summaryrefslogtreecommitdiff
path: root/arch/powerpc/kernel/entry_64.S
blob: 2cb5109a7ea3d3d4959fa0d9360248218b56d688 (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
/*
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *
 *  This file contains the system call entry code, context switch
 *  code, and exception/interrupt return code for PowerPC.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/bug.h>
#include <asm/ptrace.h>
#include <asm/irqflags.h>
#include <asm/hw_irq.h>
#include <asm/context_tracking.h>
#include <asm/tm.h>
#include <asm/ppc-opcode.h>
#include <asm/export.h>
#ifdef CONFIG_PPC_BOOK3S
#include <asm/exception-64s.h>
#else
#include <asm/exception-64e.h>
#endif

/*
 * System calls.
 */
	.section	".toc","aw"
SYS_CALL_TABLE:
	.tc sys_call_table[TC],sys_call_table

/* This value is used to mark exception frames on the stack. */
exception_marker:
	.tc	ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER

	.section	".text"
	.align 7

	.globl system_call_common
system_call_common:
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
BEGIN_FTR_SECTION
	extrdi.	r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
	bne	.Ltabort_syscall
END_FTR_SECTION_IFSET(CPU_FTR_TM)
#endif
	andi.	r10,r12,MSR_PR
	mr	r10,r1
	addi	r1,r1,-INT_FRAME_SIZE
	beq-	1f
	ld	r1,PACAKSAVE(r13)
1:	std	r10,0(r1)
	std	r11,_NIP(r1)
	std	r12,_MSR(r1)
	std	r0,GPR0(r1)
	std	r10,GPR1(r1)
	beq	2f			/* if from kernel mode */
	ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
2:	std	r2,GPR2(r1)
	std	r3,GPR3(r1)
	mfcr	r2
	std	r4,GPR4(r1)
	std	r5,GPR5(r1)
	std	r6,GPR6(r1)
	std	r7,GPR7(r1)
	std	r8,GPR8(r1)
	li	r11,0
	std	r11,GPR9(r1)
	std	r11,GPR10(r1)
	std	r11,GPR11(r1)
	std	r11,GPR12(r1)
	std	r11,_XER(r1)
	std	r11,_CTR(r1)
	std	r9,GPR13(r1)
	mflr	r10
	/*
	 * This clears CR0.SO (bit 28), which is the error indication on
	 * return from this system call.
	 */
	rldimi	r2,r11,28,(63-28)
	li	r11,0xc01
	std	r10,_LINK(r1)
	std	r11,_TRAP(r1)
	std	r3,ORIG_GPR3(r1)
	std	r2,_CCR(r1)
	ld	r2,PACATOC(r13)
	addi	r9,r1,STACK_FRAME_OVERHEAD
	ld	r11,exception_marker@toc(r2)
	std	r11,-16(r9)		/* "regshere" marker */
#if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC_SPLPAR)
BEGIN_FW_FTR_SECTION
	beq	33f
	/* if from user, see if there are any DTL entries to process */
	ld	r10,PACALPPACAPTR(r13)	/* get ptr to VPA */
	ld	r11,PACA_DTL_RIDX(r13)	/* get log read index */
	addi	r10,r10,LPPACA_DTLIDX
	LDX_BE	r10,0,r10		/* get log write index */
	cmpd	cr1,r11,r10
	beq+	cr1,33f
	bl	accumulate_stolen_time
	REST_GPR(0,r1)
	REST_4GPRS(3,r1)
	REST_2GPRS(7,r1)
	addi	r9,r1,STACK_FRAME_OVERHEAD
33:
END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE && CONFIG_PPC_SPLPAR */

	/*
	 * A syscall should always be called with interrupts enabled
	 * so we just unconditionally hard-enable here. When some kind
	 * of irq tracing is used, we additionally check that condition
	 * is correct
	 */
#if defined(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) && defined(CONFIG_BUG)
	lbz	r10,PACAIRQSOFTMASK(r13)
1:	tdnei	r10,IRQS_ENABLED
	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
#endif

#ifdef CONFIG_PPC_BOOK3E
	wrteei	1
#else
	li	r11,MSR_RI
	ori	r11,r11,MSR_EE
	mtmsrd	r11,1
#endif /* CONFIG_PPC_BOOK3E */

system_call:			/* label this so stack traces look sane */
	/* We do need to set SOFTE in the stack frame or the return
	 * from interrupt will be painful
	 */
	li	r10,IRQS_ENABLED
	std	r10,SOFTE(r1)

	CURRENT_THREAD_INFO(r11, r1)
	ld	r10,TI_FLAGS(r11)
	andi.	r11,r10,_TIF_SYSCALL_DOTRACE
	bne	.Lsyscall_dotrace		/* does not return */
	cmpldi	0,r0,NR_syscalls
	bge-	.Lsyscall_enosys

.Lsyscall:
/*
 * Need to vector to 32 Bit or default sys_call_table here,
 * based on caller's run-mode / personality.
 */
	ld	r11,SYS_CALL_TABLE@toc(2)
	andi.	r10,r10,_TIF_32BIT
	beq	15f
	addi	r11,r11,8	/* use 32-bit syscall entries */
	clrldi	r3,r3,32
	clrldi	r4,r4,32
	clrldi	r5,r5,32
	clrldi	r6,r6,32
	clrldi	r7,r7,32
	clrldi	r8,r8,32
15:
	slwi	r0,r0,4
	ldx	r12,r11,r0	/* Fetch system call handler [ptr] */
	mtctr   r12
	bctrl			/* Call handler */

.Lsyscall_exit:
	std	r3,RESULT(r1)
	CURRENT_THREAD_INFO(r12, r1)

	ld	r8,_MSR(r1)
#ifdef CONFIG_PPC_BOOK3S
	/* No MSR:RI on BookE */
	andi.	r10,r8,MSR_RI
	beq-	.Lunrecov_restore
#endif

/*
 * This is a few instructions into the actual syscall exit path (which actually
 * starts at .Lsyscall_exit) to cater to kprobe blacklisting and to reduce the
 * number of visible symbols for profiling purposes.
 *
 * We can probe from system_call until this point as MSR_RI is set. But once it
 * is cleared below, we won't be able to take a trap.
 *
 * This is blacklisted from kprobes further below with _ASM_NOKPROBE_SYMBOL().
 */
system_call_exit:
	/*
	 * Disable interrupts so current_thread_info()->flags can't change,
	 * and so that we don't get interrupted after loading SRR0/1.
	 */
#ifdef CONFIG_PPC_BOOK3E
	wrteei	0
#else
	/*
	 * For performance reasons we clear RI the same time that we
	 * clear EE. We only need to clear RI just before we restore r13
	 * below, but batching it with EE saves us one expensive mtmsrd call.
	 * We have to be careful to restore RI if we branch anywhere from
	 * here (eg syscall_exit_work).
	 */
	li	r11,0
	mtmsrd	r11,1
#endif /* CONFIG_PPC_BOOK3E */

	ld	r9,TI_FLAGS(r12)
	li	r11,-MAX_ERRNO
	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
	bne-	.Lsyscall_exit_work

	andi.	r0,r8,MSR_FP
	beq 2f
#ifdef CONFIG_ALTIVEC
	andis.	r0,r8,MSR_VEC@h
	bne	3f
#endif
2:	addi    r3,r1,STACK_FRAME_OVERHEAD
#ifdef CONFIG_PPC_BOOK3S
	li	r10,MSR_RI
	mtmsrd	r10,1		/* Restore RI */
#endif
	bl	restore_math
#ifdef CONFIG_PPC_BOOK3S
	li	r11,0
	mtmsrd	r11,1
#endif
	ld	r8,_MSR(r1)
	ld	r3,RESULT(r1)
	li	r11,-MAX_ERRNO

3:	cmpld	r3,r11
	ld	r5,_CCR(r1)
	bge-	.Lsyscall_error
.Lsyscall_error_cont:
	ld	r7,_NIP(r1)
BEGIN_FTR_SECTION
	stdcx.	r0,0,r1			/* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
	andi.	r6,r8,MSR_PR
	ld	r4,_LINK(r1)

	beq-	1f
	ACCOUNT_CPU_USER_EXIT(r13, r11, r12)

BEGIN_FTR_SECTION
	HMT_MEDIUM_LOW
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)

	ld	r13,GPR13(r1)	/* only restore r13 if returning to usermode */
	ld	r2,GPR2(r1)
	ld	r1,GPR1(r1)
	mtlr	r4
	mtcr	r5
	mtspr	SPRN_SRR0,r7
	mtspr	SPRN_SRR1,r8
	RFI_TO_USER
	b	.	/* prevent speculative execution */

	/* exit to kernel */
1:	ld	r2,GPR2(r1)
	ld	r1,GPR1(r1)
	mtlr	r4
	mtcr	r5
	mtspr	SPRN_SRR0,r7
	mtspr	SPRN_SRR1,r8
	RFI_TO_KERNEL
	b	.	/* prevent speculative execution */

.Lsyscall_error:
	oris	r5,r5,0x1000	/* Set SO bit in CR */
	neg	r3,r3
	std	r5,_CCR(r1)
	b	.Lsyscall_error_cont

/* Traced system call support */
.Lsyscall_dotrace:
	bl	save_nvgprs
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_enter

	/*
	 * We use the return value of do_syscall_trace_enter() as the syscall
	 * number. If the syscall was rejected for any reason do_syscall_trace_enter()
	 * returns an invalid syscall number and the test below against
	 * NR_syscalls will fail.
	 */
	mr	r0,r3

	/* Restore argument registers just clobbered and/or possibly changed. */
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r5,GPR5(r1)
	ld	r6,GPR6(r1)
	ld	r7,GPR7(r1)
	ld	r8,GPR8(r1)

	/* Repopulate r9 and r10 for the syscall path */
	addi	r9,r1,STACK_FRAME_OVERHEAD
	CURRENT_THREAD_INFO(r10, r1)
	ld	r10,TI_FLAGS(r10)

	cmpldi	r0,NR_syscalls
	blt+	.Lsyscall

	/* Return code is already in r3 thanks to do_syscall_trace_enter() */
	b	.Lsyscall_exit


.Lsyscall_enosys:
	li	r3,-ENOSYS
	b	.Lsyscall_exit
	
.Lsyscall_exit_work:
#ifdef CONFIG_PPC_BOOK3S
	li	r10,MSR_RI
	mtmsrd	r10,1		/* Restore RI */
#endif
	/* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr.
	 If TIF_NOERROR is set, just save r3 as it is. */

	andi.	r0,r9,_TIF_RESTOREALL
	beq+	0f
	REST_NVGPRS(r1)
	b	2f
0:	cmpld	r3,r11		/* r11 is -MAX_ERRNO */
	blt+	1f
	andi.	r0,r9,_TIF_NOERROR
	bne-	1f
	ld	r5,_CCR(r1)
	neg	r3,r3
	oris	r5,r5,0x1000	/* Set SO bit in CR */
	std	r5,_CCR(r1)
1:	std	r3,GPR3(r1)
2:	andi.	r0,r9,(_TIF_PERSYSCALL_MASK)
	beq	4f

	/* Clear per-syscall TIF flags if any are set.  */

	li	r11,_TIF_PERSYSCALL_MASK
	addi	r12,r12,TI_FLAGS
3:	ldarx	r10,0,r12
	andc	r10,r10,r11
	stdcx.	r10,0,r12
	bne-	3b
	subi	r12,r12,TI_FLAGS

4:	/* Anything else left to do? */
BEGIN_FTR_SECTION
	lis	r3,INIT_PPR@highest	/* Set thread.ppr = 3 */
	ld	r10,PACACURRENT(r13)
	sldi	r3,r3,32	/* bits 11-13 are used for ppr */
	std	r3,TASKTHREADPPR(r10)
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)

	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP)
	beq	ret_from_except_lite

	/* Re-enable interrupts */
#ifdef CONFIG_PPC_BOOK3E
	wrteei	1
#else
	li	r10,MSR_RI
	ori	r10,r10,MSR_EE
	mtmsrd	r10,1
#endif /* CONFIG_PPC_BOOK3E */

	bl	save_nvgprs
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_leave
	b	ret_from_except

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
.Ltabort_syscall:
	/* Firstly we need to enable TM in the kernel */
	mfmsr	r10
	li	r9, 1
	rldimi	r10, r9, MSR_TM_LG, 63-MSR_TM_LG
	mtmsrd	r10, 0

	/* tabort, this dooms the transaction, nothing else */
	li	r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
	TABORT(R9)

	/*
	 * Return directly to userspace. We have corrupted user register state,
	 * but userspace will never see that register state. Execution will
	 * resume after the tbegin of the aborted transaction with the
	 * checkpointed register state.
	 */
	li	r9, MSR_RI
	andc	r10, r10, r9
	mtmsrd	r10, 1
	mtspr	SPRN_SRR0, r11
	mtspr	SPRN_SRR1, r12
	RFI_TO_USER
	b	.	/* prevent speculative execution */
#endif
_ASM_NOKPROBE_SYMBOL(system_call_common);
_ASM_NOKPROBE_SYMBOL(system_call_exit);

/* Save non-volatile GPRs, if not already saved. */
_GLOBAL(save_nvgprs)
	ld	r11,_TRAP(r1)
	andi.	r0,r11,1
	beqlr-
	SAVE_NVGPRS(r1)
	clrrdi	r0,r11,1
	std	r0,_TRAP(r1)
	blr
_ASM_NOKPROBE_SYMBOL(save_nvgprs);

	
/*
 * The sigsuspend and rt_sigsuspend system calls can call do_signal
 * and thus put the process into the stopped state where we might
 * want to examine its user state with ptrace.  Therefore we need
 * to save all the nonvolatile registers (r14 - r31) before calling
 * the C code.  Similarly, fork, vfork and clone need the full
 * register state on the stack so that it can be copied to the child.
 */

_GLOBAL(ppc_fork)
	bl	save_nvgprs
	bl	sys_fork
	b	.Lsyscall_exit

_GLOBAL(ppc_vfork)
	bl	save_nvgprs
	bl	sys_vfork
	b	.Lsyscall_exit

_GLOBAL(ppc_clone)
	bl	save_nvgprs
	bl	sys_clone
	b	.Lsyscall_exit

_GLOBAL(ppc32_swapcontext)
	bl	save_nvgprs
	bl	compat_sys_swapcontext
	b	.Lsyscall_exit

_GLOBAL(ppc64_swapcontext)
	bl	save_nvgprs
	bl	sys_swapcontext
	b	.Lsyscall_exit

_GLOBAL(ppc_switch_endian)
	bl	save_nvgprs
	bl	sys_switch_endian
	b	.Lsyscall_exit

_GLOBAL(ret_from_fork)
	bl	schedule_tail
	REST_NVGPRS(r1)
	li	r3,0
	b	.Lsyscall_exit

_GLOBAL(ret_from_kernel_thread)
	bl	schedule_tail
	REST_NVGPRS(r1)
	mtlr	r14
	mr	r3,r15
#ifdef PPC64_ELF_ABI_v2
	mr	r12,r14
#endif
	blrl
	li	r3,0
	b	.Lsyscall_exit

/*
 * This routine switches between two different tasks.  The process
 * state of one is saved on its kernel stack.  Then the state
 * of the other is restored from its kernel stack.  The memory
 * management hardware is updated to the second process's state.
 * Finally, we can return to the second process, via ret_from_except.
 * On entry, r3 points to the THREAD for the current task, r4
 * points to the THREAD for the new task.
 *
 * Note: there are two ways to get to the "going out" portion
 * of this code; either by coming in via the entry (_switch)
 * or via "fork" which must set up an environment equivalent
 * to the "_switch" path.  If you change this you'll have to change
 * the fork code also.
 *
 * The code which creates the new task context is in 'copy_thread'
 * in arch/powerpc/kernel/process.c 
 */
	.align	7
_GLOBAL(_switch)
	mflr	r0
	std	r0,16(r1)
	stdu	r1,-SWITCH_FRAME_SIZE(r1)
	/* r3-r13 are caller saved -- Cort */
	SAVE_8GPRS(14, r1)
	SAVE_10GPRS(22, r1)
	std	r0,_NIP(r1)	/* Return to switch caller */
	mfcr	r23
	std	r23,_CCR(r1)
	std	r1,KSP(r3)	/* Set old stack pointer */

	/*
	 * On SMP kernels, care must be taken because a task may be
	 * scheduled off CPUx and on to CPUy. Memory ordering must be
	 * considered.
	 *
	 * Cacheable stores on CPUx will be visible when the task is
	 * scheduled on CPUy by virtue of the core scheduler barriers
	 * (see "Notes on Program-Order guarantees on SMP systems." in
	 * kernel/sched/core.c).
	 *
	 * Uncacheable stores in the case of involuntary preemption must
	 * be taken care of. The smp_mb__before_spin_lock() in __schedule()
	 * is implemented as hwsync on powerpc, which orders MMIO too. So
	 * long as there is an hwsync in the context switch path, it will
	 * be executed on the source CPU after the task has performed
	 * all MMIO ops on that CPU, and on the destination CPU before the
	 * task performs any MMIO ops there.
	 */

	/*
	 * The kernel context switch path must contain a spin_lock,
	 * which contains larx/stcx, which will clear any reservation
	 * of the task being switched.
	 */
#ifdef CONFIG_PPC_BOOK3S
/* Cancel all explict user streams as they will have no use after context
 * switch and will stop the HW from creating streams itself
 */
	DCBT_STOP_ALL_STREAM_IDS(r6)
#endif

	addi	r6,r4,-THREAD	/* Convert THREAD to 'current' */
	std	r6,PACACURRENT(r13)	/* Set new 'current' */

	ld	r8,KSP(r4)	/* new stack pointer */
#ifdef CONFIG_PPC_BOOK3S_64
BEGIN_MMU_FTR_SECTION
	b	2f
END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)
BEGIN_FTR_SECTION
	clrrdi	r6,r8,28	/* get its ESID */
	clrrdi	r9,r1,28	/* get current sp ESID */
FTR_SECTION_ELSE
	clrrdi	r6,r8,40	/* get its 1T ESID */
	clrrdi	r9,r1,40	/* get current sp 1T ESID */
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_1T_SEGMENT)
	clrldi.	r0,r6,2		/* is new ESID c00000000? */
	cmpd	cr1,r6,r9	/* or is new ESID the same as current ESID? */
	cror	eq,4*cr1+eq,eq
	beq	2f		/* if yes, don't slbie it */

	/* Bolt in the new stack SLB entry */
	ld	r7,KSP_VSID(r4)	/* Get new stack's VSID */
	oris	r0,r6,(SLB_ESID_V)@h
	ori	r0,r0,(SLB_NUM_BOLTED-1)@l
BEGIN_FTR_SECTION
	li	r9,MMU_SEGSIZE_1T	/* insert B field */
	oris	r6,r6,(MMU_SEGSIZE_1T << SLBIE_SSIZE_SHIFT)@h
	rldimi	r7,r9,SLB_VSID_SSIZE_SHIFT,0
END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)

	/* Update the last bolted SLB.  No write barriers are needed
	 * here, provided we only update the current CPU's SLB shadow
	 * buffer.
	 */
	ld	r9,PACA_SLBSHADOWPTR(r13)
	li	r12,0
	std	r12,SLBSHADOW_STACKESID(r9)	/* Clear ESID */
	li	r12,SLBSHADOW_STACKVSID
	STDX_BE	r7,r12,r9			/* Save VSID */
	li	r12,SLBSHADOW_STACKESID
	STDX_BE	r0,r12,r9			/* Save ESID */

	/* No need to check for MMU_FTR_NO_SLBIE_B here, since when
	 * we have 1TB segments, the only CPUs known to have the errata
	 * only support less than 1TB of system memory and we'll never
	 * actually hit this code path.
	 */

	slbie	r6
	slbie	r6		/* Workaround POWER5 < DD2.1 issue */
	slbmte	r7,r0
	isync
2:
#endif /* CONFIG_PPC_BOOK3S_64 */

	CURRENT_THREAD_INFO(r7, r8)  /* base of new stack */
	/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
	   because we don't need to leave the 288-byte ABI gap at the
	   top of the kernel stack. */
	addi	r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE

	/*
	 * PMU interrupts in radix may come in here. They will use r1, not
	 * PACAKSAVE, so this stack switch will not cause a problem. They
	 * will store to the process stack, which may then be migrated to
	 * another CPU. However the rq lock release on this CPU paired with
	 * the rq lock acquire on the new CPU before the stack becomes
	 * active on the new CPU, will order those stores.
	 */
	mr	r1,r8		/* start using new stack pointer */
	std	r7,PACAKSAVE(r13)

	ld	r6,_CCR(r1)
	mtcrf	0xFF,r6

	/* r3-r13 are destroyed -- Cort */
	REST_8GPRS(14, r1)
	REST_10GPRS(22, r1)

	/* convert old thread to its task_struct for return value */
	addi	r3,r3,-THREAD
	ld	r7,_NIP(r1)	/* Return to _switch caller in new task */
	mtlr	r7
	addi	r1,r1,SWITCH_FRAME_SIZE
	blr

	.align	7
_GLOBAL(ret_from_except)
	ld	r11,_TRAP(r1)
	andi.	r0,r11,1
	bne	ret_from_except_lite
	REST_NVGPRS(r1)

_GLOBAL(ret_from_except_lite)
	/*
	 * Disable interrupts so that current_thread_info()->flags
	 * can't change between when we test it and when we return
	 * from the interrupt.
	 */
#ifdef CONFIG_PPC_BOOK3E
	wrteei	0
#else
	li	r10,MSR_RI
	mtmsrd	r10,1		  /* Update machine state */
#endif /* CONFIG_PPC_BOOK3E */

	CURRENT_THREAD_INFO(r9, r1)
	ld	r3,_MSR(r1)
#ifdef CONFIG_PPC_BOOK3E
	ld	r10,PACACURRENT(r13)
#endif /* CONFIG_PPC_BOOK3E */
	ld	r4,TI_FLAGS(r9)
	andi.	r3,r3,MSR_PR
	beq	resume_kernel
#ifdef CONFIG_PPC_BOOK3E
	lwz	r3,(THREAD+THREAD_DBCR0)(r10)
#endif /* CONFIG_PPC_BOOK3E */

	/* Check current_thread_info()->flags */
	andi.	r0,r4,_TIF_USER_WORK_MASK
	bne	1f
#ifdef CONFIG_PPC_BOOK3E
	/*
	 * Check to see if the dbcr0 register is set up to debug.
	 * Use the internal debug mode bit to do this.
	 */
	andis.	r0,r3,DBCR0_IDM@h
	beq	restore
	mfmsr	r0
	rlwinm	r0,r0,0,~MSR_DE	/* Clear MSR.DE */
	mtmsr	r0
	mtspr	SPRN_DBCR0,r3
	li	r10, -1
	mtspr	SPRN_DBSR,r10
	b	restore
#else
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	restore_math
	b	restore
#endif
1:	andi.	r0,r4,_TIF_NEED_RESCHED
	beq	2f
	bl	restore_interrupts
	SCHEDULE_USER
	b	ret_from_except_lite
2:
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	andi.	r0,r4,_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM
	bne	3f		/* only restore TM if nothing else to do */
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	restore_tm_state
	b	restore
3:
#endif
	bl	save_nvgprs
	/*
	 * Use a non volatile GPR to save and restore our thread_info flags
	 * across the call to restore_interrupts.
	 */
	mr	r30,r4
	bl	restore_interrupts
	mr	r4,r30
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_notify_resume
	b	ret_from_except

resume_kernel:
	/* check current_thread_info, _TIF_EMULATE_STACK_STORE */
	andis.	r8,r4,_TIF_EMULATE_STACK_STORE@h
	beq+	1f

	addi	r8,r1,INT_FRAME_SIZE	/* Get the kprobed function entry */

	ld	r3,GPR1(r1)
	subi	r3,r3,INT_FRAME_SIZE	/* dst: Allocate a trampoline exception frame */
	mr	r4,r1			/* src:  current exception frame */
	mr	r1,r3			/* Reroute the trampoline frame to r1 */

	/* Copy from the original to the trampoline. */
	li	r5,INT_FRAME_SIZE/8	/* size: INT_FRAME_SIZE */
	li	r6,0			/* start offset: 0 */
	mtctr	r5
2:	ldx	r0,r6,r4
	stdx	r0,r6,r3
	addi	r6,r6,8
	bdnz	2b

	/* Do real store operation to complete stdu */
	ld	r5,GPR1(r1)
	std	r8,0(r5)

	/* Clear _TIF_EMULATE_STACK_STORE flag */
	lis	r11,_TIF_EMULATE_STACK_STORE@h
	addi	r5,r9,TI_FLAGS
0:	ldarx	r4,0,r5
	andc	r4,r4,r11
	stdcx.	r4,0,r5
	bne-	0b
1:

#ifdef CONFIG_PREEMPT
	/* Check if we need to preempt */
	andi.	r0,r4,_TIF_NEED_RESCHED
	beq+	restore
	/* Check that preempt_count() == 0 and interrupts are enabled */
	lwz	r8,TI_PREEMPT(r9)
	cmpwi	cr0,r8,0
	bne	restore
	ld	r0,SOFTE(r1)
	andi.	r0,r0,IRQS_DISABLED
	bne	restore

	/*
	 * Here we are preempting the current task. We want to make
	 * sure we are soft-disabled first and reconcile irq state.
	 */
	RECONCILE_IRQ_STATE(r3,r4)
1:	bl	preempt_schedule_irq

	/* Re-test flags and eventually loop */
	CURRENT_THREAD_INFO(r9, r1)
	ld	r4,TI_FLAGS(r9)
	andi.	r0,r4,_TIF_NEED_RESCHED
	bne	1b

	/*
	 * arch_local_irq_restore() from preempt_schedule_irq above may
	 * enable hard interrupt but we really should disable interrupts
	 * when we return from the interrupt, and so that we don't get
	 * interrupted after loading SRR0/1.
	 */
#ifdef CONFIG_PPC_BOOK3E
	wrteei	0
#else
	li	r10,MSR_RI
	mtmsrd	r10,1		  /* Update machine state */
#endif /* CONFIG_PPC_BOOK3E */
#endif /* CONFIG_PREEMPT */

	.globl	fast_exc_return_irq
fast_exc_return_irq:
restore:
	/*
	 * This is the main kernel exit path. First we check if we
	 * are about to re-enable interrupts
	 */
	ld	r5,SOFTE(r1)
	lbz	r6,PACAIRQSOFTMASK(r13)
	andi.	r5,r5,IRQS_DISABLED
	bne	.Lrestore_irq_off

	/* We are enabling, were we already enabled ? Yes, just return */
	andi.	r6,r6,IRQS_DISABLED
	beq	cr0,.Ldo_restore

	/*
	 * We are about to soft-enable interrupts (we are hard disabled
	 * at this point). We check if there's anything that needs to
	 * be replayed first.
	 */
	lbz	r0,PACAIRQHAPPENED(r13)
	cmpwi	cr0,r0,0
	bne-	.Lrestore_check_irq_replay

	/*
	 * Get here when nothing happened while soft-disabled, just
	 * soft-enable and move-on. We will hard-enable as a side
	 * effect of rfi
	 */
.Lrestore_no_replay:
	TRACE_ENABLE_INTS
	li	r0,IRQS_ENABLED
	stb	r0,PACAIRQSOFTMASK(r13);

	/*
	 * Final return path. BookE is handled in a different file
	 */
.Ldo_restore:
#ifdef CONFIG_PPC_BOOK3E
	b	exception_return_book3e
#else
	/*
	 * Clear the reservation. If we know the CPU tracks the address of
	 * the reservation then we can potentially save some cycles and use
	 * a larx. On POWER6 and POWER7 this is significantly faster.
	 */
BEGIN_FTR_SECTION
	stdcx.	r0,0,r1		/* to clear the reservation */
FTR_SECTION_ELSE
	ldarx	r4,0,r1
ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)

	/*
	 * Some code path such as load_up_fpu or altivec return directly
	 * here. They run entirely hard disabled and do not alter the
	 * interrupt state. They also don't use lwarx/stwcx. and thus
	 * are known not to leave dangling reservations.
	 */
	.globl	fast_exception_return
fast_exception_return:
	ld	r3,_MSR(r1)
	ld	r4,_CTR(r1)
	ld	r0,_LINK(r1)
	mtctr	r4
	mtlr	r0
	ld	r4,_XER(r1)
	mtspr	SPRN_XER,r4

	REST_8GPRS(5, r1)

	andi.	r0,r3,MSR_RI
	beq-	.Lunrecov_restore

	/* Load PPR from thread struct before we clear MSR:RI */
BEGIN_FTR_SECTION
	ld	r2,PACACURRENT(r13)
	ld	r2,TASKTHREADPPR(r2)
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)

	/*
	 * Clear RI before restoring r13.  If we are returning to
	 * userspace and we take an exception after restoring r13,
	 * we end up corrupting the userspace r13 value.
	 */
	li	r4,0
	mtmsrd	r4,1

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	/* TM debug */
	std	r3, PACATMSCRATCH(r13) /* Stash returned-to MSR */
#endif
	/*
	 * r13 is our per cpu area, only restore it if we are returning to
	 * userspace the value stored in the stack frame may belong to
	 * another CPU.
	 */
	andi.	r0,r3,MSR_PR
	beq	1f
BEGIN_FTR_SECTION
	mtspr	SPRN_PPR,r2	/* Restore PPR */
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
	REST_GPR(13, r1)

	mtspr	SPRN_SRR1,r3

	ld	r2,_CCR(r1)
	mtcrf	0xFF,r2
	ld	r2,_NIP(r1)
	mtspr	SPRN_SRR0,r2

	ld	r0,GPR0(r1)
	ld	r2,GPR2(r1)
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r1,GPR1(r1)
	RFI_TO_USER
	b	.	/* prevent speculative execution */

1:	mtspr	SPRN_SRR1,r3

	ld	r2,_CCR(r1)
	mtcrf	0xFF,r2
	ld	r2,_NIP(r1)
	mtspr	SPRN_SRR0,r2

	ld	r0,GPR0(r1)
	ld	r2,GPR2(r1)
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r1,GPR1(r1)
	RFI_TO_KERNEL
	b	.	/* prevent speculative execution */

#endif /* CONFIG_PPC_BOOK3E */

	/*
	 * We are returning to a context with interrupts soft disabled.
	 *
	 * However, we may also about to hard enable, so we need to
	 * make sure that in this case, we also clear PACA_IRQ_HARD_DIS
	 * or that bit can get out of sync and bad things will happen
	 */
.Lrestore_irq_off:
	ld	r3,_MSR(r1)
	lbz	r7,PACAIRQHAPPENED(r13)
	andi.	r0,r3,MSR_EE
	beq	1f
	rlwinm	r7,r7,0,~PACA_IRQ_HARD_DIS
	stb	r7,PACAIRQHAPPENED(r13)
1:
#if defined(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) && defined(CONFIG_BUG)
	/* The interrupt should not have soft enabled. */
	lbz	r7,PACAIRQSOFTMASK(r13)
1:	tdeqi	r7,IRQS_ENABLED
	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
#endif
	b	.Ldo_restore

	/*
	 * Something did happen, check if a re-emit is needed
	 * (this also clears paca->irq_happened)
	 */
.Lrestore_check_irq_replay:
	/* XXX: We could implement a fast path here where we check
	 * for irq_happened being just 0x01, in which case we can
	 * clear it and return. That means that we would potentially
	 * miss a decrementer having wrapped all the way around.
	 *
	 * Still, this might be useful for things like hash_page
	 */
	bl	__check_irq_replay
	cmpwi	cr0,r3,0
	beq	.Lrestore_no_replay
 
	/*
	 * We need to re-emit an interrupt. We do so by re-using our
	 * existing exception frame. We first change the trap value,
	 * but we need to ensure we preserve the low nibble of it
	 */
	ld	r4,_TRAP(r1)
	clrldi	r4,r4,60
	or	r4,r4,r3
	std	r4,_TRAP(r1)

	/*
	 * Then find the right handler and call it. Interrupts are
	 * still soft-disabled and we keep them that way.
	*/
	cmpwi	cr0,r3,0x500
	bne	1f
	addi	r3,r1,STACK_FRAME_OVERHEAD;
 	bl	do_IRQ
	b	ret_from_except
1:	cmpwi	cr0,r3,0xf00
	bne	1f
	addi	r3,r1,STACK_FRAME_OVERHEAD;
	bl	performance_monitor_exception
	b	ret_from_except
1:	cmpwi	cr0,r3,0xe60
	bne	1f
	addi	r3,r1,STACK_FRAME_OVERHEAD;
	bl	handle_hmi_exception
	b	ret_from_except
1:	cmpwi	cr0,r3,0x900
	bne	1f
	addi	r3,r1,STACK_FRAME_OVERHEAD;
	bl	timer_interrupt
	b	ret_from_except
#ifdef CONFIG_PPC_DOORBELL
1:
#ifdef CONFIG_PPC_BOOK3E
	cmpwi	cr0,r3,0x280
#else
	cmpwi	cr0,r3,0xa00
#endif /* CONFIG_PPC_BOOK3E */
	bne	1f
	addi	r3,r1,STACK_FRAME_OVERHEAD;
	bl	doorbell_exception
#endif /* CONFIG_PPC_DOORBELL */
1:	b	ret_from_except /* What else to do here ? */
 
.Lunrecov_restore:
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	unrecoverable_exception
	b	.Lunrecov_restore

_ASM_NOKPROBE_SYMBOL(ret_from_except);
_ASM_NOKPROBE_SYMBOL(ret_from_except_lite);
_ASM_NOKPROBE_SYMBOL(resume_kernel);
_ASM_NOKPROBE_SYMBOL(fast_exc_return_irq);
_ASM_NOKPROBE_SYMBOL(restore);
_ASM_NOKPROBE_SYMBOL(fast_exception_return);


#ifdef CONFIG_PPC_RTAS
/*
 * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
 * called with the MMU off.
 *
 * In addition, we need to be in 32b mode, at least for now.
 * 
 * Note: r3 is an input parameter to rtas, so don't trash it...
 */
_GLOBAL(enter_rtas)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-RTAS_FRAME_SIZE(r1)	/* Save SP and create stack space. */

	/* Because RTAS is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_GPR(2, r1)			/* Save the TOC */
	SAVE_GPR(13, r1)		/* Save paca */
	SAVE_8GPRS(14, r1)		/* Save the non-volatiles */
	SAVE_10GPRS(22, r1)		/* ditto */

	mfcr	r4
	std	r4,_CCR(r1)
	mfctr	r5
	std	r5,_CTR(r1)
	mfspr	r6,SPRN_XER
	std	r6,_XER(r1)
	mfdar	r7
	std	r7,_DAR(r1)
	mfdsisr	r8
	std	r8,_DSISR(r1)

	/* Temporary workaround to clear CR until RTAS can be modified to
	 * ignore all bits.
	 */
	li	r0,0
	mtcr	r0

#ifdef CONFIG_BUG
	/* There is no way it is acceptable to get here with interrupts enabled,
	 * check it with the asm equivalent of WARN_ON
	 */
	lbz	r0,PACAIRQSOFTMASK(r13)
1:	tdeqi	r0,IRQS_ENABLED
	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
#endif

	/* Hard-disable interrupts */
	mfmsr	r6
	rldicl	r7,r6,48,1
	rotldi	r7,r7,16
	mtmsrd	r7,1

	/* Unfortunately, the stack pointer and the MSR are also clobbered,
	 * so they are saved in the PACA which allows us to restore
	 * our original state after RTAS returns.
         */
	std	r1,PACAR1(r13)
        std	r6,PACASAVEDMSR(r13)

	/* Setup our real return addr */	
	LOAD_REG_ADDR(r4,rtas_return_loc)
	clrldi	r4,r4,2			/* convert to realmode address */
       	mtlr	r4

	li	r0,0
	ori	r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
	andc	r0,r6,r0
	
        li      r9,1
        rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE
	andc	r6,r0,r9

__enter_rtas:
	sync				/* disable interrupts so SRR0/1 */
	mtmsrd	r0			/* don't get trashed */

	LOAD_REG_ADDR(r4, rtas)
	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
	ld	r4,RTASBASE(r4)		/* get the rtas->base value */
	
	mtspr	SPRN_SRR0,r5
	mtspr	SPRN_SRR1,r6
	RFI_TO_KERNEL
	b	.	/* prevent speculative execution */

rtas_return_loc:
	FIXUP_ENDIAN

	/*
	 * Clear RI and set SF before anything.
	 */
	mfmsr   r6
	li	r0,MSR_RI
	andc	r6,r6,r0
	sldi	r0,r0,(MSR_SF_LG - MSR_RI_LG)
	or	r6,r6,r0
	sync
	mtmsrd  r6

	/* relocation is off at this point */
	GET_PACA(r4)
	clrldi	r4,r4,2			/* convert to realmode address */

	bcl	20,31,$+4
0:	mflr	r3
	ld	r3,(1f-0b)(r3)		/* get &rtas_restore_regs */

        ld	r1,PACAR1(r4)           /* Restore our SP */
        ld	r4,PACASAVEDMSR(r4)     /* Restore our MSR */

	mtspr	SPRN_SRR0,r3
	mtspr	SPRN_SRR1,r4
	RFI_TO_KERNEL
	b	.	/* prevent speculative execution */
_ASM_NOKPROBE_SYMBOL(__enter_rtas)
_ASM_NOKPROBE_SYMBOL(rtas_return_loc)

	.align	3
1:	.8byte	rtas_restore_regs

rtas_restore_regs:
	/* relocation is on at this point */
	REST_GPR(2, r1)			/* Restore the TOC */
	REST_GPR(13, r1)		/* Restore paca */
	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
	REST_10GPRS(22, r1)		/* ditto */

	GET_PACA(r13)

	ld	r4,_CCR(r1)
	mtcr	r4
	ld	r5,_CTR(r1)
	mtctr	r5
	ld	r6,_XER(r1)
	mtspr	SPRN_XER,r6
	ld	r7,_DAR(r1)
	mtdar	r7
	ld	r8,_DSISR(r1)
	mtdsisr	r8

        addi	r1,r1,RTAS_FRAME_SIZE	/* Unstack our frame */
	ld	r0,16(r1)		/* get return address */

	mtlr    r0
        blr				/* return to caller */

#endif /* CONFIG_PPC_RTAS */

_GLOBAL(enter_prom)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-PROM_FRAME_SIZE(r1)	/* Save SP and create stack space */

	/* Because PROM is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * PROM might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_GPR(2, r1)
	SAVE_GPR(13, r1)
	SAVE_8GPRS(14, r1)
	SAVE_10GPRS(22, r1)
	mfcr	r10
	mfmsr	r11
	std	r10,_CCR(r1)
	std	r11,_MSR(r1)

	/* Put PROM address in SRR0 */
	mtsrr0	r4

	/* Setup our trampoline return addr in LR */
	bcl	20,31,$+4
0:	mflr	r4
	addi	r4,r4,(1f - 0b)
       	mtlr	r4

	/* Prepare a 32-bit mode big endian MSR
	 */
#ifdef CONFIG_PPC_BOOK3E
	rlwinm	r11,r11,0,1,31
	mtsrr1	r11
	rfi
#else /* CONFIG_PPC_BOOK3E */
	LOAD_REG_IMMEDIATE(r12, MSR_SF | MSR_ISF | MSR_LE)
	andc	r11,r11,r12
	mtsrr1	r11
	RFI_TO_KERNEL
#endif /* CONFIG_PPC_BOOK3E */

1:	/* Return from OF */
	FIXUP_ENDIAN

	/* Just make sure that r1 top 32 bits didn't get
	 * corrupt by OF
	 */
	rldicl	r1,r1,0,32

	/* Restore the MSR (back to 64 bits) */
	ld	r0,_MSR(r1)
	MTMSRD(r0)
        isync

	/* Restore other registers */
	REST_GPR(2, r1)
	REST_GPR(13, r1)
	REST_8GPRS(14, r1)
	REST_10GPRS(22, r1)
	ld	r4,_CCR(r1)
	mtcr	r4
	
        addi	r1,r1,PROM_FRAME_SIZE
	ld	r0,16(r1)
	mtlr    r0
        blr