xref: /linux/arch/arm/kernel/traps.c (revision 52338415)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/traps.c
4  *
5  *  Copyright (C) 1995-2009 Russell King
6  *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
7  *
8  *  'traps.c' handles hardware exceptions after we have saved some state in
9  *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
10  *  kill the offending process.
11  */
12 #include <linux/signal.h>
13 #include <linux/personality.h>
14 #include <linux/kallsyms.h>
15 #include <linux/spinlock.h>
16 #include <linux/uaccess.h>
17 #include <linux/hardirq.h>
18 #include <linux/kdebug.h>
19 #include <linux/kprobes.h>
20 #include <linux/module.h>
21 #include <linux/kexec.h>
22 #include <linux/bug.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/sched/signal.h>
26 #include <linux/sched/debug.h>
27 #include <linux/sched/task_stack.h>
28 #include <linux/irq.h>
29 
30 #include <linux/atomic.h>
31 #include <asm/cacheflush.h>
32 #include <asm/exception.h>
33 #include <asm/unistd.h>
34 #include <asm/traps.h>
35 #include <asm/ptrace.h>
36 #include <asm/unwind.h>
37 #include <asm/tls.h>
38 #include <asm/system_misc.h>
39 #include <asm/opcodes.h>
40 
41 
42 static const char *handler[]= {
43 	"prefetch abort",
44 	"data abort",
45 	"address exception",
46 	"interrupt",
47 	"undefined instruction",
48 };
49 
50 void *vectors_page;
51 
52 #ifdef CONFIG_DEBUG_USER
53 unsigned int user_debug;
54 
55 static int __init user_debug_setup(char *str)
56 {
57 	get_option(&str, &user_debug);
58 	return 1;
59 }
60 __setup("user_debug=", user_debug_setup);
61 #endif
62 
63 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
64 
65 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
66 {
67 #ifdef CONFIG_KALLSYMS
68 	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
69 #else
70 	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
71 #endif
72 
73 	if (in_entry_text(from))
74 		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
75 }
76 
77 void dump_backtrace_stm(u32 *stack, u32 instruction)
78 {
79 	char str[80], *p;
80 	unsigned int x;
81 	int reg;
82 
83 	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
84 		if (instruction & BIT(reg)) {
85 			p += sprintf(p, " r%d:%08x", reg, *stack--);
86 			if (++x == 6) {
87 				x = 0;
88 				p = str;
89 				printk("%s\n", str);
90 			}
91 		}
92 	}
93 	if (p != str)
94 		printk("%s\n", str);
95 }
96 
97 #ifndef CONFIG_ARM_UNWIND
98 /*
99  * Stack pointers should always be within the kernels view of
100  * physical memory.  If it is not there, then we can't dump
101  * out any information relating to the stack.
102  */
103 static int verify_stack(unsigned long sp)
104 {
105 	if (sp < PAGE_OFFSET ||
106 	    (sp > (unsigned long)high_memory && high_memory != NULL))
107 		return -EFAULT;
108 
109 	return 0;
110 }
111 #endif
112 
113 /*
114  * Dump out the contents of some memory nicely...
115  */
116 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
117 		     unsigned long top)
118 {
119 	unsigned long first;
120 	mm_segment_t fs;
121 	int i;
122 
123 	/*
124 	 * We need to switch to kernel mode so that we can use __get_user
125 	 * to safely read from kernel space.  Note that we now dump the
126 	 * code first, just in case the backtrace kills us.
127 	 */
128 	fs = get_fs();
129 	set_fs(KERNEL_DS);
130 
131 	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
132 
133 	for (first = bottom & ~31; first < top; first += 32) {
134 		unsigned long p;
135 		char str[sizeof(" 12345678") * 8 + 1];
136 
137 		memset(str, ' ', sizeof(str));
138 		str[sizeof(str) - 1] = '\0';
139 
140 		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
141 			if (p >= bottom && p < top) {
142 				unsigned long val;
143 				if (__get_user(val, (unsigned long *)p) == 0)
144 					sprintf(str + i * 9, " %08lx", val);
145 				else
146 					sprintf(str + i * 9, " ????????");
147 			}
148 		}
149 		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
150 	}
151 
152 	set_fs(fs);
153 }
154 
155 static void __dump_instr(const char *lvl, struct pt_regs *regs)
156 {
157 	unsigned long addr = instruction_pointer(regs);
158 	const int thumb = thumb_mode(regs);
159 	const int width = thumb ? 4 : 8;
160 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
161 	int i;
162 
163 	/*
164 	 * Note that we now dump the code first, just in case the backtrace
165 	 * kills us.
166 	 */
167 
168 	for (i = -4; i < 1 + !!thumb; i++) {
169 		unsigned int val, bad;
170 
171 		if (thumb)
172 			bad = get_user(val, &((u16 *)addr)[i]);
173 		else
174 			bad = get_user(val, &((u32 *)addr)[i]);
175 
176 		if (!bad)
177 			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
178 					width, val);
179 		else {
180 			p += sprintf(p, "bad PC value");
181 			break;
182 		}
183 	}
184 	printk("%sCode: %s\n", lvl, str);
185 }
186 
187 static void dump_instr(const char *lvl, struct pt_regs *regs)
188 {
189 	mm_segment_t fs;
190 
191 	if (!user_mode(regs)) {
192 		fs = get_fs();
193 		set_fs(KERNEL_DS);
194 		__dump_instr(lvl, regs);
195 		set_fs(fs);
196 	} else {
197 		__dump_instr(lvl, regs);
198 	}
199 }
200 
201 #ifdef CONFIG_ARM_UNWIND
202 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
203 {
204 	unwind_backtrace(regs, tsk);
205 }
206 #else
207 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
208 {
209 	unsigned int fp, mode;
210 	int ok = 1;
211 
212 	printk("Backtrace: ");
213 
214 	if (!tsk)
215 		tsk = current;
216 
217 	if (regs) {
218 		fp = frame_pointer(regs);
219 		mode = processor_mode(regs);
220 	} else if (tsk != current) {
221 		fp = thread_saved_fp(tsk);
222 		mode = 0x10;
223 	} else {
224 		asm("mov %0, fp" : "=r" (fp) : : "cc");
225 		mode = 0x10;
226 	}
227 
228 	if (!fp) {
229 		pr_cont("no frame pointer");
230 		ok = 0;
231 	} else if (verify_stack(fp)) {
232 		pr_cont("invalid frame pointer 0x%08x", fp);
233 		ok = 0;
234 	} else if (fp < (unsigned long)end_of_stack(tsk))
235 		pr_cont("frame pointer underflow");
236 	pr_cont("\n");
237 
238 	if (ok)
239 		c_backtrace(fp, mode);
240 }
241 #endif
242 
243 void show_stack(struct task_struct *tsk, unsigned long *sp)
244 {
245 	dump_backtrace(NULL, tsk);
246 	barrier();
247 }
248 
249 #ifdef CONFIG_PREEMPT
250 #define S_PREEMPT " PREEMPT"
251 #else
252 #define S_PREEMPT ""
253 #endif
254 #ifdef CONFIG_SMP
255 #define S_SMP " SMP"
256 #else
257 #define S_SMP ""
258 #endif
259 #ifdef CONFIG_THUMB2_KERNEL
260 #define S_ISA " THUMB2"
261 #else
262 #define S_ISA " ARM"
263 #endif
264 
265 static int __die(const char *str, int err, struct pt_regs *regs)
266 {
267 	struct task_struct *tsk = current;
268 	static int die_counter;
269 	int ret;
270 
271 	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
272 	         str, err, ++die_counter);
273 
274 	/* trap and error numbers are mostly meaningless on ARM */
275 	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
276 	if (ret == NOTIFY_STOP)
277 		return 1;
278 
279 	print_modules();
280 	__show_regs(regs);
281 	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
282 		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
283 
284 	if (!user_mode(regs) || in_interrupt()) {
285 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
286 			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
287 		dump_backtrace(regs, tsk);
288 		dump_instr(KERN_EMERG, regs);
289 	}
290 
291 	return 0;
292 }
293 
294 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
295 static int die_owner = -1;
296 static unsigned int die_nest_count;
297 
298 static unsigned long oops_begin(void)
299 {
300 	int cpu;
301 	unsigned long flags;
302 
303 	oops_enter();
304 
305 	/* racy, but better than risking deadlock. */
306 	raw_local_irq_save(flags);
307 	cpu = smp_processor_id();
308 	if (!arch_spin_trylock(&die_lock)) {
309 		if (cpu == die_owner)
310 			/* nested oops. should stop eventually */;
311 		else
312 			arch_spin_lock(&die_lock);
313 	}
314 	die_nest_count++;
315 	die_owner = cpu;
316 	console_verbose();
317 	bust_spinlocks(1);
318 	return flags;
319 }
320 
321 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
322 {
323 	if (regs && kexec_should_crash(current))
324 		crash_kexec(regs);
325 
326 	bust_spinlocks(0);
327 	die_owner = -1;
328 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
329 	die_nest_count--;
330 	if (!die_nest_count)
331 		/* Nest count reaches zero, release the lock. */
332 		arch_spin_unlock(&die_lock);
333 	raw_local_irq_restore(flags);
334 	oops_exit();
335 
336 	if (in_interrupt())
337 		panic("Fatal exception in interrupt");
338 	if (panic_on_oops)
339 		panic("Fatal exception");
340 	if (signr)
341 		do_exit(signr);
342 }
343 
344 /*
345  * This function is protected against re-entrancy.
346  */
347 void die(const char *str, struct pt_regs *regs, int err)
348 {
349 	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
350 	unsigned long flags = oops_begin();
351 	int sig = SIGSEGV;
352 
353 	if (!user_mode(regs))
354 		bug_type = report_bug(regs->ARM_pc, regs);
355 	if (bug_type != BUG_TRAP_TYPE_NONE)
356 		str = "Oops - BUG";
357 
358 	if (__die(str, err, regs))
359 		sig = 0;
360 
361 	oops_end(flags, regs, sig);
362 }
363 
364 void arm_notify_die(const char *str, struct pt_regs *regs,
365 		int signo, int si_code, void __user *addr,
366 		unsigned long err, unsigned long trap)
367 {
368 	if (user_mode(regs)) {
369 		current->thread.error_code = err;
370 		current->thread.trap_no = trap;
371 
372 		force_sig_fault(signo, si_code, addr);
373 	} else {
374 		die(str, regs, err);
375 	}
376 }
377 
378 #ifdef CONFIG_GENERIC_BUG
379 
380 int is_valid_bugaddr(unsigned long pc)
381 {
382 #ifdef CONFIG_THUMB2_KERNEL
383 	u16 bkpt;
384 	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
385 #else
386 	u32 bkpt;
387 	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
388 #endif
389 
390 	if (probe_kernel_address((unsigned *)pc, bkpt))
391 		return 0;
392 
393 	return bkpt == insn;
394 }
395 
396 #endif
397 
398 static LIST_HEAD(undef_hook);
399 static DEFINE_RAW_SPINLOCK(undef_lock);
400 
401 void register_undef_hook(struct undef_hook *hook)
402 {
403 	unsigned long flags;
404 
405 	raw_spin_lock_irqsave(&undef_lock, flags);
406 	list_add(&hook->node, &undef_hook);
407 	raw_spin_unlock_irqrestore(&undef_lock, flags);
408 }
409 
410 void unregister_undef_hook(struct undef_hook *hook)
411 {
412 	unsigned long flags;
413 
414 	raw_spin_lock_irqsave(&undef_lock, flags);
415 	list_del(&hook->node);
416 	raw_spin_unlock_irqrestore(&undef_lock, flags);
417 }
418 
419 static nokprobe_inline
420 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 do_undefinstr(struct pt_regs *regs)
437 {
438 	unsigned int instr;
439 	void __user *pc;
440 
441 	pc = (void __user *)instruction_pointer(regs);
442 
443 	if (processor_mode(regs) == SVC_MODE) {
444 #ifdef CONFIG_THUMB2_KERNEL
445 		if (thumb_mode(regs)) {
446 			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
447 			if (is_wide_instruction(instr)) {
448 				u16 inst2;
449 				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
450 				instr = __opcode_thumb32_compose(instr, inst2);
451 			}
452 		} else
453 #endif
454 			instr = __mem_to_opcode_arm(*(u32 *) pc);
455 	} else if (thumb_mode(regs)) {
456 		if (get_user(instr, (u16 __user *)pc))
457 			goto die_sig;
458 		instr = __mem_to_opcode_thumb16(instr);
459 		if (is_wide_instruction(instr)) {
460 			unsigned int instr2;
461 			if (get_user(instr2, (u16 __user *)pc+1))
462 				goto die_sig;
463 			instr2 = __mem_to_opcode_thumb16(instr2);
464 			instr = __opcode_thumb32_compose(instr, instr2);
465 		}
466 	} else {
467 		if (get_user(instr, (u32 __user *)pc))
468 			goto die_sig;
469 		instr = __mem_to_opcode_arm(instr);
470 	}
471 
472 	if (call_undef_hook(regs, instr) == 0)
473 		return;
474 
475 die_sig:
476 #ifdef CONFIG_DEBUG_USER
477 	if (user_debug & UDBG_UNDEFINED) {
478 		pr_info("%s (%d): undefined instruction: pc=%p\n",
479 			current->comm, task_pid_nr(current), pc);
480 		__show_regs(regs);
481 		dump_instr(KERN_INFO, regs);
482 	}
483 #endif
484 	arm_notify_die("Oops - undefined instruction", regs,
485 		       SIGILL, ILL_ILLOPC, pc, 0, 6);
486 }
487 NOKPROBE_SYMBOL(do_undefinstr)
488 
489 /*
490  * Handle FIQ similarly to NMI on x86 systems.
491  *
492  * The runtime environment for NMIs is extremely restrictive
493  * (NMIs can pre-empt critical sections meaning almost all locking is
494  * forbidden) meaning this default FIQ handling must only be used in
495  * circumstances where non-maskability improves robustness, such as
496  * watchdog or debug logic.
497  *
498  * This handler is not appropriate for general purpose use in drivers
499  * platform code and can be overrideen using set_fiq_handler.
500  */
501 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
502 {
503 	struct pt_regs *old_regs = set_irq_regs(regs);
504 
505 	nmi_enter();
506 
507 	/* nop. FIQ handlers for special arch/arm features can be added here. */
508 
509 	nmi_exit();
510 
511 	set_irq_regs(old_regs);
512 }
513 
514 /*
515  * bad_mode handles the impossible case in the vectors.  If you see one of
516  * these, then it's extremely serious, and could mean you have buggy hardware.
517  * It never returns, and never tries to sync.  We hope that we can at least
518  * dump out some state information...
519  */
520 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
521 {
522 	console_verbose();
523 
524 	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
525 
526 	die("Oops - bad mode", regs, 0);
527 	local_irq_disable();
528 	panic("bad mode");
529 }
530 
531 static int bad_syscall(int n, struct pt_regs *regs)
532 {
533 	if ((current->personality & PER_MASK) != PER_LINUX) {
534 		send_sig(SIGSEGV, current, 1);
535 		return regs->ARM_r0;
536 	}
537 
538 #ifdef CONFIG_DEBUG_USER
539 	if (user_debug & UDBG_SYSCALL) {
540 		pr_err("[%d] %s: obsolete system call %08x.\n",
541 			task_pid_nr(current), current->comm, n);
542 		dump_instr(KERN_ERR, regs);
543 	}
544 #endif
545 
546 	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
547 		       (void __user *)instruction_pointer(regs) -
548 			 (thumb_mode(regs) ? 2 : 4),
549 		       n, 0);
550 
551 	return regs->ARM_r0;
552 }
553 
554 static inline int
555 __do_cache_op(unsigned long start, unsigned long end)
556 {
557 	int ret;
558 
559 	do {
560 		unsigned long chunk = min(PAGE_SIZE, end - start);
561 
562 		if (fatal_signal_pending(current))
563 			return 0;
564 
565 		ret = flush_cache_user_range(start, start + chunk);
566 		if (ret)
567 			return ret;
568 
569 		cond_resched();
570 		start += chunk;
571 	} while (start < end);
572 
573 	return 0;
574 }
575 
576 static inline int
577 do_cache_op(unsigned long start, unsigned long end, int flags)
578 {
579 	if (end < start || flags)
580 		return -EINVAL;
581 
582 	if (!access_ok(start, end - start))
583 		return -EFAULT;
584 
585 	return __do_cache_op(start, end);
586 }
587 
588 /*
589  * Handle all unrecognised system calls.
590  *  0x9f0000 - 0x9fffff are some more esoteric system calls
591  */
592 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
593 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
594 {
595 	if ((no >> 16) != (__ARM_NR_BASE>> 16))
596 		return bad_syscall(no, regs);
597 
598 	switch (no & 0xffff) {
599 	case 0: /* branch through 0 */
600 		arm_notify_die("branch through zero", regs,
601 			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
602 		return 0;
603 
604 	case NR(breakpoint): /* SWI BREAK_POINT */
605 		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
606 		ptrace_break(regs);
607 		return regs->ARM_r0;
608 
609 	/*
610 	 * Flush a region from virtual address 'r0' to virtual address 'r1'
611 	 * _exclusive_.  There is no alignment requirement on either address;
612 	 * user space does not need to know the hardware cache layout.
613 	 *
614 	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
615 	 * is defined to be something else.  For now we ignore it, but may
616 	 * the fires of hell burn in your belly if you break this rule. ;)
617 	 *
618 	 * (at a later date, we may want to allow this call to not flush
619 	 * various aspects of the cache.  Passing '0' will guarantee that
620 	 * everything necessary gets flushed to maintain consistency in
621 	 * the specified region).
622 	 */
623 	case NR(cacheflush):
624 		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
625 
626 	case NR(usr26):
627 		if (!(elf_hwcap & HWCAP_26BIT))
628 			break;
629 		regs->ARM_cpsr &= ~MODE32_BIT;
630 		return regs->ARM_r0;
631 
632 	case NR(usr32):
633 		if (!(elf_hwcap & HWCAP_26BIT))
634 			break;
635 		regs->ARM_cpsr |= MODE32_BIT;
636 		return regs->ARM_r0;
637 
638 	case NR(set_tls):
639 		set_tls(regs->ARM_r0);
640 		return 0;
641 
642 	case NR(get_tls):
643 		return current_thread_info()->tp_value[0];
644 
645 	default:
646 		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
647 		   if not implemented, rather than raising SIGILL.  This
648 		   way the calling program can gracefully determine whether
649 		   a feature is supported.  */
650 		if ((no & 0xffff) <= 0x7ff)
651 			return -ENOSYS;
652 		break;
653 	}
654 #ifdef CONFIG_DEBUG_USER
655 	/*
656 	 * experience shows that these seem to indicate that
657 	 * something catastrophic has happened
658 	 */
659 	if (user_debug & UDBG_SYSCALL) {
660 		pr_err("[%d] %s: arm syscall %d\n",
661 		       task_pid_nr(current), current->comm, no);
662 		dump_instr("", regs);
663 		if (user_mode(regs)) {
664 			__show_regs(regs);
665 			c_backtrace(frame_pointer(regs), processor_mode(regs));
666 		}
667 	}
668 #endif
669 	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
670 		       (void __user *)instruction_pointer(regs) -
671 			 (thumb_mode(regs) ? 2 : 4),
672 		       no, 0);
673 	return 0;
674 }
675 
676 #ifdef CONFIG_TLS_REG_EMUL
677 
678 /*
679  * We might be running on an ARMv6+ processor which should have the TLS
680  * register but for some reason we can't use it, or maybe an SMP system
681  * using a pre-ARMv6 processor (there are apparently a few prototypes like
682  * that in existence) and therefore access to that register must be
683  * emulated.
684  */
685 
686 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
687 {
688 	int reg = (instr >> 12) & 15;
689 	if (reg == 15)
690 		return 1;
691 	regs->uregs[reg] = current_thread_info()->tp_value[0];
692 	regs->ARM_pc += 4;
693 	return 0;
694 }
695 
696 static struct undef_hook arm_mrc_hook = {
697 	.instr_mask	= 0x0fff0fff,
698 	.instr_val	= 0x0e1d0f70,
699 	.cpsr_mask	= PSR_T_BIT,
700 	.cpsr_val	= 0,
701 	.fn		= get_tp_trap,
702 };
703 
704 static int __init arm_mrc_hook_init(void)
705 {
706 	register_undef_hook(&arm_mrc_hook);
707 	return 0;
708 }
709 
710 late_initcall(arm_mrc_hook_init);
711 
712 #endif
713 
714 /*
715  * A data abort trap was taken, but we did not handle the instruction.
716  * Try to abort the user program, or panic if it was the kernel.
717  */
718 asmlinkage void
719 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
720 {
721 	unsigned long addr = instruction_pointer(regs);
722 
723 #ifdef CONFIG_DEBUG_USER
724 	if (user_debug & UDBG_BADABORT) {
725 		pr_err("8<--- cut here ---\n");
726 		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
727 		       task_pid_nr(current), current->comm, code, instr);
728 		dump_instr(KERN_ERR, regs);
729 		show_pte(KERN_ERR, current->mm, addr);
730 	}
731 #endif
732 
733 	arm_notify_die("unknown data abort code", regs,
734 		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
735 }
736 
737 void __readwrite_bug(const char *fn)
738 {
739 	pr_err("%s called, but not implemented\n", fn);
740 	BUG();
741 }
742 EXPORT_SYMBOL(__readwrite_bug);
743 
744 void __pte_error(const char *file, int line, pte_t pte)
745 {
746 	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
747 }
748 
749 void __pmd_error(const char *file, int line, pmd_t pmd)
750 {
751 	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
752 }
753 
754 void __pgd_error(const char *file, int line, pgd_t pgd)
755 {
756 	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
757 }
758 
759 asmlinkage void __div0(void)
760 {
761 	pr_err("Division by zero in kernel.\n");
762 	dump_stack();
763 }
764 EXPORT_SYMBOL(__div0);
765 
766 void abort(void)
767 {
768 	BUG();
769 
770 	/* if that doesn't kill us, halt */
771 	panic("Oops failed to kill thread");
772 }
773 
774 void __init trap_init(void)
775 {
776 	return;
777 }
778 
779 #ifdef CONFIG_KUSER_HELPERS
780 static void __init kuser_init(void *vectors)
781 {
782 	extern char __kuser_helper_start[], __kuser_helper_end[];
783 	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
784 
785 	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
786 
787 	/*
788 	 * vectors + 0xfe0 = __kuser_get_tls
789 	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
790 	 */
791 	if (tls_emu || has_tls_reg)
792 		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
793 }
794 #else
795 static inline void __init kuser_init(void *vectors)
796 {
797 }
798 #endif
799 
800 void __init early_trap_init(void *vectors_base)
801 {
802 #ifndef CONFIG_CPU_V7M
803 	unsigned long vectors = (unsigned long)vectors_base;
804 	extern char __stubs_start[], __stubs_end[];
805 	extern char __vectors_start[], __vectors_end[];
806 	unsigned i;
807 
808 	vectors_page = vectors_base;
809 
810 	/*
811 	 * Poison the vectors page with an undefined instruction.  This
812 	 * instruction is chosen to be undefined for both ARM and Thumb
813 	 * ISAs.  The Thumb version is an undefined instruction with a
814 	 * branch back to the undefined instruction.
815 	 */
816 	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
817 		((u32 *)vectors_base)[i] = 0xe7fddef1;
818 
819 	/*
820 	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
821 	 * into the vector page, mapped at 0xffff0000, and ensure these
822 	 * are visible to the instruction stream.
823 	 */
824 	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
825 	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
826 
827 	kuser_init(vectors_base);
828 
829 	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
830 #else /* ifndef CONFIG_CPU_V7M */
831 	/*
832 	 * on V7-M there is no need to copy the vector table to a dedicated
833 	 * memory area. The address is configurable and so a table in the kernel
834 	 * image can be used.
835 	 */
836 #endif
837 }
838