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>
37 #include <asm/opcodes.h>
39 static const char *handler[]= {
44 "undefined instruction",
49 #ifdef CONFIG_DEBUG_USER
50 unsigned int user_debug;
52 static int __init user_debug_setup(char *str)
54 get_option(&str, &user_debug);
57 __setup("user_debug=", user_debug_setup);
60 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
62 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
64 #ifdef CONFIG_KALLSYMS
65 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
67 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
70 if (in_exception_text(where))
71 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
74 #ifndef CONFIG_ARM_UNWIND
76 * Stack pointers should always be within the kernels view of
77 * physical memory. If it is not there, then we can't dump
78 * out any information relating to the stack.
80 static int verify_stack(unsigned long sp)
82 if (sp < PAGE_OFFSET ||
83 (sp > (unsigned long)high_memory && high_memory != NULL))
91 * Dump out the contents of some memory nicely...
93 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
101 * We need to switch to kernel mode so that we can use __get_user
102 * to safely read from kernel space. Note that we now dump the
103 * code first, just in case the backtrace kills us.
108 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
110 for (first = bottom & ~31; first < top; first += 32) {
112 char str[sizeof(" 12345678") * 8 + 1];
114 memset(str, ' ', sizeof(str));
115 str[sizeof(str) - 1] = '\0';
117 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
118 if (p >= bottom && p < top) {
120 if (__get_user(val, (unsigned long *)p) == 0)
121 sprintf(str + i * 9, " %08lx", val);
123 sprintf(str + i * 9, " ????????");
126 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
132 static void dump_instr(const char *lvl, struct pt_regs *regs)
134 unsigned long addr = instruction_pointer(regs);
135 const int thumb = thumb_mode(regs);
136 const int width = thumb ? 4 : 8;
138 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
142 * We need to switch to kernel mode so that we can use __get_user
143 * to safely read from kernel space. Note that we now dump the
144 * code first, just in case the backtrace kills us.
149 for (i = -4; i < 1 + !!thumb; i++) {
150 unsigned int val, bad;
153 bad = __get_user(val, &((u16 *)addr)[i]);
155 bad = __get_user(val, &((u32 *)addr)[i]);
158 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
161 p += sprintf(p, "bad PC value");
165 printk("%sCode: %s\n", lvl, str);
170 #ifdef CONFIG_ARM_UNWIND
171 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
173 unwind_backtrace(regs, tsk);
176 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
178 unsigned int fp, mode;
181 printk("Backtrace: ");
188 mode = processor_mode(regs);
189 } else if (tsk != current) {
190 fp = thread_saved_fp(tsk);
193 asm("mov %0, fp" : "=r" (fp) : : "cc");
198 printk("no frame pointer");
200 } else if (verify_stack(fp)) {
201 printk("invalid frame pointer 0x%08x", fp);
203 } else if (fp < (unsigned long)end_of_stack(tsk))
204 printk("frame pointer underflow");
208 c_backtrace(fp, mode);
212 void show_stack(struct task_struct *tsk, unsigned long *sp)
214 dump_backtrace(NULL, tsk);
218 #ifdef CONFIG_PREEMPT
219 #define S_PREEMPT " PREEMPT"
228 #ifdef CONFIG_THUMB2_KERNEL
229 #define S_ISA " THUMB2"
234 static int __die(const char *str, int err, struct pt_regs *regs)
236 struct task_struct *tsk = current;
237 static int die_counter;
240 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
241 S_ISA "\n", str, err, ++die_counter);
243 /* trap and error numbers are mostly meaningless on ARM */
244 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
245 if (ret == NOTIFY_STOP)
250 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
251 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
253 if (!user_mode(regs) || in_interrupt()) {
254 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
255 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
256 dump_backtrace(regs, tsk);
257 dump_instr(KERN_EMERG, regs);
263 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
264 static int die_owner = -1;
265 static unsigned int die_nest_count;
267 static unsigned long oops_begin(void)
274 /* racy, but better than risking deadlock. */
275 raw_local_irq_save(flags);
276 cpu = smp_processor_id();
277 if (!arch_spin_trylock(&die_lock)) {
278 if (cpu == die_owner)
279 /* nested oops. should stop eventually */;
281 arch_spin_lock(&die_lock);
290 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
292 if (regs && kexec_should_crash(current))
297 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
300 /* Nest count reaches zero, release the lock. */
301 arch_spin_unlock(&die_lock);
302 raw_local_irq_restore(flags);
306 panic("Fatal exception in interrupt");
308 panic("Fatal exception");
314 * This function is protected against re-entrancy.
316 void die(const char *str, struct pt_regs *regs, int err)
318 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
319 unsigned long flags = oops_begin();
322 if (!user_mode(regs))
323 bug_type = report_bug(regs->ARM_pc, regs);
324 if (bug_type != BUG_TRAP_TYPE_NONE)
327 if (__die(str, err, regs))
330 oops_end(flags, regs, sig);
333 void arm_notify_die(const char *str, struct pt_regs *regs,
334 struct siginfo *info, unsigned long err, unsigned long trap)
336 if (user_mode(regs)) {
337 current->thread.error_code = err;
338 current->thread.trap_no = trap;
340 force_sig_info(info->si_signo, info, current);
346 #ifdef CONFIG_GENERIC_BUG
348 int is_valid_bugaddr(unsigned long pc)
350 #ifdef CONFIG_THUMB2_KERNEL
352 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
355 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
358 if (probe_kernel_address((unsigned *)pc, bkpt))
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)
409 pc = (void __user *)instruction_pointer(regs);
411 if (processor_mode(regs) == SVC_MODE) {
412 #ifdef CONFIG_THUMB2_KERNEL
413 if (thumb_mode(regs)) {
414 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
415 if (is_wide_instruction(instr)) {
417 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
418 instr = __opcode_thumb32_compose(instr, inst2);
422 instr = __mem_to_opcode_arm(*(u32 *) pc);
423 } else if (thumb_mode(regs)) {
424 if (get_user(instr, (u16 __user *)pc))
426 instr = __mem_to_opcode_thumb16(instr);
427 if (is_wide_instruction(instr)) {
429 if (get_user(instr2, (u16 __user *)pc+1))
431 instr2 = __mem_to_opcode_thumb16(instr2);
432 instr = __opcode_thumb32_compose(instr, instr2);
434 } else if (get_user(instr, (u32 __user *)pc)) {
435 instr = __mem_to_opcode_arm(instr);
439 if (call_undef_hook(regs, instr) == 0)
443 #ifdef CONFIG_DEBUG_USER
444 if (user_debug & UDBG_UNDEFINED) {
445 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
446 current->comm, task_pid_nr(current), pc);
447 dump_instr(KERN_INFO, regs);
451 info.si_signo = SIGILL;
453 info.si_code = ILL_ILLOPC;
456 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
459 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
461 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
462 printk("You may have a hardware problem...\n");
466 * bad_mode handles the impossible case in the vectors. If you see one of
467 * these, then it's extremely serious, and could mean you have buggy hardware.
468 * It never returns, and never tries to sync. We hope that we can at least
469 * dump out some state information...
471 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
475 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
477 die("Oops - bad mode", regs, 0);
482 static int bad_syscall(int n, struct pt_regs *regs)
484 struct thread_info *thread = current_thread_info();
487 if ((current->personality & PER_MASK) != PER_LINUX &&
488 thread->exec_domain->handler) {
489 thread->exec_domain->handler(n, regs);
493 #ifdef CONFIG_DEBUG_USER
494 if (user_debug & UDBG_SYSCALL) {
495 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
496 task_pid_nr(current), current->comm, n);
497 dump_instr(KERN_ERR, regs);
501 info.si_signo = SIGILL;
503 info.si_code = ILL_ILLTRP;
504 info.si_addr = (void __user *)instruction_pointer(regs) -
505 (thumb_mode(regs) ? 2 : 4);
507 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
513 do_cache_op(unsigned long start, unsigned long end, int flags)
515 struct mm_struct *mm = current->active_mm;
516 struct vm_area_struct *vma;
518 if (end < start || flags)
521 down_read(&mm->mmap_sem);
522 vma = find_vma(mm, start);
523 if (vma && vma->vm_start < end) {
524 if (start < vma->vm_start)
525 start = vma->vm_start;
526 if (end > vma->vm_end)
529 up_read(&mm->mmap_sem);
530 return flush_cache_user_range(start, end);
532 up_read(&mm->mmap_sem);
537 * Handle all unrecognised system calls.
538 * 0x9f0000 - 0x9fffff are some more esoteric system calls
540 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
541 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
543 struct thread_info *thread = current_thread_info();
546 if ((no >> 16) != (__ARM_NR_BASE>> 16))
547 return bad_syscall(no, regs);
549 switch (no & 0xffff) {
550 case 0: /* branch through 0 */
551 info.si_signo = SIGSEGV;
553 info.si_code = SEGV_MAPERR;
556 arm_notify_die("branch through zero", regs, &info, 0, 0);
559 case NR(breakpoint): /* SWI BREAK_POINT */
560 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
561 ptrace_break(current, regs);
565 * Flush a region from virtual address 'r0' to virtual address 'r1'
566 * _exclusive_. There is no alignment requirement on either address;
567 * user space does not need to know the hardware cache layout.
569 * r2 contains flags. It should ALWAYS be passed as ZERO until it
570 * is defined to be something else. For now we ignore it, but may
571 * the fires of hell burn in your belly if you break this rule. ;)
573 * (at a later date, we may want to allow this call to not flush
574 * various aspects of the cache. Passing '0' will guarantee that
575 * everything necessary gets flushed to maintain consistency in
576 * the specified region).
579 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
582 if (!(elf_hwcap & HWCAP_26BIT))
584 regs->ARM_cpsr &= ~MODE32_BIT;
588 if (!(elf_hwcap & HWCAP_26BIT))
590 regs->ARM_cpsr |= MODE32_BIT;
594 thread->tp_value = regs->ARM_r0;
598 asm ("mcr p15, 0, %0, c13, c0, 3"
599 : : "r" (regs->ARM_r0));
602 * User space must never try to access this directly.
603 * Expect your app to break eventually if you do so.
604 * The user helper at 0xffff0fe0 must be used instead.
605 * (see entry-armv.S for details)
607 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
611 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
613 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
614 * Return zero in r0 if *MEM was changed or non-zero if no exchange
615 * happened. Also set the user C flag accordingly.
616 * If access permissions have to be fixed up then non-zero is
617 * returned and the operation has to be re-attempted.
619 * *NOTE*: This is a ghost syscall private to the kernel. Only the
620 * __kuser_cmpxchg code in entry-armv.S should be aware of its
621 * existence. Don't ever use this from user code.
625 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
626 struct pt_regs *regs);
628 unsigned long addr = regs->ARM_r2;
629 struct mm_struct *mm = current->mm;
630 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
633 regs->ARM_cpsr &= ~PSR_C_BIT;
634 down_read(&mm->mmap_sem);
635 pgd = pgd_offset(mm, addr);
636 if (!pgd_present(*pgd))
638 pmd = pmd_offset(pgd, addr);
639 if (!pmd_present(*pmd))
641 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
642 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
643 pte_unmap_unlock(pte, ptl);
646 val = *(unsigned long *)addr;
649 *(unsigned long *)addr = regs->ARM_r1;
650 regs->ARM_cpsr |= PSR_C_BIT;
652 pte_unmap_unlock(pte, ptl);
653 up_read(&mm->mmap_sem);
657 up_read(&mm->mmap_sem);
658 /* simulate a write access fault */
659 do_DataAbort(addr, 15 + (1 << 11), regs);
664 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
665 if not implemented, rather than raising SIGILL. This
666 way the calling program can gracefully determine whether
667 a feature is supported. */
668 if ((no & 0xffff) <= 0x7ff)
672 #ifdef CONFIG_DEBUG_USER
674 * experience shows that these seem to indicate that
675 * something catastrophic has happened
677 if (user_debug & UDBG_SYSCALL) {
678 printk("[%d] %s: arm syscall %d\n",
679 task_pid_nr(current), current->comm, no);
680 dump_instr("", regs);
681 if (user_mode(regs)) {
683 c_backtrace(regs->ARM_fp, processor_mode(regs));
687 info.si_signo = SIGILL;
689 info.si_code = ILL_ILLTRP;
690 info.si_addr = (void __user *)instruction_pointer(regs) -
691 (thumb_mode(regs) ? 2 : 4);
693 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
697 #ifdef CONFIG_TLS_REG_EMUL
700 * We might be running on an ARMv6+ processor which should have the TLS
701 * register but for some reason we can't use it, or maybe an SMP system
702 * using a pre-ARMv6 processor (there are apparently a few prototypes like
703 * that in existence) and therefore access to that register must be
707 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
709 int reg = (instr >> 12) & 15;
712 regs->uregs[reg] = current_thread_info()->tp_value;
717 static struct undef_hook arm_mrc_hook = {
718 .instr_mask = 0x0fff0fff,
719 .instr_val = 0x0e1d0f70,
720 .cpsr_mask = PSR_T_BIT,
725 static int __init arm_mrc_hook_init(void)
727 register_undef_hook(&arm_mrc_hook);
731 late_initcall(arm_mrc_hook_init);
735 void __bad_xchg(volatile void *ptr, int size)
737 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
738 __builtin_return_address(0), ptr, size);
741 EXPORT_SYMBOL(__bad_xchg);
744 * A data abort trap was taken, but we did not handle the instruction.
745 * Try to abort the user program, or panic if it was the kernel.
748 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
750 unsigned long addr = instruction_pointer(regs);
753 #ifdef CONFIG_DEBUG_USER
754 if (user_debug & UDBG_BADABORT) {
755 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
756 task_pid_nr(current), current->comm, code, instr);
757 dump_instr(KERN_ERR, regs);
758 show_pte(current->mm, addr);
762 info.si_signo = SIGILL;
764 info.si_code = ILL_ILLOPC;
765 info.si_addr = (void __user *)addr;
767 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
770 void __readwrite_bug(const char *fn)
772 printk("%s called, but not implemented\n", fn);
775 EXPORT_SYMBOL(__readwrite_bug);
777 void __pte_error(const char *file, int line, pte_t pte)
779 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
782 void __pmd_error(const char *file, int line, pmd_t pmd)
784 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
787 void __pgd_error(const char *file, int line, pgd_t pgd)
789 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
792 asmlinkage void __div0(void)
794 printk("Division by zero in kernel.\n");
797 EXPORT_SYMBOL(__div0);
803 /* if that doesn't kill us, halt */
804 panic("Oops failed to kill thread");
806 EXPORT_SYMBOL(abort);
808 void __init trap_init(void)
813 #ifdef CONFIG_KUSER_HELPERS
814 static void __init kuser_init(void *vectors)
816 extern char __kuser_helper_start[], __kuser_helper_end[];
817 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
819 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
822 * vectors + 0xfe0 = __kuser_get_tls
823 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
825 if (tls_emu || has_tls_reg)
826 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
829 static void __init kuser_init(void *vectors)
834 void __init early_trap_init(void *vectors_base)
836 unsigned long vectors = (unsigned long)vectors_base;
837 extern char __stubs_start[], __stubs_end[];
838 extern char __vectors_start[], __vectors_end[];
841 vectors_page = vectors_base;
844 * Poison the vectors page with an undefined instruction. This
845 * instruction is chosen to be undefined for both ARM and Thumb
846 * ISAs. The Thumb version is an undefined instruction with a
847 * branch back to the undefined instruction.
849 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
850 ((u32 *)vectors_base)[i] = 0xe7fddef1;
853 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
854 * into the vector page, mapped at 0xffff0000, and ensure these
855 * are visible to the instruction stream.
857 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
858 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
860 kuser_init(vectors_base);
862 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
863 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);