summaryrefslogtreecommitdiff
path: root/arch/mips/kernel/traps.c
blob: 7058893d5ad2227259746895558f47644e6d66bd (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
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994 - 1999, 2000, 01 Ralf Baechle
 * Copyright (C) 1995, 1996 Paul M. Antoine
 * Copyright (C) 1998 Ulf Carlsson
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2000, 01 MIPS Technologies, Inc.
 * Copyright (C) 2002, 2003, 2004, 2005  Maciej W. Rozycki
 */
#include <linux/config.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/bootmem.h>

#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/module.h>
#include <asm/pgtable.h>
#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/tlbdebug.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/watch.h>
#include <asm/types.h>

extern asmlinkage void handle_tlbm(void);
extern asmlinkage void handle_tlbl(void);
extern asmlinkage void handle_tlbs(void);
extern asmlinkage void handle_adel(void);
extern asmlinkage void handle_ades(void);
extern asmlinkage void handle_ibe(void);
extern asmlinkage void handle_dbe(void);
extern asmlinkage void handle_sys(void);
extern asmlinkage void handle_bp(void);
extern asmlinkage void handle_ri(void);
extern asmlinkage void handle_cpu(void);
extern asmlinkage void handle_ov(void);
extern asmlinkage void handle_tr(void);
extern asmlinkage void handle_fpe(void);
extern asmlinkage void handle_mdmx(void);
extern asmlinkage void handle_watch(void);
extern asmlinkage void handle_mt(void);
extern asmlinkage void handle_dsp(void);
extern asmlinkage void handle_mcheck(void);
extern asmlinkage void handle_reserved(void);

extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
	struct mips_fpu_soft_struct *ctx);

void (*board_be_init)(void);
int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
void (*board_nmi_handler_setup)(void);
void (*board_ejtag_handler_setup)(void);
void (*board_bind_eic_interrupt)(int irq, int regset);

/*
 * These constant is for searching for possible module text segments.
 * MODULE_RANGE is a guess of how much space is likely to be vmalloced.
 */
#define MODULE_RANGE (8*1024*1024)

/*
 * This routine abuses get_user()/put_user() to reference pointers
 * with at least a bit of error checking ...
 */
void show_stack(struct task_struct *task, unsigned long *sp)
{
	const int field = 2 * sizeof(unsigned long);
	long stackdata;
	int i;

	if (!sp) {
		if (task && task != current)
			sp = (unsigned long *) task->thread.reg29;
		else
			sp = (unsigned long *) &sp;
	}

	printk("Stack :");
	i = 0;
	while ((unsigned long) sp & (PAGE_SIZE - 1)) {
		if (i && ((i % (64 / field)) == 0))
			printk("\n       ");
		if (i > 39) {
			printk(" ...");
			break;
		}

		if (__get_user(stackdata, sp++)) {
			printk(" (Bad stack address)");
			break;
		}

		printk(" %0*lx", field, stackdata);
		i++;
	}
	printk("\n");
}

void show_trace(struct task_struct *task, unsigned long *stack)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned long addr;

	if (!stack) {
		if (task && task != current)
			stack = (unsigned long *) task->thread.reg29;
		else
			stack = (unsigned long *) &stack;
	}

	printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
	printk("\n");
#endif
	while (!kstack_end(stack)) {
		addr = *stack++;
		if (__kernel_text_address(addr)) {
			printk(" [<%0*lx>] ", field, addr);
			print_symbol("%s\n", addr);
		}
	}
	printk("\n");
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
	unsigned long stack;

	show_trace(current, &stack);
}

EXPORT_SYMBOL(dump_stack);

void show_code(unsigned int *pc)
{
	long i;

	printk("\nCode:");

	for(i = -3 ; i < 6 ; i++) {
		unsigned int insn;
		if (__get_user(insn, pc + i)) {
			printk(" (Bad address in epc)\n");
			break;
		}
		printk("%c%08x%c", (i?' ':'<'), insn, (i?' ':'>'));
	}
}

void show_regs(struct pt_regs *regs)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned int cause = regs->cp0_cause;
	int i;

	printk("Cpu %d\n", smp_processor_id());

	/*
	 * Saved main processor registers
	 */
	for (i = 0; i < 32; ) {
		if ((i % 4) == 0)
			printk("$%2d   :", i);
		if (i == 0)
			printk(" %0*lx", field, 0UL);
		else if (i == 26 || i == 27)
			printk(" %*s", field, "");
		else
			printk(" %0*lx", field, regs->regs[i]);

		i++;
		if ((i % 4) == 0)
			printk("\n");
	}

	printk("Hi    : %0*lx\n", field, regs->hi);
	printk("Lo    : %0*lx\n", field, regs->lo);

	/*
	 * Saved cp0 registers
	 */
	printk("epc   : %0*lx ", field, regs->cp0_epc);
	print_symbol("%s ", regs->cp0_epc);
	printk("    %s\n", print_tainted());
	printk("ra    : %0*lx ", field, regs->regs[31]);
	print_symbol("%s\n", regs->regs[31]);

	printk("Status: %08x    ", (uint32_t) regs->cp0_status);

	if (current_cpu_data.isa_level == MIPS_CPU_ISA_I) {
		if (regs->cp0_status & ST0_KUO)
			printk("KUo ");
		if (regs->cp0_status & ST0_IEO)
			printk("IEo ");
		if (regs->cp0_status & ST0_KUP)
			printk("KUp ");
		if (regs->cp0_status & ST0_IEP)
			printk("IEp ");
		if (regs->cp0_status & ST0_KUC)
			printk("KUc ");
		if (regs->cp0_status & ST0_IEC)
			printk("IEc ");
	} else {
		if (regs->cp0_status & ST0_KX)
			printk("KX ");
		if (regs->cp0_status & ST0_SX)
			printk("SX ");
		if (regs->cp0_status & ST0_UX)
			printk("UX ");
		switch (regs->cp0_status & ST0_KSU) {
		case KSU_USER:
			printk("USER ");
			break;
		case KSU_SUPERVISOR:
			printk("SUPERVISOR ");
			break;
		case KSU_KERNEL:
			printk("KERNEL ");
			break;
		default:
			printk("BAD_MODE ");
			break;
		}
		if (regs->cp0_status & ST0_ERL)
			printk("ERL ");
		if (regs->cp0_status & ST0_EXL)
			printk("EXL ");
		if (regs->cp0_status & ST0_IE)
			printk("IE ");
	}
	printk("\n");

	printk("Cause : %08x\n", cause);

	cause = (cause & CAUSEF_EXCCODE) >> CAUSEB_EXCCODE;
	if (1 <= cause && cause <= 5)
		printk("BadVA : %0*lx\n", field, regs->cp0_badvaddr);

	printk("PrId  : %08x\n", read_c0_prid());
}

void show_registers(struct pt_regs *regs)
{
	show_regs(regs);
	print_modules();
	printk("Process %s (pid: %d, threadinfo=%p, task=%p)\n",
	        current->comm, current->pid, current_thread_info(), current);
	show_stack(current, (long *) regs->regs[29]);
	show_trace(current, (long *) regs->regs[29]);
	show_code((unsigned int *) regs->cp0_epc);
	printk("\n");
}

static DEFINE_SPINLOCK(die_lock);

NORET_TYPE void ATTRIB_NORET die(const char * str, struct pt_regs * regs)
{
	static int die_counter;

	console_verbose();
	spin_lock_irq(&die_lock);
	printk("%s[#%d]:\n", str, ++die_counter);
	show_registers(regs);
	spin_unlock_irq(&die_lock);
	do_exit(SIGSEGV);
}

extern const struct exception_table_entry __start___dbe_table[];
extern const struct exception_table_entry __stop___dbe_table[];

void __declare_dbe_table(void)
{
	__asm__ __volatile__(
	".section\t__dbe_table,\"a\"\n\t"
	".previous"
	);
}

/* Given an address, look for it in the exception tables. */
static const struct exception_table_entry *search_dbe_tables(unsigned long addr)
{
	const struct exception_table_entry *e;

	e = search_extable(__start___dbe_table, __stop___dbe_table - 1, addr);
	if (!e)
		e = search_module_dbetables(addr);
	return e;
}

asmlinkage void do_be(struct pt_regs *regs)
{
	const int field = 2 * sizeof(unsigned long);
	const struct exception_table_entry *fixup = NULL;
	int data = regs->cp0_cause & 4;
	int action = MIPS_BE_FATAL;

	/* XXX For now.  Fixme, this searches the wrong table ...  */
	if (data && !user_mode(regs))
		fixup = search_dbe_tables(exception_epc(regs));

	if (fixup)
		action = MIPS_BE_FIXUP;

	if (board_be_handler)
		action = board_be_handler(regs, fixup != 0);

	switch (action) {
	case MIPS_BE_DISCARD:
		return;
	case MIPS_BE_FIXUP:
		if (fixup) {
			regs->cp0_epc = fixup->nextinsn;
			return;
		}
		break;
	default:
		break;
	}

	/*
	 * Assume it would be too dangerous to continue ...
	 */
	printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n",
	       data ? "Data" : "Instruction",
	       field, regs->cp0_epc, field, regs->regs[31]);
	die_if_kernel("Oops", regs);
	force_sig(SIGBUS, current);
}

static inline int get_insn_opcode(struct pt_regs *regs, unsigned int *opcode)
{
	unsigned int __user *epc;

	epc = (unsigned int __user *) regs->cp0_epc +
	      ((regs->cp0_cause & CAUSEF_BD) != 0);
	if (!get_user(*opcode, epc))
		return 0;

	force_sig(SIGSEGV, current);
	return 1;
}

/*
 * ll/sc emulation
 */

#define OPCODE 0xfc000000
#define BASE   0x03e00000
#define RT     0x001f0000
#define OFFSET 0x0000ffff
#define LL     0xc0000000
#define SC     0xe0000000
#define SPEC3  0x7c000000
#define RD     0x0000f800
#define FUNC   0x0000003f
#define RDHWR  0x0000003b

/*
 * The ll_bit is cleared by r*_switch.S
 */

unsigned long ll_bit;

static struct task_struct *ll_task = NULL;

static inline void simulate_ll(struct pt_regs *regs, unsigned int opcode)
{
	unsigned long value, __user *vaddr;
	long offset;
	int signal = 0;

	/*
	 * analyse the ll instruction that just caused a ri exception
	 * and put the referenced address to addr.
	 */

	/* sign extend offset */
	offset = opcode & OFFSET;
	offset <<= 16;
	offset >>= 16;

	vaddr = (unsigned long __user *)
	        ((unsigned long)(regs->regs[(opcode & BASE) >> 21]) + offset);

	if ((unsigned long)vaddr & 3) {
		signal = SIGBUS;
		goto sig;
	}
	if (get_user(value, vaddr)) {
		signal = SIGSEGV;
		goto sig;
	}

	preempt_disable();

	if (ll_task == NULL || ll_task == current) {
		ll_bit = 1;
	} else {
		ll_bit = 0;
	}
	ll_task = current;

	preempt_enable();

	compute_return_epc(regs);

	regs->regs[(opcode & RT) >> 16] = value;

	return;

sig:
	force_sig(signal, current);
}

static inline void simulate_sc(struct pt_regs *regs, unsigned int opcode)
{
	unsigned long __user *vaddr;
	unsigned long reg;
	long offset;
	int signal = 0;

	/*
	 * analyse the sc instruction that just caused a ri exception
	 * and put the referenced address to addr.
	 */

	/* sign extend offset */
	offset = opcode & OFFSET;
	offset <<= 16;
	offset >>= 16;

	vaddr = (unsigned long __user *)
	        ((unsigned long)(regs->regs[(opcode & BASE) >> 21]) + offset);
	reg = (opcode & RT) >> 16;

	if ((unsigned long)vaddr & 3) {
		signal = SIGBUS;
		goto sig;
	}

	preempt_disable();

	if (ll_bit == 0 || ll_task != current) {
		compute_return_epc(regs);
		regs->regs[reg] = 0;
		preempt_enable();
		return;
	}

	preempt_enable();

	if (put_user(regs->regs[reg], vaddr)) {
		signal = SIGSEGV;
		goto sig;
	}

	compute_return_epc(regs);
	regs->regs[reg] = 1;

	return;

sig:
	force_sig(signal, current);
}

/*
 * ll uses the opcode of lwc0 and sc uses the opcode of swc0.  That is both
 * opcodes are supposed to result in coprocessor unusable exceptions if
 * executed on ll/sc-less processors.  That's the theory.  In practice a
 * few processors such as NEC's VR4100 throw reserved instruction exceptions
 * instead, so we're doing the emulation thing in both exception handlers.
 */
static inline int simulate_llsc(struct pt_regs *regs)
{
	unsigned int opcode;

	if (unlikely(get_insn_opcode(regs, &opcode)))
		return -EFAULT;

	if ((opcode & OPCODE) == LL) {
		simulate_ll(regs, opcode);
		return 0;
	}
	if ((opcode & OPCODE) == SC) {
		simulate_sc(regs, opcode);
		return 0;
	}

	return -EFAULT;			/* Strange things going on ... */
}

/*
 * Simulate trapping 'rdhwr' instructions to provide user accessible
 * registers not implemented in hardware.  The only current use of this
 * is the thread area pointer.
 */
static inline int simulate_rdhwr(struct pt_regs *regs)
{
	struct thread_info *ti = current->thread_info;
	unsigned int opcode;

	if (unlikely(get_insn_opcode(regs, &opcode)))
		return -EFAULT;

	if (unlikely(compute_return_epc(regs)))
		return -EFAULT;

	if ((opcode & OPCODE) == SPEC3 && (opcode & FUNC) == RDHWR) {
		int rd = (opcode & RD) >> 11;
		int rt = (opcode & RT) >> 16;
		switch (rd) {
			case 29:
				regs->regs[rt] = ti->tp_value;
				return 0;
			default:
				return -EFAULT;
		}
	}

	/* Not ours.  */
	return -EFAULT;
}

asmlinkage void do_ov(struct pt_regs *regs)
{
	siginfo_t info;

	info.si_code = FPE_INTOVF;
	info.si_signo = SIGFPE;
	info.si_errno = 0;
	info.si_addr = (void __user *) regs->cp0_epc;
	force_sig_info(SIGFPE, &info, current);
}

/*
 * XXX Delayed fp exceptions when doing a lazy ctx switch XXX
 */
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
{
	if (fcr31 & FPU_CSR_UNI_X) {
		int sig;

		preempt_disable();

#ifdef CONFIG_PREEMPT
		if (!is_fpu_owner()) {
			/* We might lose fpu before disabling preempt... */
			own_fpu();
			BUG_ON(!used_math());
			restore_fp(current);
		}
#endif
		/*
	 	 * Unimplemented operation exception.  If we've got the full
		 * software emulator on-board, let's use it...
		 *
		 * Force FPU to dump state into task/thread context.  We're
		 * moving a lot of data here for what is probably a single
		 * instruction, but the alternative is to pre-decode the FP
		 * register operands before invoking the emulator, which seems
		 * a bit extreme for what should be an infrequent event.
		 */
		save_fp(current);
		/* Ensure 'resume' not overwrite saved fp context again. */
		lose_fpu();

		preempt_enable();

		/* Run the emulator */
		sig = fpu_emulator_cop1Handler (regs,
			&current->thread.fpu.soft);

		preempt_disable();

		own_fpu();	/* Using the FPU again.  */
		/*
		 * We can't allow the emulated instruction to leave any of
		 * the cause bit set in $fcr31.
		 */
		current->thread.fpu.soft.fcr31 &= ~FPU_CSR_ALL_X;

		/* Restore the hardware register state */
		restore_fp(current);

		preempt_enable();

		/* If something went wrong, signal */
		if (sig)
			force_sig(sig, current);

		return;
	}

	force_sig(SIGFPE, current);
}

asmlinkage void do_bp(struct pt_regs *regs)
{
	unsigned int opcode, bcode;
	siginfo_t info;

	die_if_kernel("Break instruction in kernel code", regs);

	if (get_insn_opcode(regs, &opcode))
		return;

	/*
	 * There is the ancient bug in the MIPS assemblers that the break
	 * code starts left to bit 16 instead to bit 6 in the opcode.
	 * Gas is bug-compatible, but not always, grrr...
	 * We handle both cases with a simple heuristics.  --macro
	 */
	bcode = ((opcode >> 6) & ((1 << 20) - 1));
	if (bcode < (1 << 10))
		bcode <<= 10;

	/*
	 * (A short test says that IRIX 5.3 sends SIGTRAP for all break
	 * insns, even for break codes that indicate arithmetic failures.
	 * Weird ...)
	 * But should we continue the brokenness???  --macro
	 */
	switch (bcode) {
	case BRK_OVERFLOW << 10:
	case BRK_DIVZERO << 10:
		if (bcode == (BRK_DIVZERO << 10))
			info.si_code = FPE_INTDIV;
		else
			info.si_code = FPE_INTOVF;
		info.si_signo = SIGFPE;
		info.si_errno = 0;
		info.si_addr = (void __user *) regs->cp0_epc;
		force_sig_info(SIGFPE, &info, current);
		break;
	default:
		force_sig(SIGTRAP, current);
	}
}

asmlinkage void do_tr(struct pt_regs *regs)
{
	unsigned int opcode, tcode = 0;
	siginfo_t info;

	die_if_kernel("Trap instruction in kernel code", regs);

	if (get_insn_opcode(regs, &opcode))
		return;

	/* Immediate versions don't provide a code.  */
	if (!(opcode & OPCODE))
		tcode = ((opcode >> 6) & ((1 << 10) - 1));

	/*
	 * (A short test says that IRIX 5.3 sends SIGTRAP for all trap
	 * insns, even for trap codes that indicate arithmetic failures.
	 * Weird ...)
	 * But should we continue the brokenness???  --macro
	 */
	switch (tcode) {
	case BRK_OVERFLOW:
	case BRK_DIVZERO:
		if (tcode == BRK_DIVZERO)
			info.si_code = FPE_INTDIV;
		else
			info.si_code = FPE_INTOVF;
		info.si_signo = SIGFPE;
		info.si_errno = 0;
		info.si_addr = (void __user *) regs->cp0_epc;
		force_sig_info(SIGFPE, &info, current);
		break;
	default:
		force_sig(SIGTRAP, current);
	}
}

asmlinkage void do_ri(struct pt_regs *regs)
{
	die_if_kernel("Reserved instruction in kernel code", regs);

	if (!cpu_has_llsc)
		if (!simulate_llsc(regs))
			return;

	if (!simulate_rdhwr(regs))
		return;

	force_sig(SIGILL, current);
}

asmlinkage void do_cpu(struct pt_regs *regs)
{
	unsigned int cpid;

	die_if_kernel("do_cpu invoked from kernel context!", regs);

	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;

	switch (cpid) {
	case 0:
		if (!cpu_has_llsc)
			if (!simulate_llsc(regs))
				return;

		if (!simulate_rdhwr(regs))
			return;

		break;

	case 1:
		preempt_disable();

		own_fpu();
		if (used_math()) {	/* Using the FPU again.  */
			restore_fp(current);
		} else {			/* First time FPU user.  */
			init_fpu();
			set_used_math();
		}

		preempt_enable();

		if (!cpu_has_fpu) {
			int sig = fpu_emulator_cop1Handler(regs,
						&current->thread.fpu.soft);
			if (sig)
				force_sig(sig, current);
		}

		return;

	case 2:
	case 3:
		break;
	}

	force_sig(SIGILL, current);
}

asmlinkage void do_mdmx(struct pt_regs *regs)
{
	force_sig(SIGILL, current);
}

asmlinkage void do_watch(struct pt_regs *regs)
{
	/*
	 * We use the watch exception where available to detect stack
	 * overflows.
	 */
	dump_tlb_all();
	show_regs(regs);
	panic("Caught WATCH exception - probably caused by stack overflow.");
}

asmlinkage void do_mcheck(struct pt_regs *regs)
{
	show_regs(regs);
	dump_tlb_all();
	/*
	 * Some chips may have other causes of machine check (e.g. SB1
	 * graduation timer)
	 */
	panic("Caught Machine Check exception - %scaused by multiple "
	      "matching entries in the TLB.",
	      (regs->cp0_status & ST0_TS) ? "" : "not ");
}

asmlinkage void do_mt(struct pt_regs *regs)
{
	die_if_kernel("MIPS MT Thread exception in kernel", regs);

	force_sig(SIGILL, current);
}


asmlinkage void do_dsp(struct pt_regs *regs)
{
	if (cpu_has_dsp)
		panic("Unexpected DSP exception\n");

	force_sig(SIGILL, current);
}

asmlinkage void do_reserved(struct pt_regs *regs)
{
	/*
	 * Game over - no way to handle this if it ever occurs.  Most probably
	 * caused by a new unknown cpu type or after another deadly
	 * hard/software error.
	 */
	show_regs(regs);
	panic("Caught reserved exception %ld - should not happen.",
	      (regs->cp0_cause & 0x7f) >> 2);
}

asmlinkage void do_default_vi(struct pt_regs *regs)
{
	show_regs(regs);
	panic("Caught unexpected vectored interrupt.");
}

/*
 * Some MIPS CPUs can enable/disable for cache parity detection, but do
 * it different ways.
 */
static inline void parity_protection_init(void)
{
	switch (current_cpu_data.cputype) {
	case CPU_24K:
	case CPU_5KC:
		write_c0_ecc(0x80000000);
		back_to_back_c0_hazard();
		/* Set the PE bit (bit 31) in the c0_errctl register. */
		printk(KERN_INFO "Cache parity protection %sabled\n",
		       (read_c0_ecc() & 0x80000000) ? "en" : "dis");
		break;
	case CPU_20KC:
	case CPU_25KF:
		/* Clear the DE bit (bit 16) in the c0_status register. */
		printk(KERN_INFO "Enable cache parity protection for "
		       "MIPS 20KC/25KF CPUs.\n");
		clear_c0_status(ST0_DE);
		break;
	default:
		break;
	}
}

asmlinkage void cache_parity_error(void)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned int reg_val;

	/* For the moment, report the problem and hang. */
	printk("Cache error exception:\n");
	printk("cp0_errorepc == %0*lx\n", field, read_c0_errorepc());
	reg_val = read_c0_cacheerr();
	printk("c0_cacheerr == %08x\n", reg_val);

	printk("Decoded c0_cacheerr: %s cache fault in %s reference.\n",
	       reg_val & (1<<30) ? "secondary" : "primary",
	       reg_val & (1<<31) ? "data" : "insn");
	printk("Error bits: %s%s%s%s%s%s%s\n",
	       reg_val & (1<<29) ? "ED " : "",
	       reg_val & (1<<28) ? "ET " : "",
	       reg_val & (1<<26) ? "EE " : "",
	       reg_val & (1<<25) ? "EB " : "",
	       reg_val & (1<<24) ? "EI " : "",
	       reg_val & (1<<23) ? "E1 " : "",
	       reg_val & (1<<22) ? "E0 " : "");
	printk("IDX: 0x%08x\n", reg_val & ((1<<22)-1));

#if defined(CONFIG_CPU_MIPS32) || defined(CONFIG_CPU_MIPS64)
	if (reg_val & (1<<22))
		printk("DErrAddr0: 0x%0*lx\n", field, read_c0_derraddr0());

	if (reg_val & (1<<23))
		printk("DErrAddr1: 0x%0*lx\n", field, read_c0_derraddr1());
#endif

	panic("Can't handle the cache error!");
}

/*
 * SDBBP EJTAG debug exception handler.
 * We skip the instruction and return to the next instruction.
 */
void ejtag_exception_handler(struct pt_regs *regs)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned long depc, old_epc;
	unsigned int debug;

	printk("SDBBP EJTAG debug exception - not handled yet, just ignored!\n");
	depc = read_c0_depc();
	debug = read_c0_debug();
	printk("c0_depc = %0*lx, DEBUG = %08x\n", field, depc, debug);
	if (debug & 0x80000000) {
		/*
		 * In branch delay slot.
		 * We cheat a little bit here and use EPC to calculate the
		 * debug return address (DEPC). EPC is restored after the
		 * calculation.
		 */
		old_epc = regs->cp0_epc;
		regs->cp0_epc = depc;
		__compute_return_epc(regs);
		depc = regs->cp0_epc;
		regs->cp0_epc = old_epc;
	} else
		depc += 4;
	write_c0_depc(depc);

#if 0
	printk("\n\n----- Enable EJTAG single stepping ----\n\n");
	write_c0_debug(debug | 0x100);
#endif
}

/*
 * NMI exception handler.
 */
void nmi_exception_handler(struct pt_regs *regs)
{
	printk("NMI taken!!!!\n");
	die("NMI", regs);
	while(1) ;
}

#define VECTORSPACING 0x100	/* for EI/VI mode */

unsigned long ebase;
unsigned long exception_handlers[32];
unsigned long vi_handlers[64];

/*
 * As a side effect of the way this is implemented we're limited
 * to interrupt handlers in the address range from
 * KSEG0 <= x < KSEG0 + 256mb on the Nevada.  Oh well ...
 */
void *set_except_vector(int n, void *addr)
{
	unsigned long handler = (unsigned long) addr;
	unsigned long old_handler = exception_handlers[n];

	exception_handlers[n] = handler;
	if (n == 0 && cpu_has_divec) {
		*(volatile u32 *)(ebase + 0x200) = 0x08000000 |
		                                 (0x03ffffff & (handler >> 2));
		flush_icache_range(ebase + 0x200, ebase + 0x204);
	}
	return (void *)old_handler;
}

#ifdef CONFIG_CPU_MIPSR2
/*
 * Shadow register allocation
 * FIXME: SMP...
 */

/* MIPSR2 shadow register sets */
struct shadow_registers {
	spinlock_t sr_lock;	/*  */
	int sr_supported;	/* Number of shadow register sets supported */
	int sr_allocated;	/* Bitmap of allocated shadow registers */
} shadow_registers;

void mips_srs_init(void)
{
#ifdef CONFIG_CPU_MIPSR2_SRS
	shadow_registers.sr_supported = ((read_c0_srsctl() >> 26) & 0x0f) + 1;
	printk ("%d MIPSR2 register sets available\n", shadow_registers.sr_supported);
#else
	shadow_registers.sr_supported = 1;
#endif
	shadow_registers.sr_allocated = 1;	/* Set 0 used by kernel */
	spin_lock_init(&shadow_registers.sr_lock);
}

int mips_srs_max(void)
{
	return shadow_registers.sr_supported;
}

int mips_srs_alloc (void)
{
	struct shadow_registers *sr = &shadow_registers;
	unsigned long flags;
	int set;

	spin_lock_irqsave(&sr->sr_lock, flags);

	for (set = 0; set < sr->sr_supported; set++) {
		if ((sr->sr_allocated & (1 << set)) == 0) {
			sr->sr_allocated |= 1 << set;
			spin_unlock_irqrestore(&sr->sr_lock, flags);
			return set;
		}
	}

	/* None available */
	spin_unlock_irqrestore(&sr->sr_lock, flags);
	return -1;
}

void mips_srs_free (int set)
{
	struct shadow_registers *sr = &shadow_registers;
	unsigned long flags;

	spin_lock_irqsave(&sr->sr_lock, flags);
	sr->sr_allocated &= ~(1 << set);
	spin_unlock_irqrestore(&sr->sr_lock, flags);
}

void *set_vi_srs_handler (int n, void *addr, int srs)
{
	unsigned long handler;
	unsigned long old_handler = vi_handlers[n];
	u32 *w;
	unsigned char *b;

	if (!cpu_has_veic && !cpu_has_vint)
		BUG();

	if (addr == NULL) {
		handler = (unsigned long) do_default_vi;
		srs = 0;
	}
	else
		handler = (unsigned long) addr;
	vi_handlers[n] = (unsigned long) addr;

	b = (unsigned char *)(ebase + 0x200 + n*VECTORSPACING);

	if (srs >= mips_srs_max())
		panic("Shadow register set %d not supported", srs);

	if (cpu_has_veic) {
		if (board_bind_eic_interrupt)
			board_bind_eic_interrupt (n, srs);
	}
	else if (cpu_has_vint) {
		/* SRSMap is only defined if shadow sets are implemented */
		if (mips_srs_max() > 1)
			change_c0_srsmap (0xf << n*4, srs << n*4);
	}

	if (srs == 0) {
		/*
		 * If no shadow set is selected then use the default handler
		 * that does normal register saving and a standard interrupt exit
		 */

		extern char except_vec_vi, except_vec_vi_lui;
		extern char except_vec_vi_ori, except_vec_vi_end;
		const int handler_len = &except_vec_vi_end - &except_vec_vi;
		const int lui_offset = &except_vec_vi_lui - &except_vec_vi;
		const int ori_offset = &except_vec_vi_ori - &except_vec_vi;

		if (handler_len > VECTORSPACING) {
			/*
			 * Sigh... panicing won't help as the console
			 * is probably not configured :(
			 */
			panic ("VECTORSPACING too small");
		}

		memcpy (b, &except_vec_vi, handler_len);
		w = (u32 *)(b + lui_offset);
		*w = (*w & 0xffff0000) | (((u32)handler >> 16) & 0xffff);
		w = (u32 *)(b + ori_offset);
		*w = (*w & 0xffff0000) | ((u32)handler & 0xffff);
		flush_icache_range((unsigned long)b, (unsigned long)(b+handler_len));
	}
	else {
		/*
		 * In other cases jump directly to the interrupt handler
		 *
		 * It is the handlers responsibility to save registers if required
		 * (eg hi/lo) and return from the exception using "eret"
		 */
		w = (u32 *)b;
		*w++ = 0x08000000 | (((u32)handler >> 2) & 0x03fffff); /* j handler */
		*w = 0;
		flush_icache_range((unsigned long)b, (unsigned long)(b+8));
	}

	return (void *)old_handler;
}

void *set_vi_handler (int n, void *addr)
{
	return set_vi_srs_handler (n, addr, 0);
}
#endif

/*
 * This is used by native signal handling
 */
asmlinkage int (*save_fp_context)(struct sigcontext *sc);
asmlinkage int (*restore_fp_context)(struct sigcontext *sc);

extern asmlinkage int _save_fp_context(struct sigcontext *sc);
extern asmlinkage int _restore_fp_context(struct sigcontext *sc);

extern asmlinkage int fpu_emulator_save_context(struct sigcontext *sc);
extern asmlinkage int fpu_emulator_restore_context(struct sigcontext *sc);

static inline void signal_init(void)
{
	if (cpu_has_fpu) {
		save_fp_context = _save_fp_context;
		restore_fp_context = _restore_fp_context;
	} else {
		save_fp_context = fpu_emulator_save_context;
		restore_fp_context = fpu_emulator_restore_context;
	}
}

#ifdef CONFIG_MIPS32_COMPAT

/*
 * This is used by 32-bit signal stuff on the 64-bit kernel
 */
asmlinkage int (*save_fp_context32)(struct sigcontext32 *sc);
asmlinkage int (*restore_fp_context32)(struct sigcontext32 *sc);

extern asmlinkage int _save_fp_context32(struct sigcontext32 *sc);
extern asmlinkage int _restore_fp_context32(struct sigcontext32 *sc);

extern asmlinkage int fpu_emulator_save_context32(struct sigcontext32 *sc);
extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 *sc);

static inline void signal32_init(void)
{
	if (cpu_has_fpu) {
		save_fp_context32 = _save_fp_context32;
		restore_fp_context32 = _restore_fp_context32;
	} else {
		save_fp_context32 = fpu_emulator_save_context32;
		restore_fp_context32 = fpu_emulator_restore_context32;
	}
}
#endif

extern void cpu_cache_init(void);
extern void tlb_init(void);
extern void flush_tlb_handlers(void);

void __init per_cpu_trap_init(void)
{
	unsigned int cpu = smp_processor_id();
	unsigned int status_set = ST0_CU0;

	/*
	 * Disable coprocessors and select 32-bit or 64-bit addressing
	 * and the 16/32 or 32/32 FPR register model.  Reset the BEV
	 * flag that some firmware may have left set and the TS bit (for
	 * IP27).  Set XX for ISA IV code to work.
	 */
#ifdef CONFIG_64BIT
	status_set |= ST0_FR|ST0_KX|ST0_SX|ST0_UX;
#endif
	if (current_cpu_data.isa_level == MIPS_CPU_ISA_IV)
		status_set |= ST0_XX;
	change_c0_status(ST0_CU|ST0_MX|ST0_FR|ST0_BEV|ST0_TS|ST0_KX|ST0_SX|ST0_UX,
			 status_set);

	if (cpu_has_dsp)
		set_c0_status(ST0_MX);

#ifdef CONFIG_CPU_MIPSR2
	write_c0_hwrena (0x0000000f); /* Allow rdhwr to all registers */
#endif

	/*
	 * Interrupt handling.
	 */
	if (cpu_has_veic || cpu_has_vint) {
		write_c0_ebase (ebase);
		/* Setting vector spacing enables EI/VI mode  */
		change_c0_intctl (0x3e0, VECTORSPACING);
	}
	if (cpu_has_divec) {
		if (cpu_has_mipsmt) {
			unsigned int vpflags = dvpe();
			set_c0_cause(CAUSEF_IV);
			evpe(vpflags);
		} else
			set_c0_cause(CAUSEF_IV);
	}

	cpu_data[cpu].asid_cache = ASID_FIRST_VERSION;
	TLBMISS_HANDLER_SETUP();

	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;
	BUG_ON(current->mm);
	enter_lazy_tlb(&init_mm, current);

	cpu_cache_init();
	tlb_init();
}

/* Install CPU exception handler */
void __init set_handler (unsigned long offset, void *addr, unsigned long size)
{
	memcpy((void *)(ebase + offset), addr, size);
	flush_icache_range(ebase + offset, ebase + offset + size);
}

/* Install uncached CPU exception handler */
void __init set_uncached_handler (unsigned long offset, void *addr, unsigned long size)
{
#ifdef CONFIG_32BIT
	unsigned long uncached_ebase = KSEG1ADDR(ebase);
#endif
#ifdef CONFIG_64BIT
	unsigned long uncached_ebase = TO_UNCAC(ebase);
#endif

	memcpy((void *)(uncached_ebase + offset), addr, size);
}

void __init trap_init(void)
{
	extern char except_vec3_generic, except_vec3_r4000;
	extern char except_vec4;
	unsigned long i;

	if (cpu_has_veic || cpu_has_vint)
		ebase = (unsigned long) alloc_bootmem_low_pages (0x200 + VECTORSPACING*64);
	else
		ebase = CAC_BASE;

#ifdef CONFIG_CPU_MIPSR2
	mips_srs_init();
#endif

	per_cpu_trap_init();

	/*
	 * Copy the generic exception handlers to their final destination.
	 * This will be overriden later as suitable for a particular
	 * configuration.
	 */
	set_handler(0x180, &except_vec3_generic, 0x80);

	/*
	 * Setup default vectors
	 */
	for (i = 0; i <= 31; i++)
		set_except_vector(i, handle_reserved);

	/*
	 * Copy the EJTAG debug exception vector handler code to it's final
	 * destination.
	 */
	if (cpu_has_ejtag && board_ejtag_handler_setup)
		board_ejtag_handler_setup ();

	/*
	 * Only some CPUs have the watch exceptions.
	 */
	if (cpu_has_watch)
		set_except_vector(23, handle_watch);

	/*
	 * Initialise interrupt handlers
	 */
	if (cpu_has_veic || cpu_has_vint) {
		int nvec = cpu_has_veic ? 64 : 8;
		for (i = 0; i < nvec; i++)
			set_vi_handler (i, NULL);
	}
	else if (cpu_has_divec)
		set_handler(0x200, &except_vec4, 0x8);

	/*
	 * Some CPUs can enable/disable for cache parity detection, but does
	 * it different ways.
	 */
	parity_protection_init();

	/*
	 * The Data Bus Errors / Instruction Bus Errors are signaled
	 * by external hardware.  Therefore these two exceptions
	 * may have board specific handlers.
	 */
	if (board_be_init)
		board_be_init();

	set_except_vector(1, handle_tlbm);
	set_except_vector(2, handle_tlbl);
	set_except_vector(3, handle_tlbs);

	set_except_vector(4, handle_adel);
	set_except_vector(5, handle_ades);

	set_except_vector(6, handle_ibe);
	set_except_vector(7, handle_dbe);

	set_except_vector(8, handle_sys);
	set_except_vector(9, handle_bp);
	set_except_vector(10, handle_ri);
	set_except_vector(11, handle_cpu);
	set_except_vector(12, handle_ov);
	set_except_vector(13, handle_tr);

	if (current_cpu_data.cputype == CPU_R6000 ||
	    current_cpu_data.cputype == CPU_R6000A) {
		/*
		 * The R6000 is the only R-series CPU that features a machine
		 * check exception (similar to the R4000 cache error) and
		 * unaligned ldc1/sdc1 exception.  The handlers have not been
		 * written yet.  Well, anyway there is no R6000 machine on the
		 * current list of targets for Linux/MIPS.
		 * (Duh, crap, there is someone with a triple R6k machine)
		 */
		//set_except_vector(14, handle_mc);
		//set_except_vector(15, handle_ndc);
	}


	if (board_nmi_handler_setup)
		board_nmi_handler_setup();

	if (cpu_has_fpu && !cpu_has_nofpuex)
		set_except_vector(15, handle_fpe);

	set_except_vector(22, handle_mdmx);

	if (cpu_has_mcheck)
		set_except_vector(24, handle_mcheck);

	if (cpu_has_mipsmt)
		set_except_vector(25, handle_mt);

	if (cpu_has_dsp)
		set_except_vector(26, handle_dsp);

	if (cpu_has_vce)
		/* Special exception: R4[04]00 uses also the divec space. */
		memcpy((void *)(CAC_BASE + 0x180), &except_vec3_r4000, 0x100);
	else if (cpu_has_4kex)
		memcpy((void *)(CAC_BASE + 0x180), &except_vec3_generic, 0x80);
	else
		memcpy((void *)(CAC_BASE + 0x080), &except_vec3_generic, 0x80);

	signal_init();
#ifdef CONFIG_MIPS32_COMPAT
	signal32_init();
#endif

	flush_icache_range(ebase, ebase + 0x400);
	flush_tlb_handlers();
}