2 * linux/arch/arm/kernel/traps.c
4 * Copyright (C) 1995-2009 Russell King
5 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
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.
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.
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>
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>
36 #include <asm/system_misc.h>
38 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
42 #ifdef CONFIG_DEBUG_USER
43 unsigned int user_debug;
45 static int __init user_debug_setup(char *str)
47 get_option(&str, &user_debug);
50 __setup("user_debug=", user_debug_setup);
53 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
55 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
57 #ifdef CONFIG_KALLSYMS
58 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
60 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
63 if (in_exception_text(where))
64 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
67 #ifndef CONFIG_ARM_UNWIND
69 * Stack pointers should always be within the kernels view of
70 * physical memory. If it is not there, then we can't dump
71 * out any information relating to the stack.
73 static int verify_stack(unsigned long sp)
75 if (sp < PAGE_OFFSET ||
76 (sp > (unsigned long)high_memory && high_memory != NULL))
84 * Dump out the contents of some memory nicely...
86 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
94 * We need to switch to kernel mode so that we can use __get_user
95 * to safely read from kernel space. Note that we now dump the
96 * code first, just in case the backtrace kills us.
101 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
103 for (first = bottom & ~31; first < top; first += 32) {
105 char str[sizeof(" 12345678") * 8 + 1];
107 memset(str, ' ', sizeof(str));
108 str[sizeof(str) - 1] = '\0';
110 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
111 if (p >= bottom && p < top) {
113 if (__get_user(val, (unsigned long *)p) == 0)
114 sprintf(str + i * 9, " %08lx", val);
116 sprintf(str + i * 9, " ????????");
119 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
125 static void dump_instr(const char *lvl, struct pt_regs *regs)
127 unsigned long addr = instruction_pointer(regs);
128 const int thumb = thumb_mode(regs);
129 const int width = thumb ? 4 : 8;
131 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
135 * We need to switch to kernel mode so that we can use __get_user
136 * to safely read from kernel space. Note that we now dump the
137 * code first, just in case the backtrace kills us.
142 for (i = -4; i < 1 + !!thumb; i++) {
143 unsigned int val, bad;
146 bad = __get_user(val, &((u16 *)addr)[i]);
148 bad = __get_user(val, &((u32 *)addr)[i]);
151 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
154 p += sprintf(p, "bad PC value");
158 printk("%sCode: %s\n", lvl, str);
163 #ifdef CONFIG_ARM_UNWIND
164 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
166 unwind_backtrace(regs, tsk);
169 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
171 unsigned int fp, mode;
174 printk("Backtrace: ");
181 mode = processor_mode(regs);
182 } else if (tsk != current) {
183 fp = thread_saved_fp(tsk);
186 asm("mov %0, fp" : "=r" (fp) : : "cc");
191 printk("no frame pointer");
193 } else if (verify_stack(fp)) {
194 printk("invalid frame pointer 0x%08x", fp);
196 } else if (fp < (unsigned long)end_of_stack(tsk))
197 printk("frame pointer underflow");
201 c_backtrace(fp, mode);
205 void show_stack(struct task_struct *tsk, unsigned long *sp)
207 dump_backtrace(NULL, tsk);
211 #ifdef CONFIG_PREEMPT
212 #define S_PREEMPT " PREEMPT"
221 #ifdef CONFIG_THUMB2_KERNEL
222 #define S_ISA " THUMB2"
227 static int __die(const char *str, int err, struct pt_regs *regs)
229 struct task_struct *tsk = current;
230 static int die_counter;
233 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
234 S_ISA "\n", str, err, ++die_counter);
236 /* trap and error numbers are mostly meaningless on ARM */
237 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
238 if (ret == NOTIFY_STOP)
243 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
244 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
246 if (!user_mode(regs) || in_interrupt()) {
247 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
248 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
249 dump_backtrace(regs, tsk);
250 dump_instr(KERN_EMERG, regs);
256 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
257 static int die_owner = -1;
258 static unsigned int die_nest_count;
260 static unsigned long oops_begin(void)
267 /* racy, but better than risking deadlock. */
268 raw_local_irq_save(flags);
269 cpu = smp_processor_id();
270 if (!arch_spin_trylock(&die_lock)) {
271 if (cpu == die_owner)
272 /* nested oops. should stop eventually */;
274 arch_spin_lock(&die_lock);
283 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
285 if (regs && kexec_should_crash(current))
290 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
293 /* Nest count reaches zero, release the lock. */
294 arch_spin_unlock(&die_lock);
295 raw_local_irq_restore(flags);
299 panic("Fatal exception in interrupt");
301 panic("Fatal exception");
307 * This function is protected against re-entrancy.
309 void die(const char *str, struct pt_regs *regs, int err)
311 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
312 unsigned long flags = oops_begin();
315 if (!user_mode(regs))
316 bug_type = report_bug(regs->ARM_pc, regs);
317 if (bug_type != BUG_TRAP_TYPE_NONE)
320 if (__die(str, err, regs))
323 oops_end(flags, regs, sig);
326 void arm_notify_die(const char *str, struct pt_regs *regs,
327 struct siginfo *info, unsigned long err, unsigned long trap)
329 if (user_mode(regs)) {
330 current->thread.error_code = err;
331 current->thread.trap_no = trap;
333 force_sig_info(info->si_signo, info, current);
339 #ifdef CONFIG_GENERIC_BUG
341 int is_valid_bugaddr(unsigned long pc)
343 #ifdef CONFIG_THUMB2_KERNEL
349 if (probe_kernel_address((unsigned *)pc, bkpt))
352 return bkpt == BUG_INSTR_VALUE;
357 static LIST_HEAD(undef_hook);
358 static DEFINE_RAW_SPINLOCK(undef_lock);
360 void register_undef_hook(struct undef_hook *hook)
364 raw_spin_lock_irqsave(&undef_lock, flags);
365 list_add(&hook->node, &undef_hook);
366 raw_spin_unlock_irqrestore(&undef_lock, flags);
369 void unregister_undef_hook(struct undef_hook *hook)
373 raw_spin_lock_irqsave(&undef_lock, flags);
374 list_del(&hook->node);
375 raw_spin_unlock_irqrestore(&undef_lock, flags);
378 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
380 struct undef_hook *hook;
382 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
384 raw_spin_lock_irqsave(&undef_lock, flags);
385 list_for_each_entry(hook, &undef_hook, node)
386 if ((instr & hook->instr_mask) == hook->instr_val &&
387 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
389 raw_spin_unlock_irqrestore(&undef_lock, flags);
391 return fn ? fn(regs, instr) : 1;
394 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
400 pc = (void __user *)instruction_pointer(regs);
402 if (processor_mode(regs) == SVC_MODE) {
403 #ifdef CONFIG_THUMB2_KERNEL
404 if (thumb_mode(regs)) {
405 instr = ((u16 *)pc)[0];
406 if (is_wide_instruction(instr)) {
408 instr |= ((u16 *)pc)[1];
413 } else if (thumb_mode(regs)) {
414 if (get_user(instr, (u16 __user *)pc))
416 if (is_wide_instruction(instr)) {
418 if (get_user(instr2, (u16 __user *)pc+1))
423 } else if (get_user(instr, (u32 __user *)pc)) {
427 if (call_undef_hook(regs, instr) == 0)
431 #ifdef CONFIG_DEBUG_USER
432 if (user_debug & UDBG_UNDEFINED) {
433 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
434 current->comm, task_pid_nr(current), pc);
435 dump_instr(KERN_INFO, regs);
439 info.si_signo = SIGILL;
441 info.si_code = ILL_ILLOPC;
444 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
447 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
449 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
450 printk("You may have a hardware problem...\n");
454 * bad_mode handles the impossible case in the vectors. If you see one of
455 * these, then it's extremely serious, and could mean you have buggy hardware.
456 * It never returns, and never tries to sync. We hope that we can at least
457 * dump out some state information...
459 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
463 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
465 die("Oops - bad mode", regs, 0);
470 static int bad_syscall(int n, struct pt_regs *regs)
472 struct thread_info *thread = current_thread_info();
475 if ((current->personality & PER_MASK) != PER_LINUX &&
476 thread->exec_domain->handler) {
477 thread->exec_domain->handler(n, regs);
481 #ifdef CONFIG_DEBUG_USER
482 if (user_debug & UDBG_SYSCALL) {
483 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
484 task_pid_nr(current), current->comm, n);
485 dump_instr(KERN_ERR, regs);
489 info.si_signo = SIGILL;
491 info.si_code = ILL_ILLTRP;
492 info.si_addr = (void __user *)instruction_pointer(regs) -
493 (thumb_mode(regs) ? 2 : 4);
495 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
500 static long do_cache_op_restart(struct restart_block *);
503 __do_cache_op(unsigned long start, unsigned long end)
506 unsigned long chunk = PAGE_SIZE;
509 if (signal_pending(current)) {
510 struct thread_info *ti = current_thread_info();
512 ti->restart_block = (struct restart_block) {
513 .fn = do_cache_op_restart,
516 ti->arm_restart_block = (struct arm_restart_block) {
525 return -ERESTART_RESTARTBLOCK;
528 ret = flush_cache_user_range(start, start + chunk);
534 } while (start < end);
539 static long do_cache_op_restart(struct restart_block *unused)
541 struct arm_restart_block *restart_block;
543 restart_block = ¤t_thread_info()->arm_restart_block;
544 return __do_cache_op(restart_block->cache.start,
545 restart_block->cache.end);
549 do_cache_op(unsigned long start, unsigned long end, int flags)
551 if (end < start || flags)
554 if (!access_ok(VERIFY_READ, start, end - start))
557 return __do_cache_op(start, end);
561 * Handle all unrecognised system calls.
562 * 0x9f0000 - 0x9fffff are some more esoteric system calls
564 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
565 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
567 struct thread_info *thread = current_thread_info();
570 if ((no >> 16) != (__ARM_NR_BASE>> 16))
571 return bad_syscall(no, regs);
573 switch (no & 0xffff) {
574 case 0: /* branch through 0 */
575 info.si_signo = SIGSEGV;
577 info.si_code = SEGV_MAPERR;
580 arm_notify_die("branch through zero", regs, &info, 0, 0);
583 case NR(breakpoint): /* SWI BREAK_POINT */
584 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
585 ptrace_break(current, regs);
589 * Flush a region from virtual address 'r0' to virtual address 'r1'
590 * _exclusive_. There is no alignment requirement on either address;
591 * user space does not need to know the hardware cache layout.
593 * r2 contains flags. It should ALWAYS be passed as ZERO until it
594 * is defined to be something else. For now we ignore it, but may
595 * the fires of hell burn in your belly if you break this rule. ;)
597 * (at a later date, we may want to allow this call to not flush
598 * various aspects of the cache. Passing '0' will guarantee that
599 * everything necessary gets flushed to maintain consistency in
600 * the specified region).
603 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
606 if (!(elf_hwcap & HWCAP_26BIT))
608 regs->ARM_cpsr &= ~MODE32_BIT;
612 if (!(elf_hwcap & HWCAP_26BIT))
614 regs->ARM_cpsr |= MODE32_BIT;
618 thread->tp_value[0] = regs->ARM_r0;
622 asm ("mcr p15, 0, %0, c13, c0, 3"
623 : : "r" (regs->ARM_r0));
626 * User space must never try to access this directly.
627 * Expect your app to break eventually if you do so.
628 * The user helper at 0xffff0fe0 must be used instead.
629 * (see entry-armv.S for details)
631 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
635 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
637 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
638 * Return zero in r0 if *MEM was changed or non-zero if no exchange
639 * happened. Also set the user C flag accordingly.
640 * If access permissions have to be fixed up then non-zero is
641 * returned and the operation has to be re-attempted.
643 * *NOTE*: This is a ghost syscall private to the kernel. Only the
644 * __kuser_cmpxchg code in entry-armv.S should be aware of its
645 * existence. Don't ever use this from user code.
649 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
650 struct pt_regs *regs);
652 unsigned long addr = regs->ARM_r2;
653 struct mm_struct *mm = current->mm;
654 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
657 regs->ARM_cpsr &= ~PSR_C_BIT;
658 down_read(&mm->mmap_sem);
659 pgd = pgd_offset(mm, addr);
660 if (!pgd_present(*pgd))
662 pmd = pmd_offset(pgd, addr);
663 if (!pmd_present(*pmd))
665 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
666 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
667 pte_unmap_unlock(pte, ptl);
670 val = *(unsigned long *)addr;
673 *(unsigned long *)addr = regs->ARM_r1;
674 regs->ARM_cpsr |= PSR_C_BIT;
676 pte_unmap_unlock(pte, ptl);
677 up_read(&mm->mmap_sem);
681 up_read(&mm->mmap_sem);
682 /* simulate a write access fault */
683 do_DataAbort(addr, 15 + (1 << 11), regs);
688 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
689 if not implemented, rather than raising SIGILL. This
690 way the calling program can gracefully determine whether
691 a feature is supported. */
692 if ((no & 0xffff) <= 0x7ff)
696 #ifdef CONFIG_DEBUG_USER
698 * experience shows that these seem to indicate that
699 * something catastrophic has happened
701 if (user_debug & UDBG_SYSCALL) {
702 printk("[%d] %s: arm syscall %d\n",
703 task_pid_nr(current), current->comm, no);
704 dump_instr("", regs);
705 if (user_mode(regs)) {
707 c_backtrace(regs->ARM_fp, processor_mode(regs));
711 info.si_signo = SIGILL;
713 info.si_code = ILL_ILLTRP;
714 info.si_addr = (void __user *)instruction_pointer(regs) -
715 (thumb_mode(regs) ? 2 : 4);
717 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
721 #ifdef CONFIG_TLS_REG_EMUL
724 * We might be running on an ARMv6+ processor which should have the TLS
725 * register but for some reason we can't use it, or maybe an SMP system
726 * using a pre-ARMv6 processor (there are apparently a few prototypes like
727 * that in existence) and therefore access to that register must be
731 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
733 int reg = (instr >> 12) & 15;
736 regs->uregs[reg] = current_thread_info()->tp_value[0];
741 static struct undef_hook arm_mrc_hook = {
742 .instr_mask = 0x0fff0fff,
743 .instr_val = 0x0e1d0f70,
744 .cpsr_mask = PSR_T_BIT,
749 static int __init arm_mrc_hook_init(void)
751 register_undef_hook(&arm_mrc_hook);
755 late_initcall(arm_mrc_hook_init);
759 void __bad_xchg(volatile void *ptr, int size)
761 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
762 __builtin_return_address(0), ptr, size);
765 EXPORT_SYMBOL(__bad_xchg);
768 * A data abort trap was taken, but we did not handle the instruction.
769 * Try to abort the user program, or panic if it was the kernel.
772 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
774 unsigned long addr = instruction_pointer(regs);
777 #ifdef CONFIG_DEBUG_USER
778 if (user_debug & UDBG_BADABORT) {
779 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
780 task_pid_nr(current), current->comm, code, instr);
781 dump_instr(KERN_ERR, regs);
782 show_pte(current->mm, addr);
786 info.si_signo = SIGILL;
788 info.si_code = ILL_ILLOPC;
789 info.si_addr = (void __user *)addr;
791 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
794 void __readwrite_bug(const char *fn)
796 printk("%s called, but not implemented\n", fn);
799 EXPORT_SYMBOL(__readwrite_bug);
801 void __pte_error(const char *file, int line, pte_t pte)
803 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
806 void __pmd_error(const char *file, int line, pmd_t pmd)
808 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
811 void __pgd_error(const char *file, int line, pgd_t pgd)
813 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
816 asmlinkage void __div0(void)
818 printk("Division by zero in kernel.\n");
821 EXPORT_SYMBOL(__div0);
827 /* if that doesn't kill us, halt */
828 panic("Oops failed to kill thread");
830 EXPORT_SYMBOL(abort);
832 void __init trap_init(void)
837 #ifdef CONFIG_KUSER_HELPERS
838 static void __init kuser_init(void *vectors)
840 extern char __kuser_helper_start[], __kuser_helper_end[];
841 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
843 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
846 * vectors + 0xfe0 = __kuser_get_tls
847 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
849 if (tls_emu || has_tls_reg)
850 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
853 static void __init kuser_init(void *vectors)
858 void __init early_trap_init(void *vectors_base)
860 #ifndef CONFIG_CPU_V7M
861 unsigned long vectors = (unsigned long)vectors_base;
862 extern char __stubs_start[], __stubs_end[];
863 extern char __vectors_start[], __vectors_end[];
866 vectors_page = vectors_base;
869 * Poison the vectors page with an undefined instruction. This
870 * instruction is chosen to be undefined for both ARM and Thumb
871 * ISAs. The Thumb version is an undefined instruction with a
872 * branch back to the undefined instruction.
874 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
875 ((u32 *)vectors_base)[i] = 0xe7fddef1;
878 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
879 * into the vector page, mapped at 0xffff0000, and ensure these
880 * are visible to the instruction stream.
882 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
883 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
885 kuser_init(vectors_base);
887 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
888 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
889 #else /* ifndef CONFIG_CPU_V7M */
891 * on V7-M there is no need to copy the vector table to a dedicated
892 * memory area. The address is configurable and so a table in the kernel