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>
28 #include <linux/irq.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/ptrace.h>
36 #include <asm/unwind.h>
38 #include <asm/system_misc.h>
39 #include <asm/opcodes.h>
42 static const char *handler[]= {
47 "undefined instruction",
52 #ifdef CONFIG_DEBUG_USER
53 unsigned int user_debug;
55 static int __init user_debug_setup(char *str)
57 get_option(&str, &user_debug);
60 __setup("user_debug=", user_debug_setup);
63 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
65 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
67 #ifdef CONFIG_KALLSYMS
68 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
70 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
73 if (in_exception_text(where))
74 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
77 #ifndef CONFIG_ARM_UNWIND
79 * Stack pointers should always be within the kernels view of
80 * physical memory. If it is not there, then we can't dump
81 * out any information relating to the stack.
83 static int verify_stack(unsigned long sp)
85 if (sp < PAGE_OFFSET ||
86 (sp > (unsigned long)high_memory && high_memory != NULL))
94 * Dump out the contents of some memory nicely...
96 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
104 * We need to switch to kernel mode so that we can use __get_user
105 * to safely read from kernel space. Note that we now dump the
106 * code first, just in case the backtrace kills us.
111 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
113 for (first = bottom & ~31; first < top; first += 32) {
115 char str[sizeof(" 12345678") * 8 + 1];
117 memset(str, ' ', sizeof(str));
118 str[sizeof(str) - 1] = '\0';
120 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
121 if (p >= bottom && p < top) {
123 if (__get_user(val, (unsigned long *)p) == 0)
124 sprintf(str + i * 9, " %08lx", val);
126 sprintf(str + i * 9, " ????????");
129 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
135 static void dump_instr(const char *lvl, struct pt_regs *regs)
137 unsigned long addr = instruction_pointer(regs);
138 const int thumb = thumb_mode(regs);
139 const int width = thumb ? 4 : 8;
141 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
145 * We need to switch to kernel mode so that we can use __get_user
146 * to safely read from kernel space. Note that we now dump the
147 * code first, just in case the backtrace kills us.
152 for (i = -4; i < 1 + !!thumb; i++) {
153 unsigned int val, bad;
156 bad = __get_user(val, &((u16 *)addr)[i]);
158 bad = __get_user(val, &((u32 *)addr)[i]);
161 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
164 p += sprintf(p, "bad PC value");
168 printk("%sCode: %s\n", lvl, str);
173 #ifdef CONFIG_ARM_UNWIND
174 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
176 unwind_backtrace(regs, tsk);
179 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
181 unsigned int fp, mode;
184 printk("Backtrace: ");
190 fp = frame_pointer(regs);
191 mode = processor_mode(regs);
192 } else if (tsk != current) {
193 fp = thread_saved_fp(tsk);
196 asm("mov %0, fp" : "=r" (fp) : : "cc");
201 pr_cont("no frame pointer");
203 } else if (verify_stack(fp)) {
204 pr_cont("invalid frame pointer 0x%08x", fp);
206 } else if (fp < (unsigned long)end_of_stack(tsk))
207 pr_cont("frame pointer underflow");
211 c_backtrace(fp, mode);
215 void show_stack(struct task_struct *tsk, unsigned long *sp)
217 dump_backtrace(NULL, tsk);
221 #ifdef CONFIG_PREEMPT
222 #define S_PREEMPT " PREEMPT"
231 #ifdef CONFIG_THUMB2_KERNEL
232 #define S_ISA " THUMB2"
237 static int __die(const char *str, int err, struct pt_regs *regs)
239 struct task_struct *tsk = current;
240 static int die_counter;
243 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
244 str, err, ++die_counter);
246 /* trap and error numbers are mostly meaningless on ARM */
247 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
248 if (ret == NOTIFY_STOP)
253 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
254 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
256 if (!user_mode(regs) || in_interrupt()) {
257 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
258 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
259 dump_backtrace(regs, tsk);
260 dump_instr(KERN_EMERG, regs);
266 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
267 static int die_owner = -1;
268 static unsigned int die_nest_count;
270 static unsigned long oops_begin(void)
277 /* racy, but better than risking deadlock. */
278 raw_local_irq_save(flags);
279 cpu = smp_processor_id();
280 if (!arch_spin_trylock(&die_lock)) {
281 if (cpu == die_owner)
282 /* nested oops. should stop eventually */;
284 arch_spin_lock(&die_lock);
293 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
295 if (regs && kexec_should_crash(current))
300 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
303 /* Nest count reaches zero, release the lock. */
304 arch_spin_unlock(&die_lock);
305 raw_local_irq_restore(flags);
309 panic("Fatal exception in interrupt");
311 panic("Fatal exception");
317 * This function is protected against re-entrancy.
319 void die(const char *str, struct pt_regs *regs, int err)
321 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
322 unsigned long flags = oops_begin();
325 if (!user_mode(regs))
326 bug_type = report_bug(regs->ARM_pc, regs);
327 if (bug_type != BUG_TRAP_TYPE_NONE)
330 if (__die(str, err, regs))
333 oops_end(flags, regs, sig);
336 void arm_notify_die(const char *str, struct pt_regs *regs,
337 struct siginfo *info, unsigned long err, unsigned long trap)
339 if (user_mode(regs)) {
340 current->thread.error_code = err;
341 current->thread.trap_no = trap;
343 force_sig_info(info->si_signo, info, current);
349 #ifdef CONFIG_GENERIC_BUG
351 int is_valid_bugaddr(unsigned long pc)
353 #ifdef CONFIG_THUMB2_KERNEL
355 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
358 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
361 if (probe_kernel_address((unsigned *)pc, bkpt))
369 static LIST_HEAD(undef_hook);
370 static DEFINE_RAW_SPINLOCK(undef_lock);
372 void register_undef_hook(struct undef_hook *hook)
376 raw_spin_lock_irqsave(&undef_lock, flags);
377 list_add(&hook->node, &undef_hook);
378 raw_spin_unlock_irqrestore(&undef_lock, flags);
381 void unregister_undef_hook(struct undef_hook *hook)
385 raw_spin_lock_irqsave(&undef_lock, flags);
386 list_del(&hook->node);
387 raw_spin_unlock_irqrestore(&undef_lock, flags);
390 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
392 struct undef_hook *hook;
394 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
396 raw_spin_lock_irqsave(&undef_lock, flags);
397 list_for_each_entry(hook, &undef_hook, node)
398 if ((instr & hook->instr_mask) == hook->instr_val &&
399 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
401 raw_spin_unlock_irqrestore(&undef_lock, flags);
403 return fn ? fn(regs, instr) : 1;
406 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
412 pc = (void __user *)instruction_pointer(regs);
414 if (processor_mode(regs) == SVC_MODE) {
415 #ifdef CONFIG_THUMB2_KERNEL
416 if (thumb_mode(regs)) {
417 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
418 if (is_wide_instruction(instr)) {
420 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
421 instr = __opcode_thumb32_compose(instr, inst2);
425 instr = __mem_to_opcode_arm(*(u32 *) pc);
426 } else if (thumb_mode(regs)) {
427 if (get_user(instr, (u16 __user *)pc))
429 instr = __mem_to_opcode_thumb16(instr);
430 if (is_wide_instruction(instr)) {
432 if (get_user(instr2, (u16 __user *)pc+1))
434 instr2 = __mem_to_opcode_thumb16(instr2);
435 instr = __opcode_thumb32_compose(instr, instr2);
438 if (get_user(instr, (u32 __user *)pc))
440 instr = __mem_to_opcode_arm(instr);
443 if (call_undef_hook(regs, instr) == 0)
447 #ifdef CONFIG_DEBUG_USER
448 if (user_debug & UDBG_UNDEFINED) {
449 pr_info("%s (%d): undefined instruction: pc=%p\n",
450 current->comm, task_pid_nr(current), pc);
452 dump_instr(KERN_INFO, regs);
456 info.si_signo = SIGILL;
458 info.si_code = ILL_ILLOPC;
461 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
465 * Handle FIQ similarly to NMI on x86 systems.
467 * The runtime environment for NMIs is extremely restrictive
468 * (NMIs can pre-empt critical sections meaning almost all locking is
469 * forbidden) meaning this default FIQ handling must only be used in
470 * circumstances where non-maskability improves robustness, such as
471 * watchdog or debug logic.
473 * This handler is not appropriate for general purpose use in drivers
474 * platform code and can be overrideen using set_fiq_handler.
476 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
478 struct pt_regs *old_regs = set_irq_regs(regs);
482 /* nop. FIQ handlers for special arch/arm features can be added here. */
486 set_irq_regs(old_regs);
490 * bad_mode handles the impossible case in the vectors. If you see one of
491 * these, then it's extremely serious, and could mean you have buggy hardware.
492 * It never returns, and never tries to sync. We hope that we can at least
493 * dump out some state information...
495 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
499 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
501 die("Oops - bad mode", regs, 0);
506 static int bad_syscall(int n, struct pt_regs *regs)
508 struct thread_info *thread = current_thread_info();
511 if ((current->personality & PER_MASK) != PER_LINUX &&
512 thread->exec_domain->handler) {
513 thread->exec_domain->handler(n, regs);
517 #ifdef CONFIG_DEBUG_USER
518 if (user_debug & UDBG_SYSCALL) {
519 pr_err("[%d] %s: obsolete system call %08x.\n",
520 task_pid_nr(current), current->comm, n);
521 dump_instr(KERN_ERR, regs);
525 info.si_signo = SIGILL;
527 info.si_code = ILL_ILLTRP;
528 info.si_addr = (void __user *)instruction_pointer(regs) -
529 (thumb_mode(regs) ? 2 : 4);
531 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
537 __do_cache_op(unsigned long start, unsigned long end)
542 unsigned long chunk = min(PAGE_SIZE, end - start);
544 if (fatal_signal_pending(current))
547 ret = flush_cache_user_range(start, start + chunk);
553 } while (start < end);
559 do_cache_op(unsigned long start, unsigned long end, int flags)
561 if (end < start || flags)
564 if (!access_ok(VERIFY_READ, start, end - start))
567 return __do_cache_op(start, end);
571 * Handle all unrecognised system calls.
572 * 0x9f0000 - 0x9fffff are some more esoteric system calls
574 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
575 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
579 if ((no >> 16) != (__ARM_NR_BASE>> 16))
580 return bad_syscall(no, regs);
582 switch (no & 0xffff) {
583 case 0: /* branch through 0 */
584 info.si_signo = SIGSEGV;
586 info.si_code = SEGV_MAPERR;
589 arm_notify_die("branch through zero", regs, &info, 0, 0);
592 case NR(breakpoint): /* SWI BREAK_POINT */
593 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
594 ptrace_break(current, regs);
598 * Flush a region from virtual address 'r0' to virtual address 'r1'
599 * _exclusive_. There is no alignment requirement on either address;
600 * user space does not need to know the hardware cache layout.
602 * r2 contains flags. It should ALWAYS be passed as ZERO until it
603 * is defined to be something else. For now we ignore it, but may
604 * the fires of hell burn in your belly if you break this rule. ;)
606 * (at a later date, we may want to allow this call to not flush
607 * various aspects of the cache. Passing '0' will guarantee that
608 * everything necessary gets flushed to maintain consistency in
609 * the specified region).
612 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
615 if (!(elf_hwcap & HWCAP_26BIT))
617 regs->ARM_cpsr &= ~MODE32_BIT;
621 if (!(elf_hwcap & HWCAP_26BIT))
623 regs->ARM_cpsr |= MODE32_BIT;
627 set_tls(regs->ARM_r0);
630 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
632 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
633 * Return zero in r0 if *MEM was changed or non-zero if no exchange
634 * happened. Also set the user C flag accordingly.
635 * If access permissions have to be fixed up then non-zero is
636 * returned and the operation has to be re-attempted.
638 * *NOTE*: This is a ghost syscall private to the kernel. Only the
639 * __kuser_cmpxchg code in entry-armv.S should be aware of its
640 * existence. Don't ever use this from user code.
644 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
645 struct pt_regs *regs);
647 unsigned long addr = regs->ARM_r2;
648 struct mm_struct *mm = current->mm;
649 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
652 regs->ARM_cpsr &= ~PSR_C_BIT;
653 down_read(&mm->mmap_sem);
654 pgd = pgd_offset(mm, addr);
655 if (!pgd_present(*pgd))
657 pmd = pmd_offset(pgd, addr);
658 if (!pmd_present(*pmd))
660 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
661 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
662 pte_unmap_unlock(pte, ptl);
665 val = *(unsigned long *)addr;
668 *(unsigned long *)addr = regs->ARM_r1;
669 regs->ARM_cpsr |= PSR_C_BIT;
671 pte_unmap_unlock(pte, ptl);
672 up_read(&mm->mmap_sem);
676 up_read(&mm->mmap_sem);
677 /* simulate a write access fault */
678 do_DataAbort(addr, 15 + (1 << 11), regs);
683 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
684 if not implemented, rather than raising SIGILL. This
685 way the calling program can gracefully determine whether
686 a feature is supported. */
687 if ((no & 0xffff) <= 0x7ff)
691 #ifdef CONFIG_DEBUG_USER
693 * experience shows that these seem to indicate that
694 * something catastrophic has happened
696 if (user_debug & UDBG_SYSCALL) {
697 pr_err("[%d] %s: arm syscall %d\n",
698 task_pid_nr(current), current->comm, no);
699 dump_instr("", regs);
700 if (user_mode(regs)) {
702 c_backtrace(frame_pointer(regs), processor_mode(regs));
706 info.si_signo = SIGILL;
708 info.si_code = ILL_ILLTRP;
709 info.si_addr = (void __user *)instruction_pointer(regs) -
710 (thumb_mode(regs) ? 2 : 4);
712 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
716 #ifdef CONFIG_TLS_REG_EMUL
719 * We might be running on an ARMv6+ processor which should have the TLS
720 * register but for some reason we can't use it, or maybe an SMP system
721 * using a pre-ARMv6 processor (there are apparently a few prototypes like
722 * that in existence) and therefore access to that register must be
726 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
728 int reg = (instr >> 12) & 15;
731 regs->uregs[reg] = current_thread_info()->tp_value[0];
736 static struct undef_hook arm_mrc_hook = {
737 .instr_mask = 0x0fff0fff,
738 .instr_val = 0x0e1d0f70,
739 .cpsr_mask = PSR_T_BIT,
744 static int __init arm_mrc_hook_init(void)
746 register_undef_hook(&arm_mrc_hook);
750 late_initcall(arm_mrc_hook_init);
754 void __bad_xchg(volatile void *ptr, int size)
756 pr_err("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
757 __builtin_return_address(0), ptr, size);
760 EXPORT_SYMBOL(__bad_xchg);
763 * A data abort trap was taken, but we did not handle the instruction.
764 * Try to abort the user program, or panic if it was the kernel.
767 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
769 unsigned long addr = instruction_pointer(regs);
772 #ifdef CONFIG_DEBUG_USER
773 if (user_debug & UDBG_BADABORT) {
774 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
775 task_pid_nr(current), current->comm, code, instr);
776 dump_instr(KERN_ERR, regs);
777 show_pte(current->mm, addr);
781 info.si_signo = SIGILL;
783 info.si_code = ILL_ILLOPC;
784 info.si_addr = (void __user *)addr;
786 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
789 void __readwrite_bug(const char *fn)
791 pr_err("%s called, but not implemented\n", fn);
794 EXPORT_SYMBOL(__readwrite_bug);
796 void __pte_error(const char *file, int line, pte_t pte)
798 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
801 void __pmd_error(const char *file, int line, pmd_t pmd)
803 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
806 void __pgd_error(const char *file, int line, pgd_t pgd)
808 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
811 asmlinkage void __div0(void)
813 pr_err("Division by zero in kernel.\n");
816 EXPORT_SYMBOL(__div0);
822 /* if that doesn't kill us, halt */
823 panic("Oops failed to kill thread");
825 EXPORT_SYMBOL(abort);
827 void __init trap_init(void)
832 #ifdef CONFIG_KUSER_HELPERS
833 static void __init kuser_init(void *vectors)
835 extern char __kuser_helper_start[], __kuser_helper_end[];
836 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
838 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
841 * vectors + 0xfe0 = __kuser_get_tls
842 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
844 if (tls_emu || has_tls_reg)
845 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
848 static inline void __init kuser_init(void *vectors)
853 void __init early_trap_init(void *vectors_base)
855 #ifndef CONFIG_CPU_V7M
856 unsigned long vectors = (unsigned long)vectors_base;
857 extern char __stubs_start[], __stubs_end[];
858 extern char __vectors_start[], __vectors_end[];
861 vectors_page = vectors_base;
864 * Poison the vectors page with an undefined instruction. This
865 * instruction is chosen to be undefined for both ARM and Thumb
866 * ISAs. The Thumb version is an undefined instruction with a
867 * branch back to the undefined instruction.
869 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
870 ((u32 *)vectors_base)[i] = 0xe7fddef1;
873 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
874 * into the vector page, mapped at 0xffff0000, and ensure these
875 * are visible to the instruction stream.
877 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
878 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
880 kuser_init(vectors_base);
882 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
883 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
884 #else /* ifndef CONFIG_CPU_V7M */
886 * on V7-M there is no need to copy the vector table to a dedicated
887 * memory area. The address is configurable and so a table in the kernel