xref: /linux/arch/arm/kernel/traps.c (revision d91517839e5d95adc0cf4b28caa7af62a71de526)
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.h>
28 
29 #include <linux/atomic.h>
30 #include <asm/cacheflush.h>
31 #include <asm/exception.h>
32 #include <asm/unistd.h>
33 #include <asm/traps.h>
34 #include <asm/unwind.h>
35 #include <asm/tls.h>
36 #include <asm/system_misc.h>
37 #include <asm/opcodes.h>
38 
39 static const char *handler[]= {
40 	"prefetch abort",
41 	"data abort",
42 	"address exception",
43 	"interrupt",
44 	"undefined instruction",
45 };
46 
47 void *vectors_page;
48 
49 #ifdef CONFIG_DEBUG_USER
50 unsigned int user_debug;
51 
52 static int __init user_debug_setup(char *str)
53 {
54 	get_option(&str, &user_debug);
55 	return 1;
56 }
57 __setup("user_debug=", user_debug_setup);
58 #endif
59 
60 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
61 
62 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
63 {
64 #ifdef CONFIG_KALLSYMS
65 	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
66 #else
67 	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
68 #endif
69 
70 	if (in_exception_text(where))
71 		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
72 }
73 
74 #ifndef CONFIG_ARM_UNWIND
75 /*
76  * Stack pointers should always be within the kernels view of
77  * physical memory.  If it is not there, then we can't dump
78  * out any information relating to the stack.
79  */
80 static int verify_stack(unsigned long sp)
81 {
82 	if (sp < PAGE_OFFSET ||
83 	    (sp > (unsigned long)high_memory && high_memory != NULL))
84 		return -EFAULT;
85 
86 	return 0;
87 }
88 #endif
89 
90 /*
91  * Dump out the contents of some memory nicely...
92  */
93 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
94 		     unsigned long top)
95 {
96 	unsigned long first;
97 	mm_segment_t fs;
98 	int i;
99 
100 	/*
101 	 * We need to switch to kernel mode so that we can use __get_user
102 	 * to safely read from kernel space.  Note that we now dump the
103 	 * code first, just in case the backtrace kills us.
104 	 */
105 	fs = get_fs();
106 	set_fs(KERNEL_DS);
107 
108 	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
109 
110 	for (first = bottom & ~31; first < top; first += 32) {
111 		unsigned long p;
112 		char str[sizeof(" 12345678") * 8 + 1];
113 
114 		memset(str, ' ', sizeof(str));
115 		str[sizeof(str) - 1] = '\0';
116 
117 		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
118 			if (p >= bottom && p < top) {
119 				unsigned long val;
120 				if (__get_user(val, (unsigned long *)p) == 0)
121 					sprintf(str + i * 9, " %08lx", val);
122 				else
123 					sprintf(str + i * 9, " ????????");
124 			}
125 		}
126 		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
127 	}
128 
129 	set_fs(fs);
130 }
131 
132 static void dump_instr(const char *lvl, struct pt_regs *regs)
133 {
134 	unsigned long addr = instruction_pointer(regs);
135 	const int thumb = thumb_mode(regs);
136 	const int width = thumb ? 4 : 8;
137 	mm_segment_t fs;
138 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
139 	int i;
140 
141 	/*
142 	 * We need to switch to kernel mode so that we can use __get_user
143 	 * to safely read from kernel space.  Note that we now dump the
144 	 * code first, just in case the backtrace kills us.
145 	 */
146 	fs = get_fs();
147 	set_fs(KERNEL_DS);
148 
149 	for (i = -4; i < 1 + !!thumb; i++) {
150 		unsigned int val, bad;
151 
152 		if (thumb)
153 			bad = __get_user(val, &((u16 *)addr)[i]);
154 		else
155 			bad = __get_user(val, &((u32 *)addr)[i]);
156 
157 		if (!bad)
158 			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
159 					width, val);
160 		else {
161 			p += sprintf(p, "bad PC value");
162 			break;
163 		}
164 	}
165 	printk("%sCode: %s\n", lvl, str);
166 
167 	set_fs(fs);
168 }
169 
170 #ifdef CONFIG_ARM_UNWIND
171 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172 {
173 	unwind_backtrace(regs, tsk);
174 }
175 #else
176 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
177 {
178 	unsigned int fp, mode;
179 	int ok = 1;
180 
181 	printk("Backtrace: ");
182 
183 	if (!tsk)
184 		tsk = current;
185 
186 	if (regs) {
187 		fp = regs->ARM_fp;
188 		mode = processor_mode(regs);
189 	} else if (tsk != current) {
190 		fp = thread_saved_fp(tsk);
191 		mode = 0x10;
192 	} else {
193 		asm("mov %0, fp" : "=r" (fp) : : "cc");
194 		mode = 0x10;
195 	}
196 
197 	if (!fp) {
198 		printk("no frame pointer");
199 		ok = 0;
200 	} else if (verify_stack(fp)) {
201 		printk("invalid frame pointer 0x%08x", fp);
202 		ok = 0;
203 	} else if (fp < (unsigned long)end_of_stack(tsk))
204 		printk("frame pointer underflow");
205 	printk("\n");
206 
207 	if (ok)
208 		c_backtrace(fp, mode);
209 }
210 #endif
211 
212 void show_stack(struct task_struct *tsk, unsigned long *sp)
213 {
214 	dump_backtrace(NULL, tsk);
215 	barrier();
216 }
217 
218 #ifdef CONFIG_PREEMPT
219 #define S_PREEMPT " PREEMPT"
220 #else
221 #define S_PREEMPT ""
222 #endif
223 #ifdef CONFIG_SMP
224 #define S_SMP " SMP"
225 #else
226 #define S_SMP ""
227 #endif
228 #ifdef CONFIG_THUMB2_KERNEL
229 #define S_ISA " THUMB2"
230 #else
231 #define S_ISA " ARM"
232 #endif
233 
234 static int __die(const char *str, int err, struct pt_regs *regs)
235 {
236 	struct task_struct *tsk = current;
237 	static int die_counter;
238 	int ret;
239 
240 	printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
241 	       S_ISA "\n", str, err, ++die_counter);
242 
243 	/* trap and error numbers are mostly meaningless on ARM */
244 	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
245 	if (ret == NOTIFY_STOP)
246 		return 1;
247 
248 	print_modules();
249 	__show_regs(regs);
250 	printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
251 		TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
252 
253 	if (!user_mode(regs) || in_interrupt()) {
254 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
255 			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
256 		dump_backtrace(regs, tsk);
257 		dump_instr(KERN_EMERG, regs);
258 	}
259 
260 	return 0;
261 }
262 
263 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
264 static int die_owner = -1;
265 static unsigned int die_nest_count;
266 
267 static unsigned long oops_begin(void)
268 {
269 	int cpu;
270 	unsigned long flags;
271 
272 	oops_enter();
273 
274 	/* racy, but better than risking deadlock. */
275 	raw_local_irq_save(flags);
276 	cpu = smp_processor_id();
277 	if (!arch_spin_trylock(&die_lock)) {
278 		if (cpu == die_owner)
279 			/* nested oops. should stop eventually */;
280 		else
281 			arch_spin_lock(&die_lock);
282 	}
283 	die_nest_count++;
284 	die_owner = cpu;
285 	console_verbose();
286 	bust_spinlocks(1);
287 	return flags;
288 }
289 
290 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
291 {
292 	if (regs && kexec_should_crash(current))
293 		crash_kexec(regs);
294 
295 	bust_spinlocks(0);
296 	die_owner = -1;
297 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
298 	die_nest_count--;
299 	if (!die_nest_count)
300 		/* Nest count reaches zero, release the lock. */
301 		arch_spin_unlock(&die_lock);
302 	raw_local_irq_restore(flags);
303 	oops_exit();
304 
305 	if (in_interrupt())
306 		panic("Fatal exception in interrupt");
307 	if (panic_on_oops)
308 		panic("Fatal exception");
309 	if (signr)
310 		do_exit(signr);
311 }
312 
313 /*
314  * This function is protected against re-entrancy.
315  */
316 void die(const char *str, struct pt_regs *regs, int err)
317 {
318 	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
319 	unsigned long flags = oops_begin();
320 	int sig = SIGSEGV;
321 
322 	if (!user_mode(regs))
323 		bug_type = report_bug(regs->ARM_pc, regs);
324 	if (bug_type != BUG_TRAP_TYPE_NONE)
325 		str = "Oops - BUG";
326 
327 	if (__die(str, err, regs))
328 		sig = 0;
329 
330 	oops_end(flags, regs, sig);
331 }
332 
333 void arm_notify_die(const char *str, struct pt_regs *regs,
334 		struct siginfo *info, unsigned long err, unsigned long trap)
335 {
336 	if (user_mode(regs)) {
337 		current->thread.error_code = err;
338 		current->thread.trap_no = trap;
339 
340 		force_sig_info(info->si_signo, info, current);
341 	} else {
342 		die(str, regs, err);
343 	}
344 }
345 
346 #ifdef CONFIG_GENERIC_BUG
347 
348 int is_valid_bugaddr(unsigned long pc)
349 {
350 #ifdef CONFIG_THUMB2_KERNEL
351 	u16 bkpt;
352 	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
353 #else
354 	u32 bkpt;
355 	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
356 #endif
357 
358 	if (probe_kernel_address((unsigned *)pc, bkpt))
359 		return 0;
360 
361 	return bkpt == insn;
362 }
363 
364 #endif
365 
366 static LIST_HEAD(undef_hook);
367 static DEFINE_RAW_SPINLOCK(undef_lock);
368 
369 void register_undef_hook(struct undef_hook *hook)
370 {
371 	unsigned long flags;
372 
373 	raw_spin_lock_irqsave(&undef_lock, flags);
374 	list_add(&hook->node, &undef_hook);
375 	raw_spin_unlock_irqrestore(&undef_lock, flags);
376 }
377 
378 void unregister_undef_hook(struct undef_hook *hook)
379 {
380 	unsigned long flags;
381 
382 	raw_spin_lock_irqsave(&undef_lock, flags);
383 	list_del(&hook->node);
384 	raw_spin_unlock_irqrestore(&undef_lock, flags);
385 }
386 
387 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
388 {
389 	struct undef_hook *hook;
390 	unsigned long flags;
391 	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
392 
393 	raw_spin_lock_irqsave(&undef_lock, flags);
394 	list_for_each_entry(hook, &undef_hook, node)
395 		if ((instr & hook->instr_mask) == hook->instr_val &&
396 		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
397 			fn = hook->fn;
398 	raw_spin_unlock_irqrestore(&undef_lock, flags);
399 
400 	return fn ? fn(regs, instr) : 1;
401 }
402 
403 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
404 {
405 	unsigned int instr;
406 	siginfo_t info;
407 	void __user *pc;
408 
409 	pc = (void __user *)instruction_pointer(regs);
410 
411 	if (processor_mode(regs) == SVC_MODE) {
412 #ifdef CONFIG_THUMB2_KERNEL
413 		if (thumb_mode(regs)) {
414 			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
415 			if (is_wide_instruction(instr)) {
416 				u16 inst2;
417 				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
418 				instr = __opcode_thumb32_compose(instr, inst2);
419 			}
420 		} else
421 #endif
422 			instr = __mem_to_opcode_arm(*(u32 *) pc);
423 	} else if (thumb_mode(regs)) {
424 		if (get_user(instr, (u16 __user *)pc))
425 			goto die_sig;
426 		instr = __mem_to_opcode_thumb16(instr);
427 		if (is_wide_instruction(instr)) {
428 			unsigned int instr2;
429 			if (get_user(instr2, (u16 __user *)pc+1))
430 				goto die_sig;
431 			instr2 = __mem_to_opcode_thumb16(instr2);
432 			instr = __opcode_thumb32_compose(instr, instr2);
433 		}
434 	} else {
435 		if (get_user(instr, (u32 __user *)pc))
436 			goto die_sig;
437 		instr = __mem_to_opcode_arm(instr);
438 	}
439 
440 	if (call_undef_hook(regs, instr) == 0)
441 		return;
442 
443 die_sig:
444 #ifdef CONFIG_DEBUG_USER
445 	if (user_debug & UDBG_UNDEFINED) {
446 		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
447 			current->comm, task_pid_nr(current), pc);
448 		dump_instr(KERN_INFO, regs);
449 	}
450 #endif
451 
452 	info.si_signo = SIGILL;
453 	info.si_errno = 0;
454 	info.si_code  = ILL_ILLOPC;
455 	info.si_addr  = pc;
456 
457 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
458 }
459 
460 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
461 {
462 	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
463 	printk("You may have a hardware problem...\n");
464 }
465 
466 /*
467  * bad_mode handles the impossible case in the vectors.  If you see one of
468  * these, then it's extremely serious, and could mean you have buggy hardware.
469  * It never returns, and never tries to sync.  We hope that we can at least
470  * dump out some state information...
471  */
472 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
473 {
474 	console_verbose();
475 
476 	printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
477 
478 	die("Oops - bad mode", regs, 0);
479 	local_irq_disable();
480 	panic("bad mode");
481 }
482 
483 static int bad_syscall(int n, struct pt_regs *regs)
484 {
485 	struct thread_info *thread = current_thread_info();
486 	siginfo_t info;
487 
488 	if ((current->personality & PER_MASK) != PER_LINUX &&
489 	    thread->exec_domain->handler) {
490 		thread->exec_domain->handler(n, regs);
491 		return regs->ARM_r0;
492 	}
493 
494 #ifdef CONFIG_DEBUG_USER
495 	if (user_debug & UDBG_SYSCALL) {
496 		printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
497 			task_pid_nr(current), current->comm, n);
498 		dump_instr(KERN_ERR, regs);
499 	}
500 #endif
501 
502 	info.si_signo = SIGILL;
503 	info.si_errno = 0;
504 	info.si_code  = ILL_ILLTRP;
505 	info.si_addr  = (void __user *)instruction_pointer(regs) -
506 			 (thumb_mode(regs) ? 2 : 4);
507 
508 	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
509 
510 	return regs->ARM_r0;
511 }
512 
513 static long do_cache_op_restart(struct restart_block *);
514 
515 static inline int
516 __do_cache_op(unsigned long start, unsigned long end)
517 {
518 	int ret;
519 
520 	do {
521 		unsigned long chunk = min(PAGE_SIZE, end - start);
522 
523 		if (signal_pending(current)) {
524 			struct thread_info *ti = current_thread_info();
525 
526 			ti->restart_block = (struct restart_block) {
527 				.fn	= do_cache_op_restart,
528 			};
529 
530 			ti->arm_restart_block = (struct arm_restart_block) {
531 				{
532 					.cache = {
533 						.start	= start,
534 						.end	= end,
535 					},
536 				},
537 			};
538 
539 			return -ERESTART_RESTARTBLOCK;
540 		}
541 
542 		ret = flush_cache_user_range(start, start + chunk);
543 		if (ret)
544 			return ret;
545 
546 		cond_resched();
547 		start += chunk;
548 	} while (start < end);
549 
550 	return 0;
551 }
552 
553 static long do_cache_op_restart(struct restart_block *unused)
554 {
555 	struct arm_restart_block *restart_block;
556 
557 	restart_block = &current_thread_info()->arm_restart_block;
558 	return __do_cache_op(restart_block->cache.start,
559 			     restart_block->cache.end);
560 }
561 
562 static inline int
563 do_cache_op(unsigned long start, unsigned long end, int flags)
564 {
565 	if (end < start || flags)
566 		return -EINVAL;
567 
568 	if (!access_ok(VERIFY_READ, start, end - start))
569 		return -EFAULT;
570 
571 	return __do_cache_op(start, end);
572 }
573 
574 /*
575  * Handle all unrecognised system calls.
576  *  0x9f0000 - 0x9fffff are some more esoteric system calls
577  */
578 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
579 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
580 {
581 	struct thread_info *thread = current_thread_info();
582 	siginfo_t info;
583 
584 	if ((no >> 16) != (__ARM_NR_BASE>> 16))
585 		return bad_syscall(no, regs);
586 
587 	switch (no & 0xffff) {
588 	case 0: /* branch through 0 */
589 		info.si_signo = SIGSEGV;
590 		info.si_errno = 0;
591 		info.si_code  = SEGV_MAPERR;
592 		info.si_addr  = NULL;
593 
594 		arm_notify_die("branch through zero", regs, &info, 0, 0);
595 		return 0;
596 
597 	case NR(breakpoint): /* SWI BREAK_POINT */
598 		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
599 		ptrace_break(current, regs);
600 		return regs->ARM_r0;
601 
602 	/*
603 	 * Flush a region from virtual address 'r0' to virtual address 'r1'
604 	 * _exclusive_.  There is no alignment requirement on either address;
605 	 * user space does not need to know the hardware cache layout.
606 	 *
607 	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
608 	 * is defined to be something else.  For now we ignore it, but may
609 	 * the fires of hell burn in your belly if you break this rule. ;)
610 	 *
611 	 * (at a later date, we may want to allow this call to not flush
612 	 * various aspects of the cache.  Passing '0' will guarantee that
613 	 * everything necessary gets flushed to maintain consistency in
614 	 * the specified region).
615 	 */
616 	case NR(cacheflush):
617 		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
618 
619 	case NR(usr26):
620 		if (!(elf_hwcap & HWCAP_26BIT))
621 			break;
622 		regs->ARM_cpsr &= ~MODE32_BIT;
623 		return regs->ARM_r0;
624 
625 	case NR(usr32):
626 		if (!(elf_hwcap & HWCAP_26BIT))
627 			break;
628 		regs->ARM_cpsr |= MODE32_BIT;
629 		return regs->ARM_r0;
630 
631 	case NR(set_tls):
632 		thread->tp_value[0] = regs->ARM_r0;
633 		if (tls_emu)
634 			return 0;
635 		if (has_tls_reg) {
636 			asm ("mcr p15, 0, %0, c13, c0, 3"
637 				: : "r" (regs->ARM_r0));
638 		} else {
639 			/*
640 			 * User space must never try to access this directly.
641 			 * Expect your app to break eventually if you do so.
642 			 * The user helper at 0xffff0fe0 must be used instead.
643 			 * (see entry-armv.S for details)
644 			 */
645 			*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
646 		}
647 		return 0;
648 
649 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
650 	/*
651 	 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
652 	 * Return zero in r0 if *MEM was changed or non-zero if no exchange
653 	 * happened.  Also set the user C flag accordingly.
654 	 * If access permissions have to be fixed up then non-zero is
655 	 * returned and the operation has to be re-attempted.
656 	 *
657 	 * *NOTE*: This is a ghost syscall private to the kernel.  Only the
658 	 * __kuser_cmpxchg code in entry-armv.S should be aware of its
659 	 * existence.  Don't ever use this from user code.
660 	 */
661 	case NR(cmpxchg):
662 	for (;;) {
663 		extern void do_DataAbort(unsigned long addr, unsigned int fsr,
664 					 struct pt_regs *regs);
665 		unsigned long val;
666 		unsigned long addr = regs->ARM_r2;
667 		struct mm_struct *mm = current->mm;
668 		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
669 		spinlock_t *ptl;
670 
671 		regs->ARM_cpsr &= ~PSR_C_BIT;
672 		down_read(&mm->mmap_sem);
673 		pgd = pgd_offset(mm, addr);
674 		if (!pgd_present(*pgd))
675 			goto bad_access;
676 		pmd = pmd_offset(pgd, addr);
677 		if (!pmd_present(*pmd))
678 			goto bad_access;
679 		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
680 		if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
681 			pte_unmap_unlock(pte, ptl);
682 			goto bad_access;
683 		}
684 		val = *(unsigned long *)addr;
685 		val -= regs->ARM_r0;
686 		if (val == 0) {
687 			*(unsigned long *)addr = regs->ARM_r1;
688 			regs->ARM_cpsr |= PSR_C_BIT;
689 		}
690 		pte_unmap_unlock(pte, ptl);
691 		up_read(&mm->mmap_sem);
692 		return val;
693 
694 		bad_access:
695 		up_read(&mm->mmap_sem);
696 		/* simulate a write access fault */
697 		do_DataAbort(addr, 15 + (1 << 11), regs);
698 	}
699 #endif
700 
701 	default:
702 		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
703 		   if not implemented, rather than raising SIGILL.  This
704 		   way the calling program can gracefully determine whether
705 		   a feature is supported.  */
706 		if ((no & 0xffff) <= 0x7ff)
707 			return -ENOSYS;
708 		break;
709 	}
710 #ifdef CONFIG_DEBUG_USER
711 	/*
712 	 * experience shows that these seem to indicate that
713 	 * something catastrophic has happened
714 	 */
715 	if (user_debug & UDBG_SYSCALL) {
716 		printk("[%d] %s: arm syscall %d\n",
717 		       task_pid_nr(current), current->comm, no);
718 		dump_instr("", regs);
719 		if (user_mode(regs)) {
720 			__show_regs(regs);
721 			c_backtrace(regs->ARM_fp, processor_mode(regs));
722 		}
723 	}
724 #endif
725 	info.si_signo = SIGILL;
726 	info.si_errno = 0;
727 	info.si_code  = ILL_ILLTRP;
728 	info.si_addr  = (void __user *)instruction_pointer(regs) -
729 			 (thumb_mode(regs) ? 2 : 4);
730 
731 	arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
732 	return 0;
733 }
734 
735 #ifdef CONFIG_TLS_REG_EMUL
736 
737 /*
738  * We might be running on an ARMv6+ processor which should have the TLS
739  * register but for some reason we can't use it, or maybe an SMP system
740  * using a pre-ARMv6 processor (there are apparently a few prototypes like
741  * that in existence) and therefore access to that register must be
742  * emulated.
743  */
744 
745 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
746 {
747 	int reg = (instr >> 12) & 15;
748 	if (reg == 15)
749 		return 1;
750 	regs->uregs[reg] = current_thread_info()->tp_value[0];
751 	regs->ARM_pc += 4;
752 	return 0;
753 }
754 
755 static struct undef_hook arm_mrc_hook = {
756 	.instr_mask	= 0x0fff0fff,
757 	.instr_val	= 0x0e1d0f70,
758 	.cpsr_mask	= PSR_T_BIT,
759 	.cpsr_val	= 0,
760 	.fn		= get_tp_trap,
761 };
762 
763 static int __init arm_mrc_hook_init(void)
764 {
765 	register_undef_hook(&arm_mrc_hook);
766 	return 0;
767 }
768 
769 late_initcall(arm_mrc_hook_init);
770 
771 #endif
772 
773 void __bad_xchg(volatile void *ptr, int size)
774 {
775 	printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
776 		__builtin_return_address(0), ptr, size);
777 	BUG();
778 }
779 EXPORT_SYMBOL(__bad_xchg);
780 
781 /*
782  * A data abort trap was taken, but we did not handle the instruction.
783  * Try to abort the user program, or panic if it was the kernel.
784  */
785 asmlinkage void
786 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
787 {
788 	unsigned long addr = instruction_pointer(regs);
789 	siginfo_t info;
790 
791 #ifdef CONFIG_DEBUG_USER
792 	if (user_debug & UDBG_BADABORT) {
793 		printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
794 			task_pid_nr(current), current->comm, code, instr);
795 		dump_instr(KERN_ERR, regs);
796 		show_pte(current->mm, addr);
797 	}
798 #endif
799 
800 	info.si_signo = SIGILL;
801 	info.si_errno = 0;
802 	info.si_code  = ILL_ILLOPC;
803 	info.si_addr  = (void __user *)addr;
804 
805 	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
806 }
807 
808 void __readwrite_bug(const char *fn)
809 {
810 	printk("%s called, but not implemented\n", fn);
811 	BUG();
812 }
813 EXPORT_SYMBOL(__readwrite_bug);
814 
815 void __pte_error(const char *file, int line, pte_t pte)
816 {
817 	printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
818 }
819 
820 void __pmd_error(const char *file, int line, pmd_t pmd)
821 {
822 	printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
823 }
824 
825 void __pgd_error(const char *file, int line, pgd_t pgd)
826 {
827 	printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
828 }
829 
830 asmlinkage void __div0(void)
831 {
832 	printk("Division by zero in kernel.\n");
833 	dump_stack();
834 }
835 EXPORT_SYMBOL(__div0);
836 
837 void abort(void)
838 {
839 	BUG();
840 
841 	/* if that doesn't kill us, halt */
842 	panic("Oops failed to kill thread");
843 }
844 EXPORT_SYMBOL(abort);
845 
846 void __init trap_init(void)
847 {
848 	return;
849 }
850 
851 #ifdef CONFIG_KUSER_HELPERS
852 static void __init kuser_init(void *vectors)
853 {
854 	extern char __kuser_helper_start[], __kuser_helper_end[];
855 	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
856 
857 	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
858 
859 	/*
860 	 * vectors + 0xfe0 = __kuser_get_tls
861 	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
862 	 */
863 	if (tls_emu || has_tls_reg)
864 		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
865 }
866 #else
867 static inline void __init kuser_init(void *vectors)
868 {
869 }
870 #endif
871 
872 void __init early_trap_init(void *vectors_base)
873 {
874 #ifndef CONFIG_CPU_V7M
875 	unsigned long vectors = (unsigned long)vectors_base;
876 	extern char __stubs_start[], __stubs_end[];
877 	extern char __vectors_start[], __vectors_end[];
878 	unsigned i;
879 
880 	vectors_page = vectors_base;
881 
882 	/*
883 	 * Poison the vectors page with an undefined instruction.  This
884 	 * instruction is chosen to be undefined for both ARM and Thumb
885 	 * ISAs.  The Thumb version is an undefined instruction with a
886 	 * branch back to the undefined instruction.
887 	 */
888 	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
889 		((u32 *)vectors_base)[i] = 0xe7fddef1;
890 
891 	/*
892 	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
893 	 * into the vector page, mapped at 0xffff0000, and ensure these
894 	 * are visible to the instruction stream.
895 	 */
896 	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
897 	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
898 
899 	kuser_init(vectors_base);
900 
901 	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
902 	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
903 #else /* ifndef CONFIG_CPU_V7M */
904 	/*
905 	 * on V7-M there is no need to copy the vector table to a dedicated
906 	 * memory area. The address is configurable and so a table in the kernel
907 	 * image can be used.
908 	 */
909 #endif
910 }
911