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