xref: /openbmc/linux/arch/arm/kernel/traps.c (revision 68198dca)
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/module.h>
23 #include <linux/kexec.h>
24 #include <linux/bug.h>
25 #include <linux/delay.h>
26 #include <linux/init.h>
27 #include <linux/sched/signal.h>
28 #include <linux/sched/debug.h>
29 #include <linux/sched/task_stack.h>
30 #include <linux/irq.h>
31 
32 #include <linux/atomic.h>
33 #include <asm/cacheflush.h>
34 #include <asm/exception.h>
35 #include <asm/unistd.h>
36 #include <asm/traps.h>
37 #include <asm/ptrace.h>
38 #include <asm/unwind.h>
39 #include <asm/tls.h>
40 #include <asm/system_misc.h>
41 #include <asm/opcodes.h>
42 
43 
44 static const char *handler[]= {
45 	"prefetch abort",
46 	"data abort",
47 	"address exception",
48 	"interrupt",
49 	"undefined instruction",
50 };
51 
52 void *vectors_page;
53 
54 #ifdef CONFIG_DEBUG_USER
55 unsigned int user_debug;
56 
57 static int __init user_debug_setup(char *str)
58 {
59 	get_option(&str, &user_debug);
60 	return 1;
61 }
62 __setup("user_debug=", user_debug_setup);
63 #endif
64 
65 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
66 
67 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
68 {
69 #ifdef CONFIG_KALLSYMS
70 	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
71 #else
72 	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
73 #endif
74 
75 	if (in_exception_text(where))
76 		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
77 }
78 
79 void dump_backtrace_stm(u32 *stack, u32 instruction)
80 {
81 	char str[80], *p;
82 	unsigned int x;
83 	int reg;
84 
85 	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
86 		if (instruction & BIT(reg)) {
87 			p += sprintf(p, " r%d:%08x", reg, *stack--);
88 			if (++x == 6) {
89 				x = 0;
90 				p = str;
91 				printk("%s\n", str);
92 			}
93 		}
94 	}
95 	if (p != str)
96 		printk("%s\n", str);
97 }
98 
99 #ifndef CONFIG_ARM_UNWIND
100 /*
101  * Stack pointers should always be within the kernels view of
102  * physical memory.  If it is not there, then we can't dump
103  * out any information relating to the stack.
104  */
105 static int verify_stack(unsigned long sp)
106 {
107 	if (sp < PAGE_OFFSET ||
108 	    (sp > (unsigned long)high_memory && high_memory != NULL))
109 		return -EFAULT;
110 
111 	return 0;
112 }
113 #endif
114 
115 /*
116  * Dump out the contents of some memory nicely...
117  */
118 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
119 		     unsigned long top)
120 {
121 	unsigned long first;
122 	mm_segment_t fs;
123 	int i;
124 
125 	/*
126 	 * We need to switch to kernel mode so that we can use __get_user
127 	 * to safely read from kernel space.  Note that we now dump the
128 	 * code first, just in case the backtrace kills us.
129 	 */
130 	fs = get_fs();
131 	set_fs(KERNEL_DS);
132 
133 	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
134 
135 	for (first = bottom & ~31; first < top; first += 32) {
136 		unsigned long p;
137 		char str[sizeof(" 12345678") * 8 + 1];
138 
139 		memset(str, ' ', sizeof(str));
140 		str[sizeof(str) - 1] = '\0';
141 
142 		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
143 			if (p >= bottom && p < top) {
144 				unsigned long val;
145 				if (__get_user(val, (unsigned long *)p) == 0)
146 					sprintf(str + i * 9, " %08lx", val);
147 				else
148 					sprintf(str + i * 9, " ????????");
149 			}
150 		}
151 		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
152 	}
153 
154 	set_fs(fs);
155 }
156 
157 static void __dump_instr(const char *lvl, struct pt_regs *regs)
158 {
159 	unsigned long addr = instruction_pointer(regs);
160 	const int thumb = thumb_mode(regs);
161 	const int width = thumb ? 4 : 8;
162 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
163 	int i;
164 
165 	/*
166 	 * Note that we now dump the code first, just in case the backtrace
167 	 * kills us.
168 	 */
169 
170 	for (i = -4; i < 1 + !!thumb; i++) {
171 		unsigned int val, bad;
172 
173 		if (thumb)
174 			bad = get_user(val, &((u16 *)addr)[i]);
175 		else
176 			bad = get_user(val, &((u32 *)addr)[i]);
177 
178 		if (!bad)
179 			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
180 					width, val);
181 		else {
182 			p += sprintf(p, "bad PC value");
183 			break;
184 		}
185 	}
186 	printk("%sCode: %s\n", lvl, str);
187 }
188 
189 static void dump_instr(const char *lvl, struct pt_regs *regs)
190 {
191 	mm_segment_t fs;
192 
193 	if (!user_mode(regs)) {
194 		fs = get_fs();
195 		set_fs(KERNEL_DS);
196 		__dump_instr(lvl, regs);
197 		set_fs(fs);
198 	} else {
199 		__dump_instr(lvl, regs);
200 	}
201 }
202 
203 #ifdef CONFIG_ARM_UNWIND
204 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
205 {
206 	unwind_backtrace(regs, tsk);
207 }
208 #else
209 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
210 {
211 	unsigned int fp, mode;
212 	int ok = 1;
213 
214 	printk("Backtrace: ");
215 
216 	if (!tsk)
217 		tsk = current;
218 
219 	if (regs) {
220 		fp = frame_pointer(regs);
221 		mode = processor_mode(regs);
222 	} else if (tsk != current) {
223 		fp = thread_saved_fp(tsk);
224 		mode = 0x10;
225 	} else {
226 		asm("mov %0, fp" : "=r" (fp) : : "cc");
227 		mode = 0x10;
228 	}
229 
230 	if (!fp) {
231 		pr_cont("no frame pointer");
232 		ok = 0;
233 	} else if (verify_stack(fp)) {
234 		pr_cont("invalid frame pointer 0x%08x", fp);
235 		ok = 0;
236 	} else if (fp < (unsigned long)end_of_stack(tsk))
237 		pr_cont("frame pointer underflow");
238 	pr_cont("\n");
239 
240 	if (ok)
241 		c_backtrace(fp, mode);
242 }
243 #endif
244 
245 void show_stack(struct task_struct *tsk, unsigned long *sp)
246 {
247 	dump_backtrace(NULL, tsk);
248 	barrier();
249 }
250 
251 #ifdef CONFIG_PREEMPT
252 #define S_PREEMPT " PREEMPT"
253 #else
254 #define S_PREEMPT ""
255 #endif
256 #ifdef CONFIG_SMP
257 #define S_SMP " SMP"
258 #else
259 #define S_SMP ""
260 #endif
261 #ifdef CONFIG_THUMB2_KERNEL
262 #define S_ISA " THUMB2"
263 #else
264 #define S_ISA " ARM"
265 #endif
266 
267 static int __die(const char *str, int err, struct pt_regs *regs)
268 {
269 	struct task_struct *tsk = current;
270 	static int die_counter;
271 	int ret;
272 
273 	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
274 	         str, err, ++die_counter);
275 
276 	/* trap and error numbers are mostly meaningless on ARM */
277 	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
278 	if (ret == NOTIFY_STOP)
279 		return 1;
280 
281 	print_modules();
282 	__show_regs(regs);
283 	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
284 		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
285 
286 	if (!user_mode(regs) || in_interrupt()) {
287 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
288 			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
289 		dump_backtrace(regs, tsk);
290 		dump_instr(KERN_EMERG, regs);
291 	}
292 
293 	return 0;
294 }
295 
296 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
297 static int die_owner = -1;
298 static unsigned int die_nest_count;
299 
300 static unsigned long oops_begin(void)
301 {
302 	int cpu;
303 	unsigned long flags;
304 
305 	oops_enter();
306 
307 	/* racy, but better than risking deadlock. */
308 	raw_local_irq_save(flags);
309 	cpu = smp_processor_id();
310 	if (!arch_spin_trylock(&die_lock)) {
311 		if (cpu == die_owner)
312 			/* nested oops. should stop eventually */;
313 		else
314 			arch_spin_lock(&die_lock);
315 	}
316 	die_nest_count++;
317 	die_owner = cpu;
318 	console_verbose();
319 	bust_spinlocks(1);
320 	return flags;
321 }
322 
323 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
324 {
325 	if (regs && kexec_should_crash(current))
326 		crash_kexec(regs);
327 
328 	bust_spinlocks(0);
329 	die_owner = -1;
330 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
331 	die_nest_count--;
332 	if (!die_nest_count)
333 		/* Nest count reaches zero, release the lock. */
334 		arch_spin_unlock(&die_lock);
335 	raw_local_irq_restore(flags);
336 	oops_exit();
337 
338 	if (in_interrupt())
339 		panic("Fatal exception in interrupt");
340 	if (panic_on_oops)
341 		panic("Fatal exception");
342 	if (signr)
343 		do_exit(signr);
344 }
345 
346 /*
347  * This function is protected against re-entrancy.
348  */
349 void die(const char *str, struct pt_regs *regs, int err)
350 {
351 	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
352 	unsigned long flags = oops_begin();
353 	int sig = SIGSEGV;
354 
355 	if (!user_mode(regs))
356 		bug_type = report_bug(regs->ARM_pc, regs);
357 	if (bug_type != BUG_TRAP_TYPE_NONE)
358 		str = "Oops - BUG";
359 
360 	if (__die(str, err, regs))
361 		sig = 0;
362 
363 	oops_end(flags, regs, sig);
364 }
365 
366 void arm_notify_die(const char *str, struct pt_regs *regs,
367 		struct siginfo *info, unsigned long err, unsigned long trap)
368 {
369 	if (user_mode(regs)) {
370 		current->thread.error_code = err;
371 		current->thread.trap_no = trap;
372 
373 		force_sig_info(info->si_signo, info, current);
374 	} else {
375 		die(str, regs, err);
376 	}
377 }
378 
379 #ifdef CONFIG_GENERIC_BUG
380 
381 int is_valid_bugaddr(unsigned long pc)
382 {
383 #ifdef CONFIG_THUMB2_KERNEL
384 	u16 bkpt;
385 	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
386 #else
387 	u32 bkpt;
388 	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
389 #endif
390 
391 	if (probe_kernel_address((unsigned *)pc, bkpt))
392 		return 0;
393 
394 	return bkpt == insn;
395 }
396 
397 #endif
398 
399 static LIST_HEAD(undef_hook);
400 static DEFINE_RAW_SPINLOCK(undef_lock);
401 
402 void register_undef_hook(struct undef_hook *hook)
403 {
404 	unsigned long flags;
405 
406 	raw_spin_lock_irqsave(&undef_lock, flags);
407 	list_add(&hook->node, &undef_hook);
408 	raw_spin_unlock_irqrestore(&undef_lock, flags);
409 }
410 
411 void unregister_undef_hook(struct undef_hook *hook)
412 {
413 	unsigned long flags;
414 
415 	raw_spin_lock_irqsave(&undef_lock, flags);
416 	list_del(&hook->node);
417 	raw_spin_unlock_irqrestore(&undef_lock, flags);
418 }
419 
420 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
421 {
422 	struct undef_hook *hook;
423 	unsigned long flags;
424 	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
425 
426 	raw_spin_lock_irqsave(&undef_lock, flags);
427 	list_for_each_entry(hook, &undef_hook, node)
428 		if ((instr & hook->instr_mask) == hook->instr_val &&
429 		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
430 			fn = hook->fn;
431 	raw_spin_unlock_irqrestore(&undef_lock, flags);
432 
433 	return fn ? fn(regs, instr) : 1;
434 }
435 
436 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
437 {
438 	unsigned int instr;
439 	siginfo_t info;
440 	void __user *pc;
441 
442 	pc = (void __user *)instruction_pointer(regs);
443 
444 	if (processor_mode(regs) == SVC_MODE) {
445 #ifdef CONFIG_THUMB2_KERNEL
446 		if (thumb_mode(regs)) {
447 			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
448 			if (is_wide_instruction(instr)) {
449 				u16 inst2;
450 				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
451 				instr = __opcode_thumb32_compose(instr, inst2);
452 			}
453 		} else
454 #endif
455 			instr = __mem_to_opcode_arm(*(u32 *) pc);
456 	} else if (thumb_mode(regs)) {
457 		if (get_user(instr, (u16 __user *)pc))
458 			goto die_sig;
459 		instr = __mem_to_opcode_thumb16(instr);
460 		if (is_wide_instruction(instr)) {
461 			unsigned int instr2;
462 			if (get_user(instr2, (u16 __user *)pc+1))
463 				goto die_sig;
464 			instr2 = __mem_to_opcode_thumb16(instr2);
465 			instr = __opcode_thumb32_compose(instr, instr2);
466 		}
467 	} else {
468 		if (get_user(instr, (u32 __user *)pc))
469 			goto die_sig;
470 		instr = __mem_to_opcode_arm(instr);
471 	}
472 
473 	if (call_undef_hook(regs, instr) == 0)
474 		return;
475 
476 die_sig:
477 #ifdef CONFIG_DEBUG_USER
478 	if (user_debug & UDBG_UNDEFINED) {
479 		pr_info("%s (%d): undefined instruction: pc=%p\n",
480 			current->comm, task_pid_nr(current), pc);
481 		__show_regs(regs);
482 		dump_instr(KERN_INFO, regs);
483 	}
484 #endif
485 
486 	info.si_signo = SIGILL;
487 	info.si_errno = 0;
488 	info.si_code  = ILL_ILLOPC;
489 	info.si_addr  = pc;
490 
491 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
492 }
493 
494 /*
495  * Handle FIQ similarly to NMI on x86 systems.
496  *
497  * The runtime environment for NMIs is extremely restrictive
498  * (NMIs can pre-empt critical sections meaning almost all locking is
499  * forbidden) meaning this default FIQ handling must only be used in
500  * circumstances where non-maskability improves robustness, such as
501  * watchdog or debug logic.
502  *
503  * This handler is not appropriate for general purpose use in drivers
504  * platform code and can be overrideen using set_fiq_handler.
505  */
506 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
507 {
508 	struct pt_regs *old_regs = set_irq_regs(regs);
509 
510 	nmi_enter();
511 
512 	/* nop. FIQ handlers for special arch/arm features can be added here. */
513 
514 	nmi_exit();
515 
516 	set_irq_regs(old_regs);
517 }
518 
519 /*
520  * bad_mode handles the impossible case in the vectors.  If you see one of
521  * these, then it's extremely serious, and could mean you have buggy hardware.
522  * It never returns, and never tries to sync.  We hope that we can at least
523  * dump out some state information...
524  */
525 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
526 {
527 	console_verbose();
528 
529 	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
530 
531 	die("Oops - bad mode", regs, 0);
532 	local_irq_disable();
533 	panic("bad mode");
534 }
535 
536 static int bad_syscall(int n, struct pt_regs *regs)
537 {
538 	siginfo_t info;
539 
540 	if ((current->personality & PER_MASK) != PER_LINUX) {
541 		send_sig(SIGSEGV, current, 1);
542 		return regs->ARM_r0;
543 	}
544 
545 #ifdef CONFIG_DEBUG_USER
546 	if (user_debug & UDBG_SYSCALL) {
547 		pr_err("[%d] %s: obsolete system call %08x.\n",
548 			task_pid_nr(current), current->comm, n);
549 		dump_instr(KERN_ERR, regs);
550 	}
551 #endif
552 
553 	info.si_signo = SIGILL;
554 	info.si_errno = 0;
555 	info.si_code  = ILL_ILLTRP;
556 	info.si_addr  = (void __user *)instruction_pointer(regs) -
557 			 (thumb_mode(regs) ? 2 : 4);
558 
559 	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
560 
561 	return regs->ARM_r0;
562 }
563 
564 static inline int
565 __do_cache_op(unsigned long start, unsigned long end)
566 {
567 	int ret;
568 
569 	do {
570 		unsigned long chunk = min(PAGE_SIZE, end - start);
571 
572 		if (fatal_signal_pending(current))
573 			return 0;
574 
575 		ret = flush_cache_user_range(start, start + chunk);
576 		if (ret)
577 			return ret;
578 
579 		cond_resched();
580 		start += chunk;
581 	} while (start < end);
582 
583 	return 0;
584 }
585 
586 static inline int
587 do_cache_op(unsigned long start, unsigned long end, int flags)
588 {
589 	if (end < start || flags)
590 		return -EINVAL;
591 
592 	if (!access_ok(VERIFY_READ, start, end - start))
593 		return -EFAULT;
594 
595 	return __do_cache_op(start, end);
596 }
597 
598 /*
599  * Handle all unrecognised system calls.
600  *  0x9f0000 - 0x9fffff are some more esoteric system calls
601  */
602 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
603 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
604 {
605 	siginfo_t info;
606 
607 	if ((no >> 16) != (__ARM_NR_BASE>> 16))
608 		return bad_syscall(no, regs);
609 
610 	switch (no & 0xffff) {
611 	case 0: /* branch through 0 */
612 		info.si_signo = SIGSEGV;
613 		info.si_errno = 0;
614 		info.si_code  = SEGV_MAPERR;
615 		info.si_addr  = NULL;
616 
617 		arm_notify_die("branch through zero", regs, &info, 0, 0);
618 		return 0;
619 
620 	case NR(breakpoint): /* SWI BREAK_POINT */
621 		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
622 		ptrace_break(current, regs);
623 		return regs->ARM_r0;
624 
625 	/*
626 	 * Flush a region from virtual address 'r0' to virtual address 'r1'
627 	 * _exclusive_.  There is no alignment requirement on either address;
628 	 * user space does not need to know the hardware cache layout.
629 	 *
630 	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
631 	 * is defined to be something else.  For now we ignore it, but may
632 	 * the fires of hell burn in your belly if you break this rule. ;)
633 	 *
634 	 * (at a later date, we may want to allow this call to not flush
635 	 * various aspects of the cache.  Passing '0' will guarantee that
636 	 * everything necessary gets flushed to maintain consistency in
637 	 * the specified region).
638 	 */
639 	case NR(cacheflush):
640 		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
641 
642 	case NR(usr26):
643 		if (!(elf_hwcap & HWCAP_26BIT))
644 			break;
645 		regs->ARM_cpsr &= ~MODE32_BIT;
646 		return regs->ARM_r0;
647 
648 	case NR(usr32):
649 		if (!(elf_hwcap & HWCAP_26BIT))
650 			break;
651 		regs->ARM_cpsr |= MODE32_BIT;
652 		return regs->ARM_r0;
653 
654 	case NR(set_tls):
655 		set_tls(regs->ARM_r0);
656 		return 0;
657 
658 	case NR(get_tls):
659 		return current_thread_info()->tp_value[0];
660 
661 	default:
662 		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
663 		   if not implemented, rather than raising SIGILL.  This
664 		   way the calling program can gracefully determine whether
665 		   a feature is supported.  */
666 		if ((no & 0xffff) <= 0x7ff)
667 			return -ENOSYS;
668 		break;
669 	}
670 #ifdef CONFIG_DEBUG_USER
671 	/*
672 	 * experience shows that these seem to indicate that
673 	 * something catastrophic has happened
674 	 */
675 	if (user_debug & UDBG_SYSCALL) {
676 		pr_err("[%d] %s: arm syscall %d\n",
677 		       task_pid_nr(current), current->comm, no);
678 		dump_instr("", regs);
679 		if (user_mode(regs)) {
680 			__show_regs(regs);
681 			c_backtrace(frame_pointer(regs), processor_mode(regs));
682 		}
683 	}
684 #endif
685 	info.si_signo = SIGILL;
686 	info.si_errno = 0;
687 	info.si_code  = ILL_ILLTRP;
688 	info.si_addr  = (void __user *)instruction_pointer(regs) -
689 			 (thumb_mode(regs) ? 2 : 4);
690 
691 	arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
692 	return 0;
693 }
694 
695 #ifdef CONFIG_TLS_REG_EMUL
696 
697 /*
698  * We might be running on an ARMv6+ processor which should have the TLS
699  * register but for some reason we can't use it, or maybe an SMP system
700  * using a pre-ARMv6 processor (there are apparently a few prototypes like
701  * that in existence) and therefore access to that register must be
702  * emulated.
703  */
704 
705 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
706 {
707 	int reg = (instr >> 12) & 15;
708 	if (reg == 15)
709 		return 1;
710 	regs->uregs[reg] = current_thread_info()->tp_value[0];
711 	regs->ARM_pc += 4;
712 	return 0;
713 }
714 
715 static struct undef_hook arm_mrc_hook = {
716 	.instr_mask	= 0x0fff0fff,
717 	.instr_val	= 0x0e1d0f70,
718 	.cpsr_mask	= PSR_T_BIT,
719 	.cpsr_val	= 0,
720 	.fn		= get_tp_trap,
721 };
722 
723 static int __init arm_mrc_hook_init(void)
724 {
725 	register_undef_hook(&arm_mrc_hook);
726 	return 0;
727 }
728 
729 late_initcall(arm_mrc_hook_init);
730 
731 #endif
732 
733 /*
734  * A data abort trap was taken, but we did not handle the instruction.
735  * Try to abort the user program, or panic if it was the kernel.
736  */
737 asmlinkage void
738 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
739 {
740 	unsigned long addr = instruction_pointer(regs);
741 	siginfo_t info;
742 
743 #ifdef CONFIG_DEBUG_USER
744 	if (user_debug & UDBG_BADABORT) {
745 		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
746 		       task_pid_nr(current), current->comm, code, instr);
747 		dump_instr(KERN_ERR, regs);
748 		show_pte(current->mm, addr);
749 	}
750 #endif
751 
752 	info.si_signo = SIGILL;
753 	info.si_errno = 0;
754 	info.si_code  = ILL_ILLOPC;
755 	info.si_addr  = (void __user *)addr;
756 
757 	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
758 }
759 
760 void __readwrite_bug(const char *fn)
761 {
762 	pr_err("%s called, but not implemented\n", fn);
763 	BUG();
764 }
765 EXPORT_SYMBOL(__readwrite_bug);
766 
767 void __pte_error(const char *file, int line, pte_t pte)
768 {
769 	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
770 }
771 
772 void __pmd_error(const char *file, int line, pmd_t pmd)
773 {
774 	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
775 }
776 
777 void __pgd_error(const char *file, int line, pgd_t pgd)
778 {
779 	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
780 }
781 
782 asmlinkage void __div0(void)
783 {
784 	pr_err("Division by zero in kernel.\n");
785 	dump_stack();
786 }
787 EXPORT_SYMBOL(__div0);
788 
789 void abort(void)
790 {
791 	BUG();
792 
793 	/* if that doesn't kill us, halt */
794 	panic("Oops failed to kill thread");
795 }
796 EXPORT_SYMBOL(abort);
797 
798 void __init trap_init(void)
799 {
800 	return;
801 }
802 
803 #ifdef CONFIG_KUSER_HELPERS
804 static void __init kuser_init(void *vectors)
805 {
806 	extern char __kuser_helper_start[], __kuser_helper_end[];
807 	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
808 
809 	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
810 
811 	/*
812 	 * vectors + 0xfe0 = __kuser_get_tls
813 	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
814 	 */
815 	if (tls_emu || has_tls_reg)
816 		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
817 }
818 #else
819 static inline void __init kuser_init(void *vectors)
820 {
821 }
822 #endif
823 
824 void __init early_trap_init(void *vectors_base)
825 {
826 #ifndef CONFIG_CPU_V7M
827 	unsigned long vectors = (unsigned long)vectors_base;
828 	extern char __stubs_start[], __stubs_end[];
829 	extern char __vectors_start[], __vectors_end[];
830 	unsigned i;
831 
832 	vectors_page = vectors_base;
833 
834 	/*
835 	 * Poison the vectors page with an undefined instruction.  This
836 	 * instruction is chosen to be undefined for both ARM and Thumb
837 	 * ISAs.  The Thumb version is an undefined instruction with a
838 	 * branch back to the undefined instruction.
839 	 */
840 	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
841 		((u32 *)vectors_base)[i] = 0xe7fddef1;
842 
843 	/*
844 	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
845 	 * into the vector page, mapped at 0xffff0000, and ensure these
846 	 * are visible to the instruction stream.
847 	 */
848 	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
849 	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
850 
851 	kuser_init(vectors_base);
852 
853 	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
854 #else /* ifndef CONFIG_CPU_V7M */
855 	/*
856 	 * on V7-M there is no need to copy the vector table to a dedicated
857 	 * memory area. The address is configurable and so a table in the kernel
858 	 * image can be used.
859 	 */
860 #endif
861 }
862