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/kprobes.h>
23 #include <linux/module.h>
24 #include <linux/kexec.h>
25 #include <linux/bug.h>
26 #include <linux/delay.h>
27 #include <linux/init.h>
28 #include <linux/sched.h>
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/unwind.h>
37 #include <asm/system_misc.h>
38 #include <asm/opcodes.h>
40 static const char *handler[]= {
45 "undefined instruction",
50 #ifdef CONFIG_DEBUG_USER
51 unsigned int user_debug;
53 static int __init user_debug_setup(char *str)
55 get_option(&str, &user_debug);
58 __setup("user_debug=", user_debug_setup);
61 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
63 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
65 #ifdef CONFIG_KALLSYMS
66 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
68 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
71 if (in_exception_text(where))
72 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
75 #ifndef CONFIG_ARM_UNWIND
77 * Stack pointers should always be within the kernels view of
78 * physical memory. If it is not there, then we can't dump
79 * out any information relating to the stack.
81 static int verify_stack(unsigned long sp)
83 if (sp < PAGE_OFFSET ||
84 (sp > (unsigned long)high_memory && high_memory != NULL))
92 * Dump out the contents of some memory nicely...
94 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
102 * We need to switch to kernel mode so that we can use __get_user
103 * to safely read from kernel space. Note that we now dump the
104 * code first, just in case the backtrace kills us.
109 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
111 for (first = bottom & ~31; first < top; first += 32) {
113 char str[sizeof(" 12345678") * 8 + 1];
115 memset(str, ' ', sizeof(str));
116 str[sizeof(str) - 1] = '\0';
118 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
119 if (p >= bottom && p < top) {
121 if (__get_user(val, (unsigned long *)p) == 0)
122 sprintf(str + i * 9, " %08lx", val);
124 sprintf(str + i * 9, " ????????");
127 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
133 static void __dump_instr(const char *lvl, struct pt_regs *regs)
135 unsigned long addr = instruction_pointer(regs);
136 const int thumb = thumb_mode(regs);
137 const int width = thumb ? 4 : 8;
138 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
142 * Note that we now dump the code first, just in case the backtrace
146 for (i = -4; i < 1 + !!thumb; i++) {
147 unsigned int val, bad;
150 bad = get_user(val, &((u16 *)addr)[i]);
152 bad = get_user(val, &((u32 *)addr)[i]);
155 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
158 p += sprintf(p, "bad PC value");
162 printk("%sCode: %s\n", lvl, str);
165 static void dump_instr(const char *lvl, struct pt_regs *regs)
169 if (!user_mode(regs)) {
172 __dump_instr(lvl, regs);
175 __dump_instr(lvl, regs);
179 #ifdef CONFIG_ARM_UNWIND
180 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
182 unwind_backtrace(regs, tsk);
185 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
187 unsigned int fp, mode;
190 printk("Backtrace: ");
197 mode = processor_mode(regs);
198 } else if (tsk != current) {
199 fp = thread_saved_fp(tsk);
202 asm("mov %0, fp" : "=r" (fp) : : "cc");
207 printk("no frame pointer");
209 } else if (verify_stack(fp)) {
210 printk("invalid frame pointer 0x%08x", fp);
212 } else if (fp < (unsigned long)end_of_stack(tsk))
213 printk("frame pointer underflow");
217 c_backtrace(fp, mode);
221 void show_stack(struct task_struct *tsk, unsigned long *sp)
223 dump_backtrace(NULL, tsk);
227 #ifdef CONFIG_PREEMPT
228 #define S_PREEMPT " PREEMPT"
237 #ifdef CONFIG_THUMB2_KERNEL
238 #define S_ISA " THUMB2"
243 static int __die(const char *str, int err, struct pt_regs *regs)
245 struct task_struct *tsk = current;
246 static int die_counter;
249 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
250 S_ISA "\n", str, err, ++die_counter);
252 /* trap and error numbers are mostly meaningless on ARM */
253 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
254 if (ret == NOTIFY_STOP)
259 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
260 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
262 if (!user_mode(regs) || in_interrupt()) {
263 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
264 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
265 dump_backtrace(regs, tsk);
266 dump_instr(KERN_EMERG, regs);
272 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
273 static int die_owner = -1;
274 static unsigned int die_nest_count;
276 static unsigned long oops_begin(void)
283 /* racy, but better than risking deadlock. */
284 raw_local_irq_save(flags);
285 cpu = smp_processor_id();
286 if (!arch_spin_trylock(&die_lock)) {
287 if (cpu == die_owner)
288 /* nested oops. should stop eventually */;
290 arch_spin_lock(&die_lock);
299 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
301 if (regs && kexec_should_crash(current))
306 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
309 /* Nest count reaches zero, release the lock. */
310 arch_spin_unlock(&die_lock);
311 raw_local_irq_restore(flags);
315 panic("Fatal exception in interrupt");
317 panic("Fatal exception");
323 * This function is protected against re-entrancy.
325 void die(const char *str, struct pt_regs *regs, int err)
327 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
328 unsigned long flags = oops_begin();
331 if (!user_mode(regs))
332 bug_type = report_bug(regs->ARM_pc, regs);
333 if (bug_type != BUG_TRAP_TYPE_NONE)
336 if (__die(str, err, regs))
339 oops_end(flags, regs, sig);
342 void arm_notify_die(const char *str, struct pt_regs *regs,
343 struct siginfo *info, unsigned long err, unsigned long trap)
345 if (user_mode(regs)) {
346 current->thread.error_code = err;
347 current->thread.trap_no = trap;
349 force_sig_info(info->si_signo, info, current);
355 #ifdef CONFIG_GENERIC_BUG
357 int is_valid_bugaddr(unsigned long pc)
359 #ifdef CONFIG_THUMB2_KERNEL
361 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
364 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
367 if (probe_kernel_address((unsigned *)pc, bkpt))
375 static LIST_HEAD(undef_hook);
376 static DEFINE_RAW_SPINLOCK(undef_lock);
378 void register_undef_hook(struct undef_hook *hook)
382 raw_spin_lock_irqsave(&undef_lock, flags);
383 list_add(&hook->node, &undef_hook);
384 raw_spin_unlock_irqrestore(&undef_lock, flags);
387 void unregister_undef_hook(struct undef_hook *hook)
391 raw_spin_lock_irqsave(&undef_lock, flags);
392 list_del(&hook->node);
393 raw_spin_unlock_irqrestore(&undef_lock, flags);
396 static nokprobe_inline
397 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
399 struct undef_hook *hook;
401 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
403 raw_spin_lock_irqsave(&undef_lock, flags);
404 list_for_each_entry(hook, &undef_hook, node)
405 if ((instr & hook->instr_mask) == hook->instr_val &&
406 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
408 raw_spin_unlock_irqrestore(&undef_lock, flags);
410 return fn ? fn(regs, instr) : 1;
413 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
419 pc = (void __user *)instruction_pointer(regs);
421 if (processor_mode(regs) == SVC_MODE) {
422 #ifdef CONFIG_THUMB2_KERNEL
423 if (thumb_mode(regs)) {
424 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
425 if (is_wide_instruction(instr)) {
427 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
428 instr = __opcode_thumb32_compose(instr, inst2);
432 instr = __mem_to_opcode_arm(*(u32 *) pc);
433 } else if (thumb_mode(regs)) {
434 if (get_user(instr, (u16 __user *)pc))
436 instr = __mem_to_opcode_thumb16(instr);
437 if (is_wide_instruction(instr)) {
439 if (get_user(instr2, (u16 __user *)pc+1))
441 instr2 = __mem_to_opcode_thumb16(instr2);
442 instr = __opcode_thumb32_compose(instr, instr2);
445 if (get_user(instr, (u32 __user *)pc))
447 instr = __mem_to_opcode_arm(instr);
450 if (call_undef_hook(regs, instr) == 0)
454 #ifdef CONFIG_DEBUG_USER
455 if (user_debug & UDBG_UNDEFINED) {
456 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
457 current->comm, task_pid_nr(current), pc);
459 dump_instr(KERN_INFO, regs);
463 info.si_signo = SIGILL;
465 info.si_code = ILL_ILLOPC;
468 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
470 NOKPROBE_SYMBOL(do_undefinstr)
472 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
474 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
475 printk("You may have a hardware problem...\n");
479 * bad_mode handles the impossible case in the vectors. If you see one of
480 * these, then it's extremely serious, and could mean you have buggy hardware.
481 * It never returns, and never tries to sync. We hope that we can at least
482 * dump out some state information...
484 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
488 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
490 die("Oops - bad mode", regs, 0);
495 static int bad_syscall(int n, struct pt_regs *regs)
497 struct thread_info *thread = current_thread_info();
500 if ((current->personality & PER_MASK) != PER_LINUX &&
501 thread->exec_domain->handler) {
502 thread->exec_domain->handler(n, regs);
506 #ifdef CONFIG_DEBUG_USER
507 if (user_debug & UDBG_SYSCALL) {
508 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
509 task_pid_nr(current), current->comm, n);
510 dump_instr(KERN_ERR, regs);
514 info.si_signo = SIGILL;
516 info.si_code = ILL_ILLTRP;
517 info.si_addr = (void __user *)instruction_pointer(regs) -
518 (thumb_mode(regs) ? 2 : 4);
520 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
526 __do_cache_op(unsigned long start, unsigned long end)
531 unsigned long chunk = min(PAGE_SIZE, end - start);
533 if (fatal_signal_pending(current))
536 ret = flush_cache_user_range(start, start + chunk);
542 } while (start < end);
548 do_cache_op(unsigned long start, unsigned long end, int flags)
550 if (end < start || flags)
553 if (!access_ok(VERIFY_READ, start, end - start))
556 return __do_cache_op(start, end);
560 * Handle all unrecognised system calls.
561 * 0x9f0000 - 0x9fffff are some more esoteric system calls
563 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
564 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
568 if ((no >> 16) != (__ARM_NR_BASE>> 16))
569 return bad_syscall(no, regs);
571 switch (no & 0xffff) {
572 case 0: /* branch through 0 */
573 info.si_signo = SIGSEGV;
575 info.si_code = SEGV_MAPERR;
578 arm_notify_die("branch through zero", regs, &info, 0, 0);
581 case NR(breakpoint): /* SWI BREAK_POINT */
582 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
583 ptrace_break(current, regs);
587 * Flush a region from virtual address 'r0' to virtual address 'r1'
588 * _exclusive_. There is no alignment requirement on either address;
589 * user space does not need to know the hardware cache layout.
591 * r2 contains flags. It should ALWAYS be passed as ZERO until it
592 * is defined to be something else. For now we ignore it, but may
593 * the fires of hell burn in your belly if you break this rule. ;)
595 * (at a later date, we may want to allow this call to not flush
596 * various aspects of the cache. Passing '0' will guarantee that
597 * everything necessary gets flushed to maintain consistency in
598 * the specified region).
601 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
604 if (!(elf_hwcap & HWCAP_26BIT))
606 regs->ARM_cpsr &= ~MODE32_BIT;
610 if (!(elf_hwcap & HWCAP_26BIT))
612 regs->ARM_cpsr |= MODE32_BIT;
616 set_tls(regs->ARM_r0);
619 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
621 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
622 * Return zero in r0 if *MEM was changed or non-zero if no exchange
623 * happened. Also set the user C flag accordingly.
624 * If access permissions have to be fixed up then non-zero is
625 * returned and the operation has to be re-attempted.
627 * *NOTE*: This is a ghost syscall private to the kernel. Only the
628 * __kuser_cmpxchg code in entry-armv.S should be aware of its
629 * existence. Don't ever use this from user code.
633 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
634 struct pt_regs *regs);
636 unsigned long addr = regs->ARM_r2;
637 struct mm_struct *mm = current->mm;
638 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
641 regs->ARM_cpsr &= ~PSR_C_BIT;
642 down_read(&mm->mmap_sem);
643 pgd = pgd_offset(mm, addr);
644 if (!pgd_present(*pgd))
646 pmd = pmd_offset(pgd, addr);
647 if (!pmd_present(*pmd))
649 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
650 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
651 pte_unmap_unlock(pte, ptl);
654 val = *(unsigned long *)addr;
657 *(unsigned long *)addr = regs->ARM_r1;
658 regs->ARM_cpsr |= PSR_C_BIT;
660 pte_unmap_unlock(pte, ptl);
661 up_read(&mm->mmap_sem);
665 up_read(&mm->mmap_sem);
666 /* simulate a write access fault */
667 do_DataAbort(addr, 15 + (1 << 11), regs);
672 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
673 if not implemented, rather than raising SIGILL. This
674 way the calling program can gracefully determine whether
675 a feature is supported. */
676 if ((no & 0xffff) <= 0x7ff)
680 #ifdef CONFIG_DEBUG_USER
682 * experience shows that these seem to indicate that
683 * something catastrophic has happened
685 if (user_debug & UDBG_SYSCALL) {
686 printk("[%d] %s: arm syscall %d\n",
687 task_pid_nr(current), current->comm, no);
688 dump_instr("", regs);
689 if (user_mode(regs)) {
691 c_backtrace(regs->ARM_fp, processor_mode(regs));
695 info.si_signo = SIGILL;
697 info.si_code = ILL_ILLTRP;
698 info.si_addr = (void __user *)instruction_pointer(regs) -
699 (thumb_mode(regs) ? 2 : 4);
701 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
705 #ifdef CONFIG_TLS_REG_EMUL
708 * We might be running on an ARMv6+ processor which should have the TLS
709 * register but for some reason we can't use it, or maybe an SMP system
710 * using a pre-ARMv6 processor (there are apparently a few prototypes like
711 * that in existence) and therefore access to that register must be
715 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
717 int reg = (instr >> 12) & 15;
720 regs->uregs[reg] = current_thread_info()->tp_value[0];
725 static struct undef_hook arm_mrc_hook = {
726 .instr_mask = 0x0fff0fff,
727 .instr_val = 0x0e1d0f70,
728 .cpsr_mask = PSR_T_BIT,
733 static int __init arm_mrc_hook_init(void)
735 register_undef_hook(&arm_mrc_hook);
739 late_initcall(arm_mrc_hook_init);
743 void __bad_xchg(volatile void *ptr, int size)
745 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
746 __builtin_return_address(0), ptr, size);
749 EXPORT_SYMBOL(__bad_xchg);
752 * A data abort trap was taken, but we did not handle the instruction.
753 * Try to abort the user program, or panic if it was the kernel.
756 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
758 unsigned long addr = instruction_pointer(regs);
761 #ifdef CONFIG_DEBUG_USER
762 if (user_debug & UDBG_BADABORT) {
763 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
764 task_pid_nr(current), current->comm, code, instr);
765 dump_instr(KERN_ERR, regs);
766 show_pte(current->mm, addr);
770 info.si_signo = SIGILL;
772 info.si_code = ILL_ILLOPC;
773 info.si_addr = (void __user *)addr;
775 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
778 void __readwrite_bug(const char *fn)
780 printk("%s called, but not implemented\n", fn);
783 EXPORT_SYMBOL(__readwrite_bug);
785 void __pte_error(const char *file, int line, pte_t pte)
787 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
790 void __pmd_error(const char *file, int line, pmd_t pmd)
792 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
795 void __pgd_error(const char *file, int line, pgd_t pgd)
797 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
800 asmlinkage void __div0(void)
802 printk("Division by zero in kernel.\n");
805 EXPORT_SYMBOL(__div0);
811 /* if that doesn't kill us, halt */
812 panic("Oops failed to kill thread");
814 EXPORT_SYMBOL(abort);
816 void __init trap_init(void)
821 #ifdef CONFIG_KUSER_HELPERS
822 static void __init kuser_init(void *vectors)
824 extern char __kuser_helper_start[], __kuser_helper_end[];
825 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
827 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
830 * vectors + 0xfe0 = __kuser_get_tls
831 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
833 if (tls_emu || has_tls_reg)
834 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
837 static inline void __init kuser_init(void *vectors)
842 void __init early_trap_init(void *vectors_base)
844 #ifndef CONFIG_CPU_V7M
845 unsigned long vectors = (unsigned long)vectors_base;
846 extern char __stubs_start[], __stubs_end[];
847 extern char __vectors_start[], __vectors_end[];
850 vectors_page = vectors_base;
853 * Poison the vectors page with an undefined instruction. This
854 * instruction is chosen to be undefined for both ARM and Thumb
855 * ISAs. The Thumb version is an undefined instruction with a
856 * branch back to the undefined instruction.
858 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
859 ((u32 *)vectors_base)[i] = 0xe7fddef1;
862 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
863 * into the vector page, mapped at 0xffff0000, and ensure these
864 * are visible to the instruction stream.
866 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
867 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
869 kuser_init(vectors_base);
871 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
872 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
873 #else /* ifndef CONFIG_CPU_V7M */
875 * on V7-M there is no need to copy the vector table to a dedicated
876 * memory area. The address is configurable and so a table in the kernel