aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/kernel/traps.c
blob: cda78d59aa31b2971ed897b9db78afd6bfb0f36e (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
/*
 *  linux/arch/arm/kernel/traps.c
 *
 *  Copyright (C) 1995-2009 Russell King
 *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  'traps.c' handles hardware exceptions after we have saved some state in
 *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
 *  kill the offending process.
 */
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/init.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/system.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/unwind.h>
#include <asm/tls.h>

#include "ptrace.h"
#include "signal.h"

static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };

#ifdef CONFIG_DEBUG_USER
unsigned int user_debug;

static int __init user_debug_setup(char *str)
{
	get_option(&str, &user_debug);
	return 1;
}
__setup("user_debug=", user_debug_setup);
#endif

static void dump_mem(const char *, const char *, unsigned long, unsigned long);

void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
{
#ifdef CONFIG_KALLSYMS
	char sym1[KSYM_SYMBOL_LEN], sym2[KSYM_SYMBOL_LEN];
	sprint_symbol(sym1, where);
	sprint_symbol(sym2, from);
	printk("[<%08lx>] (%s) from [<%08lx>] (%s)\n", where, sym1, from, sym2);
#else
	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
#endif

	if (in_exception_text(where))
		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
}

#ifndef CONFIG_ARM_UNWIND
/*
 * Stack pointers should always be within the kernels view of
 * physical memory.  If it is not there, then we can't dump
 * out any information relating to the stack.
 */
static int verify_stack(unsigned long sp)
{
	if (sp < PAGE_OFFSET ||
	    (sp > (unsigned long)high_memory && high_memory != NULL))
		return -EFAULT;

	return 0;
}
#endif

/*
 * Dump out the contents of some memory nicely...
 */
static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
		     unsigned long top)
{
	unsigned long first;
	mm_segment_t fs;
	int i;

	/*
	 * We need to switch to kernel mode so that we can use __get_user
	 * to safely read from kernel space.  Note that we now dump the
	 * code first, just in case the backtrace kills us.
	 */
	fs = get_fs();
	set_fs(KERNEL_DS);

	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);

	for (first = bottom & ~31; first < top; first += 32) {
		unsigned long p;
		char str[sizeof(" 12345678") * 8 + 1];

		memset(str, ' ', sizeof(str));
		str[sizeof(str) - 1] = '\0';

		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
			if (p >= bottom && p < top) {
				unsigned long val;
				if (__get_user(val, (unsigned long *)p) == 0)
					sprintf(str + i * 9, " %08lx", val);
				else
					sprintf(str + i * 9, " ????????");
			}
		}
		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
	}

	set_fs(fs);
}

static void dump_instr(const char *lvl, struct pt_regs *regs)
{
	unsigned long addr = instruction_pointer(regs);
	const int thumb = thumb_mode(regs);
	const int width = thumb ? 4 : 8;
	mm_segment_t fs;
	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
	int i;

	/*
	 * We need to switch to kernel mode so that we can use __get_user
	 * to safely read from kernel space.  Note that we now dump the
	 * code first, just in case the backtrace kills us.
	 */
	fs = get_fs();
	set_fs(KERNEL_DS);

	for (i = -4; i < 1; i++) {
		unsigned int val, bad;

		if (thumb)
			bad = __get_user(val, &((u16 *)addr)[i]);
		else
			bad = __get_user(val, &((u32 *)addr)[i]);

		if (!bad)
			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
					width, val);
		else {
			p += sprintf(p, "bad PC value");
			break;
		}
	}
	printk("%sCode: %s\n", lvl, str);

	set_fs(fs);
}

#ifdef CONFIG_ARM_UNWIND
static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
	unwind_backtrace(regs, tsk);
}
#else
static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
	unsigned int fp, mode;
	int ok = 1;

	printk("Backtrace: ");

	if (!tsk)
		tsk = current;

	if (regs) {
		fp = regs->ARM_fp;
		mode = processor_mode(regs);
	} else if (tsk != current) {
		fp = thread_saved_fp(tsk);
		mode = 0x10;
	} else {
		asm("mov %0, fp" : "=r" (fp) : : "cc");
		mode = 0x10;
	}

	if (!fp) {
		printk("no frame pointer");
		ok = 0;
	} else if (verify_stack(fp)) {
		printk("invalid frame pointer 0x%08x", fp);
		ok = 0;
	} else if (fp < (unsigned long)end_of_stack(tsk))
		printk("frame pointer underflow");
	printk("\n");

	if (ok)
		c_backtrace(fp, mode);
}
#endif

void dump_stack(void)
{
	dump_backtrace(NULL, NULL);
}

EXPORT_SYMBOL(dump_stack);

void show_stack(struct task_struct *tsk, unsigned long *sp)
{
	dump_backtrace(NULL, tsk);
	barrier();
}

#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#else
#define S_PREEMPT ""
#endif
#ifdef CONFIG_SMP
#define S_SMP " SMP"
#else
#define S_SMP ""
#endif

static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
{
	struct task_struct *tsk = thread->task;
	static int die_counter;
	int ret;

	printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
	       str, err, ++die_counter);
	sysfs_printk_last_file();

	/* trap and error numbers are mostly meaningless on ARM */
	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
	if (ret == NOTIFY_STOP)
		return ret;

	print_modules();
	__show_regs(regs);
	printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
		TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);

	if (!user_mode(regs) || in_interrupt()) {
		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
		dump_backtrace(regs, tsk);
		dump_instr(KERN_EMERG, regs);
	}

	return ret;
}

DEFINE_SPINLOCK(die_lock);

/*
 * This function is protected against re-entrancy.
 */
void die(const char *str, struct pt_regs *regs, int err)
{
	struct thread_info *thread = current_thread_info();
	int ret;

	oops_enter();

	spin_lock_irq(&die_lock);
	console_verbose();
	bust_spinlocks(1);
	ret = __die(str, err, thread, regs);

	if (regs && kexec_should_crash(thread->task))
		crash_kexec(regs);

	bust_spinlocks(0);
	add_taint(TAINT_DIE);
	spin_unlock_irq(&die_lock);
	oops_exit();

	if (in_interrupt())
		panic("Fatal exception in interrupt");
	if (panic_on_oops)
		panic("Fatal exception");
	if (ret != NOTIFY_STOP)
		do_exit(SIGSEGV);
}

void arm_notify_die(const char *str, struct pt_regs *regs,
		struct siginfo *info, unsigned long err, unsigned long trap)
{
	if (user_mode(regs)) {
		current->thread.error_code = err;
		current->thread.trap_no = trap;

		force_sig_info(info->si_signo, info, current);
	} else {
		die(str, regs, err);
	}
}

static LIST_HEAD(undef_hook);
static DEFINE_SPINLOCK(undef_lock);

void register_undef_hook(struct undef_hook *hook)
{
	unsigned long flags;

	spin_lock_irqsave(&undef_lock, flags);
	list_add(&hook->node, &undef_hook);
	spin_unlock_irqrestore(&undef_lock, flags);
}

void unregister_undef_hook(struct undef_hook *hook)
{
	unsigned long flags;

	spin_lock_irqsave(&undef_lock, flags);
	list_del(&hook->node);
	spin_unlock_irqrestore(&undef_lock, flags);
}

static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
{
	struct undef_hook *hook;
	unsigned long flags;
	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;

	spin_lock_irqsave(&undef_lock, flags);
	list_for_each_entry(hook, &undef_hook, node)
		if ((instr & hook->instr_mask) == hook->instr_val &&
		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
			fn = hook->fn;
	spin_unlock_irqrestore(&undef_lock, flags);

	return fn ? fn(regs, instr) : 1;
}

asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
	unsigned int correction = thumb_mode(regs) ? 2 : 4;
	unsigned int instr;
	siginfo_t info;
	void __user *pc;

	/*
	 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
	 * depending whether we're in Thumb mode or not.
	 * Correct this offset.
	 */
	regs->ARM_pc -= correction;

	pc = (void __user *)instruction_pointer(regs);

	if (processor_mode(regs) == SVC_MODE) {
		instr = *(u32 *) pc;
	} else if (thumb_mode(regs)) {
		get_user(instr, (u16 __user *)pc);
	} else {
		get_user(instr, (u32 __user *)pc);
	}

	if (call_undef_hook(regs, instr) == 0)
		return;

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_UNDEFINED) {
		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
			current->comm, task_pid_nr(current), pc);
		dump_instr(KERN_INFO, regs);
	}
#endif

	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code  = ILL_ILLOPC;
	info.si_addr  = pc;

	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
}

asmlinkage void do_unexp_fiq (struct pt_regs *regs)
{
	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
	printk("You may have a hardware problem...\n");
}

/*
 * bad_mode handles the impossible case in the vectors.  If you see one of
 * these, then it's extremely serious, and could mean you have buggy hardware.
 * It never returns, and never tries to sync.  We hope that we can at least
 * dump out some state information...
 */
asmlinkage void bad_mode(struct pt_regs *regs, int reason)
{
	console_verbose();

	printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);

	die("Oops - bad mode", regs, 0);
	local_irq_disable();
	panic("bad mode");
}

static int bad_syscall(int n, struct pt_regs *regs)
{
	struct thread_info *thread = current_thread_info();
	siginfo_t info;

	if (current->personality != PER_LINUX &&
	    current->personality != PER_LINUX_32BIT &&
	    thread->exec_domain->handler) {
		thread->exec_domain->handler(n, regs);
		return regs->ARM_r0;
	}

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_SYSCALL) {
		printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
			task_pid_nr(current), current->comm, n);
		dump_instr(KERN_ERR, regs);
	}
#endif

	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code  = ILL_ILLTRP;
	info.si_addr  = (void __user *)instruction_pointer(regs) -
			 (thumb_mode(regs) ? 2 : 4);

	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);

	return regs->ARM_r0;
}

static inline void
do_cache_op(unsigned long start, unsigned long end, int flags)
{
	struct mm_struct *mm = current->active_mm;
	struct vm_area_struct *vma;

	if (end < start || flags)
		return;

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, start);
	if (vma && vma->vm_start < end) {
		if (start < vma->vm_start)
			start = vma->vm_start;
		if (end > vma->vm_end)
			end = vma->vm_end;

		flush_cache_user_range(vma, start, end);
	}
	up_read(&mm->mmap_sem);
}

/*
 * Handle all unrecognised system calls.
 *  0x9f0000 - 0x9fffff are some more esoteric system calls
 */
#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
asmlinkage int arm_syscall(int no, struct pt_regs *regs)
{
	struct thread_info *thread = current_thread_info();
	siginfo_t info;

	if ((no >> 16) != (__ARM_NR_BASE>> 16))
		return bad_syscall(no, regs);

	switch (no & 0xffff) {
	case 0: /* branch through 0 */
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		info.si_code  = SEGV_MAPERR;
		info.si_addr  = NULL;

		arm_notify_die("branch through zero", regs, &info, 0, 0);
		return 0;

	case NR(breakpoint): /* SWI BREAK_POINT */
		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
		ptrace_break(current, regs);
		return regs->ARM_r0;

	/*
	 * Flush a region from virtual address 'r0' to virtual address 'r1'
	 * _exclusive_.  There is no alignment requirement on either address;
	 * user space does not need to know the hardware cache layout.
	 *
	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
	 * is defined to be something else.  For now we ignore it, but may
	 * the fires of hell burn in your belly if you break this rule. ;)
	 *
	 * (at a later date, we may want to allow this call to not flush
	 * various aspects of the cache.  Passing '0' will guarantee that
	 * everything necessary gets flushed to maintain consistency in
	 * the specified region).
	 */
	case NR(cacheflush):
		do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
		return 0;

	case NR(usr26):
		if (!(elf_hwcap & HWCAP_26BIT))
			break;
		regs->ARM_cpsr &= ~MODE32_BIT;
		return regs->ARM_r0;

	case NR(usr32):
		if (!(elf_hwcap & HWCAP_26BIT))
			break;
		regs->ARM_cpsr |= MODE32_BIT;
		return regs->ARM_r0;

	case NR(set_tls):
		thread->tp_value = regs->ARM_r0;
		if (tls_emu)
			return 0;
		if (has_tls_reg) {
			asm ("mcr p15, 0, %0, c13, c0, 3"
				: : "r" (regs->ARM_r0));
		} else {
			/*
			 * User space must never try to access this directly.
			 * Expect your app to break eventually if you do so.
			 * The user helper at 0xffff0fe0 must be used instead.
			 * (see entry-armv.S for details)
			 */
			*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
		}
		return 0;

#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
	/*
	 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
	 * Return zero in r0 if *MEM was changed or non-zero if no exchange
	 * happened.  Also set the user C flag accordingly.
	 * If access permissions have to be fixed up then non-zero is
	 * returned and the operation has to be re-attempted.
	 *
	 * *NOTE*: This is a ghost syscall private to the kernel.  Only the
	 * __kuser_cmpxchg code in entry-armv.S should be aware of its
	 * existence.  Don't ever use this from user code.
	 */
	case NR(cmpxchg):
	for (;;) {
		extern void do_DataAbort(unsigned long addr, unsigned int fsr,
					 struct pt_regs *regs);
		unsigned long val;
		unsigned long addr = regs->ARM_r2;
		struct mm_struct *mm = current->mm;
		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
		spinlock_t *ptl;

		regs->ARM_cpsr &= ~PSR_C_BIT;
		down_read(&mm->mmap_sem);
		pgd = pgd_offset(mm, addr);
		if (!pgd_present(*pgd))
			goto bad_access;
		pmd = pmd_offset(pgd, addr);
		if (!pmd_present(*pmd))
			goto bad_access;
		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
		if (!pte_present(*pte) || !pte_dirty(*pte)) {
			pte_unmap_unlock(pte, ptl);
			goto bad_access;
		}
		val = *(unsigned long *)addr;
		val -= regs->ARM_r0;
		if (val == 0) {
			*(unsigned long *)addr = regs->ARM_r1;
			regs->ARM_cpsr |= PSR_C_BIT;
		}
		pte_unmap_unlock(pte, ptl);
		up_read(&mm->mmap_sem);
		return val;

		bad_access:
		up_read(&mm->mmap_sem);
		/* simulate a write access fault */
		do_DataAbort(addr, 15 + (1 << 11), regs);
	}
#endif

	default:
		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
		   if not implemented, rather than raising SIGILL.  This
		   way the calling program can gracefully determine whether
		   a feature is supported.  */
		if ((no & 0xffff) <= 0x7ff)
			return -ENOSYS;
		break;
	}
#ifdef CONFIG_DEBUG_USER
	/*
	 * experience shows that these seem to indicate that
	 * something catastrophic has happened
	 */
	if (user_debug & UDBG_SYSCALL) {
		printk("[%d] %s: arm syscall %d\n",
		       task_pid_nr(current), current->comm, no);
		dump_instr("", regs);
		if (user_mode(regs)) {
			__show_regs(regs);
			c_backtrace(regs->ARM_fp, processor_mode(regs));
		}
	}
#endif
	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code  = ILL_ILLTRP;
	info.si_addr  = (void __user *)instruction_pointer(regs) -
			 (thumb_mode(regs) ? 2 : 4);

	arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
	return 0;
}

#ifdef CONFIG_TLS_REG_EMUL

/*
 * We might be running on an ARMv6+ processor which should have the TLS
 * register but for some reason we can't use it, or maybe an SMP system
 * using a pre-ARMv6 processor (there are apparently a few prototypes like
 * that in existence) and therefore access to that register must be
 * emulated.
 */

static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
{
	int reg = (instr >> 12) & 15;
	if (reg == 15)
		return 1;
	regs->uregs[reg] = current_thread_info()->tp_value;
	regs->ARM_pc += 4;
	return 0;
}

static struct undef_hook arm_mrc_hook = {
	.instr_mask	= 0x0fff0fff,
	.instr_val	= 0x0e1d0f70,
	.cpsr_mask	= PSR_T_BIT,
	.cpsr_val	= 0,
	.fn		= get_tp_trap,
};

static int __init arm_mrc_hook_init(void)
{
	register_undef_hook(&arm_mrc_hook);
	return 0;
}

late_initcall(arm_mrc_hook_init);

#endif

void __bad_xchg(volatile void *ptr, int size)
{
	printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
		__builtin_return_address(0), ptr, size);
	BUG();
}
EXPORT_SYMBOL(__bad_xchg);

/*
 * A data abort trap was taken, but we did not handle the instruction.
 * Try to abort the user program, or panic if it was the kernel.
 */
asmlinkage void
baddataabort(int code, unsigned long instr, struct pt_regs *regs)
{
	unsigned long addr = instruction_pointer(regs);
	siginfo_t info;

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_BADABORT) {
		printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
			task_pid_nr(current), current->comm, code, instr);
		dump_instr(KERN_ERR, regs);
		show_pte(current->mm, addr);
	}
#endif

	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code  = ILL_ILLOPC;
	info.si_addr  = (void __user *)addr;

	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
}

void __attribute__((noreturn)) __bug(const char *file, int line)
{
	printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
	*(int *)0 = 0;

	/* Avoid "noreturn function does return" */
	for (;;);
}
EXPORT_SYMBOL(__bug);

void __readwrite_bug(const char *fn)
{
	printk("%s called, but not implemented\n", fn);
	BUG();
}
EXPORT_SYMBOL(__readwrite_bug);

void __pte_error(const char *file, int line, unsigned long val)
{
	printk("%s:%d: bad pte %08lx.\n", file, line, val);
}

void __pmd_error(const char *file, int line, unsigned long val)
{
	printk("%s:%d: bad pmd %08lx.\n", file, line, val);
}

void __pgd_error(const char *file, int line, unsigned long val)
{
	printk("%s:%d: bad pgd %08lx.\n", file, line, val);
}

asmlinkage void __div0(void)
{
	printk("Division by zero in kernel.\n");
	dump_stack();
}
EXPORT_SYMBOL(__div0);

void abort(void)
{
	BUG();

	/* if that doesn't kill us, halt */
	panic("Oops failed to kill thread");
}
EXPORT_SYMBOL(abort);

void __init trap_init(void)
{
	return;
}

static void __init kuser_get_tls_init(unsigned long vectors)
{
	/*
	 * vectors + 0xfe0 = __kuser_get_tls
	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
	 */
	if (tls_emu || has_tls_reg)
		memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
}

void __init early_trap_init(void)
{
	unsigned long vectors = CONFIG_VECTORS_BASE;
	extern char __stubs_start[], __stubs_end[];
	extern char __vectors_start[], __vectors_end[];
	extern char __kuser_helper_start[], __kuser_helper_end[];
	int kuser_sz = __kuser_helper_end - __kuser_helper_start;

	/*
	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
	 * into the vector page, mapped at 0xffff0000, and ensure these
	 * are visible to the instruction stream.
	 */
	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
	memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
	memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);

	/*
	 * Do processor specific fixups for the kuser helpers
	 */
	kuser_get_tls_init(vectors);

	/*
	 * Copy signal return handlers into the vector page, and
	 * set sigreturn to be a pointer to these.
	 */
	memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
	       sizeof(sigreturn_codes));
	memcpy((void *)KERN_RESTART_CODE, syscall_restart_code,
	       sizeof(syscall_restart_code));

	flush_icache_range(vectors, vectors + PAGE_SIZE);
	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
}