aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/entry_32.S
blob: dd65143941a841de0f55a4830732be7a0fcada4b (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
/*
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * entry.S contains the system-call and fault low-level handling routines.
 * This also contains the timer-interrupt handler, as well as all interrupts
 * and faults that can result in a task-switch.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after a timer-interrupt and after each system call.
 *
 * I changed all the .align's to 4 (16 byte alignment), as that's faster
 * on a 486.
 *
 * Stack layout in 'syscall_exit':
 * 	ptrace needs to have all regs on the stack.
 *	if the order here is changed, it needs to be
 *	updated in fork.c:copy_process, signal.c:do_signal,
 *	ptrace.c and ptrace.h
 *
 *	 0(%esp) - %ebx
 *	 4(%esp) - %ecx
 *	 8(%esp) - %edx
 *       C(%esp) - %esi
 *	10(%esp) - %edi
 *	14(%esp) - %ebp
 *	18(%esp) - %eax
 *	1C(%esp) - %ds
 *	20(%esp) - %es
 *	24(%esp) - %fs
 *	28(%esp) - orig_eax
 *	2C(%esp) - %eip
 *	30(%esp) - %cs
 *	34(%esp) - %eflags
 *	38(%esp) - %oldesp
 *	3C(%esp) - %oldss
 *
 * "current" is in register %ebx during any slow entries.
 */

#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/irqflags.h>
#include <asm/errno.h>
#include <asm/segment.h>
#include <asm/smp.h>
#include <asm/page.h>
#include <asm/desc.h>
#include <asm/percpu.h>
#include <asm/dwarf2.h>
#include <asm/processor-flags.h>
#include <asm/ftrace.h>
#include <asm/irq_vectors.h>

/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
#include <linux/elf-em.h>
#define AUDIT_ARCH_I386		(EM_386|__AUDIT_ARCH_LE)
#define __AUDIT_ARCH_LE	   0x40000000

#ifndef CONFIG_AUDITSYSCALL
#define sysenter_audit	syscall_trace_entry
#define sysexit_audit	syscall_exit_work
#endif

/*
 * We use macros for low-level operations which need to be overridden
 * for paravirtualization.  The following will never clobber any registers:
 *   INTERRUPT_RETURN (aka. "iret")
 *   GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
 *   ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
 *
 * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
 * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
 * Allowing a register to be clobbered can shrink the paravirt replacement
 * enough to patch inline, increasing performance.
 */

#define nr_syscalls ((syscall_table_size)/4)

#ifdef CONFIG_PREEMPT
#define preempt_stop(clobbers)	DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
#else
#define preempt_stop(clobbers)
#define resume_kernel		restore_nocheck
#endif

.macro TRACE_IRQS_IRET
#ifdef CONFIG_TRACE_IRQFLAGS
	testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)     # interrupts off?
	jz 1f
	TRACE_IRQS_ON
1:
#endif
.endm

#ifdef CONFIG_VM86
#define resume_userspace_sig	check_userspace
#else
#define resume_userspace_sig	resume_userspace
#endif

#define SAVE_ALL \
	cld; \
	pushl %fs; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET fs, 0;*/\
	pushl %es; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET es, 0;*/\
	pushl %ds; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET ds, 0;*/\
	pushl %eax; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET eax, 0;\
	pushl %ebp; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ebp, 0;\
	pushl %edi; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET edi, 0;\
	pushl %esi; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET esi, 0;\
	pushl %edx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET edx, 0;\
	pushl %ecx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ecx, 0;\
	pushl %ebx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ebx, 0;\
	movl $(__USER_DS), %edx; \
	movl %edx, %ds; \
	movl %edx, %es; \
	movl $(__KERNEL_PERCPU), %edx; \
	movl %edx, %fs

#define RESTORE_INT_REGS \
	popl %ebx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ebx;\
	popl %ecx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ecx;\
	popl %edx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE edx;\
	popl %esi;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE esi;\
	popl %edi;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE edi;\
	popl %ebp;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ebp;\
	popl %eax;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE eax

#define RESTORE_REGS	\
	RESTORE_INT_REGS; \
1:	popl %ds;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	/*CFI_RESTORE ds;*/\
2:	popl %es;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	/*CFI_RESTORE es;*/\
3:	popl %fs;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	/*CFI_RESTORE fs;*/\
.pushsection .fixup,"ax";	\
4:	movl $0,(%esp);	\
	jmp 1b;		\
5:	movl $0,(%esp);	\
	jmp 2b;		\
6:	movl $0,(%esp);	\
	jmp 3b;		\
.section __ex_table,"a";\
	.align 4;	\
	.long 1b,4b;	\
	.long 2b,5b;	\
	.long 3b,6b;	\
.popsection

#define RING0_INT_FRAME \
	CFI_STARTPROC simple;\
	CFI_SIGNAL_FRAME;\
	CFI_DEF_CFA esp, 3*4;\
	/*CFI_OFFSET cs, -2*4;*/\
	CFI_OFFSET eip, -3*4

#define RING0_EC_FRAME \
	CFI_STARTPROC simple;\
	CFI_SIGNAL_FRAME;\
	CFI_DEF_CFA esp, 4*4;\
	/*CFI_OFFSET cs, -2*4;*/\
	CFI_OFFSET eip, -3*4

#define RING0_PTREGS_FRAME \
	CFI_STARTPROC simple;\
	CFI_SIGNAL_FRAME;\
	CFI_DEF_CFA esp, PT_OLDESP-PT_EBX;\
	/*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/\
	CFI_OFFSET eip, PT_EIP-PT_OLDESP;\
	/*CFI_OFFSET es, PT_ES-PT_OLDESP;*/\
	/*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/\
	CFI_OFFSET eax, PT_EAX-PT_OLDESP;\
	CFI_OFFSET ebp, PT_EBP-PT_OLDESP;\
	CFI_OFFSET edi, PT_EDI-PT_OLDESP;\
	CFI_OFFSET esi, PT_ESI-PT_OLDESP;\
	CFI_OFFSET edx, PT_EDX-PT_OLDESP;\
	CFI_OFFSET ecx, PT_ECX-PT_OLDESP;\
	CFI_OFFSET ebx, PT_EBX-PT_OLDESP

ENTRY(ret_from_fork)
	CFI_STARTPROC
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	call schedule_tail
	GET_THREAD_INFO(%ebp)
	popl %eax
	CFI_ADJUST_CFA_OFFSET -4
	pushl $0x0202			# Reset kernel eflags
	CFI_ADJUST_CFA_OFFSET 4
	popfl
	CFI_ADJUST_CFA_OFFSET -4
	jmp syscall_exit
	CFI_ENDPROC
END(ret_from_fork)

/*
 * Return to user mode is not as complex as all this looks,
 * but we want the default path for a system call return to
 * go as quickly as possible which is why some of this is
 * less clear than it otherwise should be.
 */

	# userspace resumption stub bypassing syscall exit tracing
	ALIGN
	RING0_PTREGS_FRAME
ret_from_exception:
	preempt_stop(CLBR_ANY)
ret_from_intr:
	GET_THREAD_INFO(%ebp)
check_userspace:
	movl PT_EFLAGS(%esp), %eax	# mix EFLAGS and CS
	movb PT_CS(%esp), %al
	andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
	cmpl $USER_RPL, %eax
	jb resume_kernel		# not returning to v8086 or userspace

ENTRY(resume_userspace)
	LOCKDEP_SYS_EXIT
 	DISABLE_INTERRUPTS(CLBR_ANY)	# make sure we don't miss an interrupt
					# setting need_resched or sigpending
					# between sampling and the iret
	TRACE_IRQS_OFF
	movl TI_flags(%ebp), %ecx
	andl $_TIF_WORK_MASK, %ecx	# is there any work to be done on
					# int/exception return?
	jne work_pending
	jmp restore_all
END(ret_from_exception)

#ifdef CONFIG_PREEMPT
ENTRY(resume_kernel)
	DISABLE_INTERRUPTS(CLBR_ANY)
	cmpl $0,TI_preempt_count(%ebp)	# non-zero preempt_count ?
	jnz restore_nocheck
need_resched:
	movl TI_flags(%ebp), %ecx	# need_resched set ?
	testb $_TIF_NEED_RESCHED, %cl
	jz restore_all
	testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)	# interrupts off (exception path) ?
	jz restore_all
	call preempt_schedule_irq
	jmp need_resched
END(resume_kernel)
#endif
	CFI_ENDPROC

/* SYSENTER_RETURN points to after the "sysenter" instruction in
   the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */

	# sysenter call handler stub
ENTRY(ia32_sysenter_target)
	CFI_STARTPROC simple
	CFI_SIGNAL_FRAME
	CFI_DEF_CFA esp, 0
	CFI_REGISTER esp, ebp
	movl TSS_sysenter_sp0(%esp),%esp
sysenter_past_esp:
	/*
	 * Interrupts are disabled here, but we can't trace it until
	 * enough kernel state to call TRACE_IRQS_OFF can be called - but
	 * we immediately enable interrupts at that point anyway.
	 */
	pushl $(__USER_DS)
	CFI_ADJUST_CFA_OFFSET 4
	/*CFI_REL_OFFSET ss, 0*/
	pushl %ebp
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET esp, 0
	pushfl
	orl $X86_EFLAGS_IF, (%esp)
	CFI_ADJUST_CFA_OFFSET 4
	pushl $(__USER_CS)
	CFI_ADJUST_CFA_OFFSET 4
	/*CFI_REL_OFFSET cs, 0*/
	/*
	 * Push current_thread_info()->sysenter_return to the stack.
	 * A tiny bit of offset fixup is necessary - 4*4 means the 4 words
	 * pushed above; +8 corresponds to copy_thread's esp0 setting.
	 */
	pushl (TI_sysenter_return-THREAD_SIZE+8+4*4)(%esp)
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET eip, 0

	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	ENABLE_INTERRUPTS(CLBR_NONE)

/*
 * Load the potential sixth argument from user stack.
 * Careful about security.
 */
	cmpl $__PAGE_OFFSET-3,%ebp
	jae syscall_fault
1:	movl (%ebp),%ebp
	movl %ebp,PT_EBP(%esp)
.section __ex_table,"a"
	.align 4
	.long 1b,syscall_fault
.previous

	GET_THREAD_INFO(%ebp)

	/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
	testw $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
	jnz sysenter_audit
sysenter_do_call:
	cmpl $(nr_syscalls), %eax
	jae syscall_badsys
	call *sys_call_table(,%eax,4)
	movl %eax,PT_EAX(%esp)
	LOCKDEP_SYS_EXIT
	DISABLE_INTERRUPTS(CLBR_ANY)
	TRACE_IRQS_OFF
	movl TI_flags(%ebp), %ecx
	testw $_TIF_ALLWORK_MASK, %cx
	jne sysexit_audit
sysenter_exit:
/* if something modifies registers it must also disable sysexit */
	movl PT_EIP(%esp), %edx
	movl PT_OLDESP(%esp), %ecx
	xorl %ebp,%ebp
	TRACE_IRQS_ON
1:	mov  PT_FS(%esp), %fs
	ENABLE_INTERRUPTS_SYSEXIT

#ifdef CONFIG_AUDITSYSCALL
sysenter_audit:
	testw $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
	jnz syscall_trace_entry
	addl $4,%esp
	CFI_ADJUST_CFA_OFFSET -4
	/* %esi already in 8(%esp)	   6th arg: 4th syscall arg */
	/* %edx already in 4(%esp)	   5th arg: 3rd syscall arg */
	/* %ecx already in 0(%esp)	   4th arg: 2nd syscall arg */
	movl %ebx,%ecx			/* 3rd arg: 1st syscall arg */
	movl %eax,%edx			/* 2nd arg: syscall number */
	movl $AUDIT_ARCH_I386,%eax	/* 1st arg: audit arch */
	call audit_syscall_entry
	pushl %ebx
	CFI_ADJUST_CFA_OFFSET 4
	movl PT_EAX(%esp),%eax		/* reload syscall number */
	jmp sysenter_do_call

sysexit_audit:
	testw $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %cx
	jne syscall_exit_work
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_ANY)
	movl %eax,%edx		/* second arg, syscall return value */
	cmpl $0,%eax		/* is it < 0? */
	setl %al		/* 1 if so, 0 if not */
	movzbl %al,%eax		/* zero-extend that */
	inc %eax /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
	call audit_syscall_exit
	DISABLE_INTERRUPTS(CLBR_ANY)
	TRACE_IRQS_OFF
	movl TI_flags(%ebp), %ecx
	testw $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %cx
	jne syscall_exit_work
	movl PT_EAX(%esp),%eax	/* reload syscall return value */
	jmp sysenter_exit
#endif

	CFI_ENDPROC
.pushsection .fixup,"ax"
2:	movl $0,PT_FS(%esp)
	jmp 1b
.section __ex_table,"a"
	.align 4
	.long 1b,2b
.popsection
ENDPROC(ia32_sysenter_target)

	# system call handler stub
ENTRY(system_call)
	RING0_INT_FRAME			# can't unwind into user space anyway
	pushl %eax			# save orig_eax
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	GET_THREAD_INFO(%ebp)
					# system call tracing in operation / emulation
	/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
	testw $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
	jnz syscall_trace_entry
	cmpl $(nr_syscalls), %eax
	jae syscall_badsys
syscall_call:
	call *sys_call_table(,%eax,4)
	movl %eax,PT_EAX(%esp)		# store the return value
syscall_exit:
	LOCKDEP_SYS_EXIT
	DISABLE_INTERRUPTS(CLBR_ANY)	# make sure we don't miss an interrupt
					# setting need_resched or sigpending
					# between sampling and the iret
	TRACE_IRQS_OFF
	movl TI_flags(%ebp), %ecx
	testw $_TIF_ALLWORK_MASK, %cx	# current->work
	jne syscall_exit_work

restore_all:
	movl PT_EFLAGS(%esp), %eax	# mix EFLAGS, SS and CS
	# Warning: PT_OLDSS(%esp) contains the wrong/random values if we
	# are returning to the kernel.
	# See comments in process.c:copy_thread() for details.
	movb PT_OLDSS(%esp), %ah
	movb PT_CS(%esp), %al
	andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
	cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
	CFI_REMEMBER_STATE
	je ldt_ss			# returning to user-space with LDT SS
restore_nocheck:
	TRACE_IRQS_IRET
restore_nocheck_notrace:
	RESTORE_REGS
	addl $4, %esp			# skip orig_eax/error_code
	CFI_ADJUST_CFA_OFFSET -4
irq_return:
	INTERRUPT_RETURN
.section .fixup,"ax"
ENTRY(iret_exc)
	pushl $0			# no error code
	pushl $do_iret_error
	jmp error_code
.previous
.section __ex_table,"a"
	.align 4
	.long irq_return,iret_exc
.previous

	CFI_RESTORE_STATE
ldt_ss:
	larl PT_OLDSS(%esp), %eax
	jnz restore_nocheck
	testl $0x00400000, %eax		# returning to 32bit stack?
	jnz restore_nocheck		# allright, normal return

#ifdef CONFIG_PARAVIRT
	/*
	 * The kernel can't run on a non-flat stack if paravirt mode
	 * is active.  Rather than try to fixup the high bits of
	 * ESP, bypass this code entirely.  This may break DOSemu
	 * and/or Wine support in a paravirt VM, although the option
	 * is still available to implement the setting of the high
	 * 16-bits in the INTERRUPT_RETURN paravirt-op.
	 */
	cmpl $0, pv_info+PARAVIRT_enabled
	jne restore_nocheck
#endif

	/* If returning to userspace with 16bit stack,
	 * try to fix the higher word of ESP, as the CPU
	 * won't restore it.
	 * This is an "official" bug of all the x86-compatible
	 * CPUs, which we can try to work around to make
	 * dosemu and wine happy. */
	movl PT_OLDESP(%esp), %eax
	movl %esp, %edx
	call patch_espfix_desc
	pushl $__ESPFIX_SS
	CFI_ADJUST_CFA_OFFSET 4
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	DISABLE_INTERRUPTS(CLBR_EAX)
	TRACE_IRQS_OFF
	lss (%esp), %esp
	CFI_ADJUST_CFA_OFFSET -8
	jmp restore_nocheck
	CFI_ENDPROC
ENDPROC(system_call)

	# perform work that needs to be done immediately before resumption
	ALIGN
	RING0_PTREGS_FRAME		# can't unwind into user space anyway
work_pending:
	testb $_TIF_NEED_RESCHED, %cl
	jz work_notifysig
work_resched:
	call schedule
	LOCKDEP_SYS_EXIT
	DISABLE_INTERRUPTS(CLBR_ANY)	# make sure we don't miss an interrupt
					# setting need_resched or sigpending
					# between sampling and the iret
	TRACE_IRQS_OFF
	movl TI_flags(%ebp), %ecx
	andl $_TIF_WORK_MASK, %ecx	# is there any work to be done other
					# than syscall tracing?
	jz restore_all
	testb $_TIF_NEED_RESCHED, %cl
	jnz work_resched

work_notifysig:				# deal with pending signals and
					# notify-resume requests
#ifdef CONFIG_VM86
	testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
	movl %esp, %eax
	jne work_notifysig_v86		# returning to kernel-space or
					# vm86-space
	xorl %edx, %edx
	call do_notify_resume
	jmp resume_userspace_sig

	ALIGN
work_notifysig_v86:
	pushl %ecx			# save ti_flags for do_notify_resume
	CFI_ADJUST_CFA_OFFSET 4
	call save_v86_state		# %eax contains pt_regs pointer
	popl %ecx
	CFI_ADJUST_CFA_OFFSET -4
	movl %eax, %esp
#else
	movl %esp, %eax
#endif
	xorl %edx, %edx
	call do_notify_resume
	jmp resume_userspace_sig
END(work_pending)

	# perform syscall exit tracing
	ALIGN
syscall_trace_entry:
	movl $-ENOSYS,PT_EAX(%esp)
	movl %esp, %eax
	call syscall_trace_enter
	/* What it returned is what we'll actually use.  */
	cmpl $(nr_syscalls), %eax
	jnae syscall_call
	jmp syscall_exit
END(syscall_trace_entry)

	# perform syscall exit tracing
	ALIGN
syscall_exit_work:
	testb $_TIF_WORK_SYSCALL_EXIT, %cl
	jz work_pending
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_ANY)	# could let syscall_trace_leave() call
					# schedule() instead
	movl %esp, %eax
	call syscall_trace_leave
	jmp resume_userspace
END(syscall_exit_work)
	CFI_ENDPROC

	RING0_INT_FRAME			# can't unwind into user space anyway
syscall_fault:
	GET_THREAD_INFO(%ebp)
	movl $-EFAULT,PT_EAX(%esp)
	jmp resume_userspace
END(syscall_fault)

syscall_badsys:
	movl $-ENOSYS,PT_EAX(%esp)
	jmp resume_userspace
END(syscall_badsys)
	CFI_ENDPROC

#define FIXUP_ESPFIX_STACK \
	/* since we are on a wrong stack, we cant make it a C code :( */ \
	PER_CPU(gdt_page, %ebx); \
	GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \
	addl %esp, %eax; \
	pushl $__KERNEL_DS; \
	CFI_ADJUST_CFA_OFFSET 4; \
	pushl %eax; \
	CFI_ADJUST_CFA_OFFSET 4; \
	lss (%esp), %esp; \
	CFI_ADJUST_CFA_OFFSET -8;
#define UNWIND_ESPFIX_STACK \
	movl %ss, %eax; \
	/* see if on espfix stack */ \
	cmpw $__ESPFIX_SS, %ax; \
	jne 27f; \
	movl $__KERNEL_DS, %eax; \
	movl %eax, %ds; \
	movl %eax, %es; \
	/* switch to normal stack */ \
	FIXUP_ESPFIX_STACK; \
27:;

/*
 * Build the entry stubs and pointer table with
 * some assembler magic.
 */
.section .rodata,"a"
ENTRY(interrupt)
.text

ENTRY(irq_entries_start)
	RING0_INT_FRAME
vector=0
.rept NR_VECTORS
	ALIGN
 .if vector
	CFI_ADJUST_CFA_OFFSET -4
 .endif
1:	pushl $~(vector)
	CFI_ADJUST_CFA_OFFSET 4
	jmp common_interrupt
 .previous
	.long 1b
 .text
vector=vector+1
.endr
END(irq_entries_start)

.previous
END(interrupt)
.previous

/*
 * the CPU automatically disables interrupts when executing an IRQ vector,
 * so IRQ-flags tracing has to follow that:
 */
	ALIGN
common_interrupt:
	SAVE_ALL
	TRACE_IRQS_OFF
	movl %esp,%eax
	call do_IRQ
	jmp ret_from_intr
ENDPROC(common_interrupt)
	CFI_ENDPROC

#define BUILD_INTERRUPT(name, nr)	\
ENTRY(name)				\
	RING0_INT_FRAME;		\
	pushl $~(nr);			\
	CFI_ADJUST_CFA_OFFSET 4;	\
	SAVE_ALL;			\
	TRACE_IRQS_OFF			\
	movl %esp,%eax;			\
	call smp_##name;		\
	jmp ret_from_intr;		\
	CFI_ENDPROC;			\
ENDPROC(name)

/* The include is where all of the SMP etc. interrupts come from */
#include "entry_arch.h"

KPROBE_ENTRY(page_fault)
	RING0_EC_FRAME
	pushl $do_page_fault
	CFI_ADJUST_CFA_OFFSET 4
	ALIGN
error_code:
	/* the function address is in %fs's slot on the stack */
	pushl %es
	CFI_ADJUST_CFA_OFFSET 4
	/*CFI_REL_OFFSET es, 0*/
	pushl %ds
	CFI_ADJUST_CFA_OFFSET 4
	/*CFI_REL_OFFSET ds, 0*/
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET eax, 0
	pushl %ebp
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET ebp, 0
	pushl %edi
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET edi, 0
	pushl %esi
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET esi, 0
	pushl %edx
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET edx, 0
	pushl %ecx
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET ecx, 0
	pushl %ebx
	CFI_ADJUST_CFA_OFFSET 4
	CFI_REL_OFFSET ebx, 0
	cld
	pushl %fs
	CFI_ADJUST_CFA_OFFSET 4
	/*CFI_REL_OFFSET fs, 0*/
	movl $(__KERNEL_PERCPU), %ecx
	movl %ecx, %fs
	UNWIND_ESPFIX_STACK
	popl %ecx
	CFI_ADJUST_CFA_OFFSET -4
	/*CFI_REGISTER es, ecx*/
	movl PT_FS(%esp), %edi		# get the function address
	movl PT_ORIG_EAX(%esp), %edx	# get the error code
	movl $-1, PT_ORIG_EAX(%esp)	# no syscall to restart
	mov  %ecx, PT_FS(%esp)
	/*CFI_REL_OFFSET fs, ES*/
	movl $(__USER_DS), %ecx
	movl %ecx, %ds
	movl %ecx, %es
	TRACE_IRQS_OFF
	movl %esp,%eax			# pt_regs pointer
	call *%edi
	jmp ret_from_exception
	CFI_ENDPROC
KPROBE_END(page_fault)

ENTRY(coprocessor_error)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_coprocessor_error
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(coprocessor_error)

ENTRY(simd_coprocessor_error)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_simd_coprocessor_error
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(simd_coprocessor_error)

ENTRY(device_not_available)
	RING0_INT_FRAME
	pushl $-1			# mark this as an int
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_device_not_available
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(device_not_available)

/*
 * Debug traps and NMI can happen at the one SYSENTER instruction
 * that sets up the real kernel stack. Check here, since we can't
 * allow the wrong stack to be used.
 *
 * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
 * already pushed 3 words if it hits on the sysenter instruction:
 * eflags, cs and eip.
 *
 * We just load the right stack, and push the three (known) values
 * by hand onto the new stack - while updating the return eip past
 * the instruction that would have done it for sysenter.
 */
#define FIX_STACK(offset, ok, label)		\
	cmpw $__KERNEL_CS,4(%esp);		\
	jne ok;					\
label:						\
	movl TSS_sysenter_sp0+offset(%esp),%esp;	\
	CFI_DEF_CFA esp, 0;			\
	CFI_UNDEFINED eip;			\
	pushfl;					\
	CFI_ADJUST_CFA_OFFSET 4;		\
	pushl $__KERNEL_CS;			\
	CFI_ADJUST_CFA_OFFSET 4;		\
	pushl $sysenter_past_esp;		\
	CFI_ADJUST_CFA_OFFSET 4;		\
	CFI_REL_OFFSET eip, 0

KPROBE_ENTRY(debug)
	RING0_INT_FRAME
	cmpl $ia32_sysenter_target,(%esp)
	jne debug_stack_correct
	FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
debug_stack_correct:
	pushl $-1			# mark this as an int
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	TRACE_IRQS_OFF
	xorl %edx,%edx			# error code 0
	movl %esp,%eax			# pt_regs pointer
	call do_debug
	jmp ret_from_exception
	CFI_ENDPROC
KPROBE_END(debug)

/*
 * NMI is doubly nasty. It can happen _while_ we're handling
 * a debug fault, and the debug fault hasn't yet been able to
 * clear up the stack. So we first check whether we got  an
 * NMI on the sysenter entry path, but after that we need to
 * check whether we got an NMI on the debug path where the debug
 * fault happened on the sysenter path.
 */
KPROBE_ENTRY(nmi)
	RING0_INT_FRAME
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	movl %ss, %eax
	cmpw $__ESPFIX_SS, %ax
	popl %eax
	CFI_ADJUST_CFA_OFFSET -4
	je nmi_espfix_stack
	cmpl $ia32_sysenter_target,(%esp)
	je nmi_stack_fixup
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	movl %esp,%eax
	/* Do not access memory above the end of our stack page,
	 * it might not exist.
	 */
	andl $(THREAD_SIZE-1),%eax
	cmpl $(THREAD_SIZE-20),%eax
	popl %eax
	CFI_ADJUST_CFA_OFFSET -4
	jae nmi_stack_correct
	cmpl $ia32_sysenter_target,12(%esp)
	je nmi_debug_stack_check
nmi_stack_correct:
	/* We have a RING0_INT_FRAME here */
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	TRACE_IRQS_OFF
	xorl %edx,%edx		# zero error code
	movl %esp,%eax		# pt_regs pointer
	call do_nmi
	jmp restore_nocheck_notrace
	CFI_ENDPROC

nmi_stack_fixup:
	RING0_INT_FRAME
	FIX_STACK(12,nmi_stack_correct, 1)
	jmp nmi_stack_correct

nmi_debug_stack_check:
	/* We have a RING0_INT_FRAME here */
	cmpw $__KERNEL_CS,16(%esp)
	jne nmi_stack_correct
	cmpl $debug,(%esp)
	jb nmi_stack_correct
	cmpl $debug_esp_fix_insn,(%esp)
	ja nmi_stack_correct
	FIX_STACK(24,nmi_stack_correct, 1)
	jmp nmi_stack_correct

nmi_espfix_stack:
	/* We have a RING0_INT_FRAME here.
	 *
	 * create the pointer to lss back
	 */
	pushl %ss
	CFI_ADJUST_CFA_OFFSET 4
	pushl %esp
	CFI_ADJUST_CFA_OFFSET 4
	addw $4, (%esp)
	/* copy the iret frame of 12 bytes */
	.rept 3
	pushl 16(%esp)
	CFI_ADJUST_CFA_OFFSET 4
	.endr
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	TRACE_IRQS_OFF
	FIXUP_ESPFIX_STACK		# %eax == %esp
	xorl %edx,%edx			# zero error code
	call do_nmi
	RESTORE_REGS
	lss 12+4(%esp), %esp		# back to espfix stack
	CFI_ADJUST_CFA_OFFSET -24
	jmp irq_return
	CFI_ENDPROC
KPROBE_END(nmi)

#ifdef CONFIG_PARAVIRT
ENTRY(native_iret)
	iret
.section __ex_table,"a"
	.align 4
	.long native_iret, iret_exc
.previous
END(native_iret)

ENTRY(native_irq_enable_sysexit)
	sti
	sysexit
END(native_irq_enable_sysexit)
#endif

KPROBE_ENTRY(int3)
	RING0_INT_FRAME
	pushl $-1			# mark this as an int
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	TRACE_IRQS_OFF
	xorl %edx,%edx		# zero error code
	movl %esp,%eax		# pt_regs pointer
	call do_int3
	jmp ret_from_exception
	CFI_ENDPROC
KPROBE_END(int3)

ENTRY(overflow)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_overflow
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(overflow)

ENTRY(bounds)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_bounds
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(bounds)

ENTRY(invalid_op)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_invalid_op
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(invalid_op)

ENTRY(coprocessor_segment_overrun)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_coprocessor_segment_overrun
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(coprocessor_segment_overrun)

ENTRY(invalid_TSS)
	RING0_EC_FRAME
	pushl $do_invalid_TSS
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(invalid_TSS)

ENTRY(segment_not_present)
	RING0_EC_FRAME
	pushl $do_segment_not_present
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(segment_not_present)

ENTRY(stack_segment)
	RING0_EC_FRAME
	pushl $do_stack_segment
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(stack_segment)

KPROBE_ENTRY(general_protection)
	RING0_EC_FRAME
	pushl $do_general_protection
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
KPROBE_END(general_protection)

ENTRY(alignment_check)
	RING0_EC_FRAME
	pushl $do_alignment_check
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(alignment_check)

ENTRY(divide_error)
	RING0_INT_FRAME
	pushl $0			# no error code
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_divide_error
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(divide_error)

#ifdef CONFIG_X86_MCE
ENTRY(machine_check)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl machine_check_vector
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(machine_check)
#endif

ENTRY(spurious_interrupt_bug)
	RING0_INT_FRAME
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	pushl $do_spurious_interrupt_bug
	CFI_ADJUST_CFA_OFFSET 4
	jmp error_code
	CFI_ENDPROC
END(spurious_interrupt_bug)

ENTRY(kernel_thread_helper)
	pushl $0		# fake return address for unwinder
	CFI_STARTPROC
	movl %edx,%eax
	push %edx
	CFI_ADJUST_CFA_OFFSET 4
	call *%ebx
	push %eax
	CFI_ADJUST_CFA_OFFSET 4
	call do_exit
	CFI_ENDPROC
ENDPROC(kernel_thread_helper)

#ifdef CONFIG_XEN
/* Xen doesn't set %esp to be precisely what the normal sysenter
   entrypoint expects, so fix it up before using the normal path. */
ENTRY(xen_sysenter_target)
	RING0_INT_FRAME
	addl $5*4, %esp		/* remove xen-provided frame */
	CFI_ADJUST_CFA_OFFSET -5*4
	jmp sysenter_past_esp
	CFI_ENDPROC

ENTRY(xen_hypervisor_callback)
	CFI_STARTPROC
	pushl $0
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	TRACE_IRQS_OFF

	/* Check to see if we got the event in the critical
	   region in xen_iret_direct, after we've reenabled
	   events and checked for pending events.  This simulates
	   iret instruction's behaviour where it delivers a
	   pending interrupt when enabling interrupts. */
	movl PT_EIP(%esp),%eax
	cmpl $xen_iret_start_crit,%eax
	jb   1f
	cmpl $xen_iret_end_crit,%eax
	jae  1f

	jmp  xen_iret_crit_fixup

ENTRY(xen_do_upcall)
1:	mov %esp, %eax
	call xen_evtchn_do_upcall
	jmp  ret_from_intr
	CFI_ENDPROC
ENDPROC(xen_hypervisor_callback)

# Hypervisor uses this for application faults while it executes.
# We get here for two reasons:
#  1. Fault while reloading DS, ES, FS or GS
#  2. Fault while executing IRET
# Category 1 we fix up by reattempting the load, and zeroing the segment
# register if the load fails.
# Category 2 we fix up by jumping to do_iret_error. We cannot use the
# normal Linux return path in this case because if we use the IRET hypercall
# to pop the stack frame we end up in an infinite loop of failsafe callbacks.
# We distinguish between categories by maintaining a status value in EAX.
ENTRY(xen_failsafe_callback)
	CFI_STARTPROC
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	movl $1,%eax
1:	mov 4(%esp),%ds
2:	mov 8(%esp),%es
3:	mov 12(%esp),%fs
4:	mov 16(%esp),%gs
	testl %eax,%eax
	popl %eax
	CFI_ADJUST_CFA_OFFSET -4
	lea 16(%esp),%esp
	CFI_ADJUST_CFA_OFFSET -16
	jz 5f
	addl $16,%esp
	jmp iret_exc		# EAX != 0 => Category 2 (Bad IRET)
5:	pushl $0		# EAX == 0 => Category 1 (Bad segment)
	CFI_ADJUST_CFA_OFFSET 4
	SAVE_ALL
	jmp ret_from_exception
	CFI_ENDPROC

.section .fixup,"ax"
6:	xorl %eax,%eax
	movl %eax,4(%esp)
	jmp 1b
7:	xorl %eax,%eax
	movl %eax,8(%esp)
	jmp 2b
8:	xorl %eax,%eax
	movl %eax,12(%esp)
	jmp 3b
9:	xorl %eax,%eax
	movl %eax,16(%esp)
	jmp 4b
.previous
.section __ex_table,"a"
	.align 4
	.long 1b,6b
	.long 2b,7b
	.long 3b,8b
	.long 4b,9b
.previous
ENDPROC(xen_failsafe_callback)

#endif	/* CONFIG_XEN */

#ifdef CONFIG_FTRACE
#ifdef CONFIG_DYNAMIC_FTRACE

ENTRY(mcount)
	ret
END(mcount)

ENTRY(ftrace_caller)
	pushl %eax
	pushl %ecx
	pushl %edx
	movl 0xc(%esp), %eax
	movl 0x4(%ebp), %edx
	subl $MCOUNT_INSN_SIZE, %eax

.globl ftrace_call
ftrace_call:
	call ftrace_stub

	popl %edx
	popl %ecx
	popl %eax

.globl ftrace_stub
ftrace_stub:
	ret
END(ftrace_caller)

#else /* ! CONFIG_DYNAMIC_FTRACE */

ENTRY(mcount)
	cmpl $ftrace_stub, ftrace_trace_function
	jnz trace
.globl ftrace_stub
ftrace_stub:
	ret

	/* taken from glibc */
trace:
	pushl %eax
	pushl %ecx
	pushl %edx
	movl 0xc(%esp), %eax
	movl 0x4(%ebp), %edx
	subl $MCOUNT_INSN_SIZE, %eax

	call *ftrace_trace_function

	popl %edx
	popl %ecx
	popl %eax

	jmp ftrace_stub
END(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FTRACE */

.section .rodata,"a"
#include "syscall_table_32.S"

syscall_table_size=(.-sys_call_table)