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/signal.h>
29 #include <linux/sched/debug.h>
30 #include <linux/sched/task_stack.h>
31 #include <linux/irq.h>
33 #include <linux/atomic.h>
34 #include <asm/cacheflush.h>
35 #include <asm/exception.h>
36 #include <asm/unistd.h>
37 #include <asm/traps.h>
38 #include <asm/ptrace.h>
39 #include <asm/unwind.h>
41 #include <asm/system_misc.h>
42 #include <asm/opcodes.h>
45 static const char *handler[]= {
50 "undefined instruction",
55 #ifdef CONFIG_DEBUG_USER
56 unsigned int user_debug;
58 static int __init user_debug_setup(char *str)
60 get_option(&str, &user_debug);
63 __setup("user_debug=", user_debug_setup);
66 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
68 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
70 #ifdef CONFIG_KALLSYMS
71 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
73 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
76 if (in_entry_text(from))
77 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
80 void dump_backtrace_stm(u32 *stack, u32 instruction)
86 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
87 if (instruction & BIT(reg)) {
88 p += sprintf(p, " r%d:%08x", reg, *stack--);
100 #ifndef CONFIG_ARM_UNWIND
102 * Stack pointers should always be within the kernels view of
103 * physical memory. If it is not there, then we can't dump
104 * out any information relating to the stack.
106 static int verify_stack(unsigned long sp)
108 if (sp < PAGE_OFFSET ||
109 (sp > (unsigned long)high_memory && high_memory != NULL))
117 * Dump out the contents of some memory nicely...
119 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
127 * We need to switch to kernel mode so that we can use __get_user
128 * to safely read from kernel space. Note that we now dump the
129 * code first, just in case the backtrace kills us.
134 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
136 for (first = bottom & ~31; first < top; first += 32) {
138 char str[sizeof(" 12345678") * 8 + 1];
140 memset(str, ' ', sizeof(str));
141 str[sizeof(str) - 1] = '\0';
143 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
144 if (p >= bottom && p < top) {
146 if (__get_user(val, (unsigned long *)p) == 0)
147 sprintf(str + i * 9, " %08lx", val);
149 sprintf(str + i * 9, " ????????");
152 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
158 static void __dump_instr(const char *lvl, struct pt_regs *regs)
160 unsigned long addr = instruction_pointer(regs);
161 const int thumb = thumb_mode(regs);
162 const int width = thumb ? 4 : 8;
163 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
167 * Note that we now dump the code first, just in case the backtrace
171 for (i = -4; i < 1 + !!thumb; i++) {
172 unsigned int val, bad;
175 bad = get_user(val, &((u16 *)addr)[i]);
177 bad = get_user(val, &((u32 *)addr)[i]);
180 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
183 p += sprintf(p, "bad PC value");
187 printk("%sCode: %s\n", lvl, str);
190 static void dump_instr(const char *lvl, struct pt_regs *regs)
194 if (!user_mode(regs)) {
197 __dump_instr(lvl, regs);
200 __dump_instr(lvl, regs);
204 #ifdef CONFIG_ARM_UNWIND
205 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
207 unwind_backtrace(regs, tsk);
210 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
212 unsigned int fp, mode;
215 printk("Backtrace: ");
221 fp = frame_pointer(regs);
222 mode = processor_mode(regs);
223 } else if (tsk != current) {
224 fp = thread_saved_fp(tsk);
227 asm("mov %0, fp" : "=r" (fp) : : "cc");
232 pr_cont("no frame pointer");
234 } else if (verify_stack(fp)) {
235 pr_cont("invalid frame pointer 0x%08x", fp);
237 } else if (fp < (unsigned long)end_of_stack(tsk))
238 pr_cont("frame pointer underflow");
242 c_backtrace(fp, mode);
246 void show_stack(struct task_struct *tsk, unsigned long *sp)
248 dump_backtrace(NULL, tsk);
252 #ifdef CONFIG_PREEMPT
253 #define S_PREEMPT " PREEMPT"
262 #ifdef CONFIG_THUMB2_KERNEL
263 #define S_ISA " THUMB2"
268 static int __die(const char *str, int err, struct pt_regs *regs)
270 struct task_struct *tsk = current;
271 static int die_counter;
274 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
275 str, err, ++die_counter);
277 /* trap and error numbers are mostly meaningless on ARM */
278 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
279 if (ret == NOTIFY_STOP)
284 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
285 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
287 if (!user_mode(regs) || in_interrupt()) {
288 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
289 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
290 dump_backtrace(regs, tsk);
291 dump_instr(KERN_EMERG, regs);
297 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
298 static int die_owner = -1;
299 static unsigned int die_nest_count;
301 static unsigned long oops_begin(void)
308 /* racy, but better than risking deadlock. */
309 raw_local_irq_save(flags);
310 cpu = smp_processor_id();
311 if (!arch_spin_trylock(&die_lock)) {
312 if (cpu == die_owner)
313 /* nested oops. should stop eventually */;
315 arch_spin_lock(&die_lock);
324 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
326 if (regs && kexec_should_crash(current))
331 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
334 /* Nest count reaches zero, release the lock. */
335 arch_spin_unlock(&die_lock);
336 raw_local_irq_restore(flags);
340 panic("Fatal exception in interrupt");
342 panic("Fatal exception");
348 * This function is protected against re-entrancy.
350 void die(const char *str, struct pt_regs *regs, int err)
352 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
353 unsigned long flags = oops_begin();
356 if (!user_mode(regs))
357 bug_type = report_bug(regs->ARM_pc, regs);
358 if (bug_type != BUG_TRAP_TYPE_NONE)
361 if (__die(str, err, regs))
364 oops_end(flags, regs, sig);
367 void arm_notify_die(const char *str, struct pt_regs *regs,
368 int signo, int si_code, void __user *addr,
369 unsigned long err, unsigned long trap)
371 if (user_mode(regs)) {
372 current->thread.error_code = err;
373 current->thread.trap_no = trap;
375 force_sig_fault(signo, si_code, addr, current);
381 #ifdef CONFIG_GENERIC_BUG
383 int is_valid_bugaddr(unsigned long pc)
385 #ifdef CONFIG_THUMB2_KERNEL
387 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
390 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
393 if (probe_kernel_address((unsigned *)pc, bkpt))
401 static LIST_HEAD(undef_hook);
402 static DEFINE_RAW_SPINLOCK(undef_lock);
404 void register_undef_hook(struct undef_hook *hook)
408 raw_spin_lock_irqsave(&undef_lock, flags);
409 list_add(&hook->node, &undef_hook);
410 raw_spin_unlock_irqrestore(&undef_lock, flags);
413 void unregister_undef_hook(struct undef_hook *hook)
417 raw_spin_lock_irqsave(&undef_lock, flags);
418 list_del(&hook->node);
419 raw_spin_unlock_irqrestore(&undef_lock, flags);
422 static nokprobe_inline
423 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
425 struct undef_hook *hook;
427 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
429 raw_spin_lock_irqsave(&undef_lock, flags);
430 list_for_each_entry(hook, &undef_hook, node)
431 if ((instr & hook->instr_mask) == hook->instr_val &&
432 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
434 raw_spin_unlock_irqrestore(&undef_lock, flags);
436 return fn ? fn(regs, instr) : 1;
439 asmlinkage void do_undefinstr(struct pt_regs *regs)
444 pc = (void __user *)instruction_pointer(regs);
446 if (processor_mode(regs) == SVC_MODE) {
447 #ifdef CONFIG_THUMB2_KERNEL
448 if (thumb_mode(regs)) {
449 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
450 if (is_wide_instruction(instr)) {
452 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
453 instr = __opcode_thumb32_compose(instr, inst2);
457 instr = __mem_to_opcode_arm(*(u32 *) pc);
458 } else if (thumb_mode(regs)) {
459 if (get_user(instr, (u16 __user *)pc))
461 instr = __mem_to_opcode_thumb16(instr);
462 if (is_wide_instruction(instr)) {
464 if (get_user(instr2, (u16 __user *)pc+1))
466 instr2 = __mem_to_opcode_thumb16(instr2);
467 instr = __opcode_thumb32_compose(instr, instr2);
470 if (get_user(instr, (u32 __user *)pc))
472 instr = __mem_to_opcode_arm(instr);
475 if (call_undef_hook(regs, instr) == 0)
479 #ifdef CONFIG_DEBUG_USER
480 if (user_debug & UDBG_UNDEFINED) {
481 pr_info("%s (%d): undefined instruction: pc=%p\n",
482 current->comm, task_pid_nr(current), pc);
484 dump_instr(KERN_INFO, regs);
487 arm_notify_die("Oops - undefined instruction", regs,
488 SIGILL, ILL_ILLOPC, pc, 0, 6);
490 NOKPROBE_SYMBOL(do_undefinstr)
493 * Handle FIQ similarly to NMI on x86 systems.
495 * The runtime environment for NMIs is extremely restrictive
496 * (NMIs can pre-empt critical sections meaning almost all locking is
497 * forbidden) meaning this default FIQ handling must only be used in
498 * circumstances where non-maskability improves robustness, such as
499 * watchdog or debug logic.
501 * This handler is not appropriate for general purpose use in drivers
502 * platform code and can be overrideen using set_fiq_handler.
504 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
506 struct pt_regs *old_regs = set_irq_regs(regs);
510 /* nop. FIQ handlers for special arch/arm features can be added here. */
514 set_irq_regs(old_regs);
518 * bad_mode handles the impossible case in the vectors. If you see one of
519 * these, then it's extremely serious, and could mean you have buggy hardware.
520 * It never returns, and never tries to sync. We hope that we can at least
521 * dump out some state information...
523 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
527 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
529 die("Oops - bad mode", regs, 0);
534 static int bad_syscall(int n, struct pt_regs *regs)
536 if ((current->personality & PER_MASK) != PER_LINUX) {
537 send_sig(SIGSEGV, current, 1);
541 #ifdef CONFIG_DEBUG_USER
542 if (user_debug & UDBG_SYSCALL) {
543 pr_err("[%d] %s: obsolete system call %08x.\n",
544 task_pid_nr(current), current->comm, n);
545 dump_instr(KERN_ERR, regs);
549 arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
550 (void __user *)instruction_pointer(regs) -
551 (thumb_mode(regs) ? 2 : 4),
558 __do_cache_op(unsigned long start, unsigned long end)
563 unsigned long chunk = min(PAGE_SIZE, end - start);
565 if (fatal_signal_pending(current))
568 ret = flush_cache_user_range(start, start + chunk);
574 } while (start < end);
580 do_cache_op(unsigned long start, unsigned long end, int flags)
582 if (end < start || flags)
585 if (!access_ok(VERIFY_READ, start, end - start))
588 return __do_cache_op(start, end);
592 * Handle all unrecognised system calls.
593 * 0x9f0000 - 0x9fffff are some more esoteric system calls
595 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
596 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
598 if ((no >> 16) != (__ARM_NR_BASE>> 16))
599 return bad_syscall(no, regs);
601 switch (no & 0xffff) {
602 case 0: /* branch through 0 */
603 arm_notify_die("branch through zero", regs,
604 SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
607 case NR(breakpoint): /* SWI BREAK_POINT */
608 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
609 ptrace_break(current, regs);
613 * Flush a region from virtual address 'r0' to virtual address 'r1'
614 * _exclusive_. There is no alignment requirement on either address;
615 * user space does not need to know the hardware cache layout.
617 * r2 contains flags. It should ALWAYS be passed as ZERO until it
618 * is defined to be something else. For now we ignore it, but may
619 * the fires of hell burn in your belly if you break this rule. ;)
621 * (at a later date, we may want to allow this call to not flush
622 * various aspects of the cache. Passing '0' will guarantee that
623 * everything necessary gets flushed to maintain consistency in
624 * the specified region).
627 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
630 if (!(elf_hwcap & HWCAP_26BIT))
632 regs->ARM_cpsr &= ~MODE32_BIT;
636 if (!(elf_hwcap & HWCAP_26BIT))
638 regs->ARM_cpsr |= MODE32_BIT;
642 set_tls(regs->ARM_r0);
646 return current_thread_info()->tp_value[0];
649 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
650 if not implemented, rather than raising SIGILL. This
651 way the calling program can gracefully determine whether
652 a feature is supported. */
653 if ((no & 0xffff) <= 0x7ff)
657 #ifdef CONFIG_DEBUG_USER
659 * experience shows that these seem to indicate that
660 * something catastrophic has happened
662 if (user_debug & UDBG_SYSCALL) {
663 pr_err("[%d] %s: arm syscall %d\n",
664 task_pid_nr(current), current->comm, no);
665 dump_instr("", regs);
666 if (user_mode(regs)) {
668 c_backtrace(frame_pointer(regs), processor_mode(regs));
672 arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
673 (void __user *)instruction_pointer(regs) -
674 (thumb_mode(regs) ? 2 : 4),
679 #ifdef CONFIG_TLS_REG_EMUL
682 * We might be running on an ARMv6+ processor which should have the TLS
683 * register but for some reason we can't use it, or maybe an SMP system
684 * using a pre-ARMv6 processor (there are apparently a few prototypes like
685 * that in existence) and therefore access to that register must be
689 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
691 int reg = (instr >> 12) & 15;
694 regs->uregs[reg] = current_thread_info()->tp_value[0];
699 static struct undef_hook arm_mrc_hook = {
700 .instr_mask = 0x0fff0fff,
701 .instr_val = 0x0e1d0f70,
702 .cpsr_mask = PSR_T_BIT,
707 static int __init arm_mrc_hook_init(void)
709 register_undef_hook(&arm_mrc_hook);
713 late_initcall(arm_mrc_hook_init);
718 * A data abort trap was taken, but we did not handle the instruction.
719 * Try to abort the user program, or panic if it was the kernel.
722 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
724 unsigned long addr = instruction_pointer(regs);
726 #ifdef CONFIG_DEBUG_USER
727 if (user_debug & UDBG_BADABORT) {
728 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
729 task_pid_nr(current), current->comm, code, instr);
730 dump_instr(KERN_ERR, regs);
731 show_pte(current->mm, addr);
735 arm_notify_die("unknown data abort code", regs,
736 SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
739 void __readwrite_bug(const char *fn)
741 pr_err("%s called, but not implemented\n", fn);
744 EXPORT_SYMBOL(__readwrite_bug);
746 void __pte_error(const char *file, int line, pte_t pte)
748 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
751 void __pmd_error(const char *file, int line, pmd_t pmd)
753 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
756 void __pgd_error(const char *file, int line, pgd_t pgd)
758 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
761 asmlinkage void __div0(void)
763 pr_err("Division by zero in kernel.\n");
766 EXPORT_SYMBOL(__div0);
772 /* if that doesn't kill us, halt */
773 panic("Oops failed to kill thread");
776 void __init trap_init(void)
781 #ifdef CONFIG_KUSER_HELPERS
782 static void __init kuser_init(void *vectors)
784 extern char __kuser_helper_start[], __kuser_helper_end[];
785 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
787 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
790 * vectors + 0xfe0 = __kuser_get_tls
791 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
793 if (tls_emu || has_tls_reg)
794 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
797 static inline void __init kuser_init(void *vectors)
802 void __init early_trap_init(void *vectors_base)
804 #ifndef CONFIG_CPU_V7M
805 unsigned long vectors = (unsigned long)vectors_base;
806 extern char __stubs_start[], __stubs_end[];
807 extern char __vectors_start[], __vectors_end[];
810 vectors_page = vectors_base;
813 * Poison the vectors page with an undefined instruction. This
814 * instruction is chosen to be undefined for both ARM and Thumb
815 * ISAs. The Thumb version is an undefined instruction with a
816 * branch back to the undefined instruction.
818 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
819 ((u32 *)vectors_base)[i] = 0xe7fddef1;
822 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
823 * into the vector page, mapped at 0xffff0000, and ensure these
824 * are visible to the instruction stream.
826 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
827 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
829 kuser_init(vectors_base);
831 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
832 #else /* ifndef CONFIG_CPU_V7M */
834 * on V7-M there is no need to copy the vector table to a dedicated
835 * memory area. The address is configurable and so a table in the kernel