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/system.h>
33 #include <asm/unistd.h>
34 #include <asm/traps.h>
35 #include <asm/unwind.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 thread_info *thread, struct pt_regs *regs)
238 struct task_struct *tsk = thread->task;
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), thread + 1);
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 DEFINE_RAW_SPINLOCK(die_lock);
268 * This function is protected against re-entrancy.
270 void die(const char *str, struct pt_regs *regs, int err)
272 struct thread_info *thread = current_thread_info();
277 raw_spin_lock_irq(&die_lock);
280 if (!user_mode(regs))
281 report_bug(regs->ARM_pc, regs);
282 ret = __die(str, err, thread, regs);
284 if (regs && kexec_should_crash(thread->task))
288 add_taint(TAINT_DIE);
289 raw_spin_unlock_irq(&die_lock);
293 panic("Fatal exception in interrupt");
295 panic("Fatal exception");
296 if (ret != NOTIFY_STOP)
300 void arm_notify_die(const char *str, struct pt_regs *regs,
301 struct siginfo *info, unsigned long err, unsigned long trap)
303 if (user_mode(regs)) {
304 current->thread.error_code = err;
305 current->thread.trap_no = trap;
307 force_sig_info(info->si_signo, info, current);
313 #ifdef CONFIG_GENERIC_BUG
315 int is_valid_bugaddr(unsigned long pc)
317 #ifdef CONFIG_THUMB2_KERNEL
323 if (probe_kernel_address((unsigned *)pc, bkpt))
326 return bkpt == BUG_INSTR_VALUE;
331 static LIST_HEAD(undef_hook);
332 static DEFINE_RAW_SPINLOCK(undef_lock);
334 void register_undef_hook(struct undef_hook *hook)
338 raw_spin_lock_irqsave(&undef_lock, flags);
339 list_add(&hook->node, &undef_hook);
340 raw_spin_unlock_irqrestore(&undef_lock, flags);
343 void unregister_undef_hook(struct undef_hook *hook)
347 raw_spin_lock_irqsave(&undef_lock, flags);
348 list_del(&hook->node);
349 raw_spin_unlock_irqrestore(&undef_lock, flags);
352 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
354 struct undef_hook *hook;
356 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
358 raw_spin_lock_irqsave(&undef_lock, flags);
359 list_for_each_entry(hook, &undef_hook, node)
360 if ((instr & hook->instr_mask) == hook->instr_val &&
361 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
363 raw_spin_unlock_irqrestore(&undef_lock, flags);
365 return fn ? fn(regs, instr) : 1;
368 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
370 unsigned int correction = thumb_mode(regs) ? 2 : 4;
376 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
377 * depending whether we're in Thumb mode or not.
378 * Correct this offset.
380 regs->ARM_pc -= correction;
382 pc = (void __user *)instruction_pointer(regs);
384 if (processor_mode(regs) == SVC_MODE) {
385 #ifdef CONFIG_THUMB2_KERNEL
386 if (thumb_mode(regs)) {
387 instr = ((u16 *)pc)[0];
388 if (is_wide_instruction(instr)) {
390 instr |= ((u16 *)pc)[1];
395 } else if (thumb_mode(regs)) {
396 get_user(instr, (u16 __user *)pc);
397 if (is_wide_instruction(instr)) {
399 get_user(instr2, (u16 __user *)pc+1);
404 get_user(instr, (u32 __user *)pc);
407 if (call_undef_hook(regs, instr) == 0)
410 #ifdef CONFIG_DEBUG_USER
411 if (user_debug & UDBG_UNDEFINED) {
412 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
413 current->comm, task_pid_nr(current), pc);
414 dump_instr(KERN_INFO, regs);
418 info.si_signo = SIGILL;
420 info.si_code = ILL_ILLOPC;
423 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
426 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
428 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
429 printk("You may have a hardware problem...\n");
433 * bad_mode handles the impossible case in the vectors. If you see one of
434 * these, then it's extremely serious, and could mean you have buggy hardware.
435 * It never returns, and never tries to sync. We hope that we can at least
436 * dump out some state information...
438 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
442 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
444 die("Oops - bad mode", regs, 0);
449 static int bad_syscall(int n, struct pt_regs *regs)
451 struct thread_info *thread = current_thread_info();
454 if ((current->personality & PER_MASK) != PER_LINUX &&
455 thread->exec_domain->handler) {
456 thread->exec_domain->handler(n, regs);
460 #ifdef CONFIG_DEBUG_USER
461 if (user_debug & UDBG_SYSCALL) {
462 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
463 task_pid_nr(current), current->comm, n);
464 dump_instr(KERN_ERR, regs);
468 info.si_signo = SIGILL;
470 info.si_code = ILL_ILLTRP;
471 info.si_addr = (void __user *)instruction_pointer(regs) -
472 (thumb_mode(regs) ? 2 : 4);
474 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
480 do_cache_op(unsigned long start, unsigned long end, int flags)
482 struct mm_struct *mm = current->active_mm;
483 struct vm_area_struct *vma;
485 if (end < start || flags)
488 down_read(&mm->mmap_sem);
489 vma = find_vma(mm, start);
490 if (vma && vma->vm_start < end) {
491 if (start < vma->vm_start)
492 start = vma->vm_start;
493 if (end > vma->vm_end)
496 flush_cache_user_range(vma, start, end);
498 up_read(&mm->mmap_sem);
502 * Handle all unrecognised system calls.
503 * 0x9f0000 - 0x9fffff are some more esoteric system calls
505 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
506 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
508 struct thread_info *thread = current_thread_info();
511 if ((no >> 16) != (__ARM_NR_BASE>> 16))
512 return bad_syscall(no, regs);
514 switch (no & 0xffff) {
515 case 0: /* branch through 0 */
516 info.si_signo = SIGSEGV;
518 info.si_code = SEGV_MAPERR;
521 arm_notify_die("branch through zero", regs, &info, 0, 0);
524 case NR(breakpoint): /* SWI BREAK_POINT */
525 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
526 ptrace_break(current, regs);
530 * Flush a region from virtual address 'r0' to virtual address 'r1'
531 * _exclusive_. There is no alignment requirement on either address;
532 * user space does not need to know the hardware cache layout.
534 * r2 contains flags. It should ALWAYS be passed as ZERO until it
535 * is defined to be something else. For now we ignore it, but may
536 * the fires of hell burn in your belly if you break this rule. ;)
538 * (at a later date, we may want to allow this call to not flush
539 * various aspects of the cache. Passing '0' will guarantee that
540 * everything necessary gets flushed to maintain consistency in
541 * the specified region).
544 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
548 if (!(elf_hwcap & HWCAP_26BIT))
550 regs->ARM_cpsr &= ~MODE32_BIT;
554 if (!(elf_hwcap & HWCAP_26BIT))
556 regs->ARM_cpsr |= MODE32_BIT;
560 thread->tp_value = regs->ARM_r0;
564 asm ("mcr p15, 0, %0, c13, c0, 3"
565 : : "r" (regs->ARM_r0));
568 * User space must never try to access this directly.
569 * Expect your app to break eventually if you do so.
570 * The user helper at 0xffff0fe0 must be used instead.
571 * (see entry-armv.S for details)
573 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
577 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
579 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
580 * Return zero in r0 if *MEM was changed or non-zero if no exchange
581 * happened. Also set the user C flag accordingly.
582 * If access permissions have to be fixed up then non-zero is
583 * returned and the operation has to be re-attempted.
585 * *NOTE*: This is a ghost syscall private to the kernel. Only the
586 * __kuser_cmpxchg code in entry-armv.S should be aware of its
587 * existence. Don't ever use this from user code.
591 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
592 struct pt_regs *regs);
594 unsigned long addr = regs->ARM_r2;
595 struct mm_struct *mm = current->mm;
596 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
599 regs->ARM_cpsr &= ~PSR_C_BIT;
600 down_read(&mm->mmap_sem);
601 pgd = pgd_offset(mm, addr);
602 if (!pgd_present(*pgd))
604 pmd = pmd_offset(pgd, addr);
605 if (!pmd_present(*pmd))
607 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
608 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
609 pte_unmap_unlock(pte, ptl);
612 val = *(unsigned long *)addr;
615 *(unsigned long *)addr = regs->ARM_r1;
616 regs->ARM_cpsr |= PSR_C_BIT;
618 pte_unmap_unlock(pte, ptl);
619 up_read(&mm->mmap_sem);
623 up_read(&mm->mmap_sem);
624 /* simulate a write access fault */
625 do_DataAbort(addr, 15 + (1 << 11), regs);
630 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
631 if not implemented, rather than raising SIGILL. This
632 way the calling program can gracefully determine whether
633 a feature is supported. */
634 if ((no & 0xffff) <= 0x7ff)
638 #ifdef CONFIG_DEBUG_USER
640 * experience shows that these seem to indicate that
641 * something catastrophic has happened
643 if (user_debug & UDBG_SYSCALL) {
644 printk("[%d] %s: arm syscall %d\n",
645 task_pid_nr(current), current->comm, no);
646 dump_instr("", regs);
647 if (user_mode(regs)) {
649 c_backtrace(regs->ARM_fp, processor_mode(regs));
653 info.si_signo = SIGILL;
655 info.si_code = ILL_ILLTRP;
656 info.si_addr = (void __user *)instruction_pointer(regs) -
657 (thumb_mode(regs) ? 2 : 4);
659 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
663 #ifdef CONFIG_TLS_REG_EMUL
666 * We might be running on an ARMv6+ processor which should have the TLS
667 * register but for some reason we can't use it, or maybe an SMP system
668 * using a pre-ARMv6 processor (there are apparently a few prototypes like
669 * that in existence) and therefore access to that register must be
673 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
675 int reg = (instr >> 12) & 15;
678 regs->uregs[reg] = current_thread_info()->tp_value;
683 static struct undef_hook arm_mrc_hook = {
684 .instr_mask = 0x0fff0fff,
685 .instr_val = 0x0e1d0f70,
686 .cpsr_mask = PSR_T_BIT,
691 static int __init arm_mrc_hook_init(void)
693 register_undef_hook(&arm_mrc_hook);
697 late_initcall(arm_mrc_hook_init);
701 void __bad_xchg(volatile void *ptr, int size)
703 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
704 __builtin_return_address(0), ptr, size);
707 EXPORT_SYMBOL(__bad_xchg);
710 * A data abort trap was taken, but we did not handle the instruction.
711 * Try to abort the user program, or panic if it was the kernel.
714 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
716 unsigned long addr = instruction_pointer(regs);
719 #ifdef CONFIG_DEBUG_USER
720 if (user_debug & UDBG_BADABORT) {
721 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
722 task_pid_nr(current), current->comm, code, instr);
723 dump_instr(KERN_ERR, regs);
724 show_pte(current->mm, addr);
728 info.si_signo = SIGILL;
730 info.si_code = ILL_ILLOPC;
731 info.si_addr = (void __user *)addr;
733 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
736 void __readwrite_bug(const char *fn)
738 printk("%s called, but not implemented\n", fn);
741 EXPORT_SYMBOL(__readwrite_bug);
743 void __pte_error(const char *file, int line, pte_t pte)
745 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
748 void __pmd_error(const char *file, int line, pmd_t pmd)
750 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
753 void __pgd_error(const char *file, int line, pgd_t pgd)
755 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
758 asmlinkage void __div0(void)
760 printk("Division by zero in kernel.\n");
763 EXPORT_SYMBOL(__div0);
769 /* if that doesn't kill us, halt */
770 panic("Oops failed to kill thread");
772 EXPORT_SYMBOL(abort);
774 void __init trap_init(void)
779 static void __init kuser_get_tls_init(unsigned long vectors)
782 * vectors + 0xfe0 = __kuser_get_tls
783 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
785 if (tls_emu || has_tls_reg)
786 memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
789 void __init early_trap_init(void *vectors_base)
791 unsigned long vectors = (unsigned long)vectors_base;
792 extern char __stubs_start[], __stubs_end[];
793 extern char __vectors_start[], __vectors_end[];
794 extern char __kuser_helper_start[], __kuser_helper_end[];
795 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
797 vectors_page = vectors_base;
800 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
801 * into the vector page, mapped at 0xffff0000, and ensure these
802 * are visible to the instruction stream.
804 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
805 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
806 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
809 * Do processor specific fixups for the kuser helpers
811 kuser_get_tls_init(vectors);
814 * Copy signal return handlers into the vector page, and
815 * set sigreturn to be a pointer to these.
817 memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
818 sigreturn_codes, sizeof(sigreturn_codes));
819 memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
820 syscall_restart_code, sizeof(syscall_restart_code));
822 flush_icache_range(vectors, vectors + PAGE_SIZE);
823 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);