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[]= {
43 "undefined instruction",
48 #ifdef CONFIG_DEBUG_USER
49 unsigned int user_debug;
51 static int __init user_debug_setup(char *str)
53 get_option(&str, &user_debug);
56 __setup("user_debug=", user_debug_setup);
59 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
61 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
63 #ifdef CONFIG_KALLSYMS
64 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
66 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
69 if (in_exception_text(where))
70 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
73 #ifndef CONFIG_ARM_UNWIND
75 * Stack pointers should always be within the kernels view of
76 * physical memory. If it is not there, then we can't dump
77 * out any information relating to the stack.
79 static int verify_stack(unsigned long sp)
81 if (sp < PAGE_OFFSET ||
82 (sp > (unsigned long)high_memory && high_memory != NULL))
90 * Dump out the contents of some memory nicely...
92 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
100 * We need to switch to kernel mode so that we can use __get_user
101 * to safely read from kernel space. Note that we now dump the
102 * code first, just in case the backtrace kills us.
107 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
109 for (first = bottom & ~31; first < top; first += 32) {
111 char str[sizeof(" 12345678") * 8 + 1];
113 memset(str, ' ', sizeof(str));
114 str[sizeof(str) - 1] = '\0';
116 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
117 if (p >= bottom && p < top) {
119 if (__get_user(val, (unsigned long *)p) == 0)
120 sprintf(str + i * 9, " %08lx", val);
122 sprintf(str + i * 9, " ????????");
125 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
131 static void dump_instr(const char *lvl, struct pt_regs *regs)
133 unsigned long addr = instruction_pointer(regs);
134 const int thumb = thumb_mode(regs);
135 const int width = thumb ? 4 : 8;
137 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
141 * We need to switch to kernel mode so that we can use __get_user
142 * to safely read from kernel space. Note that we now dump the
143 * code first, just in case the backtrace kills us.
148 for (i = -4; i < 1 + !!thumb; i++) {
149 unsigned int val, bad;
152 bad = __get_user(val, &((u16 *)addr)[i]);
154 bad = __get_user(val, &((u32 *)addr)[i]);
157 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
160 p += sprintf(p, "bad PC value");
164 printk("%sCode: %s\n", lvl, str);
169 #ifdef CONFIG_ARM_UNWIND
170 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172 unwind_backtrace(regs, tsk);
175 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
177 unsigned int fp, mode;
180 printk("Backtrace: ");
187 mode = processor_mode(regs);
188 } else if (tsk != current) {
189 fp = thread_saved_fp(tsk);
192 asm("mov %0, fp" : "=r" (fp) : : "cc");
197 printk("no frame pointer");
199 } else if (verify_stack(fp)) {
200 printk("invalid frame pointer 0x%08x", fp);
202 } else if (fp < (unsigned long)end_of_stack(tsk))
203 printk("frame pointer underflow");
207 c_backtrace(fp, mode);
211 void show_stack(struct task_struct *tsk, unsigned long *sp)
213 dump_backtrace(NULL, tsk);
217 #ifdef CONFIG_PREEMPT
218 #define S_PREEMPT " PREEMPT"
227 #ifdef CONFIG_THUMB2_KERNEL
228 #define S_ISA " THUMB2"
233 static int __die(const char *str, int err, struct pt_regs *regs)
235 struct task_struct *tsk = current;
236 static int die_counter;
239 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
240 S_ISA "\n", str, err, ++die_counter);
242 /* trap and error numbers are mostly meaningless on ARM */
243 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
244 if (ret == NOTIFY_STOP)
249 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
250 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
252 if (!user_mode(regs) || in_interrupt()) {
253 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
254 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
255 dump_backtrace(regs, tsk);
256 dump_instr(KERN_EMERG, regs);
262 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
263 static int die_owner = -1;
264 static unsigned int die_nest_count;
266 static unsigned long oops_begin(void)
273 /* racy, but better than risking deadlock. */
274 raw_local_irq_save(flags);
275 cpu = smp_processor_id();
276 if (!arch_spin_trylock(&die_lock)) {
277 if (cpu == die_owner)
278 /* nested oops. should stop eventually */;
280 arch_spin_lock(&die_lock);
289 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
291 if (regs && kexec_should_crash(current))
296 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
299 /* Nest count reaches zero, release the lock. */
300 arch_spin_unlock(&die_lock);
301 raw_local_irq_restore(flags);
305 panic("Fatal exception in interrupt");
307 panic("Fatal exception");
313 * This function is protected against re-entrancy.
315 void die(const char *str, struct pt_regs *regs, int err)
317 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
318 unsigned long flags = oops_begin();
321 if (!user_mode(regs))
322 bug_type = report_bug(regs->ARM_pc, regs);
323 if (bug_type != BUG_TRAP_TYPE_NONE)
326 if (__die(str, err, regs))
329 oops_end(flags, regs, sig);
332 void arm_notify_die(const char *str, struct pt_regs *regs,
333 struct siginfo *info, unsigned long err, unsigned long trap)
335 if (user_mode(regs)) {
336 current->thread.error_code = err;
337 current->thread.trap_no = trap;
339 force_sig_info(info->si_signo, info, current);
345 #ifdef CONFIG_GENERIC_BUG
347 int is_valid_bugaddr(unsigned long pc)
349 #ifdef CONFIG_THUMB2_KERNEL
355 if (probe_kernel_address((unsigned *)pc, bkpt))
358 return bkpt == BUG_INSTR_VALUE;
363 static LIST_HEAD(undef_hook);
364 static DEFINE_RAW_SPINLOCK(undef_lock);
366 void register_undef_hook(struct undef_hook *hook)
370 raw_spin_lock_irqsave(&undef_lock, flags);
371 list_add(&hook->node, &undef_hook);
372 raw_spin_unlock_irqrestore(&undef_lock, flags);
375 void unregister_undef_hook(struct undef_hook *hook)
379 raw_spin_lock_irqsave(&undef_lock, flags);
380 list_del(&hook->node);
381 raw_spin_unlock_irqrestore(&undef_lock, flags);
384 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
386 struct undef_hook *hook;
388 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
390 raw_spin_lock_irqsave(&undef_lock, flags);
391 list_for_each_entry(hook, &undef_hook, node)
392 if ((instr & hook->instr_mask) == hook->instr_val &&
393 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
395 raw_spin_unlock_irqrestore(&undef_lock, flags);
397 return fn ? fn(regs, instr) : 1;
400 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
406 pc = (void __user *)instruction_pointer(regs);
408 if (processor_mode(regs) == SVC_MODE) {
409 #ifdef CONFIG_THUMB2_KERNEL
410 if (thumb_mode(regs)) {
411 instr = ((u16 *)pc)[0];
412 if (is_wide_instruction(instr)) {
414 instr |= ((u16 *)pc)[1];
419 } else if (thumb_mode(regs)) {
420 if (get_user(instr, (u16 __user *)pc))
422 if (is_wide_instruction(instr)) {
424 if (get_user(instr2, (u16 __user *)pc+1))
429 } else if (get_user(instr, (u32 __user *)pc)) {
433 if (call_undef_hook(regs, instr) == 0)
437 #ifdef CONFIG_DEBUG_USER
438 if (user_debug & UDBG_UNDEFINED) {
439 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
440 current->comm, task_pid_nr(current), pc);
441 dump_instr(KERN_INFO, regs);
445 info.si_signo = SIGILL;
447 info.si_code = ILL_ILLOPC;
450 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
453 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
455 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
456 printk("You may have a hardware problem...\n");
460 * bad_mode handles the impossible case in the vectors. If you see one of
461 * these, then it's extremely serious, and could mean you have buggy hardware.
462 * It never returns, and never tries to sync. We hope that we can at least
463 * dump out some state information...
465 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
469 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
471 die("Oops - bad mode", regs, 0);
476 static int bad_syscall(int n, struct pt_regs *regs)
478 struct thread_info *thread = current_thread_info();
481 if ((current->personality & PER_MASK) != PER_LINUX &&
482 thread->exec_domain->handler) {
483 thread->exec_domain->handler(n, regs);
487 #ifdef CONFIG_DEBUG_USER
488 if (user_debug & UDBG_SYSCALL) {
489 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
490 task_pid_nr(current), current->comm, n);
491 dump_instr(KERN_ERR, regs);
495 info.si_signo = SIGILL;
497 info.si_code = ILL_ILLTRP;
498 info.si_addr = (void __user *)instruction_pointer(regs) -
499 (thumb_mode(regs) ? 2 : 4);
501 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
507 do_cache_op(unsigned long start, unsigned long end, int flags)
509 struct mm_struct *mm = current->active_mm;
510 struct vm_area_struct *vma;
512 if (end < start || flags)
515 down_read(&mm->mmap_sem);
516 vma = find_vma(mm, start);
517 if (vma && vma->vm_start < end) {
518 if (start < vma->vm_start)
519 start = vma->vm_start;
520 if (end > vma->vm_end)
523 up_read(&mm->mmap_sem);
524 return flush_cache_user_range(start, end);
526 up_read(&mm->mmap_sem);
531 * Handle all unrecognised system calls.
532 * 0x9f0000 - 0x9fffff are some more esoteric system calls
534 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
535 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
537 struct thread_info *thread = current_thread_info();
540 if ((no >> 16) != (__ARM_NR_BASE>> 16))
541 return bad_syscall(no, regs);
543 switch (no & 0xffff) {
544 case 0: /* branch through 0 */
545 info.si_signo = SIGSEGV;
547 info.si_code = SEGV_MAPERR;
550 arm_notify_die("branch through zero", regs, &info, 0, 0);
553 case NR(breakpoint): /* SWI BREAK_POINT */
554 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
555 ptrace_break(current, regs);
559 * Flush a region from virtual address 'r0' to virtual address 'r1'
560 * _exclusive_. There is no alignment requirement on either address;
561 * user space does not need to know the hardware cache layout.
563 * r2 contains flags. It should ALWAYS be passed as ZERO until it
564 * is defined to be something else. For now we ignore it, but may
565 * the fires of hell burn in your belly if you break this rule. ;)
567 * (at a later date, we may want to allow this call to not flush
568 * various aspects of the cache. Passing '0' will guarantee that
569 * everything necessary gets flushed to maintain consistency in
570 * the specified region).
573 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
576 if (!(elf_hwcap & HWCAP_26BIT))
578 regs->ARM_cpsr &= ~MODE32_BIT;
582 if (!(elf_hwcap & HWCAP_26BIT))
584 regs->ARM_cpsr |= MODE32_BIT;
588 thread->tp_value = regs->ARM_r0;
592 asm ("mcr p15, 0, %0, c13, c0, 3"
593 : : "r" (regs->ARM_r0));
596 * User space must never try to access this directly.
597 * Expect your app to break eventually if you do so.
598 * The user helper at 0xffff0fe0 must be used instead.
599 * (see entry-armv.S for details)
601 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
605 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
607 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
608 * Return zero in r0 if *MEM was changed or non-zero if no exchange
609 * happened. Also set the user C flag accordingly.
610 * If access permissions have to be fixed up then non-zero is
611 * returned and the operation has to be re-attempted.
613 * *NOTE*: This is a ghost syscall private to the kernel. Only the
614 * __kuser_cmpxchg code in entry-armv.S should be aware of its
615 * existence. Don't ever use this from user code.
619 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
620 struct pt_regs *regs);
622 unsigned long addr = regs->ARM_r2;
623 struct mm_struct *mm = current->mm;
624 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
627 regs->ARM_cpsr &= ~PSR_C_BIT;
628 down_read(&mm->mmap_sem);
629 pgd = pgd_offset(mm, addr);
630 if (!pgd_present(*pgd))
632 pmd = pmd_offset(pgd, addr);
633 if (!pmd_present(*pmd))
635 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
636 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
637 pte_unmap_unlock(pte, ptl);
640 val = *(unsigned long *)addr;
643 *(unsigned long *)addr = regs->ARM_r1;
644 regs->ARM_cpsr |= PSR_C_BIT;
646 pte_unmap_unlock(pte, ptl);
647 up_read(&mm->mmap_sem);
651 up_read(&mm->mmap_sem);
652 /* simulate a write access fault */
653 do_DataAbort(addr, 15 + (1 << 11), regs);
658 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
659 if not implemented, rather than raising SIGILL. This
660 way the calling program can gracefully determine whether
661 a feature is supported. */
662 if ((no & 0xffff) <= 0x7ff)
666 #ifdef CONFIG_DEBUG_USER
668 * experience shows that these seem to indicate that
669 * something catastrophic has happened
671 if (user_debug & UDBG_SYSCALL) {
672 printk("[%d] %s: arm syscall %d\n",
673 task_pid_nr(current), current->comm, no);
674 dump_instr("", regs);
675 if (user_mode(regs)) {
677 c_backtrace(regs->ARM_fp, processor_mode(regs));
681 info.si_signo = SIGILL;
683 info.si_code = ILL_ILLTRP;
684 info.si_addr = (void __user *)instruction_pointer(regs) -
685 (thumb_mode(regs) ? 2 : 4);
687 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
691 #ifdef CONFIG_TLS_REG_EMUL
694 * We might be running on an ARMv6+ processor which should have the TLS
695 * register but for some reason we can't use it, or maybe an SMP system
696 * using a pre-ARMv6 processor (there are apparently a few prototypes like
697 * that in existence) and therefore access to that register must be
701 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
703 int reg = (instr >> 12) & 15;
706 regs->uregs[reg] = current_thread_info()->tp_value;
711 static struct undef_hook arm_mrc_hook = {
712 .instr_mask = 0x0fff0fff,
713 .instr_val = 0x0e1d0f70,
714 .cpsr_mask = PSR_T_BIT,
719 static int __init arm_mrc_hook_init(void)
721 register_undef_hook(&arm_mrc_hook);
725 late_initcall(arm_mrc_hook_init);
729 void __bad_xchg(volatile void *ptr, int size)
731 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
732 __builtin_return_address(0), ptr, size);
735 EXPORT_SYMBOL(__bad_xchg);
738 * A data abort trap was taken, but we did not handle the instruction.
739 * Try to abort the user program, or panic if it was the kernel.
742 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
744 unsigned long addr = instruction_pointer(regs);
747 #ifdef CONFIG_DEBUG_USER
748 if (user_debug & UDBG_BADABORT) {
749 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
750 task_pid_nr(current), current->comm, code, instr);
751 dump_instr(KERN_ERR, regs);
752 show_pte(current->mm, addr);
756 info.si_signo = SIGILL;
758 info.si_code = ILL_ILLOPC;
759 info.si_addr = (void __user *)addr;
761 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
764 void __readwrite_bug(const char *fn)
766 printk("%s called, but not implemented\n", fn);
769 EXPORT_SYMBOL(__readwrite_bug);
771 void __pte_error(const char *file, int line, pte_t pte)
773 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
776 void __pmd_error(const char *file, int line, pmd_t pmd)
778 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
781 void __pgd_error(const char *file, int line, pgd_t pgd)
783 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
786 asmlinkage void __div0(void)
788 printk("Division by zero in kernel.\n");
791 EXPORT_SYMBOL(__div0);
797 /* if that doesn't kill us, halt */
798 panic("Oops failed to kill thread");
800 EXPORT_SYMBOL(abort);
802 void __init trap_init(void)
807 #ifdef CONFIG_KUSER_HELPERS
808 static void __init kuser_init(void *vectors)
810 extern char __kuser_helper_start[], __kuser_helper_end[];
811 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
813 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
816 * vectors + 0xfe0 = __kuser_get_tls
817 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
819 if (tls_emu || has_tls_reg)
820 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
823 static void __init kuser_init(void *vectors)
828 void __init early_trap_init(void *vectors_base)
830 unsigned long vectors = (unsigned long)vectors_base;
831 extern char __stubs_start[], __stubs_end[];
832 extern char __vectors_start[], __vectors_end[];
835 vectors_page = vectors_base;
838 * Poison the vectors page with an undefined instruction. This
839 * instruction is chosen to be undefined for both ARM and Thumb
840 * ISAs. The Thumb version is an undefined instruction with a
841 * branch back to the undefined instruction.
843 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
844 ((u32 *)vectors_base)[i] = 0xe7fddef1;
847 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
848 * into the vector page, mapped at 0xffff0000, and ensure these
849 * are visible to the instruction stream.
851 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
852 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
854 kuser_init(vectors_base);
856 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
857 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);