summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/traps.c
blob: 65a3b1e7548023948ea8d208b9872e24d74ed031 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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
 *
 *  '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/kprobes.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/irq.h>

#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/exception.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/ptrace.h>
#include <asm/unwind.h>
#include <asm/tls.h>
#include <asm/system_misc.h>
#include <asm/opcodes.h>


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

void *vectors_page;

#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, const char *loglvl)
{
	unsigned long end = frame + 4 + sizeof(struct pt_regs);

#ifdef CONFIG_KALLSYMS
	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
		loglvl, where, (void *)where, from, (void *)from);
#else
	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
		loglvl, where, from);
#endif

	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
		dump_mem(loglvl, "Exception stack", frame + 4, end);
}

void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
{
	char str[80], *p;
	unsigned int x;
	int reg;

	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
		if (instruction & BIT(reg)) {
			p += sprintf(p, " r%d:%08x", reg, *stack--);
			if (++x == 6) {
				x = 0;
				p = str;
				printk("%s%s\n", loglvl, str);
			}
		}
	}
	if (p != str)
		printk("%s%s\n", loglvl, str);
}

#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;
	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
	int i;

	/*
	 * Note that we now dump the code first, just in case the backtrace
	 * kills us.
	 */

	for (i = -4; i < 1 + !!thumb; 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);
}

static void dump_instr(const char *lvl, struct pt_regs *regs)
{
	mm_segment_t fs;

	if (!user_mode(regs)) {
		fs = get_fs();
		set_fs(KERNEL_DS);
		__dump_instr(lvl, regs);
		set_fs(fs);
	} else {
		__dump_instr(lvl, regs);
	}
}

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

	printk("%sBacktrace: ", loglvl);

	if (!tsk)
		tsk = current;

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

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

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

#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#elif defined(CONFIG_PREEMPT_RT)
#define S_PREEMPT " PREEMPT_RT"
#else
#define S_PREEMPT ""
#endif
#ifdef CONFIG_SMP
#define S_SMP " SMP"
#else
#define S_SMP ""
#endif
#ifdef CONFIG_THUMB2_KERNEL
#define S_ISA " THUMB2"
#else
#define S_ISA " ARM"
#endif

static int __die(const char *str, int err, struct pt_regs *regs)
{
	struct task_struct *tsk = current;
	static int die_counter;
	int ret;

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

	/* 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 1;

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

	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, KERN_EMERG);
		dump_instr(KERN_EMERG, regs);
	}

	return 0;
}

static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;

static unsigned long oops_begin(void)
{
	int cpu;
	unsigned long flags;

	oops_enter();

	/* racy, but better than risking deadlock. */
	raw_local_irq_save(flags);
	cpu = smp_processor_id();
	if (!arch_spin_trylock(&die_lock)) {
		if (cpu == die_owner)
			/* nested oops. should stop eventually */;
		else
			arch_spin_lock(&die_lock);
	}
	die_nest_count++;
	die_owner = cpu;
	console_verbose();
	bust_spinlocks(1);
	return flags;
}

static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
	if (regs && kexec_should_crash(current))
		crash_kexec(regs);

	bust_spinlocks(0);
	die_owner = -1;
	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
	die_nest_count--;
	if (!die_nest_count)
		/* Nest count reaches zero, release the lock. */
		arch_spin_unlock(&die_lock);
	raw_local_irq_restore(flags);
	oops_exit();

	if (in_interrupt())
		panic("Fatal exception in interrupt");
	if (panic_on_oops)
		panic("Fatal exception");
	if (signr)
		do_exit(signr);
}

/*
 * This function is protected against re-entrancy.
 */
void die(const char *str, struct pt_regs *regs, int err)
{
	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
	unsigned long flags = oops_begin();
	int sig = SIGSEGV;

	if (!user_mode(regs))
		bug_type = report_bug(regs->ARM_pc, regs);
	if (bug_type != BUG_TRAP_TYPE_NONE)
		str = "Oops - BUG";

	if (__die(str, err, regs))
		sig = 0;

	oops_end(flags, regs, sig);
}

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

		force_sig_fault(signo, si_code, addr);
	} else {
		die(str, regs, err);
	}
}

#ifdef CONFIG_GENERIC_BUG

int is_valid_bugaddr(unsigned long pc)
{
#ifdef CONFIG_THUMB2_KERNEL
	u16 bkpt;
	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
#else
	u32 bkpt;
	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
#endif

	if (probe_kernel_address((unsigned *)pc, bkpt))
		return 0;

	return bkpt == insn;
}

#endif

static LIST_HEAD(undef_hook);
static DEFINE_RAW_SPINLOCK(undef_lock);

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

	raw_spin_lock_irqsave(&undef_lock, flags);
	list_add(&hook->node, &undef_hook);
	raw_spin_unlock_irqrestore(&undef_lock, flags);
}

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

	raw_spin_lock_irqsave(&undef_lock, flags);
	list_del(&hook->node);
	raw_spin_unlock_irqrestore(&undef_lock, flags);
}

static nokprobe_inline
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;

	raw_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;
	raw_spin_unlock_irqrestore(&undef_lock, flags);

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

asmlinkage void do_undefinstr(struct pt_regs *regs)
{
	unsigned int instr;
	void __user *pc;

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

	if (processor_mode(regs) == SVC_MODE) {
#ifdef CONFIG_THUMB2_KERNEL
		if (thumb_mode(regs)) {
			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
			if (is_wide_instruction(instr)) {
				u16 inst2;
				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
				instr = __opcode_thumb32_compose(instr, inst2);
			}
		} else
#endif
			instr = __mem_to_opcode_arm(*(u32 *) pc);
	} else if (thumb_mode(regs)) {
		if (get_user(instr, (u16 __user *)pc))
			goto die_sig;
		instr = __mem_to_opcode_thumb16(instr);
		if (is_wide_instruction(instr)) {
			unsigned int instr2;
			if (get_user(instr2, (u16 __user *)pc+1))
				goto die_sig;
			instr2 = __mem_to_opcode_thumb16(instr2);
			instr = __opcode_thumb32_compose(instr, instr2);
		}
	} else {
		if (get_user(instr, (u32 __user *)pc))
			goto die_sig;
		instr = __mem_to_opcode_arm(instr);
	}

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

die_sig:
#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_UNDEFINED) {
		pr_info("%s (%d): undefined instruction: pc=%p\n",
			current->comm, task_pid_nr(current), pc);
		__show_regs(regs);
		dump_instr(KERN_INFO, regs);
	}
#endif
	arm_notify_die("Oops - undefined instruction", regs,
		       SIGILL, ILL_ILLOPC, pc, 0, 6);
}
NOKPROBE_SYMBOL(do_undefinstr)

/*
 * Handle FIQ similarly to NMI on x86 systems.
 *
 * The runtime environment for NMIs is extremely restrictive
 * (NMIs can pre-empt critical sections meaning almost all locking is
 * forbidden) meaning this default FIQ handling must only be used in
 * circumstances where non-maskability improves robustness, such as
 * watchdog or debug logic.
 *
 * This handler is not appropriate for general purpose use in drivers
 * platform code and can be overrideen using set_fiq_handler.
 */
asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
{
	struct pt_regs *old_regs = set_irq_regs(regs);

	nmi_enter();

	/* nop. FIQ handlers for special arch/arm features can be added here. */

	nmi_exit();

	set_irq_regs(old_regs);
}

/*
 * 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();

	pr_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)
{
	if ((current->personality & PER_MASK) != PER_LINUX) {
		send_sig(SIGSEGV, current, 1);
		return regs->ARM_r0;
	}

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

	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
		       (void __user *)instruction_pointer(regs) -
			 (thumb_mode(regs) ? 2 : 4),
		       n, 0);

	return regs->ARM_r0;
}

static inline int
__do_cache_op(unsigned long start, unsigned long end)
{
	int ret;

	do {
		unsigned long chunk = min(PAGE_SIZE, end - start);

		if (fatal_signal_pending(current))
			return 0;

		ret = flush_icache_user_range(start, start + chunk);
		if (ret)
			return ret;

		cond_resched();
		start += chunk;
	} while (start < end);

	return 0;
}

static inline int
do_cache_op(unsigned long start, unsigned long end, int flags)
{
	if (end < start || flags)
		return -EINVAL;

	if (!access_ok(start, end - start))
		return -EFAULT;

	return __do_cache_op(start, end);
}

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

	switch (no & 0xffff) {
	case 0: /* branch through 0 */
		arm_notify_die("branch through zero", regs,
			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
		return 0;

	case NR(breakpoint): /* SWI BREAK_POINT */
		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
		ptrace_break(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):
		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);

	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):
		set_tls(regs->ARM_r0);
		return 0;

	case NR(get_tls):
		return current_thread_info()->tp_value[0];

	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) {
		pr_err("[%d] %s: arm syscall %d\n",
		       task_pid_nr(current), current->comm, no);
		dump_instr(KERN_ERR, regs);
		if (user_mode(regs)) {
			__show_regs(regs);
			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
		}
	}
#endif
	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
		       (void __user *)instruction_pointer(regs) -
			 (thumb_mode(regs) ? 2 : 4),
		       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[0];
	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

/*
 * 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);

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_BADABORT) {
		pr_err("8<--- cut here ---\n");
		pr_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(KERN_ERR, current->mm, addr);
	}
#endif

	arm_notify_die("unknown data abort code", regs,
		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
}

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

void __pte_error(const char *file, int line, pte_t pte)
{
	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
}

void __pmd_error(const char *file, int line, pmd_t pmd)
{
	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
}

void __pgd_error(const char *file, int line, pgd_t pgd)
{
	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
}

asmlinkage void __div0(void)
{
	pr_err("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");
}

void __init trap_init(void)
{
	return;
}

#ifdef CONFIG_KUSER_HELPERS
static void __init kuser_init(void *vectors)
{
	extern char __kuser_helper_start[], __kuser_helper_end[];
	int kuser_sz = __kuser_helper_end - __kuser_helper_start;

	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);

	/*
	 * vectors + 0xfe0 = __kuser_get_tls
	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
	 */
	if (tls_emu || has_tls_reg)
		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
}
#else
static inline void __init kuser_init(void *vectors)
{
}
#endif

void __init early_trap_init(void *vectors_base)
{
#ifndef CONFIG_CPU_V7M
	unsigned long vectors = (unsigned long)vectors_base;
	extern char __stubs_start[], __stubs_end[];
	extern char __vectors_start[], __vectors_end[];
	unsigned i;

	vectors_page = vectors_base;

	/*
	 * Poison the vectors page with an undefined instruction.  This
	 * instruction is chosen to be undefined for both ARM and Thumb
	 * ISAs.  The Thumb version is an undefined instruction with a
	 * branch back to the undefined instruction.
	 */
	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
		((u32 *)vectors_base)[i] = 0xe7fddef1;

	/*
	 * 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 + 0x1000, __stubs_start, __stubs_end - __stubs_start);

	kuser_init(vectors_base);

	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
#else /* ifndef CONFIG_CPU_V7M */
	/*
	 * on V7-M there is no need to copy the vector table to a dedicated
	 * memory area. The address is configurable and so a table in the kernel
	 * image can be used.
	 */
#endif
}