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>
40 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
44 #ifdef CONFIG_DEBUG_USER
45 unsigned int user_debug;
47 static int __init user_debug_setup(char *str)
49 get_option(&str, &user_debug);
52 __setup("user_debug=", user_debug_setup);
55 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
57 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
59 #ifdef CONFIG_KALLSYMS
60 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
62 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
65 if (in_exception_text(where))
66 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
69 #ifndef CONFIG_ARM_UNWIND
71 * Stack pointers should always be within the kernels view of
72 * physical memory. If it is not there, then we can't dump
73 * out any information relating to the stack.
75 static int verify_stack(unsigned long sp)
77 if (sp < PAGE_OFFSET ||
78 (sp > (unsigned long)high_memory && high_memory != NULL))
86 * Dump out the contents of some memory nicely...
88 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
96 * We need to switch to kernel mode so that we can use __get_user
97 * to safely read from kernel space. Note that we now dump the
98 * code first, just in case the backtrace kills us.
103 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
105 for (first = bottom & ~31; first < top; first += 32) {
107 char str[sizeof(" 12345678") * 8 + 1];
109 memset(str, ' ', sizeof(str));
110 str[sizeof(str) - 1] = '\0';
112 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
113 if (p >= bottom && p < top) {
115 if (__get_user(val, (unsigned long *)p) == 0)
116 sprintf(str + i * 9, " %08lx", val);
118 sprintf(str + i * 9, " ????????");
121 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
127 static void dump_instr(const char *lvl, struct pt_regs *regs)
129 unsigned long addr = instruction_pointer(regs);
130 const int thumb = thumb_mode(regs);
131 const int width = thumb ? 4 : 8;
133 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
137 * We need to switch to kernel mode so that we can use __get_user
138 * to safely read from kernel space. Note that we now dump the
139 * code first, just in case the backtrace kills us.
144 for (i = -4; i < 1 + !!thumb; i++) {
145 unsigned int val, bad;
148 bad = __get_user(val, &((u16 *)addr)[i]);
150 bad = __get_user(val, &((u32 *)addr)[i]);
153 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
156 p += sprintf(p, "bad PC value");
160 printk("%sCode: %s\n", lvl, str);
165 #ifdef CONFIG_ARM_UNWIND
166 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
168 unwind_backtrace(regs, tsk);
171 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
173 unsigned int fp, mode;
176 printk("Backtrace: ");
183 mode = processor_mode(regs);
184 } else if (tsk != current) {
185 fp = thread_saved_fp(tsk);
188 asm("mov %0, fp" : "=r" (fp) : : "cc");
193 printk("no frame pointer");
195 } else if (verify_stack(fp)) {
196 printk("invalid frame pointer 0x%08x", fp);
198 } else if (fp < (unsigned long)end_of_stack(tsk))
199 printk("frame pointer underflow");
203 c_backtrace(fp, mode);
207 void dump_stack(void)
209 dump_backtrace(NULL, NULL);
212 EXPORT_SYMBOL(dump_stack);
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);
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
358 if (probe_kernel_address((unsigned *)pc, bkpt))
361 return bkpt == BUG_INSTR_VALUE;
366 static LIST_HEAD(undef_hook);
367 static DEFINE_RAW_SPINLOCK(undef_lock);
369 void register_undef_hook(struct undef_hook *hook)
373 raw_spin_lock_irqsave(&undef_lock, flags);
374 list_add(&hook->node, &undef_hook);
375 raw_spin_unlock_irqrestore(&undef_lock, flags);
378 void unregister_undef_hook(struct undef_hook *hook)
382 raw_spin_lock_irqsave(&undef_lock, flags);
383 list_del(&hook->node);
384 raw_spin_unlock_irqrestore(&undef_lock, flags);
387 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
389 struct undef_hook *hook;
391 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
393 raw_spin_lock_irqsave(&undef_lock, flags);
394 list_for_each_entry(hook, &undef_hook, node)
395 if ((instr & hook->instr_mask) == hook->instr_val &&
396 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
398 raw_spin_unlock_irqrestore(&undef_lock, flags);
400 return fn ? fn(regs, instr) : 1;
403 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
405 unsigned int correction = thumb_mode(regs) ? 2 : 4;
411 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
412 * depending whether we're in Thumb mode or not.
413 * Correct this offset.
415 regs->ARM_pc -= correction;
417 pc = (void __user *)instruction_pointer(regs);
419 if (processor_mode(regs) == SVC_MODE) {
420 #ifdef CONFIG_THUMB2_KERNEL
421 if (thumb_mode(regs)) {
422 instr = ((u16 *)pc)[0];
423 if (is_wide_instruction(instr)) {
425 instr |= ((u16 *)pc)[1];
430 } else if (thumb_mode(regs)) {
431 get_user(instr, (u16 __user *)pc);
432 if (is_wide_instruction(instr)) {
434 get_user(instr2, (u16 __user *)pc+1);
439 get_user(instr, (u32 __user *)pc);
442 if (call_undef_hook(regs, instr) == 0)
445 #ifdef CONFIG_DEBUG_USER
446 if (user_debug & UDBG_UNDEFINED) {
447 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
448 current->comm, task_pid_nr(current), pc);
449 dump_instr(KERN_INFO, regs);
453 info.si_signo = SIGILL;
455 info.si_code = ILL_ILLOPC;
458 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
461 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
463 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
464 printk("You may have a hardware problem...\n");
468 * bad_mode handles the impossible case in the vectors. If you see one of
469 * these, then it's extremely serious, and could mean you have buggy hardware.
470 * It never returns, and never tries to sync. We hope that we can at least
471 * dump out some state information...
473 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
477 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
479 die("Oops - bad mode", regs, 0);
484 static int bad_syscall(int n, struct pt_regs *regs)
486 struct thread_info *thread = current_thread_info();
489 if ((current->personality & PER_MASK) != PER_LINUX &&
490 thread->exec_domain->handler) {
491 thread->exec_domain->handler(n, regs);
495 #ifdef CONFIG_DEBUG_USER
496 if (user_debug & UDBG_SYSCALL) {
497 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
498 task_pid_nr(current), current->comm, n);
499 dump_instr(KERN_ERR, regs);
503 info.si_signo = SIGILL;
505 info.si_code = ILL_ILLTRP;
506 info.si_addr = (void __user *)instruction_pointer(regs) -
507 (thumb_mode(regs) ? 2 : 4);
509 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
515 do_cache_op(unsigned long start, unsigned long end, int flags)
517 struct mm_struct *mm = current->active_mm;
518 struct vm_area_struct *vma;
520 if (end < start || flags)
523 down_read(&mm->mmap_sem);
524 vma = find_vma(mm, start);
525 if (vma && vma->vm_start < end) {
526 if (start < vma->vm_start)
527 start = vma->vm_start;
528 if (end > vma->vm_end)
531 up_read(&mm->mmap_sem);
532 return flush_cache_user_range(start, end);
534 up_read(&mm->mmap_sem);
539 * Handle all unrecognised system calls.
540 * 0x9f0000 - 0x9fffff are some more esoteric system calls
542 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
543 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
545 struct thread_info *thread = current_thread_info();
548 if ((no >> 16) != (__ARM_NR_BASE>> 16))
549 return bad_syscall(no, regs);
551 switch (no & 0xffff) {
552 case 0: /* branch through 0 */
553 info.si_signo = SIGSEGV;
555 info.si_code = SEGV_MAPERR;
558 arm_notify_die("branch through zero", regs, &info, 0, 0);
561 case NR(breakpoint): /* SWI BREAK_POINT */
562 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
563 ptrace_break(current, regs);
567 * Flush a region from virtual address 'r0' to virtual address 'r1'
568 * _exclusive_. There is no alignment requirement on either address;
569 * user space does not need to know the hardware cache layout.
571 * r2 contains flags. It should ALWAYS be passed as ZERO until it
572 * is defined to be something else. For now we ignore it, but may
573 * the fires of hell burn in your belly if you break this rule. ;)
575 * (at a later date, we may want to allow this call to not flush
576 * various aspects of the cache. Passing '0' will guarantee that
577 * everything necessary gets flushed to maintain consistency in
578 * the specified region).
581 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
584 if (!(elf_hwcap & HWCAP_26BIT))
586 regs->ARM_cpsr &= ~MODE32_BIT;
590 if (!(elf_hwcap & HWCAP_26BIT))
592 regs->ARM_cpsr |= MODE32_BIT;
596 thread->tp_value = regs->ARM_r0;
600 asm ("mcr p15, 0, %0, c13, c0, 3"
601 : : "r" (regs->ARM_r0));
604 * User space must never try to access this directly.
605 * Expect your app to break eventually if you do so.
606 * The user helper at 0xffff0fe0 must be used instead.
607 * (see entry-armv.S for details)
609 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
613 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
615 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
616 * Return zero in r0 if *MEM was changed or non-zero if no exchange
617 * happened. Also set the user C flag accordingly.
618 * If access permissions have to be fixed up then non-zero is
619 * returned and the operation has to be re-attempted.
621 * *NOTE*: This is a ghost syscall private to the kernel. Only the
622 * __kuser_cmpxchg code in entry-armv.S should be aware of its
623 * existence. Don't ever use this from user code.
627 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
628 struct pt_regs *regs);
630 unsigned long addr = regs->ARM_r2;
631 struct mm_struct *mm = current->mm;
632 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
635 regs->ARM_cpsr &= ~PSR_C_BIT;
636 down_read(&mm->mmap_sem);
637 pgd = pgd_offset(mm, addr);
638 if (!pgd_present(*pgd))
640 pmd = pmd_offset(pgd, addr);
641 if (!pmd_present(*pmd))
643 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
644 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
645 pte_unmap_unlock(pte, ptl);
648 val = *(unsigned long *)addr;
651 *(unsigned long *)addr = regs->ARM_r1;
652 regs->ARM_cpsr |= PSR_C_BIT;
654 pte_unmap_unlock(pte, ptl);
655 up_read(&mm->mmap_sem);
659 up_read(&mm->mmap_sem);
660 /* simulate a write access fault */
661 do_DataAbort(addr, 15 + (1 << 11), regs);
666 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
667 if not implemented, rather than raising SIGILL. This
668 way the calling program can gracefully determine whether
669 a feature is supported. */
670 if ((no & 0xffff) <= 0x7ff)
674 #ifdef CONFIG_DEBUG_USER
676 * experience shows that these seem to indicate that
677 * something catastrophic has happened
679 if (user_debug & UDBG_SYSCALL) {
680 printk("[%d] %s: arm syscall %d\n",
681 task_pid_nr(current), current->comm, no);
682 dump_instr("", regs);
683 if (user_mode(regs)) {
685 c_backtrace(regs->ARM_fp, processor_mode(regs));
689 info.si_signo = SIGILL;
691 info.si_code = ILL_ILLTRP;
692 info.si_addr = (void __user *)instruction_pointer(regs) -
693 (thumb_mode(regs) ? 2 : 4);
695 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
699 #ifdef CONFIG_TLS_REG_EMUL
702 * We might be running on an ARMv6+ processor which should have the TLS
703 * register but for some reason we can't use it, or maybe an SMP system
704 * using a pre-ARMv6 processor (there are apparently a few prototypes like
705 * that in existence) and therefore access to that register must be
709 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
711 int reg = (instr >> 12) & 15;
714 regs->uregs[reg] = current_thread_info()->tp_value;
719 static struct undef_hook arm_mrc_hook = {
720 .instr_mask = 0x0fff0fff,
721 .instr_val = 0x0e1d0f70,
722 .cpsr_mask = PSR_T_BIT,
727 static int __init arm_mrc_hook_init(void)
729 register_undef_hook(&arm_mrc_hook);
733 late_initcall(arm_mrc_hook_init);
737 void __bad_xchg(volatile void *ptr, int size)
739 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
740 __builtin_return_address(0), ptr, size);
743 EXPORT_SYMBOL(__bad_xchg);
746 * A data abort trap was taken, but we did not handle the instruction.
747 * Try to abort the user program, or panic if it was the kernel.
750 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
752 unsigned long addr = instruction_pointer(regs);
755 #ifdef CONFIG_DEBUG_USER
756 if (user_debug & UDBG_BADABORT) {
757 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
758 task_pid_nr(current), current->comm, code, instr);
759 dump_instr(KERN_ERR, regs);
760 show_pte(current->mm, addr);
764 info.si_signo = SIGILL;
766 info.si_code = ILL_ILLOPC;
767 info.si_addr = (void __user *)addr;
769 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
772 void __readwrite_bug(const char *fn)
774 printk("%s called, but not implemented\n", fn);
777 EXPORT_SYMBOL(__readwrite_bug);
779 void __pte_error(const char *file, int line, pte_t pte)
781 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
784 void __pmd_error(const char *file, int line, pmd_t pmd)
786 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
789 void __pgd_error(const char *file, int line, pgd_t pgd)
791 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
794 asmlinkage void __div0(void)
796 printk("Division by zero in kernel.\n");
799 EXPORT_SYMBOL(__div0);
805 /* if that doesn't kill us, halt */
806 panic("Oops failed to kill thread");
808 EXPORT_SYMBOL(abort);
810 void __init trap_init(void)
815 static void __init kuser_get_tls_init(unsigned long vectors)
818 * vectors + 0xfe0 = __kuser_get_tls
819 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
821 if (tls_emu || has_tls_reg)
822 memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
825 void __init early_trap_init(void *vectors_base)
827 unsigned long vectors = (unsigned long)vectors_base;
828 extern char __stubs_start[], __stubs_end[];
829 extern char __vectors_start[], __vectors_end[];
830 extern char __kuser_helper_start[], __kuser_helper_end[];
831 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
833 vectors_page = vectors_base;
836 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
837 * into the vector page, mapped at 0xffff0000, and ensure these
838 * are visible to the instruction stream.
840 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
841 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
842 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
845 * Do processor specific fixups for the kuser helpers
847 kuser_get_tls_init(vectors);
850 * Copy signal return handlers into the vector page, and
851 * set sigreturn to be a pointer to these.
853 memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
854 sigreturn_codes, sizeof(sigreturn_codes));
855 memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
856 syscall_restart_code, sizeof(syscall_restart_code));
858 flush_icache_range(vectors, vectors + PAGE_SIZE);
859 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);