summaryrefslogtreecommitdiff
path: root/kernel/bpf/hashtab.c
blob: d7ebb12ffffcac5a1916ff41fb19ed2bb887796f (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
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 */
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/jhash.h>
#include <linux/filter.h>
#include <linux/rculist_nulls.h>
#include <linux/random.h>
#include <uapi/linux/btf.h>
#include <linux/rcupdate_trace.h>
#include "percpu_freelist.h"
#include "bpf_lru_list.h"
#include "map_in_map.h"

#define HTAB_CREATE_FLAG_MASK						\
	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\
	 BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED)

#define BATCH_OPS(_name)			\
	.map_lookup_batch =			\
	_name##_map_lookup_batch,		\
	.map_lookup_and_delete_batch =		\
	_name##_map_lookup_and_delete_batch,	\
	.map_update_batch =			\
	generic_map_update_batch,		\
	.map_delete_batch =			\
	generic_map_delete_batch

/*
 * The bucket lock has two protection scopes:
 *
 * 1) Serializing concurrent operations from BPF programs on different
 *    CPUs
 *
 * 2) Serializing concurrent operations from BPF programs and sys_bpf()
 *
 * BPF programs can execute in any context including perf, kprobes and
 * tracing. As there are almost no limits where perf, kprobes and tracing
 * can be invoked from the lock operations need to be protected against
 * deadlocks. Deadlocks can be caused by recursion and by an invocation in
 * the lock held section when functions which acquire this lock are invoked
 * from sys_bpf(). BPF recursion is prevented by incrementing the per CPU
 * variable bpf_prog_active, which prevents BPF programs attached to perf
 * events, kprobes and tracing to be invoked before the prior invocation
 * from one of these contexts completed. sys_bpf() uses the same mechanism
 * by pinning the task to the current CPU and incrementing the recursion
 * protection accross the map operation.
 *
 * This has subtle implications on PREEMPT_RT. PREEMPT_RT forbids certain
 * operations like memory allocations (even with GFP_ATOMIC) from atomic
 * contexts. This is required because even with GFP_ATOMIC the memory
 * allocator calls into code pathes which acquire locks with long held lock
 * sections. To ensure the deterministic behaviour these locks are regular
 * spinlocks, which are converted to 'sleepable' spinlocks on RT. The only
 * true atomic contexts on an RT kernel are the low level hardware
 * handling, scheduling, low level interrupt handling, NMIs etc. None of
 * these contexts should ever do memory allocations.
 *
 * As regular device interrupt handlers and soft interrupts are forced into
 * thread context, the existing code which does
 *   spin_lock*(); alloc(GPF_ATOMIC); spin_unlock*();
 * just works.
 *
 * In theory the BPF locks could be converted to regular spinlocks as well,
 * but the bucket locks and percpu_freelist locks can be taken from
 * arbitrary contexts (perf, kprobes, tracepoints) which are required to be
 * atomic contexts even on RT. These mechanisms require preallocated maps,
 * so there is no need to invoke memory allocations within the lock held
 * sections.
 *
 * BPF maps which need dynamic allocation are only used from (forced)
 * thread context on RT and can therefore use regular spinlocks which in
 * turn allows to invoke memory allocations from the lock held section.
 *
 * On a non RT kernel this distinction is neither possible nor required.
 * spinlock maps to raw_spinlock and the extra code is optimized out by the
 * compiler.
 */
struct bucket {
	struct hlist_nulls_head head;
	union {
		raw_spinlock_t raw_lock;
		spinlock_t     lock;
	};
};

#define HASHTAB_MAP_LOCK_COUNT 8
#define HASHTAB_MAP_LOCK_MASK (HASHTAB_MAP_LOCK_COUNT - 1)

struct bpf_htab {
	struct bpf_map map;
	struct bucket *buckets;
	void *elems;
	union {
		struct pcpu_freelist freelist;
		struct bpf_lru lru;
	};
	struct htab_elem *__percpu *extra_elems;
	atomic_t count;	/* number of elements in this hashtable */
	u32 n_buckets;	/* number of hash buckets */
	u32 elem_size;	/* size of each element in bytes */
	u32 hashrnd;
	struct lock_class_key lockdep_key;
	int __percpu *map_locked[HASHTAB_MAP_LOCK_COUNT];
};

/* each htab element is struct htab_elem + key + value */
struct htab_elem {
	union {
		struct hlist_nulls_node hash_node;
		struct {
			void *padding;
			union {
				struct bpf_htab *htab;
				struct pcpu_freelist_node fnode;
				struct htab_elem *batch_flink;
			};
		};
	};
	union {
		struct rcu_head rcu;
		struct bpf_lru_node lru_node;
	};
	u32 hash;
	char key[] __aligned(8);
};

static inline bool htab_is_prealloc(const struct bpf_htab *htab)
{
	return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
}

static inline bool htab_use_raw_lock(const struct bpf_htab *htab)
{
	return (!IS_ENABLED(CONFIG_PREEMPT_RT) || htab_is_prealloc(htab));
}

static void htab_init_buckets(struct bpf_htab *htab)
{
	unsigned i;

	for (i = 0; i < htab->n_buckets; i++) {
		INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
		if (htab_use_raw_lock(htab)) {
			raw_spin_lock_init(&htab->buckets[i].raw_lock);
			lockdep_set_class(&htab->buckets[i].raw_lock,
					  &htab->lockdep_key);
		} else {
			spin_lock_init(&htab->buckets[i].lock);
			lockdep_set_class(&htab->buckets[i].lock,
					  &htab->lockdep_key);
		}
		cond_resched();
	}
}

static inline int htab_lock_bucket(const struct bpf_htab *htab,
				   struct bucket *b, u32 hash,
				   unsigned long *pflags)
{
	unsigned long flags;

	hash = hash & HASHTAB_MAP_LOCK_MASK;

	migrate_disable();
	if (unlikely(__this_cpu_inc_return(*(htab->map_locked[hash])) != 1)) {
		__this_cpu_dec(*(htab->map_locked[hash]));
		migrate_enable();
		return -EBUSY;
	}

	if (htab_use_raw_lock(htab))
		raw_spin_lock_irqsave(&b->raw_lock, flags);
	else
		spin_lock_irqsave(&b->lock, flags);
	*pflags = flags;

	return 0;
}

static inline void htab_unlock_bucket(const struct bpf_htab *htab,
				      struct bucket *b, u32 hash,
				      unsigned long flags)
{
	hash = hash & HASHTAB_MAP_LOCK_MASK;
	if (htab_use_raw_lock(htab))
		raw_spin_unlock_irqrestore(&b->raw_lock, flags);
	else
		spin_unlock_irqrestore(&b->lock, flags);
	__this_cpu_dec(*(htab->map_locked[hash]));
	migrate_enable();
}

static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);

static bool htab_is_lru(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
}

static bool htab_is_percpu(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
}

static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
				     void __percpu *pptr)
{
	*(void __percpu **)(l->key + key_size) = pptr;
}

static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
{
	return *(void __percpu **)(l->key + key_size);
}

static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
{
	return *(void **)(l->key + roundup(map->key_size, 8));
}

static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
{
	return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);
}

static void htab_free_elems(struct bpf_htab *htab)
{
	int i;

	if (!htab_is_percpu(htab))
		goto free_elems;

	for (i = 0; i < htab->map.max_entries; i++) {
		void __percpu *pptr;

		pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
					 htab->map.key_size);
		free_percpu(pptr);
		cond_resched();
	}
free_elems:
	bpf_map_area_free(htab->elems);
}

/* The LRU list has a lock (lru_lock). Each htab bucket has a lock
 * (bucket_lock). If both locks need to be acquired together, the lock
 * order is always lru_lock -> bucket_lock and this only happens in
 * bpf_lru_list.c logic. For example, certain code path of
 * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(),
 * will acquire lru_lock first followed by acquiring bucket_lock.
 *
 * In hashtab.c, to avoid deadlock, lock acquisition of
 * bucket_lock followed by lru_lock is not allowed. In such cases,
 * bucket_lock needs to be released first before acquiring lru_lock.
 */
static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
					  u32 hash)
{
	struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
	struct htab_elem *l;

	if (node) {
		l = container_of(node, struct htab_elem, lru_node);
		memcpy(l->key, key, htab->map.key_size);
		return l;
	}

	return NULL;
}

static int prealloc_init(struct bpf_htab *htab)
{
	u32 num_entries = htab->map.max_entries;
	int err = -ENOMEM, i;

	if (!htab_is_percpu(htab) && !htab_is_lru(htab))
		num_entries += num_possible_cpus();

	htab->elems = bpf_map_area_alloc((u64)htab->elem_size * num_entries,
					 htab->map.numa_node);
	if (!htab->elems)
		return -ENOMEM;

	if (!htab_is_percpu(htab))
		goto skip_percpu_elems;

	for (i = 0; i < num_entries; i++) {
		u32 size = round_up(htab->map.value_size, 8);
		void __percpu *pptr;

		pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
					    GFP_USER | __GFP_NOWARN);
		if (!pptr)
			goto free_elems;
		htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
				  pptr);
		cond_resched();
	}

skip_percpu_elems:
	if (htab_is_lru(htab))
		err = bpf_lru_init(&htab->lru,
				   htab->map.map_flags & BPF_F_NO_COMMON_LRU,
				   offsetof(struct htab_elem, hash) -
				   offsetof(struct htab_elem, lru_node),
				   htab_lru_map_delete_node,
				   htab);
	else
		err = pcpu_freelist_init(&htab->freelist);

	if (err)
		goto free_elems;

	if (htab_is_lru(htab))
		bpf_lru_populate(&htab->lru, htab->elems,
				 offsetof(struct htab_elem, lru_node),
				 htab->elem_size, num_entries);
	else
		pcpu_freelist_populate(&htab->freelist,
				       htab->elems + offsetof(struct htab_elem, fnode),
				       htab->elem_size, num_entries);

	return 0;

free_elems:
	htab_free_elems(htab);
	return err;
}

static void prealloc_destroy(struct bpf_htab *htab)
{
	htab_free_elems(htab);

	if (htab_is_lru(htab))
		bpf_lru_destroy(&htab->lru);
	else
		pcpu_freelist_destroy(&htab->freelist);
}

static int alloc_extra_elems(struct bpf_htab *htab)
{
	struct htab_elem *__percpu *pptr, *l_new;
	struct pcpu_freelist_node *l;
	int cpu;

	pptr = bpf_map_alloc_percpu(&htab->map, sizeof(struct htab_elem *), 8,
				    GFP_USER | __GFP_NOWARN);
	if (!pptr)
		return -ENOMEM;

	for_each_possible_cpu(cpu) {
		l = pcpu_freelist_pop(&htab->freelist);
		/* pop will succeed, since prealloc_init()
		 * preallocated extra num_possible_cpus elements
		 */
		l_new = container_of(l, struct htab_elem, fnode);
		*per_cpu_ptr(pptr, cpu) = l_new;
	}
	htab->extra_elems = pptr;
	return 0;
}

/* Called from syscall */
static int htab_map_alloc_check(union bpf_attr *attr)
{
	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	/* percpu_lru means each cpu has its own LRU list.
	 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
	 * the map's value itself is percpu.  percpu_lru has
	 * nothing to do with the map's value.
	 */
	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
	bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
	int numa_node = bpf_map_attr_numa_node(attr);

	BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
		     offsetof(struct htab_elem, hash_node.pprev));
	BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
		     offsetof(struct htab_elem, hash_node.pprev));

	if (lru && !bpf_capable())
		/* LRU implementation is much complicated than other
		 * maps.  Hence, limit to CAP_BPF.
		 */
		return -EPERM;

	if (zero_seed && !capable(CAP_SYS_ADMIN))
		/* Guard against local DoS, and discourage production use. */
		return -EPERM;

	if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK ||
	    !bpf_map_flags_access_ok(attr->map_flags))
		return -EINVAL;

	if (!lru && percpu_lru)
		return -EINVAL;

	if (lru && !prealloc)
		return -ENOTSUPP;

	if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
		return -EINVAL;

	/* check sanity of attributes.
	 * value_size == 0 may be allowed in the future to use map as a set
	 */
	if (attr->max_entries == 0 || attr->key_size == 0 ||
	    attr->value_size == 0)
		return -EINVAL;

	if ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE -
	   sizeof(struct htab_elem))
		/* if key_size + value_size is bigger, the user space won't be
		 * able to access the elements via bpf syscall. This check
		 * also makes sure that the elem_size doesn't overflow and it's
		 * kmalloc-able later in htab_map_update_elem()
		 */
		return -E2BIG;

	return 0;
}

static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
{
	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	/* percpu_lru means each cpu has its own LRU list.
	 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
	 * the map's value itself is percpu.  percpu_lru has
	 * nothing to do with the map's value.
	 */
	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
	struct bpf_htab *htab;
	int err, i;

	htab = kzalloc(sizeof(*htab), GFP_USER | __GFP_ACCOUNT);
	if (!htab)
		return ERR_PTR(-ENOMEM);

	lockdep_register_key(&htab->lockdep_key);

	bpf_map_init_from_attr(&htab->map, attr);

	if (percpu_lru) {
		/* ensure each CPU's lru list has >=1 elements.
		 * since we are at it, make each lru list has the same
		 * number of elements.
		 */
		htab->map.max_entries = roundup(attr->max_entries,
						num_possible_cpus());
		if (htab->map.max_entries < attr->max_entries)
			htab->map.max_entries = rounddown(attr->max_entries,
							  num_possible_cpus());
	}

	/* hash table size must be power of 2 */
	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);

	htab->elem_size = sizeof(struct htab_elem) +
			  round_up(htab->map.key_size, 8);
	if (percpu)
		htab->elem_size += sizeof(void *);
	else
		htab->elem_size += round_up(htab->map.value_size, 8);

	err = -E2BIG;
	/* prevent zero size kmalloc and check for u32 overflow */
	if (htab->n_buckets == 0 ||
	    htab->n_buckets > U32_MAX / sizeof(struct bucket))
		goto free_htab;

	err = -ENOMEM;
	htab->buckets = bpf_map_area_alloc(htab->n_buckets *
					   sizeof(struct bucket),
					   htab->map.numa_node);
	if (!htab->buckets)
		goto free_htab;

	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++) {
		htab->map_locked[i] = bpf_map_alloc_percpu(&htab->map,
							   sizeof(int),
							   sizeof(int),
							   GFP_USER);
		if (!htab->map_locked[i])
			goto free_map_locked;
	}

	if (htab->map.map_flags & BPF_F_ZERO_SEED)
		htab->hashrnd = 0;
	else
		htab->hashrnd = get_random_int();

	htab_init_buckets(htab);

	if (prealloc) {
		err = prealloc_init(htab);
		if (err)
			goto free_map_locked;

		if (!percpu && !lru) {
			/* lru itself can remove the least used element, so
			 * there is no need for an extra elem during map_update.
			 */
			err = alloc_extra_elems(htab);
			if (err)
				goto free_prealloc;
		}
	}

	return &htab->map;

free_prealloc:
	prealloc_destroy(htab);
free_map_locked:
	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
		free_percpu(htab->map_locked[i]);
	bpf_map_area_free(htab->buckets);
free_htab:
	lockdep_unregister_key(&htab->lockdep_key);
	kfree(htab);
	return ERR_PTR(err);
}

static inline u32 htab_map_hash(const void *key, u32 key_len, u32 hashrnd)
{
	return jhash(key, key_len, hashrnd);
}

static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &htab->buckets[hash & (htab->n_buckets - 1)];
}

static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &__select_bucket(htab, hash)->head;
}

/* this lookup function can only be called with bucket lock taken */
static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
					 void *key, u32 key_size)
{
	struct hlist_nulls_node *n;
	struct htab_elem *l;

	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l->hash == hash && !memcmp(&l->key, key, key_size))
			return l;

	return NULL;
}

/* can be called without bucket lock. it will repeat the loop in
 * the unlikely event when elements moved from one bucket into another
 * while link list is being walked
 */
static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
					       u32 hash, void *key,
					       u32 key_size, u32 n_buckets)
{
	struct hlist_nulls_node *n;
	struct htab_elem *l;

again:
	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l->hash == hash && !memcmp(&l->key, key, key_size))
			return l;

	if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
		goto again;

	return NULL;
}

/* Called from syscall or from eBPF program directly, so
 * arguments have to match bpf_map_lookup_elem() exactly.
 * The return value is adjusted by BPF instructions
 * in htab_map_gen_lookup().
 */
static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct htab_elem *l;
	u32 hash, key_size;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	head = select_bucket(htab, hash);

	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);

	return l;
}

static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l)
		return l->key + round_up(map->key_size, 8);

	return NULL;
}

/* inline bpf_map_lookup_elem() call.
 * Instead of:
 * bpf_prog
 *   bpf_map_lookup_elem
 *     map->ops->map_lookup_elem
 *       htab_map_lookup_elem
 *         __htab_map_lookup_elem
 * do:
 * bpf_prog
 *   __htab_map_lookup_elem
 */
static int htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	return insn - insn_buf;
}

static __always_inline void *__htab_lru_map_lookup_elem(struct bpf_map *map,
							void *key, const bool mark)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l) {
		if (mark)
			bpf_lru_node_set_ref(&l->lru_node);
		return l->key + round_up(map->key_size, 8);
	}

	return NULL;
}

static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
{
	return __htab_lru_map_lookup_elem(map, key, true);
}

static void *htab_lru_map_lookup_elem_sys(struct bpf_map *map, void *key)
{
	return __htab_lru_map_lookup_elem(map, key, false);
}

static int htab_lru_map_gen_lookup(struct bpf_map *map,
				   struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;
	const int ref_reg = BPF_REG_1;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
	*insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
			      offsetof(struct htab_elem, lru_node) +
			      offsetof(struct bpf_lru_node, ref));
	*insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
	*insn++ = BPF_ST_MEM(BPF_B, ret,
			     offsetof(struct htab_elem, lru_node) +
			     offsetof(struct bpf_lru_node, ref),
			     1);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	return insn - insn_buf;
}

/* It is called from the bpf_lru_list when the LRU needs to delete
 * older elements from the htab.
 */
static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
{
	struct bpf_htab *htab = (struct bpf_htab *)arg;
	struct htab_elem *l = NULL, *tgt_l;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	unsigned long flags;
	struct bucket *b;
	int ret;

	tgt_l = container_of(node, struct htab_elem, lru_node);
	b = __select_bucket(htab, tgt_l->hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, tgt_l->hash, &flags);
	if (ret)
		return false;

	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l == tgt_l) {
			hlist_nulls_del_rcu(&l->hash_node);
			break;
		}

	htab_unlock_bucket(htab, b, tgt_l->hash, flags);

	return l == tgt_l;
}

/* Called from syscall */
static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct htab_elem *l, *next_l;
	u32 hash, key_size;
	int i = 0;

	WARN_ON_ONCE(!rcu_read_lock_held());

	key_size = map->key_size;

	if (!key)
		goto find_first_elem;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	head = select_bucket(htab, hash);

	/* lookup the key */
	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);

	if (!l)
		goto find_first_elem;

	/* key was found, get next key in the same bucket */
	next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
				  struct htab_elem, hash_node);

	if (next_l) {
		/* if next elem in this hash list is non-zero, just return it */
		memcpy(next_key, next_l->key, key_size);
		return 0;
	}

	/* no more elements in this hash list, go to the next bucket */
	i = hash & (htab->n_buckets - 1);
	i++;

find_first_elem:
	/* iterate over buckets */
	for (; i < htab->n_buckets; i++) {
		head = select_bucket(htab, i);

		/* pick first element in the bucket */
		next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
					  struct htab_elem, hash_node);
		if (next_l) {
			/* if it's not empty, just return it */
			memcpy(next_key, next_l->key, key_size);
			return 0;
		}
	}

	/* iterated over all buckets and all elements */
	return -ENOENT;
}

static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
{
	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
		free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
	kfree(l);
}

static void htab_elem_free_rcu(struct rcu_head *head)
{
	struct htab_elem *l = container_of(head, struct htab_elem, rcu);
	struct bpf_htab *htab = l->htab;

	htab_elem_free(htab, l);
}

static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)
{
	struct bpf_map *map = &htab->map;
	void *ptr;

	if (map->ops->map_fd_put_ptr) {
		ptr = fd_htab_map_get_ptr(map, l);
		map->ops->map_fd_put_ptr(ptr);
	}
}

static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
{
	htab_put_fd_value(htab, l);

	if (htab_is_prealloc(htab)) {
		__pcpu_freelist_push(&htab->freelist, &l->fnode);
	} else {
		atomic_dec(&htab->count);
		l->htab = htab;
		call_rcu(&l->rcu, htab_elem_free_rcu);
	}
}

static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
			    void *value, bool onallcpus)
{
	if (!onallcpus) {
		/* copy true value_size bytes */
		memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
	} else {
		u32 size = round_up(htab->map.value_size, 8);
		int off = 0, cpu;

		for_each_possible_cpu(cpu) {
			bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
					value + off, size);
			off += size;
		}
	}
}

static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,
			    void *value, bool onallcpus)
{
	/* When using prealloc and not setting the initial value on all cpus,
	 * zero-fill element values for other cpus (just as what happens when
	 * not using prealloc). Otherwise, bpf program has no way to ensure
	 * known initial values for cpus other than current one
	 * (onallcpus=false always when coming from bpf prog).
	 */
	if (htab_is_prealloc(htab) && !onallcpus) {
		u32 size = round_up(htab->map.value_size, 8);
		int current_cpu = raw_smp_processor_id();
		int cpu;

		for_each_possible_cpu(cpu) {
			if (cpu == current_cpu)
				bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value,
						size);
			else
				memset(per_cpu_ptr(pptr, cpu), 0, size);
		}
	} else {
		pcpu_copy_value(htab, pptr, value, onallcpus);
	}
}

static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
	       BITS_PER_LONG == 64;
}

static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
					 void *value, u32 key_size, u32 hash,
					 bool percpu, bool onallcpus,
					 struct htab_elem *old_elem)
{
	u32 size = htab->map.value_size;
	bool prealloc = htab_is_prealloc(htab);
	struct htab_elem *l_new, **pl_new;
	void __percpu *pptr;

	if (prealloc) {
		if (old_elem) {
			/* if we're updating the existing element,
			 * use per-cpu extra elems to avoid freelist_pop/push
			 */
			pl_new = this_cpu_ptr(htab->extra_elems);
			l_new = *pl_new;
			htab_put_fd_value(htab, old_elem);
			*pl_new = old_elem;
		} else {
			struct pcpu_freelist_node *l;

			l = __pcpu_freelist_pop(&htab->freelist);
			if (!l)
				return ERR_PTR(-E2BIG);
			l_new = container_of(l, struct htab_elem, fnode);
		}
	} else {
		if (atomic_inc_return(&htab->count) > htab->map.max_entries)
			if (!old_elem) {
				/* when map is full and update() is replacing
				 * old element, it's ok to allocate, since
				 * old element will be freed immediately.
				 * Otherwise return an error
				 */
				l_new = ERR_PTR(-E2BIG);
				goto dec_count;
			}
		l_new = bpf_map_kmalloc_node(&htab->map, htab->elem_size,
					     GFP_ATOMIC | __GFP_NOWARN,
					     htab->map.numa_node);
		if (!l_new) {
			l_new = ERR_PTR(-ENOMEM);
			goto dec_count;
		}
		check_and_init_map_lock(&htab->map,
					l_new->key + round_up(key_size, 8));
	}

	memcpy(l_new->key, key, key_size);
	if (percpu) {
		size = round_up(size, 8);
		if (prealloc) {
			pptr = htab_elem_get_ptr(l_new, key_size);
		} else {
			/* alloc_percpu zero-fills */
			pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
						    GFP_ATOMIC | __GFP_NOWARN);
			if (!pptr) {
				kfree(l_new);
				l_new = ERR_PTR(-ENOMEM);
				goto dec_count;
			}
		}

		pcpu_init_value(htab, pptr, value, onallcpus);

		if (!prealloc)
			htab_elem_set_ptr(l_new, key_size, pptr);
	} else if (fd_htab_map_needs_adjust(htab)) {
		size = round_up(size, 8);
		memcpy(l_new->key + round_up(key_size, 8), value, size);
	} else {
		copy_map_value(&htab->map,
			       l_new->key + round_up(key_size, 8),
			       value);
	}

	l_new->hash = hash;
	return l_new;
dec_count:
	atomic_dec(&htab->count);
	return l_new;
}

static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
		       u64 map_flags)
{
	if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
		/* elem already exists */
		return -EEXIST;

	if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
		/* elem doesn't exist, cannot update it */
		return -ENOENT;

	return 0;
}

/* Called from syscall or from eBPF program */
static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
				u64 map_flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	if (unlikely(map_flags & BPF_F_LOCK)) {
		if (unlikely(!map_value_has_spin_lock(map)))
			return -EINVAL;
		/* find an element without taking the bucket lock */
		l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
					      htab->n_buckets);
		ret = check_flags(htab, l_old, map_flags);
		if (ret)
			return ret;
		if (l_old) {
			/* grab the element lock and update value in place */
			copy_map_value_locked(map,
					      l_old->key + round_up(key_size, 8),
					      value, false);
			return 0;
		}
		/* fall through, grab the bucket lock and lookup again.
		 * 99.9% chance that the element won't be found,
		 * but second lookup under lock has to be done.
		 */
	}

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
		/* first lookup without the bucket lock didn't find the element,
		 * but second lookup with the bucket lock found it.
		 * This case is highly unlikely, but has to be dealt with:
		 * grab the element lock in addition to the bucket lock
		 * and update element in place
		 */
		copy_map_value_locked(map,
				      l_old->key + round_up(key_size, 8),
				      value, false);
		ret = 0;
		goto err;
	}

	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
				l_old);
	if (IS_ERR(l_new)) {
		/* all pre-allocated elements are in use or memory exhausted */
		ret = PTR_ERR(l_new);
		goto err;
	}

	/* add new element to the head of the list, so that
	 * concurrent search will find it before old elem
	 */
	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	if (l_old) {
		hlist_nulls_del_rcu(&l_old->hash_node);
		if (!htab_is_prealloc(htab))
			free_htab_elem(htab, l_old);
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
				    u64 map_flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new, *l_old = NULL;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	/* For LRU, we need to alloc before taking bucket's
	 * spinlock because getting free nodes from LRU may need
	 * to remove older elements from htab and this removal
	 * operation will need a bucket lock.
	 */
	l_new = prealloc_lru_pop(htab, key, hash);
	if (!l_new)
		return -ENOMEM;
	memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	/* add new element to the head of the list, so that
	 * concurrent search will find it before old elem
	 */
	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	if (l_old) {
		bpf_lru_node_set_ref(&l_new->lru_node);
		hlist_nulls_del_rcu(&l_old->hash_node);
	}
	ret = 0;

err:
	htab_unlock_bucket(htab, b, hash, flags);

	if (ret)
		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
	else if (l_old)
		bpf_lru_push_free(&htab->lru, &l_old->lru_node);

	return ret;
}

static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
					 void *value, u64 map_flags,
					 bool onallcpus)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (l_old) {
		/* per-cpu hash map can update value in-place */
		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
				value, onallcpus);
	} else {
		l_new = alloc_htab_elem(htab, key, value, key_size,
					hash, true, onallcpus, NULL);
		if (IS_ERR(l_new)) {
			ret = PTR_ERR(l_new);
			goto err;
		}
		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
					     void *value, u64 map_flags,
					     bool onallcpus)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	/* For LRU, we need to alloc before taking bucket's
	 * spinlock because LRU's elem alloc may need
	 * to remove older elem from htab and this removal
	 * operation will need a bucket lock.
	 */
	if (map_flags != BPF_EXIST) {
		l_new = prealloc_lru_pop(htab, key, hash);
		if (!l_new)
			return -ENOMEM;
	}

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (l_old) {
		bpf_lru_node_set_ref(&l_old->lru_node);

		/* per-cpu hash map can update value in-place */
		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
				value, onallcpus);
	} else {
		pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),
				value, onallcpus);
		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
		l_new = NULL;
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	if (l_new)
		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
	return ret;
}

static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
				       void *value, u64 map_flags)
{
	return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
}

static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
					   void *value, u64 map_flags)
{
	return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
						 false);
}

/* Called from syscall or from eBPF program */
static int htab_map_delete_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct bucket *b;
	struct htab_elem *l;
	unsigned long flags;
	u32 hash, key_size;
	int ret;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);
	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l) {
		hlist_nulls_del_rcu(&l->hash_node);
		free_htab_elem(htab, l);
	} else {
		ret = -ENOENT;
	}

	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct bucket *b;
	struct htab_elem *l;
	unsigned long flags;
	u32 hash, key_size;
	int ret;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);
	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l)
		hlist_nulls_del_rcu(&l->hash_node);
	else
		ret = -ENOENT;

	htab_unlock_bucket(htab, b, hash, flags);
	if (l)
		bpf_lru_push_free(&htab->lru, &l->lru_node);
	return ret;
}

static void delete_all_elements(struct bpf_htab *htab)
{
	int i;

	for (i = 0; i < htab->n_buckets; i++) {
		struct hlist_nulls_head *head = select_bucket(htab, i);
		struct hlist_nulls_node *n;
		struct htab_elem *l;

		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
			hlist_nulls_del_rcu(&l->hash_node);
			htab_elem_free(htab, l);
		}
	}
}

/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	int i;

	/* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback.
	 * bpf_free_used_maps() is called after bpf prog is no longer executing.
	 * There is no need to synchronize_rcu() here to protect map elements.
	 */

	/* some of free_htab_elem() callbacks for elements of this map may
	 * not have executed. Wait for them.
	 */
	rcu_barrier();
	if (!htab_is_prealloc(htab))
		delete_all_elements(htab);
	else
		prealloc_destroy(htab);

	free_percpu(htab->extra_elems);
	bpf_map_area_free(htab->buckets);
	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
		free_percpu(htab->map_locked[i]);
	lockdep_unregister_key(&htab->lockdep_key);
	kfree(htab);
}

static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
				   struct seq_file *m)
{
	void *value;

	rcu_read_lock();

	value = htab_map_lookup_elem(map, key);
	if (!value) {
		rcu_read_unlock();
		return;
	}

	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
	seq_puts(m, ": ");
	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
	seq_puts(m, "\n");

	rcu_read_unlock();
}

static int
__htab_map_lookup_and_delete_batch(struct bpf_map *map,
				   const union bpf_attr *attr,
				   union bpf_attr __user *uattr,
				   bool do_delete, bool is_lru_map,
				   bool is_percpu)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	u32 bucket_cnt, total, key_size, value_size, roundup_key_size;
	void *keys = NULL, *values = NULL, *value, *dst_key, *dst_val;
	void __user *uvalues = u64_to_user_ptr(attr->batch.values);
	void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
	void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);
	u32 batch, max_count, size, bucket_size;
	struct htab_elem *node_to_free = NULL;
	u64 elem_map_flags, map_flags;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	unsigned long flags = 0;
	bool locked = false;
	struct htab_elem *l;
	struct bucket *b;
	int ret = 0;

	elem_map_flags = attr->batch.elem_flags;
	if ((elem_map_flags & ~BPF_F_LOCK) ||
	    ((elem_map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map)))
		return -EINVAL;

	map_flags = attr->batch.flags;
	if (map_flags)
		return -EINVAL;

	max_count = attr->batch.count;
	if (!max_count)
		return 0;

	if (put_user(0, &uattr->batch.count))
		return -EFAULT;

	batch = 0;
	if (ubatch && copy_from_user(&batch, ubatch, sizeof(batch)))
		return -EFAULT;

	if (batch >= htab->n_buckets)
		return -ENOENT;

	key_size = htab->map.key_size;
	roundup_key_size = round_up(htab->map.key_size, 8);
	value_size = htab->map.value_size;
	size = round_up(value_size, 8);
	if (is_percpu)
		value_size = size * num_possible_cpus();
	total = 0;
	/* while experimenting with hash tables with sizes ranging from 10 to
	 * 1000, it was observed that a bucket can have upto 5 entries.
	 */
	bucket_size = 5;

alloc:
	/* We cannot do copy_from_user or copy_to_user inside
	 * the rcu_read_lock. Allocate enough space here.
	 */
	keys = kvmalloc(key_size * bucket_size, GFP_USER | __GFP_NOWARN);
	values = kvmalloc(value_size * bucket_size, GFP_USER | __GFP_NOWARN);
	if (!keys || !values) {
		ret = -ENOMEM;
		goto after_loop;
	}

again:
	bpf_disable_instrumentation();
	rcu_read_lock();
again_nocopy:
	dst_key = keys;
	dst_val = values;
	b = &htab->buckets[batch];
	head = &b->head;
	/* do not grab the lock unless need it (bucket_cnt > 0). */
	if (locked) {
		ret = htab_lock_bucket(htab, b, batch, &flags);
		if (ret)
			goto next_batch;
	}

	bucket_cnt = 0;
	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		bucket_cnt++;

	if (bucket_cnt && !locked) {
		locked = true;
		goto again_nocopy;
	}

	if (bucket_cnt > (max_count - total)) {
		if (total == 0)
			ret = -ENOSPC;
		/* Note that since bucket_cnt > 0 here, it is implicit
		 * that the locked was grabbed, so release it.
		 */
		htab_unlock_bucket(htab, b, batch, flags);
		rcu_read_unlock();
		bpf_enable_instrumentation();
		goto after_loop;
	}

	if (bucket_cnt > bucket_size) {
		bucket_size = bucket_cnt;
		/* Note that since bucket_cnt > 0 here, it is implicit
		 * that the locked was grabbed, so release it.
		 */
		htab_unlock_bucket(htab, b, batch, flags);
		rcu_read_unlock();
		bpf_enable_instrumentation();
		kvfree(keys);
		kvfree(values);
		goto alloc;
	}

	/* Next block is only safe to run if you have grabbed the lock */
	if (!locked)
		goto next_batch;

	hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
		memcpy(dst_key, l->key, key_size);

		if (is_percpu) {
			int off = 0, cpu;
			void __percpu *pptr;

			pptr = htab_elem_get_ptr(l, map->key_size);
			for_each_possible_cpu(cpu) {
				bpf_long_memcpy(dst_val + off,
						per_cpu_ptr(pptr, cpu), size);
				off += size;
			}
		} else {
			value = l->key + roundup_key_size;
			if (elem_map_flags & BPF_F_LOCK)
				copy_map_value_locked(map, dst_val, value,
						      true);
			else
				copy_map_value(map, dst_val, value);
			check_and_init_map_lock(map, dst_val);
		}
		if (do_delete) {
			hlist_nulls_del_rcu(&l->hash_node);

			/* bpf_lru_push_free() will acquire lru_lock, which
			 * may cause deadlock. See comments in function
			 * prealloc_lru_pop(). Let us do bpf_lru_push_free()
			 * after releasing the bucket lock.
			 */
			if (is_lru_map) {
				l->batch_flink = node_to_free;
				node_to_free = l;
			} else {
				free_htab_elem(htab, l);
			}
		}
		dst_key += key_size;
		dst_val += value_size;
	}

	htab_unlock_bucket(htab, b, batch, flags);
	locked = false;

	while (node_to_free) {
		l = node_to_free;
		node_to_free = node_to_free->batch_flink;
		bpf_lru_push_free(&htab->lru, &l->lru_node);
	}

next_batch:
	/* If we are not copying data, we can go to next bucket and avoid
	 * unlocking the rcu.
	 */
	if (!bucket_cnt && (batch + 1 < htab->n_buckets)) {
		batch++;
		goto again_nocopy;
	}

	rcu_read_unlock();
	bpf_enable_instrumentation();
	if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys,
	    key_size * bucket_cnt) ||
	    copy_to_user(uvalues + total * value_size, values,
	    value_size * bucket_cnt))) {
		ret = -EFAULT;
		goto after_loop;
	}

	total += bucket_cnt;
	batch++;
	if (batch >= htab->n_buckets) {
		ret = -ENOENT;
		goto after_loop;
	}
	goto again;

after_loop:
	if (ret == -EFAULT)
		goto out;

	/* copy # of entries and next batch */
	ubatch = u64_to_user_ptr(attr->batch.out_batch);
	if (copy_to_user(ubatch, &batch, sizeof(batch)) ||
	    put_user(total, &uattr->batch.count))
		ret = -EFAULT;

out:
	kvfree(keys);
	kvfree(values);
	return ret;
}

static int
htab_percpu_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
			     union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  false, true);
}

static int
htab_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
					const union bpf_attr *attr,
					union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  false, true);
}

static int
htab_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
		      union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  false, false);
}

static int
htab_map_lookup_and_delete_batch(struct bpf_map *map,
				 const union bpf_attr *attr,
				 union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  false, false);
}

static int
htab_lru_percpu_map_lookup_batch(struct bpf_map *map,
				 const union bpf_attr *attr,
				 union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  true, true);
}

static int
htab_lru_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
					    const union bpf_attr *attr,
					    union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  true, true);
}

static int
htab_lru_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
			  union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  true, false);
}

static int
htab_lru_map_lookup_and_delete_batch(struct bpf_map *map,
				     const union bpf_attr *attr,
				     union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  true, false);
}

struct bpf_iter_seq_hash_map_info {
	struct bpf_map *map;
	struct bpf_htab *htab;
	void *percpu_value_buf; // non-zero means percpu hash
	u32 bucket_id;
	u32 skip_elems;
};

static struct htab_elem *
bpf_hash_map_seq_find_next(struct bpf_iter_seq_hash_map_info *info,
			   struct htab_elem *prev_elem)
{
	const struct bpf_htab *htab = info->htab;
	u32 skip_elems = info->skip_elems;
	u32 bucket_id = info->bucket_id;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	struct htab_elem *elem;
	struct bucket *b;
	u32 i, count;

	if (bucket_id >= htab->n_buckets)
		return NULL;

	/* try to find next elem in the same bucket */
	if (prev_elem) {
		/* no update/deletion on this bucket, prev_elem should be still valid
		 * and we won't skip elements.
		 */
		n = rcu_dereference_raw(hlist_nulls_next_rcu(&prev_elem->hash_node));
		elem = hlist_nulls_entry_safe(n, struct htab_elem, hash_node);
		if (elem)
			return elem;

		/* not found, unlock and go to the next bucket */
		b = &htab->buckets[bucket_id++];
		rcu_read_unlock();
		skip_elems = 0;
	}

	for (i = bucket_id; i < htab->n_buckets; i++) {
		b = &htab->buckets[i];
		rcu_read_lock();

		count = 0;
		head = &b->head;
		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
			if (count >= skip_elems) {
				info->bucket_id = i;
				info->skip_elems = count;
				return elem;
			}
			count++;
		}

		rcu_read_unlock();
		skip_elems = 0;
	}

	info->bucket_id = i;
	info->skip_elems = 0;
	return NULL;
}

static void *bpf_hash_map_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;
	struct htab_elem *elem;

	elem = bpf_hash_map_seq_find_next(info, NULL);
	if (!elem)
		return NULL;

	if (*pos == 0)
		++*pos;
	return elem;
}

static void *bpf_hash_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;

	++*pos;
	++info->skip_elems;
	return bpf_hash_map_seq_find_next(info, v);
}

static int __bpf_hash_map_seq_show(struct seq_file *seq, struct htab_elem *elem)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;
	u32 roundup_key_size, roundup_value_size;
	struct bpf_iter__bpf_map_elem ctx = {};
	struct bpf_map *map = info->map;
	struct bpf_iter_meta meta;
	int ret = 0, off = 0, cpu;
	struct bpf_prog *prog;
	void __percpu *pptr;

	meta.seq = seq;
	prog = bpf_iter_get_info(&meta, elem == NULL);
	if (prog) {
		ctx.meta = &meta;
		ctx.map = info->map;
		if (elem) {
			roundup_key_size = round_up(map->key_size, 8);
			ctx.key = elem->key;
			if (!info->percpu_value_buf) {
				ctx.value = elem->key + roundup_key_size;
			} else {
				roundup_value_size = round_up(map->value_size, 8);
				pptr = htab_elem_get_ptr(elem, map->key_size);
				for_each_possible_cpu(cpu) {
					bpf_long_memcpy(info->percpu_value_buf + off,
							per_cpu_ptr(pptr, cpu),
							roundup_value_size);
					off += roundup_value_size;
				}
				ctx.value = info->percpu_value_buf;
			}
		}
		ret = bpf_iter_run_prog(prog, &ctx);
	}

	return ret;
}

static int bpf_hash_map_seq_show(struct seq_file *seq, void *v)
{
	return __bpf_hash_map_seq_show(seq, v);
}

static void bpf_hash_map_seq_stop(struct seq_file *seq, void *v)
{
	if (!v)
		(void)__bpf_hash_map_seq_show(seq, NULL);
	else
		rcu_read_unlock();
}

static int bpf_iter_init_hash_map(void *priv_data,
				  struct bpf_iter_aux_info *aux)
{
	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
	struct bpf_map *map = aux->map;
	void *value_buf;
	u32 buf_size;

	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
		buf_size = round_up(map->value_size, 8) * num_possible_cpus();
		value_buf = kmalloc(buf_size, GFP_USER | __GFP_NOWARN);
		if (!value_buf)
			return -ENOMEM;

		seq_info->percpu_value_buf = value_buf;
	}

	seq_info->map = map;
	seq_info->htab = container_of(map, struct bpf_htab, map);
	return 0;
}

static void bpf_iter_fini_hash_map(void *priv_data)
{
	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;

	kfree(seq_info->percpu_value_buf);
}

static const struct seq_operations bpf_hash_map_seq_ops = {
	.start	= bpf_hash_map_seq_start,
	.next	= bpf_hash_map_seq_next,
	.stop	= bpf_hash_map_seq_stop,
	.show	= bpf_hash_map_seq_show,
};

static const struct bpf_iter_seq_info iter_seq_info = {
	.seq_ops		= &bpf_hash_map_seq_ops,
	.init_seq_private	= bpf_iter_init_hash_map,
	.fini_seq_private	= bpf_iter_fini_hash_map,
	.seq_priv_size		= sizeof(struct bpf_iter_seq_hash_map_info),
};

static int bpf_for_each_hash_elem(struct bpf_map *map, void *callback_fn,
				  void *callback_ctx, u64 flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	struct htab_elem *elem;
	u32 roundup_key_size;
	int i, num_elems = 0;
	void __percpu *pptr;
	struct bucket *b;
	void *key, *val;
	bool is_percpu;
	u64 ret = 0;

	if (flags != 0)
		return -EINVAL;

	is_percpu = htab_is_percpu(htab);

	roundup_key_size = round_up(map->key_size, 8);
	/* disable migration so percpu value prepared here will be the
	 * same as the one seen by the bpf program with bpf_map_lookup_elem().
	 */
	if (is_percpu)
		migrate_disable();
	for (i = 0; i < htab->n_buckets; i++) {
		b = &htab->buckets[i];
		rcu_read_lock();
		head = &b->head;
		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
			key = elem->key;
			if (is_percpu) {
				/* current cpu value for percpu map */
				pptr = htab_elem_get_ptr(elem, map->key_size);
				val = this_cpu_ptr(pptr);
			} else {
				val = elem->key + roundup_key_size;
			}
			num_elems++;
			ret = BPF_CAST_CALL(callback_fn)((u64)(long)map,
					(u64)(long)key, (u64)(long)val,
					(u64)(long)callback_ctx, 0);
			/* return value: 0 - continue, 1 - stop and return */
			if (ret) {
				rcu_read_unlock();
				goto out;
			}
		}
		rcu_read_unlock();
	}
out:
	if (is_percpu)
		migrate_enable();
	return num_elems;
}

static int htab_map_btf_id;
const struct bpf_map_ops htab_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = htab_map_alloc_check,
	.map_alloc = htab_map_alloc,
	.map_free = htab_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_map_lookup_elem,
	.map_update_elem = htab_map_update_elem,
	.map_delete_elem = htab_map_delete_elem,
	.map_gen_lookup = htab_map_gen_lookup,
	.map_seq_show_elem = htab_map_seq_show_elem,
	.map_set_for_each_callback_args = map_set_for_each_callback_args,
	.map_for_each_callback = bpf_for_each_hash_elem,
	BATCH_OPS(htab),
	.map_btf_name = "bpf_htab",
	.map_btf_id = &htab_map_btf_id,
	.iter_seq_info = &iter_seq_info,
};

static int htab_lru_map_btf_id;
const struct bpf_map_ops htab_lru_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = htab_map_alloc_check,
	.map_alloc = htab_map_alloc,
	.map_free = htab_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_lru_map_lookup_elem,
	.map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
	.map_update_elem = htab_lru_map_update_elem,
	.map_delete_elem = htab_lru_map_delete_elem,
	.map_gen_lookup = htab_lru_map_gen_lookup,
	.map_seq_show_elem = htab_map_seq_show_elem,
	.map_set_for_each_callback_args = map_set_for_each_callback_args,
	.map_for_each_callback = bpf_for_each_hash_elem,
	BATCH_OPS(htab_lru),
	.map_btf_name = "bpf_htab",
	.map_btf_id = &htab_lru_map_btf_id,
	.iter_seq_info = &iter_seq_info,
};

/* Called from eBPF program */
static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l)
		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
	else
		return NULL;
}

static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l) {
		bpf_lru_node_set_ref(&l->lru_node);
		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
	}

	return NULL;
}

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
{
	struct htab_elem *l;
	void __percpu *pptr;
	int ret = -ENOENT;
	int cpu, off = 0;
	u32 size;

	/* per_cpu areas are zero-filled and bpf programs can only
	 * access 'value_size' of them, so copying rounded areas
	 * will not leak any kernel data
	 */
	size = round_up(map->value_size, 8);
	rcu_read_lock();
	l = __htab_map_lookup_elem(map, key);
	if (!l)
		goto out;
	/* We do not mark LRU map element here in order to not mess up
	 * eviction heuristics when user space does a map walk.
	 */
	pptr = htab_elem_get_ptr(l, map->key_size);
	for_each_possible_cpu(cpu) {
		bpf_long_memcpy(value + off,
				per_cpu_ptr(pptr, cpu), size);
		off += size;
	}
	ret = 0;
out:
	rcu_read_unlock();
	return ret;
}

int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
			   u64 map_flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	int ret;

	rcu_read_lock();
	if (htab_is_lru(htab))
		ret = __htab_lru_percpu_map_update_elem(map, key, value,
							map_flags, true);
	else
		ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
						    true);
	rcu_read_unlock();

	return ret;
}

static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
					  struct seq_file *m)
{
	struct htab_elem *l;
	void __percpu *pptr;
	int cpu;

	rcu_read_lock();

	l = __htab_map_lookup_elem(map, key);
	if (!l) {
		rcu_read_unlock();
		return;
	}

	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
	seq_puts(m, ": {\n");
	pptr = htab_elem_get_ptr(l, map->key_size);
	for_each_possible_cpu(cpu) {
		seq_printf(m, "\tcpu%d: ", cpu);
		btf_type_seq_show(map->btf, map->btf_value_type_id,
				  per_cpu_ptr(pptr, cpu), m);
		seq_puts(m, "\n");
	}
	seq_puts(m, "}\n");

	rcu_read_unlock();
}

static int htab_percpu_map_btf_id;
const struct bpf_map_ops htab_percpu_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = htab_map_alloc_check,
	.map_alloc = htab_map_alloc,
	.map_free = htab_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_percpu_map_lookup_elem,
	.map_update_elem = htab_percpu_map_update_elem,
	.map_delete_elem = htab_map_delete_elem,
	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
	.map_set_for_each_callback_args = map_set_for_each_callback_args,
	.map_for_each_callback = bpf_for_each_hash_elem,
	BATCH_OPS(htab_percpu),
	.map_btf_name = "bpf_htab",
	.map_btf_id = &htab_percpu_map_btf_id,
	.iter_seq_info = &iter_seq_info,
};

static int htab_lru_percpu_map_btf_id;
const struct bpf_map_ops htab_lru_percpu_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = htab_map_alloc_check,
	.map_alloc = htab_map_alloc,
	.map_free = htab_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_lru_percpu_map_lookup_elem,
	.map_update_elem = htab_lru_percpu_map_update_elem,
	.map_delete_elem = htab_lru_map_delete_elem,
	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
	.map_set_for_each_callback_args = map_set_for_each_callback_args,
	.map_for_each_callback = bpf_for_each_hash_elem,
	BATCH_OPS(htab_lru_percpu),
	.map_btf_name = "bpf_htab",
	.map_btf_id = &htab_lru_percpu_map_btf_id,
	.iter_seq_info = &iter_seq_info,
};

static int fd_htab_map_alloc_check(union bpf_attr *attr)
{
	if (attr->value_size != sizeof(u32))
		return -EINVAL;
	return htab_map_alloc_check(attr);
}

static void fd_htab_map_free(struct bpf_map *map)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_node *n;
	struct hlist_nulls_head *head;
	struct htab_elem *l;
	int i;

	for (i = 0; i < htab->n_buckets; i++) {
		head = select_bucket(htab, i);

		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
			void *ptr = fd_htab_map_get_ptr(map, l);

			map->ops->map_fd_put_ptr(ptr);
		}
	}

	htab_map_free(map);
}

/* only called from syscall */
int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
{
	void **ptr;
	int ret = 0;

	if (!map->ops->map_fd_sys_lookup_elem)
		return -ENOTSUPP;

	rcu_read_lock();
	ptr = htab_map_lookup_elem(map, key);
	if (ptr)
		*value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
	else
		ret = -ENOENT;
	rcu_read_unlock();

	return ret;
}

/* only called from syscall */
int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
				void *key, void *value, u64 map_flags)
{
	void *ptr;
	int ret;
	u32 ufd = *(u32 *)value;

	ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
	if (IS_ERR(ptr))
		return PTR_ERR(ptr);

	ret = htab_map_update_elem(map, key, &ptr, map_flags);
	if (ret)
		map->ops->map_fd_put_ptr(ptr);

	return ret;
}

static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
{
	struct bpf_map *map, *inner_map_meta;

	inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
	if (IS_ERR(inner_map_meta))
		return inner_map_meta;

	map = htab_map_alloc(attr);
	if (IS_ERR(map)) {
		bpf_map_meta_free(inner_map_meta);
		return map;
	}

	map->inner_map_meta = inner_map_meta;

	return map;
}

static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);

	if (!inner_map)
		return NULL;

	return READ_ONCE(*inner_map);
}

static int htab_of_map_gen_lookup(struct bpf_map *map,
				  struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);

	return insn - insn_buf;
}

static void htab_of_map_free(struct bpf_map *map)
{
	bpf_map_meta_free(map->inner_map_meta);
	fd_htab_map_free(map);
}

static int htab_of_maps_map_btf_id;
const struct bpf_map_ops htab_of_maps_map_ops = {
	.map_alloc_check = fd_htab_map_alloc_check,
	.map_alloc = htab_of_map_alloc,
	.map_free = htab_of_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_of_map_lookup_elem,
	.map_delete_elem = htab_map_delete_elem,
	.map_fd_get_ptr = bpf_map_fd_get_ptr,
	.map_fd_put_ptr = bpf_map_fd_put_ptr,
	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
	.map_gen_lookup = htab_of_map_gen_lookup,
	.map_check_btf = map_check_no_btf,
	.map_btf_name = "bpf_htab",
	.map_btf_id = &htab_of_maps_map_btf_id,
};