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/delay.h>
25 #include <linux/init.h>
26 #include <linux/sched.h>
28 #include <linux/atomic.h>
29 #include <asm/cacheflush.h>
30 #include <asm/exception.h>
31 #include <asm/system.h>
32 #include <asm/unistd.h>
33 #include <asm/traps.h>
34 #include <asm/unwind.h>
39 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
43 #ifdef CONFIG_DEBUG_USER
44 unsigned int user_debug;
46 static int __init user_debug_setup(char *str)
48 get_option(&str, &user_debug);
51 __setup("user_debug=", user_debug_setup);
54 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
56 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
58 #ifdef CONFIG_KALLSYMS
59 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
61 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
64 if (in_exception_text(where))
65 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
68 #ifndef CONFIG_ARM_UNWIND
70 * Stack pointers should always be within the kernels view of
71 * physical memory. If it is not there, then we can't dump
72 * out any information relating to the stack.
74 static int verify_stack(unsigned long sp)
76 if (sp < PAGE_OFFSET ||
77 (sp > (unsigned long)high_memory && high_memory != NULL))
85 * Dump out the contents of some memory nicely...
87 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
95 * We need to switch to kernel mode so that we can use __get_user
96 * to safely read from kernel space. Note that we now dump the
97 * code first, just in case the backtrace kills us.
102 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
104 for (first = bottom & ~31; first < top; first += 32) {
106 char str[sizeof(" 12345678") * 8 + 1];
108 memset(str, ' ', sizeof(str));
109 str[sizeof(str) - 1] = '\0';
111 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
112 if (p >= bottom && p < top) {
114 if (__get_user(val, (unsigned long *)p) == 0)
115 sprintf(str + i * 9, " %08lx", val);
117 sprintf(str + i * 9, " ????????");
120 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
126 static void dump_instr(const char *lvl, struct pt_regs *regs)
128 unsigned long addr = instruction_pointer(regs);
129 const int thumb = thumb_mode(regs);
130 const int width = thumb ? 4 : 8;
132 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
136 * We need to switch to kernel mode so that we can use __get_user
137 * to safely read from kernel space. Note that we now dump the
138 * code first, just in case the backtrace kills us.
143 for (i = -4; i < 1 + !!thumb; i++) {
144 unsigned int val, bad;
147 bad = __get_user(val, &((u16 *)addr)[i]);
149 bad = __get_user(val, &((u32 *)addr)[i]);
152 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
155 p += sprintf(p, "bad PC value");
159 printk("%sCode: %s\n", lvl, str);
164 #ifdef CONFIG_ARM_UNWIND
165 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
167 unwind_backtrace(regs, tsk);
170 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172 unsigned int fp, mode;
175 printk("Backtrace: ");
182 mode = processor_mode(regs);
183 } else if (tsk != current) {
184 fp = thread_saved_fp(tsk);
187 asm("mov %0, fp" : "=r" (fp) : : "cc");
192 printk("no frame pointer");
194 } else if (verify_stack(fp)) {
195 printk("invalid frame pointer 0x%08x", fp);
197 } else if (fp < (unsigned long)end_of_stack(tsk))
198 printk("frame pointer underflow");
202 c_backtrace(fp, mode);
206 void dump_stack(void)
208 dump_backtrace(NULL, NULL);
211 EXPORT_SYMBOL(dump_stack);
213 void show_stack(struct task_struct *tsk, unsigned long *sp)
215 dump_backtrace(NULL, tsk);
219 #ifdef CONFIG_PREEMPT
220 #define S_PREEMPT " PREEMPT"
230 static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
232 struct task_struct *tsk = thread->task;
233 static int die_counter;
236 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
237 str, err, ++die_counter);
239 /* trap and error numbers are mostly meaningless on ARM */
240 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
241 if (ret == NOTIFY_STOP)
246 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
247 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
249 if (!user_mode(regs) || in_interrupt()) {
250 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
251 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
252 dump_backtrace(regs, tsk);
253 dump_instr(KERN_EMERG, regs);
259 static DEFINE_SPINLOCK(die_lock);
262 * This function is protected against re-entrancy.
264 void die(const char *str, struct pt_regs *regs, int err)
266 struct thread_info *thread = current_thread_info();
271 spin_lock_irq(&die_lock);
274 ret = __die(str, err, thread, regs);
276 if (regs && kexec_should_crash(thread->task))
280 add_taint(TAINT_DIE);
281 spin_unlock_irq(&die_lock);
285 panic("Fatal exception in interrupt");
287 panic("Fatal exception");
288 if (ret != NOTIFY_STOP)
292 void arm_notify_die(const char *str, struct pt_regs *regs,
293 struct siginfo *info, unsigned long err, unsigned long trap)
295 if (user_mode(regs)) {
296 current->thread.error_code = err;
297 current->thread.trap_no = trap;
299 force_sig_info(info->si_signo, info, current);
305 static LIST_HEAD(undef_hook);
306 static DEFINE_SPINLOCK(undef_lock);
308 void register_undef_hook(struct undef_hook *hook)
312 spin_lock_irqsave(&undef_lock, flags);
313 list_add(&hook->node, &undef_hook);
314 spin_unlock_irqrestore(&undef_lock, flags);
317 void unregister_undef_hook(struct undef_hook *hook)
321 spin_lock_irqsave(&undef_lock, flags);
322 list_del(&hook->node);
323 spin_unlock_irqrestore(&undef_lock, flags);
326 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
328 struct undef_hook *hook;
330 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
332 spin_lock_irqsave(&undef_lock, flags);
333 list_for_each_entry(hook, &undef_hook, node)
334 if ((instr & hook->instr_mask) == hook->instr_val &&
335 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
337 spin_unlock_irqrestore(&undef_lock, flags);
339 return fn ? fn(regs, instr) : 1;
342 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
344 unsigned int correction = thumb_mode(regs) ? 2 : 4;
350 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
351 * depending whether we're in Thumb mode or not.
352 * Correct this offset.
354 regs->ARM_pc -= correction;
356 pc = (void __user *)instruction_pointer(regs);
358 if (processor_mode(regs) == SVC_MODE) {
359 #ifdef CONFIG_THUMB2_KERNEL
360 if (thumb_mode(regs)) {
361 instr = ((u16 *)pc)[0];
362 if (is_wide_instruction(instr)) {
364 instr |= ((u16 *)pc)[1];
369 } else if (thumb_mode(regs)) {
370 get_user(instr, (u16 __user *)pc);
371 if (is_wide_instruction(instr)) {
373 get_user(instr2, (u16 __user *)pc+1);
378 get_user(instr, (u32 __user *)pc);
381 if (call_undef_hook(regs, instr) == 0)
384 #ifdef CONFIG_DEBUG_USER
385 if (user_debug & UDBG_UNDEFINED) {
386 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
387 current->comm, task_pid_nr(current), pc);
388 dump_instr(KERN_INFO, regs);
392 info.si_signo = SIGILL;
394 info.si_code = ILL_ILLOPC;
397 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
400 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
402 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
403 printk("You may have a hardware problem...\n");
407 * bad_mode handles the impossible case in the vectors. If you see one of
408 * these, then it's extremely serious, and could mean you have buggy hardware.
409 * It never returns, and never tries to sync. We hope that we can at least
410 * dump out some state information...
412 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
416 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
418 die("Oops - bad mode", regs, 0);
423 static int bad_syscall(int n, struct pt_regs *regs)
425 struct thread_info *thread = current_thread_info();
428 if ((current->personality & PER_MASK) != PER_LINUX &&
429 thread->exec_domain->handler) {
430 thread->exec_domain->handler(n, regs);
434 #ifdef CONFIG_DEBUG_USER
435 if (user_debug & UDBG_SYSCALL) {
436 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
437 task_pid_nr(current), current->comm, n);
438 dump_instr(KERN_ERR, regs);
442 info.si_signo = SIGILL;
444 info.si_code = ILL_ILLTRP;
445 info.si_addr = (void __user *)instruction_pointer(regs) -
446 (thumb_mode(regs) ? 2 : 4);
448 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
454 do_cache_op(unsigned long start, unsigned long end, int flags)
456 struct mm_struct *mm = current->active_mm;
457 struct vm_area_struct *vma;
459 if (end < start || flags)
462 down_read(&mm->mmap_sem);
463 vma = find_vma(mm, start);
464 if (vma && vma->vm_start < end) {
465 if (start < vma->vm_start)
466 start = vma->vm_start;
467 if (end > vma->vm_end)
470 flush_cache_user_range(vma, start, end);
472 up_read(&mm->mmap_sem);
476 * Handle all unrecognised system calls.
477 * 0x9f0000 - 0x9fffff are some more esoteric system calls
479 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
480 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
482 struct thread_info *thread = current_thread_info();
485 if ((no >> 16) != (__ARM_NR_BASE>> 16))
486 return bad_syscall(no, regs);
488 switch (no & 0xffff) {
489 case 0: /* branch through 0 */
490 info.si_signo = SIGSEGV;
492 info.si_code = SEGV_MAPERR;
495 arm_notify_die("branch through zero", regs, &info, 0, 0);
498 case NR(breakpoint): /* SWI BREAK_POINT */
499 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
500 ptrace_break(current, regs);
504 * Flush a region from virtual address 'r0' to virtual address 'r1'
505 * _exclusive_. There is no alignment requirement on either address;
506 * user space does not need to know the hardware cache layout.
508 * r2 contains flags. It should ALWAYS be passed as ZERO until it
509 * is defined to be something else. For now we ignore it, but may
510 * the fires of hell burn in your belly if you break this rule. ;)
512 * (at a later date, we may want to allow this call to not flush
513 * various aspects of the cache. Passing '0' will guarantee that
514 * everything necessary gets flushed to maintain consistency in
515 * the specified region).
518 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
522 if (!(elf_hwcap & HWCAP_26BIT))
524 regs->ARM_cpsr &= ~MODE32_BIT;
528 if (!(elf_hwcap & HWCAP_26BIT))
530 regs->ARM_cpsr |= MODE32_BIT;
534 thread->tp_value = regs->ARM_r0;
538 asm ("mcr p15, 0, %0, c13, c0, 3"
539 : : "r" (regs->ARM_r0));
542 * User space must never try to access this directly.
543 * Expect your app to break eventually if you do so.
544 * The user helper at 0xffff0fe0 must be used instead.
545 * (see entry-armv.S for details)
547 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
551 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
553 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
554 * Return zero in r0 if *MEM was changed or non-zero if no exchange
555 * happened. Also set the user C flag accordingly.
556 * If access permissions have to be fixed up then non-zero is
557 * returned and the operation has to be re-attempted.
559 * *NOTE*: This is a ghost syscall private to the kernel. Only the
560 * __kuser_cmpxchg code in entry-armv.S should be aware of its
561 * existence. Don't ever use this from user code.
565 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
566 struct pt_regs *regs);
568 unsigned long addr = regs->ARM_r2;
569 struct mm_struct *mm = current->mm;
570 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
573 regs->ARM_cpsr &= ~PSR_C_BIT;
574 down_read(&mm->mmap_sem);
575 pgd = pgd_offset(mm, addr);
576 if (!pgd_present(*pgd))
578 pmd = pmd_offset(pgd, addr);
579 if (!pmd_present(*pmd))
581 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
582 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
583 pte_unmap_unlock(pte, ptl);
586 val = *(unsigned long *)addr;
589 *(unsigned long *)addr = regs->ARM_r1;
590 regs->ARM_cpsr |= PSR_C_BIT;
592 pte_unmap_unlock(pte, ptl);
593 up_read(&mm->mmap_sem);
597 up_read(&mm->mmap_sem);
598 /* simulate a write access fault */
599 do_DataAbort(addr, 15 + (1 << 11), regs);
604 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
605 if not implemented, rather than raising SIGILL. This
606 way the calling program can gracefully determine whether
607 a feature is supported. */
608 if ((no & 0xffff) <= 0x7ff)
612 #ifdef CONFIG_DEBUG_USER
614 * experience shows that these seem to indicate that
615 * something catastrophic has happened
617 if (user_debug & UDBG_SYSCALL) {
618 printk("[%d] %s: arm syscall %d\n",
619 task_pid_nr(current), current->comm, no);
620 dump_instr("", regs);
621 if (user_mode(regs)) {
623 c_backtrace(regs->ARM_fp, processor_mode(regs));
627 info.si_signo = SIGILL;
629 info.si_code = ILL_ILLTRP;
630 info.si_addr = (void __user *)instruction_pointer(regs) -
631 (thumb_mode(regs) ? 2 : 4);
633 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
637 #ifdef CONFIG_TLS_REG_EMUL
640 * We might be running on an ARMv6+ processor which should have the TLS
641 * register but for some reason we can't use it, or maybe an SMP system
642 * using a pre-ARMv6 processor (there are apparently a few prototypes like
643 * that in existence) and therefore access to that register must be
647 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
649 int reg = (instr >> 12) & 15;
652 regs->uregs[reg] = current_thread_info()->tp_value;
657 static struct undef_hook arm_mrc_hook = {
658 .instr_mask = 0x0fff0fff,
659 .instr_val = 0x0e1d0f70,
660 .cpsr_mask = PSR_T_BIT,
665 static int __init arm_mrc_hook_init(void)
667 register_undef_hook(&arm_mrc_hook);
671 late_initcall(arm_mrc_hook_init);
675 void __bad_xchg(volatile void *ptr, int size)
677 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
678 __builtin_return_address(0), ptr, size);
681 EXPORT_SYMBOL(__bad_xchg);
684 * A data abort trap was taken, but we did not handle the instruction.
685 * Try to abort the user program, or panic if it was the kernel.
688 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
690 unsigned long addr = instruction_pointer(regs);
693 #ifdef CONFIG_DEBUG_USER
694 if (user_debug & UDBG_BADABORT) {
695 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
696 task_pid_nr(current), current->comm, code, instr);
697 dump_instr(KERN_ERR, regs);
698 show_pte(current->mm, addr);
702 info.si_signo = SIGILL;
704 info.si_code = ILL_ILLOPC;
705 info.si_addr = (void __user *)addr;
707 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
710 void __attribute__((noreturn)) __bug(const char *file, int line)
712 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
715 /* Avoid "noreturn function does return" */
718 EXPORT_SYMBOL(__bug);
720 void __readwrite_bug(const char *fn)
722 printk("%s called, but not implemented\n", fn);
725 EXPORT_SYMBOL(__readwrite_bug);
727 void __pte_error(const char *file, int line, pte_t pte)
729 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
732 void __pmd_error(const char *file, int line, pmd_t pmd)
734 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
737 void __pgd_error(const char *file, int line, pgd_t pgd)
739 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
742 asmlinkage void __div0(void)
744 printk("Division by zero in kernel.\n");
747 EXPORT_SYMBOL(__div0);
753 /* if that doesn't kill us, halt */
754 panic("Oops failed to kill thread");
756 EXPORT_SYMBOL(abort);
758 void __init trap_init(void)
763 static void __init kuser_get_tls_init(unsigned long vectors)
766 * vectors + 0xfe0 = __kuser_get_tls
767 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
769 if (tls_emu || has_tls_reg)
770 memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
773 void __init early_trap_init(void)
775 #if defined(CONFIG_CPU_USE_DOMAINS)
776 unsigned long vectors = CONFIG_VECTORS_BASE;
778 unsigned long vectors = (unsigned long)vectors_page;
780 extern char __stubs_start[], __stubs_end[];
781 extern char __vectors_start[], __vectors_end[];
782 extern char __kuser_helper_start[], __kuser_helper_end[];
783 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
786 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
787 * into the vector page, mapped at 0xffff0000, and ensure these
788 * are visible to the instruction stream.
790 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
791 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
792 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
795 * Do processor specific fixups for the kuser helpers
797 kuser_get_tls_init(vectors);
800 * Copy signal return handlers into the vector page, and
801 * set sigreturn to be a pointer to these.
803 memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
804 sigreturn_codes, sizeof(sigreturn_codes));
805 memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
806 syscall_restart_code, sizeof(syscall_restart_code));
808 flush_icache_range(vectors, vectors + PAGE_SIZE);
809 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);