aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/kernel/entry_64.S
blob: a7ae7fd1010fdbddcd596aa0aae01ee160b7bb66 (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
/*
 *  linux/arch/x86_64/entry.S
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2000, 2001, 2002  Andi Kleen SuSE Labs
 *  Copyright (C) 2000  Pavel Machek <pavel@suse.cz>
 */

/*
 * entry.S contains the system-call and fault low-level handling routines.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after an interrupt and after each system call.
 *
 * Normal syscalls and interrupts don't save a full stack frame, this is
 * only done for syscall tracing, signals or fork/exec et.al.
 *
 * A note on terminology:
 * - top of stack: Architecture defined interrupt frame from SS to RIP
 * at the top of the kernel process stack.
 * - partial stack frame: partially saved registers upto R11.
 * - full stack frame: Like partial stack frame, but all register saved.
 *
 * Some macro usage:
 * - CFI macros are used to generate dwarf2 unwind information for better
 * backtraces. They don't change any code.
 * - SAVE_ALL/RESTORE_ALL - Save/restore all registers
 * - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify.
 * There are unfortunately lots of special cases where some registers
 * not touched. The macro is a big mess that should be cleaned up.
 * - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS.
 * Gives a full stack frame.
 * - ENTRY/END Define functions in the symbol table.
 * - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack
 * frame that is otherwise undefined after a SYSCALL
 * - TRACE_IRQ_* - Trace hard interrupt state for lock debugging.
 * - errorentry/paranoidentry/zeroentry - Define exception entry points.
 */

#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/cache.h>
#include <asm/errno.h>
#include <asm/dwarf2.h>
#include <asm/calling.h>
#include <asm/asm-offsets.h>
#include <asm/msr.h>
#include <asm/unistd.h>
#include <asm/thread_info.h>
#include <asm/hw_irq.h>
#include <asm/page_types.h>
#include <asm/irqflags.h>
#include <asm/paravirt.h>
#include <asm/ftrace.h>
#include <asm/percpu.h>

/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
#include <linux/elf-em.h>
#define AUDIT_ARCH_X86_64	(EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
#define __AUDIT_ARCH_64BIT 0x80000000
#define __AUDIT_ARCH_LE	   0x40000000

	.code64
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
	retq
END(mcount)

ENTRY(ftrace_caller)
	cmpl $0, function_trace_stop
	jne  ftrace_stub

	MCOUNT_SAVE_FRAME

	movq 0x38(%rsp), %rdi
	movq 8(%rbp), %rsi
	subq $MCOUNT_INSN_SIZE, %rdi

GLOBAL(ftrace_call)
	call ftrace_stub

	MCOUNT_RESTORE_FRAME

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
GLOBAL(ftrace_graph_call)
	jmp ftrace_stub
#endif

GLOBAL(ftrace_stub)
	retq
END(ftrace_caller)

#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(mcount)
	cmpl $0, function_trace_stop
	jne  ftrace_stub

	cmpq $ftrace_stub, ftrace_trace_function
	jnz trace

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	cmpq $ftrace_stub, ftrace_graph_return
	jnz ftrace_graph_caller

	cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
	jnz ftrace_graph_caller
#endif

GLOBAL(ftrace_stub)
	retq

trace:
	MCOUNT_SAVE_FRAME

	movq 0x38(%rsp), %rdi
	movq 8(%rbp), %rsi
	subq $MCOUNT_INSN_SIZE, %rdi

	call   *ftrace_trace_function

	MCOUNT_RESTORE_FRAME

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

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
	cmpl $0, function_trace_stop
	jne ftrace_stub

	MCOUNT_SAVE_FRAME

	leaq 8(%rbp), %rdi
	movq 0x38(%rsp), %rsi
	movq (%rbp), %rdx
	subq $MCOUNT_INSN_SIZE, %rsi

	call	prepare_ftrace_return

	MCOUNT_RESTORE_FRAME

	retq
END(ftrace_graph_caller)

GLOBAL(return_to_handler)
	subq  $24, %rsp

	/* Save the return values */
	movq %rax, (%rsp)
	movq %rdx, 8(%rsp)
	movq %rbp, %rdi

	call ftrace_return_to_handler

	movq %rax, %rdi
	movq 8(%rsp), %rdx
	movq (%rsp), %rax
	addq $24, %rsp
	jmp *%rdi
#endif


#ifndef CONFIG_PREEMPT
#define retint_kernel retint_restore_args
#endif

#ifdef CONFIG_PARAVIRT
ENTRY(native_usergs_sysret64)
	swapgs
	sysretq
ENDPROC(native_usergs_sysret64)
#endif /* CONFIG_PARAVIRT */


.macro TRACE_IRQS_IRETQ offset=ARGOFFSET
#ifdef CONFIG_TRACE_IRQFLAGS
	bt   $9,EFLAGS-\offset(%rsp)	/* interrupts off? */
	jnc  1f
	TRACE_IRQS_ON
1:
#endif
.endm

/*
 * C code is not supposed to know about undefined top of stack. Every time
 * a C function with an pt_regs argument is called from the SYSCALL based
 * fast path FIXUP_TOP_OF_STACK is needed.
 * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
 * manipulation.
 */

	/* %rsp:at FRAMEEND */
	.macro FIXUP_TOP_OF_STACK tmp offset=0
	movq PER_CPU_VAR(old_rsp),\tmp
	movq \tmp,RSP+\offset(%rsp)
	movq $__USER_DS,SS+\offset(%rsp)
	movq $__USER_CS,CS+\offset(%rsp)
	movq $-1,RCX+\offset(%rsp)
	movq R11+\offset(%rsp),\tmp  /* get eflags */
	movq \tmp,EFLAGS+\offset(%rsp)
	.endm

	.macro RESTORE_TOP_OF_STACK tmp offset=0
	movq RSP+\offset(%rsp),\tmp
	movq \tmp,PER_CPU_VAR(old_rsp)
	movq EFLAGS+\offset(%rsp),\tmp
	movq \tmp,R11+\offset(%rsp)
	.endm

	.macro FAKE_STACK_FRAME child_rip
	/* push in order ss, rsp, eflags, cs, rip */
	xorl %eax, %eax
	pushq_cfi $__KERNEL_DS /* ss */
	/*CFI_REL_OFFSET	ss,0*/
	pushq_cfi %rax /* rsp */
	CFI_REL_OFFSET	rsp,0
	pushq_cfi $X86_EFLAGS_IF /* eflags - interrupts on */
	/*CFI_REL_OFFSET	rflags,0*/
	pushq_cfi $__KERNEL_CS /* cs */
	/*CFI_REL_OFFSET	cs,0*/
	pushq_cfi \child_rip /* rip */
	CFI_REL_OFFSET	rip,0
	pushq_cfi %rax /* orig rax */
	.endm

	.macro UNFAKE_STACK_FRAME
	addq $8*6, %rsp
	CFI_ADJUST_CFA_OFFSET	-(6*8)
	.endm

/*
 * initial frame state for interrupts (and exceptions without error code)
 */
	.macro EMPTY_FRAME start=1 offset=0
	.if \start
	CFI_STARTPROC simple
	CFI_SIGNAL_FRAME
	CFI_DEF_CFA rsp,8+\offset
	.else
	CFI_DEF_CFA_OFFSET 8+\offset
	.endif
	.endm

/*
 * initial frame state for interrupts (and exceptions without error code)
 */
	.macro INTR_FRAME start=1 offset=0
	EMPTY_FRAME \start, SS+8+\offset-RIP
	/*CFI_REL_OFFSET ss, SS+\offset-RIP*/
	CFI_REL_OFFSET rsp, RSP+\offset-RIP
	/*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
	/*CFI_REL_OFFSET cs, CS+\offset-RIP*/
	CFI_REL_OFFSET rip, RIP+\offset-RIP
	.endm

/*
 * initial frame state for exceptions with error code (and interrupts
 * with vector already pushed)
 */
	.macro XCPT_FRAME start=1 offset=0
	INTR_FRAME \start, RIP+\offset-ORIG_RAX
	/*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
	.endm

/*
 * frame that enables calling into C.
 */
	.macro PARTIAL_FRAME start=1 offset=0
	XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
	CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
	CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
	CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
	CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET
	CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET
	CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET
	CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET
	CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET
	CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET
	.endm

/*
 * frame that enables passing a complete pt_regs to a C function.
 */
	.macro DEFAULT_FRAME start=1 offset=0
	PARTIAL_FRAME \start, R11+\offset-R15
	CFI_REL_OFFSET rbx, RBX+\offset
	CFI_REL_OFFSET rbp, RBP+\offset
	CFI_REL_OFFSET r12, R12+\offset
	CFI_REL_OFFSET r13, R13+\offset
	CFI_REL_OFFSET r14, R14+\offset
	CFI_REL_OFFSET r15, R15+\offset
	.endm

/* save partial stack frame */
ENTRY(save_args)
	XCPT_FRAME
	cld
	movq_cfi rdi, RDI+16-ARGOFFSET
	movq_cfi rsi, RSI+16-ARGOFFSET
	movq_cfi rdx, RDX+16-ARGOFFSET
	movq_cfi rcx, RCX+16-ARGOFFSET
	movq_cfi rax, RAX+16-ARGOFFSET
	movq_cfi  r8,  R8+16-ARGOFFSET
	movq_cfi  r9,  R9+16-ARGOFFSET
	movq_cfi r10, R10+16-ARGOFFSET
	movq_cfi r11, R11+16-ARGOFFSET

	leaq -ARGOFFSET+16(%rsp),%rdi	/* arg1 for handler */
	movq_cfi rbp, 8		/* push %rbp */
	leaq 8(%rsp), %rbp		/* mov %rsp, %ebp */
	testl $3, CS(%rdi)
	je 1f
	SWAPGS
	/*
	 * irq_count is used to check if a CPU is already on an interrupt stack
	 * or not. While this is essentially redundant with preempt_count it is
	 * a little cheaper to use a separate counter in the PDA (short of
	 * moving irq_enter into assembly, which would be too much work)
	 */
1:	incl PER_CPU_VAR(irq_count)
	jne 2f
	popq_cfi %rax			/* move return address... */
	mov PER_CPU_VAR(irq_stack_ptr),%rsp
	EMPTY_FRAME 0
	pushq_cfi %rbp			/* backlink for unwinder */
	pushq_cfi %rax			/* ... to the new stack */
	/*
	 * We entered an interrupt context - irqs are off:
	 */
2:	TRACE_IRQS_OFF
	ret
	CFI_ENDPROC
END(save_args)

ENTRY(save_rest)
	PARTIAL_FRAME 1 REST_SKIP+8
	movq 5*8+16(%rsp), %r11	/* save return address */
	movq_cfi rbx, RBX+16
	movq_cfi rbp, RBP+16
	movq_cfi r12, R12+16
	movq_cfi r13, R13+16
	movq_cfi r14, R14+16
	movq_cfi r15, R15+16
	movq %r11, 8(%rsp)	/* return address */
	FIXUP_TOP_OF_STACK %r11, 16
	ret
	CFI_ENDPROC
END(save_rest)

/* save complete stack frame */
	.pushsection .kprobes.text, "ax"
ENTRY(save_paranoid)
	XCPT_FRAME 1 RDI+8
	cld
	movq_cfi rdi, RDI+8
	movq_cfi rsi, RSI+8
	movq_cfi rdx, RDX+8
	movq_cfi rcx, RCX+8
	movq_cfi rax, RAX+8
	movq_cfi r8, R8+8
	movq_cfi r9, R9+8
	movq_cfi r10, R10+8
	movq_cfi r11, R11+8
	movq_cfi rbx, RBX+8
	movq_cfi rbp, RBP+8
	movq_cfi r12, R12+8
	movq_cfi r13, R13+8
	movq_cfi r14, R14+8
	movq_cfi r15, R15+8
	movl $1,%ebx
	movl $MSR_GS_BASE,%ecx
	rdmsr
	testl %edx,%edx
	js 1f	/* negative -> in kernel */
	SWAPGS
	xorl %ebx,%ebx
1:	ret
	CFI_ENDPROC
END(save_paranoid)
	.popsection

/*
 * A newly forked process directly context switches into this address.
 *
 * rdi: prev task we switched from
 */
ENTRY(ret_from_fork)
	DEFAULT_FRAME

	LOCK ; btr $TIF_FORK,TI_flags(%r8)

	pushq_cfi kernel_eflags(%rip)
	popfq_cfi				# reset kernel eflags

	call schedule_tail			# rdi: 'prev' task parameter

	GET_THREAD_INFO(%rcx)

	RESTORE_REST

	testl $3, CS-ARGOFFSET(%rsp)		# from kernel_thread?
	je   int_ret_from_sys_call

	testl $_TIF_IA32, TI_flags(%rcx)	# 32-bit compat task needs IRET
	jnz  int_ret_from_sys_call

	RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
	jmp ret_from_sys_call			# go to the SYSRET fastpath

	CFI_ENDPROC
END(ret_from_fork)

/*
 * System call entry. Upto 6 arguments in registers are supported.
 *
 * SYSCALL does not save anything on the stack and does not change the
 * stack pointer.
 */

/*
 * Register setup:
 * rax  system call number
 * rdi  arg0
 * rcx  return address for syscall/sysret, C arg3
 * rsi  arg1
 * rdx  arg2
 * r10  arg3 	(--> moved to rcx for C)
 * r8   arg4
 * r9   arg5
 * r11  eflags for syscall/sysret, temporary for C
 * r12-r15,rbp,rbx saved by C code, not touched.
 *
 * Interrupts are off on entry.
 * Only called from user space.
 *
 * XXX	if we had a free scratch register we could save the RSP into the stack frame
 *      and report it properly in ps. Unfortunately we haven't.
 *
 * When user can change the frames always force IRET. That is because
 * it deals with uncanonical addresses better. SYSRET has trouble
 * with them due to bugs in both AMD and Intel CPUs.
 */

ENTRY(system_call)
	CFI_STARTPROC	simple
	CFI_SIGNAL_FRAME
	CFI_DEF_CFA	rsp,KERNEL_STACK_OFFSET
	CFI_REGISTER	rip,rcx
	/*CFI_REGISTER	rflags,r11*/
	SWAPGS_UNSAFE_STACK
	/*
	 * A hypervisor implementation might want to use a label
	 * after the swapgs, so that it can do the swapgs
	 * for the guest and jump here on syscall.
	 */
ENTRY(system_call_after_swapgs)

	movq	%rsp,PER_CPU_VAR(old_rsp)
	movq	PER_CPU_VAR(kernel_stack),%rsp
	/*
	 * No need to follow this irqs off/on section - it's straight
	 * and short:
	 */
	ENABLE_INTERRUPTS(CLBR_NONE)
	SAVE_ARGS 8,1
	movq  %rax,ORIG_RAX-ARGOFFSET(%rsp)
	movq  %rcx,RIP-ARGOFFSET(%rsp)
	CFI_REL_OFFSET rip,RIP-ARGOFFSET
	GET_THREAD_INFO(%rcx)
	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%rcx)
	jnz tracesys
system_call_fastpath:
	cmpq $__NR_syscall_max,%rax
	ja badsys
	movq %r10,%rcx
	call *sys_call_table(,%rax,8)  # XXX:	 rip relative
	movq %rax,RAX-ARGOFFSET(%rsp)
/*
 * Syscall return path ending with SYSRET (fast path)
 * Has incomplete stack frame and undefined top of stack.
 */
ret_from_sys_call:
	movl $_TIF_ALLWORK_MASK,%edi
	/* edi:	flagmask */
sysret_check:
	LOCKDEP_SYS_EXIT
	GET_THREAD_INFO(%rcx)
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	movl TI_flags(%rcx),%edx
	andl %edi,%edx
	jnz  sysret_careful
	CFI_REMEMBER_STATE
	/*
	 * sysretq will re-enable interrupts:
	 */
	TRACE_IRQS_ON
	movq RIP-ARGOFFSET(%rsp),%rcx
	CFI_REGISTER	rip,rcx
	RESTORE_ARGS 0,-ARG_SKIP,1
	/*CFI_REGISTER	rflags,r11*/
	movq	PER_CPU_VAR(old_rsp), %rsp
	USERGS_SYSRET64

	CFI_RESTORE_STATE
	/* Handle reschedules */
	/* edx:	work, edi: workmask */
sysret_careful:
	bt $TIF_NEED_RESCHED,%edx
	jnc sysret_signal
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
	pushq_cfi %rdi
	call schedule
	popq_cfi %rdi
	jmp sysret_check

	/* Handle a signal */
sysret_signal:
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
#ifdef CONFIG_AUDITSYSCALL
	bt $TIF_SYSCALL_AUDIT,%edx
	jc sysret_audit
#endif
	/*
	 * We have a signal, or exit tracing or single-step.
	 * These all wind up with the iret return path anyway,
	 * so just join that path right now.
	 */
	FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
	jmp int_check_syscall_exit_work

badsys:
	movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
	jmp ret_from_sys_call

#ifdef CONFIG_AUDITSYSCALL
	/*
	 * Fast path for syscall audit without full syscall trace.
	 * We just call audit_syscall_entry() directly, and then
	 * jump back to the normal fast path.
	 */
auditsys:
	movq %r10,%r9			/* 6th arg: 4th syscall arg */
	movq %rdx,%r8			/* 5th arg: 3rd syscall arg */
	movq %rsi,%rcx			/* 4th arg: 2nd syscall arg */
	movq %rdi,%rdx			/* 3rd arg: 1st syscall arg */
	movq %rax,%rsi			/* 2nd arg: syscall number */
	movl $AUDIT_ARCH_X86_64,%edi	/* 1st arg: audit arch */
	call audit_syscall_entry
	LOAD_ARGS 0		/* reload call-clobbered registers */
	jmp system_call_fastpath

	/*
	 * Return fast path for syscall audit.  Call audit_syscall_exit()
	 * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
	 * masked off.
	 */
sysret_audit:
	movq RAX-ARGOFFSET(%rsp),%rsi	/* second arg, syscall return value */
	cmpq $0,%rsi		/* is it < 0? */
	setl %al		/* 1 if so, 0 if not */
	movzbl %al,%edi		/* zero-extend that into %edi */
	inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
	call audit_syscall_exit
	movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
	jmp sysret_check
#endif	/* CONFIG_AUDITSYSCALL */

	/* Do syscall tracing */
tracesys:
#ifdef CONFIG_AUDITSYSCALL
	testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
	jz auditsys
#endif
	SAVE_REST
	movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
	FIXUP_TOP_OF_STACK %rdi
	movq %rsp,%rdi
	call syscall_trace_enter
	/*
	 * Reload arg registers from stack in case ptrace changed them.
	 * We don't reload %rax because syscall_trace_enter() returned
	 * the value it wants us to use in the table lookup.
	 */
	LOAD_ARGS ARGOFFSET, 1
	RESTORE_REST
	cmpq $__NR_syscall_max,%rax
	ja   int_ret_from_sys_call	/* RAX(%rsp) set to -ENOSYS above */
	movq %r10,%rcx	/* fixup for C */
	call *sys_call_table(,%rax,8)
	movq %rax,RAX-ARGOFFSET(%rsp)
	/* Use IRET because user could have changed frame */

/*
 * Syscall return path ending with IRET.
 * Has correct top of stack, but partial stack frame.
 */
GLOBAL(int_ret_from_sys_call)
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	testl $3,CS-ARGOFFSET(%rsp)
	je retint_restore_args
	movl $_TIF_ALLWORK_MASK,%edi
	/* edi:	mask to check */
GLOBAL(int_with_check)
	LOCKDEP_SYS_EXIT_IRQ
	GET_THREAD_INFO(%rcx)
	movl TI_flags(%rcx),%edx
	andl %edi,%edx
	jnz   int_careful
	andl    $~TS_COMPAT,TI_status(%rcx)
	jmp   retint_swapgs

	/* Either reschedule or signal or syscall exit tracking needed. */
	/* First do a reschedule test. */
	/* edx:	work, edi: workmask */
int_careful:
	bt $TIF_NEED_RESCHED,%edx
	jnc  int_very_careful
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
	pushq_cfi %rdi
	call schedule
	popq_cfi %rdi
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	jmp int_with_check

	/* handle signals and tracing -- both require a full stack frame */
int_very_careful:
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
int_check_syscall_exit_work:
	SAVE_REST
	/* Check for syscall exit trace */
	testl $_TIF_WORK_SYSCALL_EXIT,%edx
	jz int_signal
	pushq_cfi %rdi
	leaq 8(%rsp),%rdi	# &ptregs -> arg1
	call syscall_trace_leave
	popq_cfi %rdi
	andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
	jmp int_restore_rest

int_signal:
	testl $_TIF_DO_NOTIFY_MASK,%edx
	jz 1f
	movq %rsp,%rdi		# &ptregs -> arg1
	xorl %esi,%esi		# oldset -> arg2
	call do_notify_resume
1:	movl $_TIF_WORK_MASK,%edi
int_restore_rest:
	RESTORE_REST
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	jmp int_with_check
	CFI_ENDPROC
END(system_call)

/*
 * Certain special system calls that need to save a complete full stack frame.
 */
	.macro PTREGSCALL label,func,arg
ENTRY(\label)
	PARTIAL_FRAME 1 8		/* offset 8: return address */
	subq $REST_SKIP, %rsp
	CFI_ADJUST_CFA_OFFSET REST_SKIP
	call save_rest
	DEFAULT_FRAME 0 8		/* offset 8: return address */
	leaq 8(%rsp), \arg	/* pt_regs pointer */
	call \func
	jmp ptregscall_common
	CFI_ENDPROC
END(\label)
	.endm

	PTREGSCALL stub_clone, sys_clone, %r8
	PTREGSCALL stub_fork, sys_fork, %rdi
	PTREGSCALL stub_vfork, sys_vfork, %rdi
	PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
	PTREGSCALL stub_iopl, sys_iopl, %rsi

ENTRY(ptregscall_common)
	DEFAULT_FRAME 1 8	/* offset 8: return address */
	RESTORE_TOP_OF_STACK %r11, 8
	movq_cfi_restore R15+8, r15
	movq_cfi_restore R14+8, r14
	movq_cfi_restore R13+8, r13
	movq_cfi_restore R12+8, r12
	movq_cfi_restore RBP+8, rbp
	movq_cfi_restore RBX+8, rbx
	ret $REST_SKIP		/* pop extended registers */
	CFI_ENDPROC
END(ptregscall_common)

ENTRY(stub_execve)
	CFI_STARTPROC
	addq $8, %rsp
	PARTIAL_FRAME 0
	SAVE_REST
	FIXUP_TOP_OF_STACK %r11
	movq %rsp, %rcx
	call sys_execve
	RESTORE_TOP_OF_STACK %r11
	movq %rax,RAX(%rsp)
	RESTORE_REST
	jmp int_ret_from_sys_call
	CFI_ENDPROC
END(stub_execve)

/*
 * sigreturn is special because it needs to restore all registers on return.
 * This cannot be done with SYSRET, so use the IRET return path instead.
 */
ENTRY(stub_rt_sigreturn)
	CFI_STARTPROC
	addq $8, %rsp
	PARTIAL_FRAME 0
	SAVE_REST
	movq %rsp,%rdi
	FIXUP_TOP_OF_STACK %r11
	call sys_rt_sigreturn
	movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
	RESTORE_REST
	jmp int_ret_from_sys_call
	CFI_ENDPROC
END(stub_rt_sigreturn)

/*
 * Build the entry stubs and pointer table with some assembler magic.
 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
 * single cache line on all modern x86 implementations.
 */
	.section .init.rodata,"a"
ENTRY(interrupt)
	.text
	.p2align 5
	.p2align CONFIG_X86_L1_CACHE_SHIFT
ENTRY(irq_entries_start)
	INTR_FRAME
vector=FIRST_EXTERNAL_VECTOR
.rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
	.balign 32
  .rept	7
    .if vector < NR_VECTORS
      .if vector <> FIRST_EXTERNAL_VECTOR
	CFI_ADJUST_CFA_OFFSET -8
      .endif
1:	pushq_cfi $(~vector+0x80)	/* Note: always in signed byte range */
      .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
	jmp 2f
      .endif
      .previous
	.quad 1b
      .text
vector=vector+1
    .endif
  .endr
2:	jmp common_interrupt
.endr
	CFI_ENDPROC
END(irq_entries_start)

.previous
END(interrupt)
.previous

/*
 * Interrupt entry/exit.
 *
 * Interrupt entry points save only callee clobbered registers in fast path.
 *
 * Entry runs with interrupts off.
 */

/* 0(%rsp): ~(interrupt number) */
	.macro interrupt func
	subq $ORIG_RAX-ARGOFFSET+8, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-ARGOFFSET+8
	call save_args
	PARTIAL_FRAME 0
	call \func
	.endm

/*
 * Interrupt entry/exit should be protected against kprobes
 */
	.pushsection .kprobes.text, "ax"
	/*
	 * The interrupt stubs push (~vector+0x80) onto the stack and
	 * then jump to common_interrupt.
	 */
	.p2align CONFIG_X86_L1_CACHE_SHIFT
common_interrupt:
	XCPT_FRAME
	addq $-0x80,(%rsp)		/* Adjust vector to [-256,-1] range */
	interrupt do_IRQ
	/* 0(%rsp): old_rsp-ARGOFFSET */
ret_from_intr:
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	decl PER_CPU_VAR(irq_count)
	leaveq
	CFI_RESTORE		rbp
	CFI_DEF_CFA_REGISTER	rsp
	CFI_ADJUST_CFA_OFFSET	-8
exit_intr:
	GET_THREAD_INFO(%rcx)
	testl $3,CS-ARGOFFSET(%rsp)
	je retint_kernel

	/* Interrupt came from user space */
	/*
	 * Has a correct top of stack, but a partial stack frame
	 * %rcx: thread info. Interrupts off.
	 */
retint_with_reschedule:
	movl $_TIF_WORK_MASK,%edi
retint_check:
	LOCKDEP_SYS_EXIT_IRQ
	movl TI_flags(%rcx),%edx
	andl %edi,%edx
	CFI_REMEMBER_STATE
	jnz  retint_careful

retint_swapgs:		/* return to user-space */
	/*
	 * The iretq could re-enable interrupts:
	 */
	DISABLE_INTERRUPTS(CLBR_ANY)
	TRACE_IRQS_IRETQ
	SWAPGS
	jmp restore_args

retint_restore_args:	/* return to kernel space */
	DISABLE_INTERRUPTS(CLBR_ANY)
	/*
	 * The iretq could re-enable interrupts:
	 */
	TRACE_IRQS_IRETQ
restore_args:
	RESTORE_ARGS 0,8,0

irq_return:
	INTERRUPT_RETURN

	.section __ex_table, "a"
	.quad irq_return, bad_iret
	.previous

#ifdef CONFIG_PARAVIRT
ENTRY(native_iret)
	iretq

	.section __ex_table,"a"
	.quad native_iret, bad_iret
	.previous
#endif

	.section .fixup,"ax"
bad_iret:
	/*
	 * The iret traps when the %cs or %ss being restored is bogus.
	 * We've lost the original trap vector and error code.
	 * #GPF is the most likely one to get for an invalid selector.
	 * So pretend we completed the iret and took the #GPF in user mode.
	 *
	 * We are now running with the kernel GS after exception recovery.
	 * But error_entry expects us to have user GS to match the user %cs,
	 * so swap back.
	 */
	pushq $0

	SWAPGS
	jmp general_protection

	.previous

	/* edi: workmask, edx: work */
retint_careful:
	CFI_RESTORE_STATE
	bt    $TIF_NEED_RESCHED,%edx
	jnc   retint_signal
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
	pushq_cfi %rdi
	call  schedule
	popq_cfi %rdi
	GET_THREAD_INFO(%rcx)
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	jmp retint_check

retint_signal:
	testl $_TIF_DO_NOTIFY_MASK,%edx
	jz    retint_swapgs
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
	SAVE_REST
	movq $-1,ORIG_RAX(%rsp)
	xorl %esi,%esi		# oldset
	movq %rsp,%rdi		# &pt_regs
	call do_notify_resume
	RESTORE_REST
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	GET_THREAD_INFO(%rcx)
	jmp retint_with_reschedule

#ifdef CONFIG_PREEMPT
	/* Returning to kernel space. Check if we need preemption */
	/* rcx:	 threadinfo. interrupts off. */
ENTRY(retint_kernel)
	cmpl $0,TI_preempt_count(%rcx)
	jnz  retint_restore_args
	bt  $TIF_NEED_RESCHED,TI_flags(%rcx)
	jnc  retint_restore_args
	bt   $9,EFLAGS-ARGOFFSET(%rsp)	/* interrupts off? */
	jnc  retint_restore_args
	call preempt_schedule_irq
	jmp exit_intr
#endif

	CFI_ENDPROC
END(common_interrupt)
/*
 * End of kprobes section
 */
       .popsection

/*
 * APIC interrupts.
 */
.macro apicinterrupt num sym do_sym
ENTRY(\sym)
	INTR_FRAME
	pushq_cfi $~(\num)
	interrupt \do_sym
	jmp ret_from_intr
	CFI_ENDPROC
END(\sym)
.endm

#ifdef CONFIG_SMP
apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
	irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
apicinterrupt REBOOT_VECTOR \
	reboot_interrupt smp_reboot_interrupt
#endif

#ifdef CONFIG_X86_UV
apicinterrupt UV_BAU_MESSAGE \
	uv_bau_message_intr1 uv_bau_message_interrupt
#endif
apicinterrupt LOCAL_TIMER_VECTOR \
	apic_timer_interrupt smp_apic_timer_interrupt
apicinterrupt X86_PLATFORM_IPI_VECTOR \
	x86_platform_ipi smp_x86_platform_ipi

#ifdef CONFIG_SMP
apicinterrupt INVALIDATE_TLB_VECTOR_START+0 \
	invalidate_interrupt0 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+1 \
	invalidate_interrupt1 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+2 \
	invalidate_interrupt2 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+3 \
	invalidate_interrupt3 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+4 \
	invalidate_interrupt4 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+5 \
	invalidate_interrupt5 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+6 \
	invalidate_interrupt6 smp_invalidate_interrupt
apicinterrupt INVALIDATE_TLB_VECTOR_START+7 \
	invalidate_interrupt7 smp_invalidate_interrupt
#endif

apicinterrupt THRESHOLD_APIC_VECTOR \
	threshold_interrupt smp_threshold_interrupt
apicinterrupt THERMAL_APIC_VECTOR \
	thermal_interrupt smp_thermal_interrupt

#ifdef CONFIG_X86_MCE
apicinterrupt MCE_SELF_VECTOR \
	mce_self_interrupt smp_mce_self_interrupt
#endif

#ifdef CONFIG_SMP
apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
	call_function_single_interrupt smp_call_function_single_interrupt
apicinterrupt CALL_FUNCTION_VECTOR \
	call_function_interrupt smp_call_function_interrupt
apicinterrupt RESCHEDULE_VECTOR \
	reschedule_interrupt smp_reschedule_interrupt
#endif

apicinterrupt ERROR_APIC_VECTOR \
	error_interrupt smp_error_interrupt
apicinterrupt SPURIOUS_APIC_VECTOR \
	spurious_interrupt smp_spurious_interrupt

#ifdef CONFIG_IRQ_WORK
apicinterrupt IRQ_WORK_VECTOR \
	irq_work_interrupt smp_irq_work_interrupt
#endif

/*
 * Exception entry points.
 */
.macro zeroentry sym do_sym
ENTRY(\sym)
	INTR_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	pushq_cfi $-1		/* ORIG_RAX: no syscall to restart */
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call error_entry
	DEFAULT_FRAME 0
	movq %rsp,%rdi		/* pt_regs pointer */
	xorl %esi,%esi		/* no error code */
	call \do_sym
	jmp error_exit		/* %ebx: no swapgs flag */
	CFI_ENDPROC
END(\sym)
.endm

.macro paranoidzeroentry sym do_sym
ENTRY(\sym)
	INTR_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	pushq_cfi $-1		/* ORIG_RAX: no syscall to restart */
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call save_paranoid
	TRACE_IRQS_OFF
	movq %rsp,%rdi		/* pt_regs pointer */
	xorl %esi,%esi		/* no error code */
	call \do_sym
	jmp paranoid_exit	/* %ebx: no swapgs flag */
	CFI_ENDPROC
END(\sym)
.endm

#define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
.macro paranoidzeroentry_ist sym do_sym ist
ENTRY(\sym)
	INTR_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	pushq_cfi $-1		/* ORIG_RAX: no syscall to restart */
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call save_paranoid
	TRACE_IRQS_OFF
	movq %rsp,%rdi		/* pt_regs pointer */
	xorl %esi,%esi		/* no error code */
	subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
	call \do_sym
	addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
	jmp paranoid_exit	/* %ebx: no swapgs flag */
	CFI_ENDPROC
END(\sym)
.endm

.macro errorentry sym do_sym
ENTRY(\sym)
	XCPT_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call error_entry
	DEFAULT_FRAME 0
	movq %rsp,%rdi			/* pt_regs pointer */
	movq ORIG_RAX(%rsp),%rsi	/* get error code */
	movq $-1,ORIG_RAX(%rsp)		/* no syscall to restart */
	call \do_sym
	jmp error_exit			/* %ebx: no swapgs flag */
	CFI_ENDPROC
END(\sym)
.endm

	/* error code is on the stack already */
.macro paranoiderrorentry sym do_sym
ENTRY(\sym)
	XCPT_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call save_paranoid
	DEFAULT_FRAME 0
	TRACE_IRQS_OFF
	movq %rsp,%rdi			/* pt_regs pointer */
	movq ORIG_RAX(%rsp),%rsi	/* get error code */
	movq $-1,ORIG_RAX(%rsp)		/* no syscall to restart */
	call \do_sym
	jmp paranoid_exit		/* %ebx: no swapgs flag */
	CFI_ENDPROC
END(\sym)
.endm

zeroentry divide_error do_divide_error
zeroentry overflow do_overflow
zeroentry bounds do_bounds
zeroentry invalid_op do_invalid_op
zeroentry device_not_available do_device_not_available
paranoiderrorentry double_fault do_double_fault
zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
errorentry invalid_TSS do_invalid_TSS
errorentry segment_not_present do_segment_not_present
zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
zeroentry coprocessor_error do_coprocessor_error
errorentry alignment_check do_alignment_check
zeroentry simd_coprocessor_error do_simd_coprocessor_error

	/* Reload gs selector with exception handling */
	/* edi:  new selector */
ENTRY(native_load_gs_index)
	CFI_STARTPROC
	pushfq_cfi
	DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
	SWAPGS
gs_change:
	movl %edi,%gs
2:	mfence		/* workaround */
	SWAPGS
	popfq_cfi
	ret
	CFI_ENDPROC
END(native_load_gs_index)

	.section __ex_table,"a"
	.align 8
	.quad gs_change,bad_gs
	.previous
	.section .fixup,"ax"
	/* running with kernelgs */
bad_gs:
	SWAPGS			/* switch back to user gs */
	xorl %eax,%eax
	movl %eax,%gs
	jmp  2b
	.previous

ENTRY(kernel_thread_helper)
	pushq $0		# fake return address
	CFI_STARTPROC
	/*
	 * Here we are in the child and the registers are set as they were
	 * at kernel_thread() invocation in the parent.
	 */
	call *%rsi
	# exit
	mov %eax, %edi
	call do_exit
	ud2			# padding for call trace
	CFI_ENDPROC
END(kernel_thread_helper)

/*
 * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
 *
 * C extern interface:
 *	 extern long execve(const char *name, char **argv, char **envp)
 *
 * asm input arguments:
 *	rdi: name, rsi: argv, rdx: envp
 *
 * We want to fallback into:
 *	extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs)
 *
 * do_sys_execve asm fallback arguments:
 *	rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
 */
ENTRY(kernel_execve)
	CFI_STARTPROC
	FAKE_STACK_FRAME $0
	SAVE_ALL
	movq %rsp,%rcx
	call sys_execve
	movq %rax, RAX(%rsp)
	RESTORE_REST
	testq %rax,%rax
	je int_ret_from_sys_call
	RESTORE_ARGS
	UNFAKE_STACK_FRAME
	ret
	CFI_ENDPROC
END(kernel_execve)

/* Call softirq on interrupt stack. Interrupts are off. */
ENTRY(call_softirq)
	CFI_STARTPROC
	pushq_cfi %rbp
	CFI_REL_OFFSET rbp,0
	mov  %rsp,%rbp
	CFI_DEF_CFA_REGISTER rbp
	incl PER_CPU_VAR(irq_count)
	cmove PER_CPU_VAR(irq_stack_ptr),%rsp
	push  %rbp			# backlink for old unwinder
	call __do_softirq
	leaveq
	CFI_RESTORE		rbp
	CFI_DEF_CFA_REGISTER	rsp
	CFI_ADJUST_CFA_OFFSET   -8
	decl PER_CPU_VAR(irq_count)
	ret
	CFI_ENDPROC
END(call_softirq)

#ifdef CONFIG_XEN
zeroentry xen_hypervisor_callback xen_do_hypervisor_callback

/*
 * A note on the "critical region" in our callback handler.
 * We want to avoid stacking callback handlers due to events occurring
 * during handling of the last event. To do this, we keep events disabled
 * until we've done all processing. HOWEVER, we must enable events before
 * popping the stack frame (can't be done atomically) and so it would still
 * be possible to get enough handler activations to overflow the stack.
 * Although unlikely, bugs of that kind are hard to track down, so we'd
 * like to avoid the possibility.
 * So, on entry to the handler we detect whether we interrupted an
 * existing activation in its critical region -- if so, we pop the current
 * activation and restart the handler using the previous one.
 */
ENTRY(xen_do_hypervisor_callback)   # do_hypervisor_callback(struct *pt_regs)
	CFI_STARTPROC
/*
 * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
 * see the correct pointer to the pt_regs
 */
	movq %rdi, %rsp            # we don't return, adjust the stack frame
	CFI_ENDPROC
	DEFAULT_FRAME
11:	incl PER_CPU_VAR(irq_count)
	movq %rsp,%rbp
	CFI_DEF_CFA_REGISTER rbp
	cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
	pushq %rbp			# backlink for old unwinder
	call xen_evtchn_do_upcall
	popq %rsp
	CFI_DEF_CFA_REGISTER rsp
	decl PER_CPU_VAR(irq_count)
	jmp  error_exit
	CFI_ENDPROC
END(do_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 do not need to fix up as Xen has already reloaded all segment
 * registers that could be reloaded and zeroed the others.
 * Category 2 we fix up by killing the current process. 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 comparing each saved segment register
 * with its current contents: any discrepancy means we in category 1.
 */
ENTRY(xen_failsafe_callback)
	INTR_FRAME 1 (6*8)
	/*CFI_REL_OFFSET gs,GS*/
	/*CFI_REL_OFFSET fs,FS*/
	/*CFI_REL_OFFSET es,ES*/
	/*CFI_REL_OFFSET ds,DS*/
	CFI_REL_OFFSET r11,8
	CFI_REL_OFFSET rcx,0
	movw %ds,%cx
	cmpw %cx,0x10(%rsp)
	CFI_REMEMBER_STATE
	jne 1f
	movw %es,%cx
	cmpw %cx,0x18(%rsp)
	jne 1f
	movw %fs,%cx
	cmpw %cx,0x20(%rsp)
	jne 1f
	movw %gs,%cx
	cmpw %cx,0x28(%rsp)
	jne 1f
	/* All segments match their saved values => Category 2 (Bad IRET). */
	movq (%rsp),%rcx
	CFI_RESTORE rcx
	movq 8(%rsp),%r11
	CFI_RESTORE r11
	addq $0x30,%rsp
	CFI_ADJUST_CFA_OFFSET -0x30
	pushq_cfi $0	/* RIP */
	pushq_cfi %r11
	pushq_cfi %rcx
	jmp general_protection
	CFI_RESTORE_STATE
1:	/* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
	movq (%rsp),%rcx
	CFI_RESTORE rcx
	movq 8(%rsp),%r11
	CFI_RESTORE r11
	addq $0x30,%rsp
	CFI_ADJUST_CFA_OFFSET -0x30
	pushq_cfi $0
	SAVE_ALL
	jmp error_exit
	CFI_ENDPROC
END(xen_failsafe_callback)

apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
	xen_hvm_callback_vector xen_evtchn_do_upcall

#endif /* CONFIG_XEN */

/*
 * Some functions should be protected against kprobes
 */
	.pushsection .kprobes.text, "ax"

paranoidzeroentry_ist debug do_debug DEBUG_STACK
paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
paranoiderrorentry stack_segment do_stack_segment
#ifdef CONFIG_XEN
zeroentry xen_debug do_debug
zeroentry xen_int3 do_int3
errorentry xen_stack_segment do_stack_segment
#endif
errorentry general_protection do_general_protection
errorentry page_fault do_page_fault
#ifdef CONFIG_X86_MCE
paranoidzeroentry machine_check *machine_check_vector(%rip)
#endif

	/*
	 * "Paranoid" exit path from exception stack.
	 * Paranoid because this is used by NMIs and cannot take
	 * any kernel state for granted.
	 * We don't do kernel preemption checks here, because only
	 * NMI should be common and it does not enable IRQs and
	 * cannot get reschedule ticks.
	 *
	 * "trace" is 0 for the NMI handler only, because irq-tracing
	 * is fundamentally NMI-unsafe. (we cannot change the soft and
	 * hard flags at once, atomically)
	 */

	/* ebx:	no swapgs flag */
ENTRY(paranoid_exit)
	DEFAULT_FRAME
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	testl %ebx,%ebx				/* swapgs needed? */
	jnz paranoid_restore
	testl $3,CS(%rsp)
	jnz   paranoid_userspace
paranoid_swapgs:
	TRACE_IRQS_IRETQ 0
	SWAPGS_UNSAFE_STACK
	RESTORE_ALL 8
	jmp irq_return
paranoid_restore:
	TRACE_IRQS_IRETQ 0
	RESTORE_ALL 8
	jmp irq_return
paranoid_userspace:
	GET_THREAD_INFO(%rcx)
	movl TI_flags(%rcx),%ebx
	andl $_TIF_WORK_MASK,%ebx
	jz paranoid_swapgs
	movq %rsp,%rdi			/* &pt_regs */
	call sync_regs
	movq %rax,%rsp			/* switch stack for scheduling */
	testl $_TIF_NEED_RESCHED,%ebx
	jnz paranoid_schedule
	movl %ebx,%edx			/* arg3: thread flags */
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_NONE)
	xorl %esi,%esi 			/* arg2: oldset */
	movq %rsp,%rdi 			/* arg1: &pt_regs */
	call do_notify_resume
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	jmp paranoid_userspace
paranoid_schedule:
	TRACE_IRQS_ON
	ENABLE_INTERRUPTS(CLBR_ANY)
	call schedule
	DISABLE_INTERRUPTS(CLBR_ANY)
	TRACE_IRQS_OFF
	jmp paranoid_userspace
	CFI_ENDPROC
END(paranoid_exit)

/*
 * Exception entry point. This expects an error code/orig_rax on the stack.
 * returns in "no swapgs flag" in %ebx.
 */
ENTRY(error_entry)
	XCPT_FRAME
	CFI_ADJUST_CFA_OFFSET 15*8
	/* oldrax contains error code */
	cld
	movq_cfi rdi, RDI+8
	movq_cfi rsi, RSI+8
	movq_cfi rdx, RDX+8
	movq_cfi rcx, RCX+8
	movq_cfi rax, RAX+8
	movq_cfi  r8,  R8+8
	movq_cfi  r9,  R9+8
	movq_cfi r10, R10+8
	movq_cfi r11, R11+8
	movq_cfi rbx, RBX+8
	movq_cfi rbp, RBP+8
	movq_cfi r12, R12+8
	movq_cfi r13, R13+8
	movq_cfi r14, R14+8
	movq_cfi r15, R15+8
	xorl %ebx,%ebx
	testl $3,CS+8(%rsp)
	je error_kernelspace
error_swapgs:
	SWAPGS
error_sti:
	TRACE_IRQS_OFF
	ret

/*
 * There are two places in the kernel that can potentially fault with
 * usergs. Handle them here. The exception handlers after iret run with
 * kernel gs again, so don't set the user space flag. B stepping K8s
 * sometimes report an truncated RIP for IRET exceptions returning to
 * compat mode. Check for these here too.
 */
error_kernelspace:
	incl %ebx
	leaq irq_return(%rip),%rcx
	cmpq %rcx,RIP+8(%rsp)
	je error_swapgs
	movl %ecx,%eax	/* zero extend */
	cmpq %rax,RIP+8(%rsp)
	je bstep_iret
	cmpq $gs_change,RIP+8(%rsp)
	je error_swapgs
	jmp error_sti

bstep_iret:
	/* Fix truncated RIP */
	movq %rcx,RIP+8(%rsp)
	jmp error_swapgs
	CFI_ENDPROC
END(error_entry)


/* ebx:	no swapgs flag (1: don't need swapgs, 0: need it) */
ENTRY(error_exit)
	DEFAULT_FRAME
	movl %ebx,%eax
	RESTORE_REST
	DISABLE_INTERRUPTS(CLBR_NONE)
	TRACE_IRQS_OFF
	GET_THREAD_INFO(%rcx)
	testl %eax,%eax
	jne retint_kernel
	LOCKDEP_SYS_EXIT_IRQ
	movl TI_flags(%rcx),%edx
	movl $_TIF_WORK_MASK,%edi
	andl %edi,%edx
	jnz retint_careful
	jmp retint_swapgs
	CFI_ENDPROC
END(error_exit)


	/* runs on exception stack */
ENTRY(nmi)
	INTR_FRAME
	PARAVIRT_ADJUST_EXCEPTION_FRAME
	pushq_cfi $-1
	subq $ORIG_RAX-R15, %rsp
	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
	call save_paranoid
	DEFAULT_FRAME 0
	/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
	movq %rsp,%rdi
	movq $-1,%rsi
	call do_nmi
#ifdef CONFIG_TRACE_IRQFLAGS
	/* paranoidexit; without TRACE_IRQS_OFF */
	/* ebx:	no swapgs flag */
	DISABLE_INTERRUPTS(CLBR_NONE)
	testl %ebx,%ebx				/* swapgs needed? */
	jnz nmi_restore
	testl $3,CS(%rsp)
	jnz nmi_userspace
nmi_swapgs:
	SWAPGS_UNSAFE_STACK
nmi_restore:
	RESTORE_ALL 8
	jmp irq_return
nmi_userspace:
	GET_THREAD_INFO(%rcx)
	movl TI_flags(%rcx),%ebx
	andl $_TIF_WORK_MASK,%ebx
	jz nmi_swapgs
	movq %rsp,%rdi			/* &pt_regs */
	call sync_regs
	movq %rax,%rsp			/* switch stack for scheduling */
	testl $_TIF_NEED_RESCHED,%ebx
	jnz nmi_schedule
	movl %ebx,%edx			/* arg3: thread flags */
	ENABLE_INTERRUPTS(CLBR_NONE)
	xorl %esi,%esi 			/* arg2: oldset */
	movq %rsp,%rdi 			/* arg1: &pt_regs */
	call do_notify_resume
	DISABLE_INTERRUPTS(CLBR_NONE)
	jmp nmi_userspace
nmi_schedule:
	ENABLE_INTERRUPTS(CLBR_ANY)
	call schedule
	DISABLE_INTERRUPTS(CLBR_ANY)
	jmp nmi_userspace
	CFI_ENDPROC
#else
	jmp paranoid_exit
	CFI_ENDPROC
#endif
END(nmi)

ENTRY(ignore_sysret)
	CFI_STARTPROC
	mov $-ENOSYS,%eax
	sysret
	CFI_ENDPROC
END(ignore_sysret)

/*
 * End of kprobes section
 */
	.popsection