xref: /openbmc/linux/arch/arm/kernel/traps.c (revision 96ac6d43)
1 /*
2  *  linux/arch/arm/kernel/traps.c
3  *
4  *  Copyright (C) 1995-2009 Russell King
5  *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  *  'traps.c' handles hardware exceptions after we have saved some state in
12  *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
13  *  kill the offending process.
14  */
15 #include <linux/signal.h>
16 #include <linux/personality.h>
17 #include <linux/kallsyms.h>
18 #include <linux/spinlock.h>
19 #include <linux/uaccess.h>
20 #include <linux/hardirq.h>
21 #include <linux/kdebug.h>
22 #include <linux/kprobes.h>
23 #include <linux/module.h>
24 #include <linux/kexec.h>
25 #include <linux/bug.h>
26 #include <linux/delay.h>
27 #include <linux/init.h>
28 #include <linux/sched/signal.h>
29 #include <linux/sched/debug.h>
30 #include <linux/sched/task_stack.h>
31 #include <linux/irq.h>
32 
33 #include <linux/atomic.h>
34 #include <asm/cacheflush.h>
35 #include <asm/exception.h>
36 #include <asm/unistd.h>
37 #include <asm/traps.h>
38 #include <asm/ptrace.h>
39 #include <asm/unwind.h>
40 #include <asm/tls.h>
41 #include <asm/system_misc.h>
42 #include <asm/opcodes.h>
43 
44 
45 static const char *handler[]= {
46 	"prefetch abort",
47 	"data abort",
48 	"address exception",
49 	"interrupt",
50 	"undefined instruction",
51 };
52 
53 void *vectors_page;
54 
55 #ifdef CONFIG_DEBUG_USER
56 unsigned int user_debug;
57 
58 static int __init user_debug_setup(char *str)
59 {
60 	get_option(&str, &user_debug);
61 	return 1;
62 }
63 __setup("user_debug=", user_debug_setup);
64 #endif
65 
66 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
67 
68 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
69 {
70 #ifdef CONFIG_KALLSYMS
71 	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
72 #else
73 	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
74 #endif
75 
76 	if (in_entry_text(from))
77 		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
78 }
79 
80 void dump_backtrace_stm(u32 *stack, u32 instruction)
81 {
82 	char str[80], *p;
83 	unsigned int x;
84 	int reg;
85 
86 	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
87 		if (instruction & BIT(reg)) {
88 			p += sprintf(p, " r%d:%08x", reg, *stack--);
89 			if (++x == 6) {
90 				x = 0;
91 				p = str;
92 				printk("%s\n", str);
93 			}
94 		}
95 	}
96 	if (p != str)
97 		printk("%s\n", str);
98 }
99 
100 #ifndef CONFIG_ARM_UNWIND
101 /*
102  * Stack pointers should always be within the kernels view of
103  * physical memory.  If it is not there, then we can't dump
104  * out any information relating to the stack.
105  */
106 static int verify_stack(unsigned long sp)
107 {
108 	if (sp < PAGE_OFFSET ||
109 	    (sp > (unsigned long)high_memory && high_memory != NULL))
110 		return -EFAULT;
111 
112 	return 0;
113 }
114 #endif
115 
116 /*
117  * Dump out the contents of some memory nicely...
118  */
119 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
120 		     unsigned long top)
121 {
122 	unsigned long first;
123 	mm_segment_t fs;
124 	int i;
125 
126 	/*
127 	 * We need to switch to kernel mode so that we can use __get_user
128 	 * to safely read from kernel space.  Note that we now dump the
129 	 * code first, just in case the backtrace kills us.
130 	 */
131 	fs = get_fs();
132 	set_fs(KERNEL_DS);
133 
134 	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
135 
136 	for (first = bottom & ~31; first < top; first += 32) {
137 		unsigned long p;
138 		char str[sizeof(" 12345678") * 8 + 1];
139 
140 		memset(str, ' ', sizeof(str));
141 		str[sizeof(str) - 1] = '\0';
142 
143 		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
144 			if (p >= bottom && p < top) {
145 				unsigned long val;
146 				if (__get_user(val, (unsigned long *)p) == 0)
147 					sprintf(str + i * 9, " %08lx", val);
148 				else
149 					sprintf(str + i * 9, " ????????");
150 			}
151 		}
152 		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
153 	}
154 
155 	set_fs(fs);
156 }
157 
158 static void __dump_instr(const char *lvl, struct pt_regs *regs)
159 {
160 	unsigned long addr = instruction_pointer(regs);
161 	const int thumb = thumb_mode(regs);
162 	const int width = thumb ? 4 : 8;
163 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
164 	int i;
165 
166 	/*
167 	 * Note that we now dump the code first, just in case the backtrace
168 	 * kills us.
169 	 */
170 
171 	for (i = -4; i < 1 + !!thumb; i++) {
172 		unsigned int val, bad;
173 
174 		if (thumb)
175 			bad = get_user(val, &((u16 *)addr)[i]);
176 		else
177 			bad = get_user(val, &((u32 *)addr)[i]);
178 
179 		if (!bad)
180 			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
181 					width, val);
182 		else {
183 			p += sprintf(p, "bad PC value");
184 			break;
185 		}
186 	}
187 	printk("%sCode: %s\n", lvl, str);
188 }
189 
190 static void dump_instr(const char *lvl, struct pt_regs *regs)
191 {
192 	mm_segment_t fs;
193 
194 	if (!user_mode(regs)) {
195 		fs = get_fs();
196 		set_fs(KERNEL_DS);
197 		__dump_instr(lvl, regs);
198 		set_fs(fs);
199 	} else {
200 		__dump_instr(lvl, regs);
201 	}
202 }
203 
204 #ifdef CONFIG_ARM_UNWIND
205 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
206 {
207 	unwind_backtrace(regs, tsk);
208 }
209 #else
210 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
211 {
212 	unsigned int fp, mode;
213 	int ok = 1;
214 
215 	printk("Backtrace: ");
216 
217 	if (!tsk)
218 		tsk = current;
219 
220 	if (regs) {
221 		fp = frame_pointer(regs);
222 		mode = processor_mode(regs);
223 	} else if (tsk != current) {
224 		fp = thread_saved_fp(tsk);
225 		mode = 0x10;
226 	} else {
227 		asm("mov %0, fp" : "=r" (fp) : : "cc");
228 		mode = 0x10;
229 	}
230 
231 	if (!fp) {
232 		pr_cont("no frame pointer");
233 		ok = 0;
234 	} else if (verify_stack(fp)) {
235 		pr_cont("invalid frame pointer 0x%08x", fp);
236 		ok = 0;
237 	} else if (fp < (unsigned long)end_of_stack(tsk))
238 		pr_cont("frame pointer underflow");
239 	pr_cont("\n");
240 
241 	if (ok)
242 		c_backtrace(fp, mode);
243 }
244 #endif
245 
246 void show_stack(struct task_struct *tsk, unsigned long *sp)
247 {
248 	dump_backtrace(NULL, tsk);
249 	barrier();
250 }
251 
252 #ifdef CONFIG_PREEMPT
253 #define S_PREEMPT " PREEMPT"
254 #else
255 #define S_PREEMPT ""
256 #endif
257 #ifdef CONFIG_SMP
258 #define S_SMP " SMP"
259 #else
260 #define S_SMP ""
261 #endif
262 #ifdef CONFIG_THUMB2_KERNEL
263 #define S_ISA " THUMB2"
264 #else
265 #define S_ISA " ARM"
266 #endif
267 
268 static int __die(const char *str, int err, struct pt_regs *regs)
269 {
270 	struct task_struct *tsk = current;
271 	static int die_counter;
272 	int ret;
273 
274 	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
275 	         str, err, ++die_counter);
276 
277 	/* trap and error numbers are mostly meaningless on ARM */
278 	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
279 	if (ret == NOTIFY_STOP)
280 		return 1;
281 
282 	print_modules();
283 	__show_regs(regs);
284 	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
285 		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
286 
287 	if (!user_mode(regs) || in_interrupt()) {
288 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
289 			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
290 		dump_backtrace(regs, tsk);
291 		dump_instr(KERN_EMERG, regs);
292 	}
293 
294 	return 0;
295 }
296 
297 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
298 static int die_owner = -1;
299 static unsigned int die_nest_count;
300 
301 static unsigned long oops_begin(void)
302 {
303 	int cpu;
304 	unsigned long flags;
305 
306 	oops_enter();
307 
308 	/* racy, but better than risking deadlock. */
309 	raw_local_irq_save(flags);
310 	cpu = smp_processor_id();
311 	if (!arch_spin_trylock(&die_lock)) {
312 		if (cpu == die_owner)
313 			/* nested oops. should stop eventually */;
314 		else
315 			arch_spin_lock(&die_lock);
316 	}
317 	die_nest_count++;
318 	die_owner = cpu;
319 	console_verbose();
320 	bust_spinlocks(1);
321 	return flags;
322 }
323 
324 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
325 {
326 	if (regs && kexec_should_crash(current))
327 		crash_kexec(regs);
328 
329 	bust_spinlocks(0);
330 	die_owner = -1;
331 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
332 	die_nest_count--;
333 	if (!die_nest_count)
334 		/* Nest count reaches zero, release the lock. */
335 		arch_spin_unlock(&die_lock);
336 	raw_local_irq_restore(flags);
337 	oops_exit();
338 
339 	if (in_interrupt())
340 		panic("Fatal exception in interrupt");
341 	if (panic_on_oops)
342 		panic("Fatal exception");
343 	if (signr)
344 		do_exit(signr);
345 }
346 
347 /*
348  * This function is protected against re-entrancy.
349  */
350 void die(const char *str, struct pt_regs *regs, int err)
351 {
352 	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
353 	unsigned long flags = oops_begin();
354 	int sig = SIGSEGV;
355 
356 	if (!user_mode(regs))
357 		bug_type = report_bug(regs->ARM_pc, regs);
358 	if (bug_type != BUG_TRAP_TYPE_NONE)
359 		str = "Oops - BUG";
360 
361 	if (__die(str, err, regs))
362 		sig = 0;
363 
364 	oops_end(flags, regs, sig);
365 }
366 
367 void arm_notify_die(const char *str, struct pt_regs *regs,
368 		int signo, int si_code, void __user *addr,
369 		unsigned long err, unsigned long trap)
370 {
371 	if (user_mode(regs)) {
372 		current->thread.error_code = err;
373 		current->thread.trap_no = trap;
374 
375 		force_sig_fault(signo, si_code, addr, current);
376 	} else {
377 		die(str, regs, err);
378 	}
379 }
380 
381 #ifdef CONFIG_GENERIC_BUG
382 
383 int is_valid_bugaddr(unsigned long pc)
384 {
385 #ifdef CONFIG_THUMB2_KERNEL
386 	u16 bkpt;
387 	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
388 #else
389 	u32 bkpt;
390 	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
391 #endif
392 
393 	if (probe_kernel_address((unsigned *)pc, bkpt))
394 		return 0;
395 
396 	return bkpt == insn;
397 }
398 
399 #endif
400 
401 static LIST_HEAD(undef_hook);
402 static DEFINE_RAW_SPINLOCK(undef_lock);
403 
404 void register_undef_hook(struct undef_hook *hook)
405 {
406 	unsigned long flags;
407 
408 	raw_spin_lock_irqsave(&undef_lock, flags);
409 	list_add(&hook->node, &undef_hook);
410 	raw_spin_unlock_irqrestore(&undef_lock, flags);
411 }
412 
413 void unregister_undef_hook(struct undef_hook *hook)
414 {
415 	unsigned long flags;
416 
417 	raw_spin_lock_irqsave(&undef_lock, flags);
418 	list_del(&hook->node);
419 	raw_spin_unlock_irqrestore(&undef_lock, flags);
420 }
421 
422 static nokprobe_inline
423 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
424 {
425 	struct undef_hook *hook;
426 	unsigned long flags;
427 	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
428 
429 	raw_spin_lock_irqsave(&undef_lock, flags);
430 	list_for_each_entry(hook, &undef_hook, node)
431 		if ((instr & hook->instr_mask) == hook->instr_val &&
432 		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
433 			fn = hook->fn;
434 	raw_spin_unlock_irqrestore(&undef_lock, flags);
435 
436 	return fn ? fn(regs, instr) : 1;
437 }
438 
439 asmlinkage void do_undefinstr(struct pt_regs *regs)
440 {
441 	unsigned int instr;
442 	void __user *pc;
443 
444 	pc = (void __user *)instruction_pointer(regs);
445 
446 	if (processor_mode(regs) == SVC_MODE) {
447 #ifdef CONFIG_THUMB2_KERNEL
448 		if (thumb_mode(regs)) {
449 			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
450 			if (is_wide_instruction(instr)) {
451 				u16 inst2;
452 				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
453 				instr = __opcode_thumb32_compose(instr, inst2);
454 			}
455 		} else
456 #endif
457 			instr = __mem_to_opcode_arm(*(u32 *) pc);
458 	} else if (thumb_mode(regs)) {
459 		if (get_user(instr, (u16 __user *)pc))
460 			goto die_sig;
461 		instr = __mem_to_opcode_thumb16(instr);
462 		if (is_wide_instruction(instr)) {
463 			unsigned int instr2;
464 			if (get_user(instr2, (u16 __user *)pc+1))
465 				goto die_sig;
466 			instr2 = __mem_to_opcode_thumb16(instr2);
467 			instr = __opcode_thumb32_compose(instr, instr2);
468 		}
469 	} else {
470 		if (get_user(instr, (u32 __user *)pc))
471 			goto die_sig;
472 		instr = __mem_to_opcode_arm(instr);
473 	}
474 
475 	if (call_undef_hook(regs, instr) == 0)
476 		return;
477 
478 die_sig:
479 #ifdef CONFIG_DEBUG_USER
480 	if (user_debug & UDBG_UNDEFINED) {
481 		pr_info("%s (%d): undefined instruction: pc=%p\n",
482 			current->comm, task_pid_nr(current), pc);
483 		__show_regs(regs);
484 		dump_instr(KERN_INFO, regs);
485 	}
486 #endif
487 	arm_notify_die("Oops - undefined instruction", regs,
488 		       SIGILL, ILL_ILLOPC, pc, 0, 6);
489 }
490 NOKPROBE_SYMBOL(do_undefinstr)
491 
492 /*
493  * Handle FIQ similarly to NMI on x86 systems.
494  *
495  * The runtime environment for NMIs is extremely restrictive
496  * (NMIs can pre-empt critical sections meaning almost all locking is
497  * forbidden) meaning this default FIQ handling must only be used in
498  * circumstances where non-maskability improves robustness, such as
499  * watchdog or debug logic.
500  *
501  * This handler is not appropriate for general purpose use in drivers
502  * platform code and can be overrideen using set_fiq_handler.
503  */
504 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
505 {
506 	struct pt_regs *old_regs = set_irq_regs(regs);
507 
508 	nmi_enter();
509 
510 	/* nop. FIQ handlers for special arch/arm features can be added here. */
511 
512 	nmi_exit();
513 
514 	set_irq_regs(old_regs);
515 }
516 
517 /*
518  * bad_mode handles the impossible case in the vectors.  If you see one of
519  * these, then it's extremely serious, and could mean you have buggy hardware.
520  * It never returns, and never tries to sync.  We hope that we can at least
521  * dump out some state information...
522  */
523 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
524 {
525 	console_verbose();
526 
527 	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
528 
529 	die("Oops - bad mode", regs, 0);
530 	local_irq_disable();
531 	panic("bad mode");
532 }
533 
534 static int bad_syscall(int n, struct pt_regs *regs)
535 {
536 	if ((current->personality & PER_MASK) != PER_LINUX) {
537 		send_sig(SIGSEGV, current, 1);
538 		return regs->ARM_r0;
539 	}
540 
541 #ifdef CONFIG_DEBUG_USER
542 	if (user_debug & UDBG_SYSCALL) {
543 		pr_err("[%d] %s: obsolete system call %08x.\n",
544 			task_pid_nr(current), current->comm, n);
545 		dump_instr(KERN_ERR, regs);
546 	}
547 #endif
548 
549 	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
550 		       (void __user *)instruction_pointer(regs) -
551 			 (thumb_mode(regs) ? 2 : 4),
552 		       n, 0);
553 
554 	return regs->ARM_r0;
555 }
556 
557 static inline int
558 __do_cache_op(unsigned long start, unsigned long end)
559 {
560 	int ret;
561 
562 	do {
563 		unsigned long chunk = min(PAGE_SIZE, end - start);
564 
565 		if (fatal_signal_pending(current))
566 			return 0;
567 
568 		ret = flush_cache_user_range(start, start + chunk);
569 		if (ret)
570 			return ret;
571 
572 		cond_resched();
573 		start += chunk;
574 	} while (start < end);
575 
576 	return 0;
577 }
578 
579 static inline int
580 do_cache_op(unsigned long start, unsigned long end, int flags)
581 {
582 	if (end < start || flags)
583 		return -EINVAL;
584 
585 	if (!access_ok(start, end - start))
586 		return -EFAULT;
587 
588 	return __do_cache_op(start, end);
589 }
590 
591 /*
592  * Handle all unrecognised system calls.
593  *  0x9f0000 - 0x9fffff are some more esoteric system calls
594  */
595 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
596 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
597 {
598 	if ((no >> 16) != (__ARM_NR_BASE>> 16))
599 		return bad_syscall(no, regs);
600 
601 	switch (no & 0xffff) {
602 	case 0: /* branch through 0 */
603 		arm_notify_die("branch through zero", regs,
604 			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
605 		return 0;
606 
607 	case NR(breakpoint): /* SWI BREAK_POINT */
608 		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
609 		ptrace_break(current, regs);
610 		return regs->ARM_r0;
611 
612 	/*
613 	 * Flush a region from virtual address 'r0' to virtual address 'r1'
614 	 * _exclusive_.  There is no alignment requirement on either address;
615 	 * user space does not need to know the hardware cache layout.
616 	 *
617 	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
618 	 * is defined to be something else.  For now we ignore it, but may
619 	 * the fires of hell burn in your belly if you break this rule. ;)
620 	 *
621 	 * (at a later date, we may want to allow this call to not flush
622 	 * various aspects of the cache.  Passing '0' will guarantee that
623 	 * everything necessary gets flushed to maintain consistency in
624 	 * the specified region).
625 	 */
626 	case NR(cacheflush):
627 		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
628 
629 	case NR(usr26):
630 		if (!(elf_hwcap & HWCAP_26BIT))
631 			break;
632 		regs->ARM_cpsr &= ~MODE32_BIT;
633 		return regs->ARM_r0;
634 
635 	case NR(usr32):
636 		if (!(elf_hwcap & HWCAP_26BIT))
637 			break;
638 		regs->ARM_cpsr |= MODE32_BIT;
639 		return regs->ARM_r0;
640 
641 	case NR(set_tls):
642 		set_tls(regs->ARM_r0);
643 		return 0;
644 
645 	case NR(get_tls):
646 		return current_thread_info()->tp_value[0];
647 
648 	default:
649 		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
650 		   if not implemented, rather than raising SIGILL.  This
651 		   way the calling program can gracefully determine whether
652 		   a feature is supported.  */
653 		if ((no & 0xffff) <= 0x7ff)
654 			return -ENOSYS;
655 		break;
656 	}
657 #ifdef CONFIG_DEBUG_USER
658 	/*
659 	 * experience shows that these seem to indicate that
660 	 * something catastrophic has happened
661 	 */
662 	if (user_debug & UDBG_SYSCALL) {
663 		pr_err("[%d] %s: arm syscall %d\n",
664 		       task_pid_nr(current), current->comm, no);
665 		dump_instr("", regs);
666 		if (user_mode(regs)) {
667 			__show_regs(regs);
668 			c_backtrace(frame_pointer(regs), processor_mode(regs));
669 		}
670 	}
671 #endif
672 	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
673 		       (void __user *)instruction_pointer(regs) -
674 			 (thumb_mode(regs) ? 2 : 4),
675 		       no, 0);
676 	return 0;
677 }
678 
679 #ifdef CONFIG_TLS_REG_EMUL
680 
681 /*
682  * We might be running on an ARMv6+ processor which should have the TLS
683  * register but for some reason we can't use it, or maybe an SMP system
684  * using a pre-ARMv6 processor (there are apparently a few prototypes like
685  * that in existence) and therefore access to that register must be
686  * emulated.
687  */
688 
689 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
690 {
691 	int reg = (instr >> 12) & 15;
692 	if (reg == 15)
693 		return 1;
694 	regs->uregs[reg] = current_thread_info()->tp_value[0];
695 	regs->ARM_pc += 4;
696 	return 0;
697 }
698 
699 static struct undef_hook arm_mrc_hook = {
700 	.instr_mask	= 0x0fff0fff,
701 	.instr_val	= 0x0e1d0f70,
702 	.cpsr_mask	= PSR_T_BIT,
703 	.cpsr_val	= 0,
704 	.fn		= get_tp_trap,
705 };
706 
707 static int __init arm_mrc_hook_init(void)
708 {
709 	register_undef_hook(&arm_mrc_hook);
710 	return 0;
711 }
712 
713 late_initcall(arm_mrc_hook_init);
714 
715 #endif
716 
717 /*
718  * A data abort trap was taken, but we did not handle the instruction.
719  * Try to abort the user program, or panic if it was the kernel.
720  */
721 asmlinkage void
722 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
723 {
724 	unsigned long addr = instruction_pointer(regs);
725 
726 #ifdef CONFIG_DEBUG_USER
727 	if (user_debug & UDBG_BADABORT) {
728 		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
729 		       task_pid_nr(current), current->comm, code, instr);
730 		dump_instr(KERN_ERR, regs);
731 		show_pte(current->mm, addr);
732 	}
733 #endif
734 
735 	arm_notify_die("unknown data abort code", regs,
736 		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
737 }
738 
739 void __readwrite_bug(const char *fn)
740 {
741 	pr_err("%s called, but not implemented\n", fn);
742 	BUG();
743 }
744 EXPORT_SYMBOL(__readwrite_bug);
745 
746 void __pte_error(const char *file, int line, pte_t pte)
747 {
748 	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
749 }
750 
751 void __pmd_error(const char *file, int line, pmd_t pmd)
752 {
753 	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
754 }
755 
756 void __pgd_error(const char *file, int line, pgd_t pgd)
757 {
758 	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
759 }
760 
761 asmlinkage void __div0(void)
762 {
763 	pr_err("Division by zero in kernel.\n");
764 	dump_stack();
765 }
766 EXPORT_SYMBOL(__div0);
767 
768 void abort(void)
769 {
770 	BUG();
771 
772 	/* if that doesn't kill us, halt */
773 	panic("Oops failed to kill thread");
774 }
775 
776 void __init trap_init(void)
777 {
778 	return;
779 }
780 
781 #ifdef CONFIG_KUSER_HELPERS
782 static void __init kuser_init(void *vectors)
783 {
784 	extern char __kuser_helper_start[], __kuser_helper_end[];
785 	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
786 
787 	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
788 
789 	/*
790 	 * vectors + 0xfe0 = __kuser_get_tls
791 	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
792 	 */
793 	if (tls_emu || has_tls_reg)
794 		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
795 }
796 #else
797 static inline void __init kuser_init(void *vectors)
798 {
799 }
800 #endif
801 
802 void __init early_trap_init(void *vectors_base)
803 {
804 #ifndef CONFIG_CPU_V7M
805 	unsigned long vectors = (unsigned long)vectors_base;
806 	extern char __stubs_start[], __stubs_end[];
807 	extern char __vectors_start[], __vectors_end[];
808 	unsigned i;
809 
810 	vectors_page = vectors_base;
811 
812 	/*
813 	 * Poison the vectors page with an undefined instruction.  This
814 	 * instruction is chosen to be undefined for both ARM and Thumb
815 	 * ISAs.  The Thumb version is an undefined instruction with a
816 	 * branch back to the undefined instruction.
817 	 */
818 	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
819 		((u32 *)vectors_base)[i] = 0xe7fddef1;
820 
821 	/*
822 	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
823 	 * into the vector page, mapped at 0xffff0000, and ensure these
824 	 * are visible to the instruction stream.
825 	 */
826 	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
827 	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
828 
829 	kuser_init(vectors_base);
830 
831 	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
832 #else /* ifndef CONFIG_CPU_V7M */
833 	/*
834 	 * on V7-M there is no need to copy the vector table to a dedicated
835 	 * memory area. The address is configurable and so a table in the kernel
836 	 * image can be used.
837 	 */
838 #endif
839 }
840