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/ptrace.h>
35 #include <asm/unwind.h>
37 #include <asm/system_misc.h>
38 #include <asm/opcodes.h>
41 static const char *handler[]= {
46 "undefined instruction",
51 #ifdef CONFIG_DEBUG_USER
52 unsigned int user_debug;
54 static int __init user_debug_setup(char *str)
56 get_option(&str, &user_debug);
59 __setup("user_debug=", user_debug_setup);
62 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
64 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
66 #ifdef CONFIG_KALLSYMS
67 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
69 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
72 if (in_exception_text(where))
73 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
76 #ifndef CONFIG_ARM_UNWIND
78 * Stack pointers should always be within the kernels view of
79 * physical memory. If it is not there, then we can't dump
80 * out any information relating to the stack.
82 static int verify_stack(unsigned long sp)
84 if (sp < PAGE_OFFSET ||
85 (sp > (unsigned long)high_memory && high_memory != NULL))
93 * Dump out the contents of some memory nicely...
95 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
103 * We need to switch to kernel mode so that we can use __get_user
104 * to safely read from kernel space. Note that we now dump the
105 * code first, just in case the backtrace kills us.
110 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
112 for (first = bottom & ~31; first < top; first += 32) {
114 char str[sizeof(" 12345678") * 8 + 1];
116 memset(str, ' ', sizeof(str));
117 str[sizeof(str) - 1] = '\0';
119 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
120 if (p >= bottom && p < top) {
122 if (__get_user(val, (unsigned long *)p) == 0)
123 sprintf(str + i * 9, " %08lx", val);
125 sprintf(str + i * 9, " ????????");
128 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
134 static void dump_instr(const char *lvl, struct pt_regs *regs)
136 unsigned long addr = instruction_pointer(regs);
137 const int thumb = thumb_mode(regs);
138 const int width = thumb ? 4 : 8;
140 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
144 * We need to switch to kernel mode so that we can use __get_user
145 * to safely read from kernel space. Note that we now dump the
146 * code first, just in case the backtrace kills us.
151 for (i = -4; i < 1 + !!thumb; i++) {
152 unsigned int val, bad;
155 bad = __get_user(val, &((u16 *)addr)[i]);
157 bad = __get_user(val, &((u32 *)addr)[i]);
160 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
163 p += sprintf(p, "bad PC value");
167 printk("%sCode: %s\n", lvl, str);
172 #ifdef CONFIG_ARM_UNWIND
173 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
175 unwind_backtrace(regs, tsk);
178 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
180 unsigned int fp, mode;
183 printk("Backtrace: ");
189 fp = frame_pointer(regs);
190 mode = processor_mode(regs);
191 } else if (tsk != current) {
192 fp = thread_saved_fp(tsk);
195 asm("mov %0, fp" : "=r" (fp) : : "cc");
200 printk("no frame pointer");
202 } else if (verify_stack(fp)) {
203 printk("invalid frame pointer 0x%08x", fp);
205 } else if (fp < (unsigned long)end_of_stack(tsk))
206 printk("frame pointer underflow");
210 c_backtrace(fp, mode);
214 void show_stack(struct task_struct *tsk, unsigned long *sp)
216 dump_backtrace(NULL, tsk);
220 #ifdef CONFIG_PREEMPT
221 #define S_PREEMPT " PREEMPT"
230 #ifdef CONFIG_THUMB2_KERNEL
231 #define S_ISA " THUMB2"
236 static int __die(const char *str, int err, struct pt_regs *regs)
238 struct task_struct *tsk = current;
239 static int die_counter;
242 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
243 S_ISA "\n", str, err, ++die_counter);
245 /* trap and error numbers are mostly meaningless on ARM */
246 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
247 if (ret == NOTIFY_STOP)
252 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
253 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
255 if (!user_mode(regs) || in_interrupt()) {
256 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
257 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
258 dump_backtrace(regs, tsk);
259 dump_instr(KERN_EMERG, regs);
265 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
266 static int die_owner = -1;
267 static unsigned int die_nest_count;
269 static unsigned long oops_begin(void)
276 /* racy, but better than risking deadlock. */
277 raw_local_irq_save(flags);
278 cpu = smp_processor_id();
279 if (!arch_spin_trylock(&die_lock)) {
280 if (cpu == die_owner)
281 /* nested oops. should stop eventually */;
283 arch_spin_lock(&die_lock);
292 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
294 if (regs && kexec_should_crash(current))
299 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
302 /* Nest count reaches zero, release the lock. */
303 arch_spin_unlock(&die_lock);
304 raw_local_irq_restore(flags);
308 panic("Fatal exception in interrupt");
310 panic("Fatal exception");
316 * This function is protected against re-entrancy.
318 void die(const char *str, struct pt_regs *regs, int err)
320 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
321 unsigned long flags = oops_begin();
324 if (!user_mode(regs))
325 bug_type = report_bug(regs->ARM_pc, regs);
326 if (bug_type != BUG_TRAP_TYPE_NONE)
329 if (__die(str, err, regs))
332 oops_end(flags, regs, sig);
335 void arm_notify_die(const char *str, struct pt_regs *regs,
336 struct siginfo *info, unsigned long err, unsigned long trap)
338 if (user_mode(regs)) {
339 current->thread.error_code = err;
340 current->thread.trap_no = trap;
342 force_sig_info(info->si_signo, info, current);
348 #ifdef CONFIG_GENERIC_BUG
350 int is_valid_bugaddr(unsigned long pc)
352 #ifdef CONFIG_THUMB2_KERNEL
354 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
357 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
360 if (probe_kernel_address((unsigned *)pc, bkpt))
368 static LIST_HEAD(undef_hook);
369 static DEFINE_RAW_SPINLOCK(undef_lock);
371 void register_undef_hook(struct undef_hook *hook)
375 raw_spin_lock_irqsave(&undef_lock, flags);
376 list_add(&hook->node, &undef_hook);
377 raw_spin_unlock_irqrestore(&undef_lock, flags);
380 void unregister_undef_hook(struct undef_hook *hook)
384 raw_spin_lock_irqsave(&undef_lock, flags);
385 list_del(&hook->node);
386 raw_spin_unlock_irqrestore(&undef_lock, flags);
389 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
391 struct undef_hook *hook;
393 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
395 raw_spin_lock_irqsave(&undef_lock, flags);
396 list_for_each_entry(hook, &undef_hook, node)
397 if ((instr & hook->instr_mask) == hook->instr_val &&
398 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
400 raw_spin_unlock_irqrestore(&undef_lock, flags);
402 return fn ? fn(regs, instr) : 1;
405 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
411 pc = (void __user *)instruction_pointer(regs);
413 if (processor_mode(regs) == SVC_MODE) {
414 #ifdef CONFIG_THUMB2_KERNEL
415 if (thumb_mode(regs)) {
416 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
417 if (is_wide_instruction(instr)) {
419 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
420 instr = __opcode_thumb32_compose(instr, inst2);
424 instr = __mem_to_opcode_arm(*(u32 *) pc);
425 } else if (thumb_mode(regs)) {
426 if (get_user(instr, (u16 __user *)pc))
428 instr = __mem_to_opcode_thumb16(instr);
429 if (is_wide_instruction(instr)) {
431 if (get_user(instr2, (u16 __user *)pc+1))
433 instr2 = __mem_to_opcode_thumb16(instr2);
434 instr = __opcode_thumb32_compose(instr, instr2);
437 if (get_user(instr, (u32 __user *)pc))
439 instr = __mem_to_opcode_arm(instr);
442 if (call_undef_hook(regs, instr) == 0)
446 #ifdef CONFIG_DEBUG_USER
447 if (user_debug & UDBG_UNDEFINED) {
448 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
449 current->comm, task_pid_nr(current), pc);
451 dump_instr(KERN_INFO, regs);
455 info.si_signo = SIGILL;
457 info.si_code = ILL_ILLOPC;
460 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
463 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
465 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
466 printk("You may have a hardware problem...\n");
470 * bad_mode handles the impossible case in the vectors. If you see one of
471 * these, then it's extremely serious, and could mean you have buggy hardware.
472 * It never returns, and never tries to sync. We hope that we can at least
473 * dump out some state information...
475 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
479 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
481 die("Oops - bad mode", regs, 0);
486 static int bad_syscall(int n, struct pt_regs *regs)
488 struct thread_info *thread = current_thread_info();
491 if ((current->personality & PER_MASK) != PER_LINUX &&
492 thread->exec_domain->handler) {
493 thread->exec_domain->handler(n, regs);
497 #ifdef CONFIG_DEBUG_USER
498 if (user_debug & UDBG_SYSCALL) {
499 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
500 task_pid_nr(current), current->comm, n);
501 dump_instr(KERN_ERR, regs);
505 info.si_signo = SIGILL;
507 info.si_code = ILL_ILLTRP;
508 info.si_addr = (void __user *)instruction_pointer(regs) -
509 (thumb_mode(regs) ? 2 : 4);
511 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
516 static long do_cache_op_restart(struct restart_block *);
519 __do_cache_op(unsigned long start, unsigned long end)
524 unsigned long chunk = min(PAGE_SIZE, end - start);
526 if (signal_pending(current)) {
527 struct thread_info *ti = current_thread_info();
529 ti->restart_block = (struct restart_block) {
530 .fn = do_cache_op_restart,
533 ti->arm_restart_block = (struct arm_restart_block) {
542 return -ERESTART_RESTARTBLOCK;
545 ret = flush_cache_user_range(start, start + chunk);
551 } while (start < end);
556 static long do_cache_op_restart(struct restart_block *unused)
558 struct arm_restart_block *restart_block;
560 restart_block = ¤t_thread_info()->arm_restart_block;
561 return __do_cache_op(restart_block->cache.start,
562 restart_block->cache.end);
566 do_cache_op(unsigned long start, unsigned long end, int flags)
568 if (end < start || flags)
571 if (!access_ok(VERIFY_READ, start, end - start))
574 return __do_cache_op(start, end);
578 * Handle all unrecognised system calls.
579 * 0x9f0000 - 0x9fffff are some more esoteric system calls
581 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
582 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
584 struct thread_info *thread = current_thread_info();
587 if ((no >> 16) != (__ARM_NR_BASE>> 16))
588 return bad_syscall(no, regs);
590 switch (no & 0xffff) {
591 case 0: /* branch through 0 */
592 info.si_signo = SIGSEGV;
594 info.si_code = SEGV_MAPERR;
597 arm_notify_die("branch through zero", regs, &info, 0, 0);
600 case NR(breakpoint): /* SWI BREAK_POINT */
601 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
602 ptrace_break(current, regs);
606 * Flush a region from virtual address 'r0' to virtual address 'r1'
607 * _exclusive_. There is no alignment requirement on either address;
608 * user space does not need to know the hardware cache layout.
610 * r2 contains flags. It should ALWAYS be passed as ZERO until it
611 * is defined to be something else. For now we ignore it, but may
612 * the fires of hell burn in your belly if you break this rule. ;)
614 * (at a later date, we may want to allow this call to not flush
615 * various aspects of the cache. Passing '0' will guarantee that
616 * everything necessary gets flushed to maintain consistency in
617 * the specified region).
620 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
623 if (!(elf_hwcap & HWCAP_26BIT))
625 regs->ARM_cpsr &= ~MODE32_BIT;
629 if (!(elf_hwcap & HWCAP_26BIT))
631 regs->ARM_cpsr |= MODE32_BIT;
635 thread->tp_value[0] = regs->ARM_r0;
639 asm ("mcr p15, 0, %0, c13, c0, 3"
640 : : "r" (regs->ARM_r0));
643 * User space must never try to access this directly.
644 * Expect your app to break eventually if you do so.
645 * The user helper at 0xffff0fe0 must be used instead.
646 * (see entry-armv.S for details)
648 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
652 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
654 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
655 * Return zero in r0 if *MEM was changed or non-zero if no exchange
656 * happened. Also set the user C flag accordingly.
657 * If access permissions have to be fixed up then non-zero is
658 * returned and the operation has to be re-attempted.
660 * *NOTE*: This is a ghost syscall private to the kernel. Only the
661 * __kuser_cmpxchg code in entry-armv.S should be aware of its
662 * existence. Don't ever use this from user code.
666 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
667 struct pt_regs *regs);
669 unsigned long addr = regs->ARM_r2;
670 struct mm_struct *mm = current->mm;
671 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
674 regs->ARM_cpsr &= ~PSR_C_BIT;
675 down_read(&mm->mmap_sem);
676 pgd = pgd_offset(mm, addr);
677 if (!pgd_present(*pgd))
679 pmd = pmd_offset(pgd, addr);
680 if (!pmd_present(*pmd))
682 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
683 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
684 pte_unmap_unlock(pte, ptl);
687 val = *(unsigned long *)addr;
690 *(unsigned long *)addr = regs->ARM_r1;
691 regs->ARM_cpsr |= PSR_C_BIT;
693 pte_unmap_unlock(pte, ptl);
694 up_read(&mm->mmap_sem);
698 up_read(&mm->mmap_sem);
699 /* simulate a write access fault */
700 do_DataAbort(addr, 15 + (1 << 11), regs);
705 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
706 if not implemented, rather than raising SIGILL. This
707 way the calling program can gracefully determine whether
708 a feature is supported. */
709 if ((no & 0xffff) <= 0x7ff)
713 #ifdef CONFIG_DEBUG_USER
715 * experience shows that these seem to indicate that
716 * something catastrophic has happened
718 if (user_debug & UDBG_SYSCALL) {
719 printk("[%d] %s: arm syscall %d\n",
720 task_pid_nr(current), current->comm, no);
721 dump_instr("", regs);
722 if (user_mode(regs)) {
724 c_backtrace(frame_pointer(regs), processor_mode(regs));
728 info.si_signo = SIGILL;
730 info.si_code = ILL_ILLTRP;
731 info.si_addr = (void __user *)instruction_pointer(regs) -
732 (thumb_mode(regs) ? 2 : 4);
734 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
738 #ifdef CONFIG_TLS_REG_EMUL
741 * We might be running on an ARMv6+ processor which should have the TLS
742 * register but for some reason we can't use it, or maybe an SMP system
743 * using a pre-ARMv6 processor (there are apparently a few prototypes like
744 * that in existence) and therefore access to that register must be
748 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
750 int reg = (instr >> 12) & 15;
753 regs->uregs[reg] = current_thread_info()->tp_value[0];
758 static struct undef_hook arm_mrc_hook = {
759 .instr_mask = 0x0fff0fff,
760 .instr_val = 0x0e1d0f70,
761 .cpsr_mask = PSR_T_BIT,
766 static int __init arm_mrc_hook_init(void)
768 register_undef_hook(&arm_mrc_hook);
772 late_initcall(arm_mrc_hook_init);
776 void __bad_xchg(volatile void *ptr, int size)
778 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
779 __builtin_return_address(0), ptr, size);
782 EXPORT_SYMBOL(__bad_xchg);
785 * A data abort trap was taken, but we did not handle the instruction.
786 * Try to abort the user program, or panic if it was the kernel.
789 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
791 unsigned long addr = instruction_pointer(regs);
794 #ifdef CONFIG_DEBUG_USER
795 if (user_debug & UDBG_BADABORT) {
796 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
797 task_pid_nr(current), current->comm, code, instr);
798 dump_instr(KERN_ERR, regs);
799 show_pte(current->mm, addr);
803 info.si_signo = SIGILL;
805 info.si_code = ILL_ILLOPC;
806 info.si_addr = (void __user *)addr;
808 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
811 void __readwrite_bug(const char *fn)
813 printk("%s called, but not implemented\n", fn);
816 EXPORT_SYMBOL(__readwrite_bug);
818 void __pte_error(const char *file, int line, pte_t pte)
820 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
823 void __pmd_error(const char *file, int line, pmd_t pmd)
825 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
828 void __pgd_error(const char *file, int line, pgd_t pgd)
830 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
833 asmlinkage void __div0(void)
835 printk("Division by zero in kernel.\n");
838 EXPORT_SYMBOL(__div0);
844 /* if that doesn't kill us, halt */
845 panic("Oops failed to kill thread");
847 EXPORT_SYMBOL(abort);
849 void __init trap_init(void)
854 #ifdef CONFIG_KUSER_HELPERS
855 static void __init kuser_init(void *vectors)
857 extern char __kuser_helper_start[], __kuser_helper_end[];
858 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
860 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
863 * vectors + 0xfe0 = __kuser_get_tls
864 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
866 if (tls_emu || has_tls_reg)
867 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
870 static inline void __init kuser_init(void *vectors)
875 void __init early_trap_init(void *vectors_base)
877 #ifndef CONFIG_CPU_V7M
878 unsigned long vectors = (unsigned long)vectors_base;
879 extern char __stubs_start[], __stubs_end[];
880 extern char __vectors_start[], __vectors_end[];
883 vectors_page = vectors_base;
886 * Poison the vectors page with an undefined instruction. This
887 * instruction is chosen to be undefined for both ARM and Thumb
888 * ISAs. The Thumb version is an undefined instruction with a
889 * branch back to the undefined instruction.
891 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
892 ((u32 *)vectors_base)[i] = 0xe7fddef1;
895 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
896 * into the vector page, mapped at 0xffff0000, and ensure these
897 * are visible to the instruction stream.
899 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
900 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
902 kuser_init(vectors_base);
904 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
905 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
906 #else /* ifndef CONFIG_CPU_V7M */
908 * on V7-M there is no need to copy the vector table to a dedicated
909 * memory area. The address is configurable and so a table in the kernel