if (add_filter && hook_filter->nr_filters == BTF_KFUNC_FILTER_MAX_CNT) {
			ret = -E2BIG;
			goto end;
		}
	}

	if (!tab) {
		tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
		if (!tab)
			return -ENOMEM;
		btf->kfunc_set_tab = tab;
	}

	set = tab->sets[hook];
	/* Warn when register_btf_kfunc_id_set is called twice for the same hook
	 * for module sets.
	 */
	if (WARN_ON_ONCE(set && !vmlinux_set)) {
		ret = -EINVAL;
		goto end;
	}

	/* We don't need to allocate, concatenate, and sort module sets, because
	 * only one is allowed per hook. Hence, we can directly assign the
	 * pointer and return.
	 */
	if (!vmlinux_set) {
		tab->sets[hook] = add_set;
		goto do_add_filter;
	}

	/* In case of vmlinux sets, there may be more than one set being
	 * registered per hook. To create a unified set, we allocate a new set
	 * and concatenate all individual sets being registered. While each set
	 * is individually sorted, they may become unsorted when concatenated,
	 * hence re-sorting the final set again is required to make binary
	 * searching the set using btf_id_set8_contains function work.
	 */
	set_cnt = set ? set->cnt : 0;

	if (set_cnt > U32_MAX - add_set->cnt) {
		ret = -EOVERFLOW;
		goto end;
	}

	if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) {
		ret = -E2BIG;
		goto end;
	}

	/* Grow set */
	set = krealloc(tab->sets[hook],
		       offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]),
		       GFP_KERNEL | __GFP_NOWARN);
	if (!set) {
		ret = -ENOMEM;
		goto end;
	}

	/* For newly allocated set, initialize set->cnt to 0 */
	if (!tab->sets[hook])
		set->cnt = 0;
	tab->sets[hook] = set;

	/* Concatenate the two sets */
	memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0]));
	set->cnt += add_set->cnt;

	sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);

do_add_filter:
	if (add_filter) {
		hook_filter = &tab->hook_filters[hook];
		hook_filter->filters[hook_filter->nr_filters++] = kset->filter;
	}
	return 0;
end:
	btf_free_kfunc_set_tab(btf);
	return ret;
}

static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
					enum btf_kfunc_hook hook,
					u32 kfunc_btf_id,
					const struct bpf_prog *prog)
{
	struct btf_kfunc_hook_filter *hook_filter;
	struct btf_id_set8 *set;
	u32 *id, i;

	if (hook >= BTF_KFUNC_HOOK_MAX)
		return NULL;
	if (!btf->kfunc_set_tab)
		return NULL;
	hook_filter = &btf->kfunc_set_tab->hook_filters[hook];
	for (i = 0; i < hook_filter->nr_filters; i++) {
		if (hook_filter->filters[i](prog, kfunc_btf_id))
			return NULL;
	}
	set = btf->kfunc_set_tab->sets[hook];
	if (!set)
		return NULL;
	id = btf_id_set8_contains(set, kfunc_btf_id);
	if (!id)
		return NULL;
	/* The flags for BTF ID are located next to it */
	return id + 1;
}

static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
{
	switch (prog_type) {
	case BPF_PROG_TYPE_UNSPEC:
		return BTF_KFUNC_HOOK_COMMON;
	case BPF_PROG_TYPE_XDP:
		return BTF_KFUNC_HOOK_XDP;
	case BPF_PROG_TYPE_SCHED_CLS:
		return BTF_KFUNC_HOOK_TC;
	case BPF_PROG_TYPE_STRUCT_OPS:
		return BTF_KFUNC_HOOK_STRUCT_OPS;
	case BPF_PROG_TYPE_TRACING:
	case BPF_PROG_TYPE_LSM:
		return BTF_KFUNC_HOOK_TRACING;
	case BPF_PROG_TYPE_SYSCALL:
		return BTF_KFUNC_HOOK_SYSCALL;
	case BPF_PROG_TYPE_CGROUP_SKB:
		return BTF_KFUNC_HOOK_CGROUP_SKB;
	case BPF_PROG_TYPE_SCHED_ACT:
		return BTF_KFUNC_HOOK_SCHED_ACT;
	case BPF_PROG_TYPE_SK_SKB:
		return BTF_KFUNC_HOOK_SK_SKB;
	case BPF_PROG_TYPE_SOCKET_FILTER:
		return BTF_KFUNC_HOOK_SOCKET_FILTER;
	case BPF_PROG_TYPE_LWT_OUT:
	case BPF_PROG_TYPE_LWT_IN:
	case BPF_PROG_TYPE_LWT_XMIT:
	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
		return BTF_KFUNC_HOOK_LWT;
	case BPF_PROG_TYPE_NETFILTER:
		return BTF_KFUNC_HOOK_NETFILTER;
	default:
		return BTF_KFUNC_HOOK_MAX;
	}
}

/* Caution:
 * Reference to the module (obtained using btf_try_get_module) corresponding to
 * the struct btf *MUST* be held when calling this function from verifier
 * context. This is usually true as we stash references in prog's kfunc_btf_tab;
 * keeping the reference for the duration of the call provides the necessary
 * protection for looking up a well-formed btf->kfunc_set_tab.
 */
u32 *btf_kfunc_id_set_contains(const struct btf *btf,
			       u32 kfunc_btf_id,
			       const struct bpf_prog *prog)
{
	enum bpf_prog_type prog_type = resolve_prog_type(prog);
	enum btf_kfunc_hook hook;
	u32 *kfunc_flags;

	kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, kfunc_btf_id, prog);
	if (kfunc_flags)
		return kfunc_flags;

	hook = bpf_prog_type_to_kfunc_hook(prog_type);
	return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id, prog);
}

u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
				const struct bpf_prog *prog)
{
	return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, kfunc_btf_id, prog);
}

static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
				       const struct btf_kfunc_id_set *kset)
{
	struct btf *btf;
	int ret, i;

	btf = btf_get_module_btf(kset->owner);
	if (!btf) {
		if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
			pr_err("missing vmlinux BTF, cannot register kfuncs\n");
			return -ENOENT;
		}
		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
			pr_warn("missing module BTF, cannot register kfuncs\n");
		return 0;
	}
	if (IS_ERR(btf))
		return PTR_ERR(btf);

	for (i = 0; i < kset->set->cnt; i++) {
		ret = btf_check_kfunc_protos(btf, kset->set->pairs[i].id,
					     kset->set->pairs[i].flags);
		if (ret)
			goto err_out;
	}

	ret = btf_populate_kfunc_set(btf, hook, kset);

err_out:
	btf_put(btf);
	return ret;
}

/* This function must be invoked only from initcalls/module init functions */
int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
			      const struct btf_kfunc_id_set *kset)
{
	enum btf_kfunc_hook hook;

	hook = bpf_prog_type_to_kfunc_hook(prog_type);
	return __register_btf_kfunc_id_set(hook, kset);
}
EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);

/* This function must be invoked only from initcalls/module init functions */
int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset)
{
	return __register_btf_kfunc_id_set(BTF_KFUNC_HOOK_FMODRET, kset);
}
EXPORT_SYMBOL_GPL(register_btf_fmodret_id_set);

s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
{
	struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
	struct btf_id_dtor_kfunc *dtor;

	if (!tab)
		return -ENOENT;
	/* Even though the size of tab->dtors[0] is > sizeof(u32), we only need
	 * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func.
	 */
	BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0);
	dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func);
	if (!dtor)
		return -ENOENT;
	return dtor->kfunc_btf_id;
}

static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt)
{
	const struct btf_type *dtor_func, *dtor_func_proto, *t;
	const struct btf_param *args;
	s32 dtor_btf_id;
	u32 nr_args, i;

	for (i = 0; i < cnt; i++) {
		dtor_btf_id = dtors[i].kfunc_btf_id;

		dtor_func = btf_type_by_id(btf, dtor_btf_id);
		if (!dtor_func || !btf_type_is_func(dtor_func))
			return -EINVAL;

		dtor_func_proto = btf_type_by_id(btf, dtor_func->type);
		if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto))
			return -EINVAL;

		/* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
		t = btf_type_by_id(btf, dtor_func_proto->type);
		if (!t || !btf_type_is_void(t))
			return -EINVAL;

		nr_args = btf_type_vlen(dtor_func_proto);
		if (nr_args != 1)
			return -EINVAL;
		args = btf_params(dtor_func_proto);
		t = btf_type_by_id(btf, args[0].type);
		/* Allow any pointer type, as width on targets Linux supports
		 * will be same for all pointer types (i.e. sizeof(void *))
		 */
		if (!t || !btf_type_is_ptr(t))
			return -EINVAL;
	}
	return 0;
}

/* This function must be invoked only from initcalls/module init functions */
int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
				struct module *owner)
{
	struct btf_id_dtor_kfunc_tab *tab;
	struct btf *btf;
	u32 tab_cnt;
	int ret;

	btf = btf_get_module_btf(owner);
	if (!btf) {
		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
			return -ENOENT;
		}
		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
			pr_err("missing module BTF, cannot register dtor kfuncs\n");
			return -ENOENT;
		}
		return 0;
	}
	if (IS_ERR(btf))
		return PTR_ERR(btf);

	if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
		pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
		ret = -E2BIG;
		goto end;
	}

	/* Ensure that the prototype of dtor kfuncs being registered is sane */
	ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt);
	if (ret < 0)
		goto end;

	tab = btf->dtor_kfunc_tab;
	/* Only one call allowed for modules */
	if (WARN_ON_ONCE(tab && btf_is_module(btf))) {
		ret = -EINVAL;
		goto end;
	}

	tab_cnt = tab ? tab->cnt : 0;
	if (tab_cnt > U32_MAX - add_cnt) {
		ret = -EOVERFLOW;
		goto end;
	}
	if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
		pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
		ret = -E2BIG;
		goto end;
	}

	tab = krealloc(btf->dtor_kfunc_tab,
		       offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]),
		       GFP_KERNEL | __GFP_NOWARN);
	if (!tab) {
		ret = -ENOMEM;
		goto end;
	}

	if (!btf->dtor_kfunc_tab)
		tab->cnt = 0;
	btf->dtor_kfunc_tab = tab;

	memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0]));
	tab->cnt += add_cnt;

	sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);

end:
	if (ret)
		btf_free_dtor_kfunc_tab(btf);
	btf_put(btf);
	return ret;
}
EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs);

#define MAX_TYPES_ARE_COMPAT_DEPTH 2

/* Check local and target types for compatibility. This check is used for
 * type-based CO-RE relocations and follow slightly different rules than
 * field-based relocations. This function assumes that root types were already
 * checked for name match. Beyond that initial root-level name check, names
 * are completely ignored. Compatibility rules are as follows:
 *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs/ENUM64s are considered compatible, but
 *     kind should match for local and target types (i.e., STRUCT is not
 *     compatible with UNION);
 *   - for ENUMs/ENUM64s, the size is ignored;
 *   - for INT, size and signedness are ignored;
 *   - for ARRAY, dimensionality is ignored, element types are checked for
 *     compatibility recursively;
 *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
 *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
 *   - FUNC_PROTOs are compatible if they have compatible signature: same
 *     number of input args and compatible return and argument types.
 * These rules are not set in stone and probably will be adjusted as we get
 * more experience with using BPF CO-RE relocations.
 */
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
			      const struct btf *targ_btf, __u32 targ_id)
{
	return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
					   MAX_TYPES_ARE_COMPAT_DEPTH);
}

#define MAX_TYPES_MATCH_DEPTH 2

int bpf_core_types_match(const struct btf *local_btf, u32 local_id,
			 const struct btf *targ_btf, u32 targ_id)
{
	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false,
				      MAX_TYPES_MATCH_DEPTH);
}

static bool bpf_core_is_flavor_sep(const char *s)
{
	/* check X___Y name pattern, where X and Y are not underscores */
	return s[0] != '_' &&				      /* X */
	       s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
	       s[4] != '_';				      /* Y */
}

size_t bpf_core_essential_name_len(const char *name)
{
	size_t n = strlen(name);
	int i;

	for (i = n - 5; i >= 0; i--) {
		if (bpf_core_is_flavor_sep(name + i))
			return i + 1;
	}
	return n;
}

struct bpf_cand_cache {
	const char *name;
	u32 name_len;
	u16 kind;
	u16 cnt;
	struct {
		const struct btf *btf;
		u32 id;
	} cands[];
};

static void bpf_free_cands(struct bpf_cand_cache *cands)
{
	if (!cands->cnt)
		/* empty candidate array was allocated on stack */
		return;
	kfree(cands);
}

static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands)
{
	kfree(cands->name);
	kfree(cands);
}

#define VMLINUX_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE];

#define MODULE_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE];

static DEFINE_MUTEX(cand_cache_mutex);

static void __print_cand_cache(struct bpf_verifier_log *log,
			       struct bpf_cand_cache **cache,
			       int cache_size)
{
	struct bpf_cand_cache *cc;
	int i, j;

	for (i = 0; i < cache_size; i++) {
		cc = cache[i];
		if (!cc)
			continue;
		bpf_log(log, "[%d]%s(", i, cc->name);
		for (j = 0; j < cc->cnt; j++) {
			bpf_log(log, "%d", cc->cands[j].id);
			if (j < cc->cnt - 1)
				bpf_log(log, " ");
		}
		bpf_log(log, "), ");
	}
}

static void print_cand_cache(struct bpf_verifier_log *log)
{
	mutex_lock(&cand_cache_mutex);
	bpf_log(log, "vmlinux_cand_cache:");
	__print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
	bpf_log(log, "\nmodule_cand_cache:");
	__print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE);
	bpf_log(log, "\n");
	mutex_unlock(&cand_cache_mutex);
}

static u32 hash_cands(struct bpf_cand_cache *cands)
{
	return jhash(cands->name, cands->name_len, 0);
}

static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands,
					       struct bpf_cand_cache **cache,
					       int cache_size)
{
	struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size];

	if (cc && cc->name_len == cands->name_len &&
	    !strncmp(cc->name, cands->name, cands->name_len))
		return cc;
	return NULL;
}

static size_t sizeof_cands(int cnt)
{
	return offsetof(struct bpf_cand_cache, cands[cnt]);
}

static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
						  struct bpf_cand_cache **cache,
						  int cache_size)
{
	struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands;

	if (*cc) {
		bpf_free_cands_from_cache(*cc);
		*cc = NULL;
	}
	new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
	if (!new_cands) {
		bpf_free_cands(cands);
		return ERR_PTR(-ENOMEM);
	}
	/* strdup the name, since it will stay in cache.
	 * the cands->name points to strings in prog's BTF and the prog can be unloaded.
	 */
	new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
	bpf_free_cands(cands);
	if (!new_cands->name) {
		kfree(new_cands);
		return ERR_PTR(-ENOMEM);
	}
	*cc = new_cands;
	return new_cands;
}

#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache,
			       int cache_size)
{
	struct bpf_cand_cache *cc;
	int i, j;

	for (i = 0; i < cache_size; i++) {
		cc = cache[i];
		if (!cc)
			continue;
		if (!btf) {
			/* when new module is loaded purge all of module_cand_cache,
			 * since new module might have candidates with the name
			 * that matches cached cands.
			 */
			bpf_free_cands_from_cache(cc);
			cache[i] = NULL;
			continue;
		}
		/* when module is unloaded purge cache entries
		 * that match module's btf
		 */
		for (j = 0; j < cc->cnt; j++)
			if (cc->cands[j].btf == btf) {
				bpf_free_cands_from_cache(cc);
				cache[i] = NULL;
				break;
			}
	}

}

static void purge_cand_cache(struct btf *btf)
{
	mutex_lock(&cand_cache_mutex);
	__purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE);
	mutex_unlock(&cand_cache_mutex);
}
#endif

static struct bpf_cand_cache *
bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
		   int targ_start_id)
{
	struct bpf_cand_cache *new_cands;
	const struct btf_type *t;
	const char *targ_name;
	size_t targ_essent_len;
	int n, i;

	n = btf_nr_types(targ_btf);
	for (i = targ_start_id; i < n; i++) {
		t = btf_type_by_id(targ_btf, i);
		if (btf_kind(t) != cands->kind)
			continue;

		targ_name = btf_name_by_offset(targ_btf, t->name_off);
		if (!targ_name)
			continue;

		/* the resched point is before strncmp to make sure that search
		 * for non-existing name will have a chance to schedule().
		 */
		cond_resched();

		if (strncmp(cands->name, targ_name, cands->name_len) != 0)
			continue;

		targ_essent_len = bpf_core_essential_name_len(targ_name);
		if (targ_essent_len != cands->name_len)
			continue;

		/* most of the time there is only one candidate for a given kind+name pair */
		new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
		if (!new_cands) {
			bpf_free_cands(cands);
			return ERR_PTR(-ENOMEM);
		}

		memcpy(new_cands, cands, sizeof_cands(cands->cnt));
		bpf_free_cands(cands);
		cands = new_cands;
		cands->cands[cands->cnt].btf = targ_btf;
		cands->cands[cands->cnt].id = i;
		cands->cnt++;
	}
	return cands;
}

static struct bpf_cand_cache *
bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
{
	struct bpf_cand_cache *cands, *cc, local_cand = {};
	const struct btf *local_btf = ctx->btf;
	const struct btf_type *local_type;
	const struct btf *main_btf;
	size_t local_essent_len;
	struct btf *mod_btf;
	const char *name;
	int id;

	main_btf = bpf_get_btf_vmlinux();
	if (IS_ERR(main_btf))
		return ERR_CAST(main_btf);
	if (!main_btf)
		return ERR_PTR(-EINVAL);

	local_type = btf_type_by_id(local_btf, local_type_id);
	if (!local_type)
		return ERR_PTR(-EINVAL);

	name = btf_name_by_offset(local_btf, local_type->name_off);
	if (str_is_empty(name))
		return ERR_PTR(-EINVAL);
	local_essent_len = bpf_core_essential_name_len(name);

	cands = &local_cand;
	cands->name = name;
	cands->kind = btf_kind(local_type);
	cands->name_len = local_essent_len;

	cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
	/* cands is a pointer to stack here */
	if (cc) {
		if (cc->cnt)
			return cc;
		goto check_modules;
	}

	/* Attempt to find target candidates in vmlinux BTF first */
	cands = bpf_core_add_cands(cands, main_btf, 1);
	if (IS_ERR(cands))
		return ERR_CAST(cands);

	/* cands is a pointer to kmalloced memory here if cands->cnt > 0 */

	/* populate cache even when cands->cnt == 0 */
	cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
	if (IS_ERR(cc))
		return ERR_CAST(cc);

	/* if vmlinux BTF has any candidate, don't go for module BTFs */
	if (cc->cnt)
		return cc;

check_modules:
	/* cands is a pointer to stack here and cands->cnt == 0 */
	cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
	if (cc)
		/* if cache has it return it even if cc->cnt == 0 */
		return cc;

	/* If candidate is not found in vmlinux's BTF then search in module's BTFs */
	spin_lock_bh(&btf_idr_lock);
	idr_for_each_entry(&btf_idr, mod_btf, id) {
		if (!btf_is_module(mod_btf))
			continue;
		/* linear search could be slow hence unlock/lock
		 * the IDR to avoiding holding it for too long
		 */
		btf_get(mod_btf);
		spin_unlock_bh(&btf_idr_lock);
		cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
		btf_put(mod_btf);
		if (IS_ERR(cands))
			return ERR_CAST(cands);
		spin_lock_bh(&btf_idr_lock);
	}
	spin_unlock_bh(&btf_idr_lock);
	/* cands is a pointer to kmalloced memory here if cands->cnt > 0
	 * or pointer to stack if cands->cnd == 0.
	 * Copy it into the cache even when cands->cnt == 0 and
	 * return the result.
	 */
	return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
}

int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
		   int relo_idx, void *insn)
{
	bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL;
	struct bpf_core_cand_list cands = {};
	struct bpf_core_relo_res targ_res;
	struct bpf_core_spec *specs;
	int err;

	/* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
	 * into arrays of btf_ids of struct fields and array indices.
	 */
	specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
	if (!specs)
		return -ENOMEM;

	if (need_cands) {
		struct bpf_cand_cache *cc;
		int i;

		mutex_lock(&cand_cache_mutex);
		cc = bpf_core_find_cands(ctx, relo->type_id);
		if (IS_ERR(cc)) {
			bpf_log(ctx->log, "target candidate search failed for %d\n",
				relo->type_id);
			err = PTR_ERR(cc);
			goto out;
		}
		if (cc->cnt) {
			cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
			if (!cands.cands) {
				err = -ENOMEM;
				goto out;
			}
		}
		for (i = 0; i < cc->cnt; i++) {
			bpf_log(ctx->log,
				"CO-RE relocating %s %s: found target candidate [%d]\n",
				btf_kind_str[cc->kind], cc->name, cc->cands[i].id);
			cands.cands[i].btf = cc->cands[i].btf;
			cands.cands[i].id = cc->cands[i].id;
		}
		cands.len = cc->cnt;
		/* cand_cache_mutex needs to span the cache lookup and
		 * copy of btf pointer into bpf_core_cand_list,
		 * since module can be unloaded while bpf_core_calc_relo_insn
		 * is working with module's btf.
		 */
	}

	err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs,
				      &targ_res);
	if (err)
		goto out;

	err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx,
				  &targ_res);

out:
	kfree(specs);
	if (need_cands) {
		kfree(cands.cands);
		mutex_unlock(&cand_cache_mutex);
		if (ctx->log->level & BPF_LOG_LEVEL2)
			print_cand_cache(ctx->log);
	}
	return err;
}

bool btf_nested_type_is_trusted(struct bpf_verifier_log *log,
				const struct bpf_reg_state *reg,
				const char *field_name, u32 btf_id, const char *suffix)
{
	struct btf *btf = reg->btf;
	const struct btf_type *walk_type, *safe_type;
	const char *tname;
	char safe_tname[64];
	long ret, safe_id;
	const struct btf_member *member;
	u32 i;

	walk_type = btf_type_by_id(btf, reg->btf_id);
	if (!walk_type)
		return false;

	tname = btf_name_by_offset(btf, walk_type->name_off);

	ret = snprintf(safe_tname, sizeof(safe_tname), "%s%s", tname, suffix);
	if (ret < 0)
		return false;

	safe_id = btf_find_by_name_kind(btf, safe_tname, BTF_INFO_KIND(walk_type->info));
	if (safe_id < 0)
		return false;

	safe_type = btf_type_by_id(btf, safe_id);
	if (!safe_type)
		return false;

	for_each_member(i, safe_type, member) {
		const char *m_name = __btf_name_by_offset(btf, member->name_off);
		const struct btf_type *mtype = btf_type_by_id(btf, member->type);
		u32 id;

		if (!btf_type_is_ptr(mtype))
			continue;

		btf_type_skip_modifiers(btf, mtype->type, &id);
		/* If we match on both type and name, the field is considered trusted. */
		if (btf_id == id && !strcmp(field_name, m_name))
			return true;
	}

	return false;
}

bool btf_type_ids_nocast_alias(struct bpf_verifier_log *log,
			       const struct btf *reg_btf, u32 reg_id,
			       const struct btf *arg_btf, u32 arg_id)
{
	const char *reg_name, *arg_name, *search_needle;
	const struct btf_type *reg_type, *arg_type;
	int reg_len, arg_len, cmp_len;
	size_t pattern_len = sizeof(NOCAST_ALIAS_SUFFIX) - sizeof(char);

	reg_type = btf_type_by_id(reg_btf, reg_id);
	if (!reg_type)
		return false;

	arg_type = btf_type_by_id(arg_btf, arg_id);
	if (!arg_type)
		return false;

	reg_name = btf_name_by_offset(reg_btf, reg_type->name_off);
	arg_name = btf_name_by_offset(arg_btf, arg_type->name_off);

	reg_len = strlen(reg_name);
	arg_len = strlen(arg_name);

	/* Exactly one of the two type names may be suffixed with ___init, so
	 * if the strings are the same size, they can't possibly be no-cast
	 * aliases of one another. If you have two of the same type names, e.g.
	 * they're both nf_conn___init, it would be improper to return true
	 * because they are _not_ no-cast aliases, they are the same type.
	 */
	if (reg_len == arg_len)
		return false;

	/* Either of the two names must be the other name, suffixed with ___init. */
	if ((reg_len != arg_len + pattern_len) &&
	    (arg_len != reg_len + pattern_len))
		return false;

	if (reg_len < arg_len) {
		search_needle = strstr(arg_name, NOCAST_ALIAS_SUFFIX);
		cmp_len = reg_len;
	} else {
		search_needle = strstr(reg_name, NOCAST_ALIAS_SUFFIX);
		cmp_len = arg_len;
	}

	if (!search_needle)
		return false;

	/* ___init suffix must come at the end of the name */
	if (*(search_needle + pattern_len) != '\0')
		return false;

	return !strncmp(reg_name, arg_name, cmp_len);
}