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/module.h>
16 #include <linux/signal.h>
17 #include <linux/spinlock.h>
18 #include <linux/personality.h>
19 #include <linux/kallsyms.h>
20 #include <linux/delay.h>
21 #include <linux/hardirq.h>
22 #include <linux/init.h>
23 #include <linux/uaccess.h>
25 #include <asm/atomic.h>
26 #include <asm/cacheflush.h>
27 #include <asm/system.h>
28 #include <asm/unistd.h>
29 #include <asm/traps.h>
30 #include <asm/unwind.h>
35 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
37 #ifdef CONFIG_DEBUG_USER
38 unsigned int user_debug;
40 static int __init user_debug_setup(char *str)
42 get_option(&str, &user_debug);
45 __setup("user_debug=", user_debug_setup);
48 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
50 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
52 #ifdef CONFIG_KALLSYMS
53 char sym1[KSYM_SYMBOL_LEN], sym2[KSYM_SYMBOL_LEN];
54 sprint_symbol(sym1, where);
55 sprint_symbol(sym2, from);
56 printk("[<%08lx>] (%s) from [<%08lx>] (%s)\n", where, sym1, from, sym2);
58 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
61 if (in_exception_text(where))
62 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
65 #ifndef CONFIG_ARM_UNWIND
67 * Stack pointers should always be within the kernels view of
68 * physical memory. If it is not there, then we can't dump
69 * out any information relating to the stack.
71 static int verify_stack(unsigned long sp)
73 if (sp < PAGE_OFFSET ||
74 (sp > (unsigned long)high_memory && high_memory != NULL))
82 * Dump out the contents of some memory nicely...
84 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
92 * We need to switch to kernel mode so that we can use __get_user
93 * to safely read from kernel space. Note that we now dump the
94 * code first, just in case the backtrace kills us.
99 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
101 for (first = bottom & ~31; first < top; first += 32) {
103 char str[sizeof(" 12345678") * 8 + 1];
105 memset(str, ' ', sizeof(str));
106 str[sizeof(str) - 1] = '\0';
108 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
109 if (p >= bottom && p < top) {
111 if (__get_user(val, (unsigned long *)p) == 0)
112 sprintf(str + i * 9, " %08lx", val);
114 sprintf(str + i * 9, " ????????");
117 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
123 static void dump_instr(const char *lvl, struct pt_regs *regs)
125 unsigned long addr = instruction_pointer(regs);
126 const int thumb = thumb_mode(regs);
127 const int width = thumb ? 4 : 8;
129 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
133 * We need to switch to kernel mode so that we can use __get_user
134 * to safely read from kernel space. Note that we now dump the
135 * code first, just in case the backtrace kills us.
140 for (i = -4; i < 1; i++) {
141 unsigned int val, bad;
144 bad = __get_user(val, &((u16 *)addr)[i]);
146 bad = __get_user(val, &((u32 *)addr)[i]);
149 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
152 p += sprintf(p, "bad PC value");
156 printk("%sCode: %s\n", lvl, str);
161 #ifdef CONFIG_ARM_UNWIND
162 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
164 unwind_backtrace(regs, tsk);
167 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
169 unsigned int fp, mode;
172 printk("Backtrace: ");
179 mode = processor_mode(regs);
180 } else if (tsk != current) {
181 fp = thread_saved_fp(tsk);
184 asm("mov %0, fp" : "=r" (fp) : : "cc");
189 printk("no frame pointer");
191 } else if (verify_stack(fp)) {
192 printk("invalid frame pointer 0x%08x", fp);
194 } else if (fp < (unsigned long)end_of_stack(tsk))
195 printk("frame pointer underflow");
199 c_backtrace(fp, mode);
203 void dump_stack(void)
205 dump_backtrace(NULL, NULL);
208 EXPORT_SYMBOL(dump_stack);
210 void show_stack(struct task_struct *tsk, unsigned long *sp)
212 dump_backtrace(NULL, tsk);
216 #ifdef CONFIG_PREEMPT
217 #define S_PREEMPT " PREEMPT"
227 static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
229 struct task_struct *tsk = thread->task;
230 static int die_counter;
232 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
233 str, err, ++die_counter);
234 sysfs_printk_last_file();
237 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
238 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
240 if (!user_mode(regs) || in_interrupt()) {
241 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
242 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
243 dump_backtrace(regs, tsk);
244 dump_instr(KERN_EMERG, regs);
248 DEFINE_SPINLOCK(die_lock);
251 * This function is protected against re-entrancy.
253 NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
255 struct thread_info *thread = current_thread_info();
259 spin_lock_irq(&die_lock);
262 __die(str, err, thread, regs);
264 add_taint(TAINT_DIE);
265 spin_unlock_irq(&die_lock);
269 panic("Fatal exception in interrupt");
272 panic("Fatal exception");
277 void arm_notify_die(const char *str, struct pt_regs *regs,
278 struct siginfo *info, unsigned long err, unsigned long trap)
280 if (user_mode(regs)) {
281 current->thread.error_code = err;
282 current->thread.trap_no = trap;
284 force_sig_info(info->si_signo, info, current);
290 static LIST_HEAD(undef_hook);
291 static DEFINE_SPINLOCK(undef_lock);
293 void register_undef_hook(struct undef_hook *hook)
297 spin_lock_irqsave(&undef_lock, flags);
298 list_add(&hook->node, &undef_hook);
299 spin_unlock_irqrestore(&undef_lock, flags);
302 void unregister_undef_hook(struct undef_hook *hook)
306 spin_lock_irqsave(&undef_lock, flags);
307 list_del(&hook->node);
308 spin_unlock_irqrestore(&undef_lock, flags);
311 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
313 struct undef_hook *hook;
315 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
317 spin_lock_irqsave(&undef_lock, flags);
318 list_for_each_entry(hook, &undef_hook, node)
319 if ((instr & hook->instr_mask) == hook->instr_val &&
320 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
322 spin_unlock_irqrestore(&undef_lock, flags);
324 return fn ? fn(regs, instr) : 1;
327 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
329 unsigned int correction = thumb_mode(regs) ? 2 : 4;
335 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
336 * depending whether we're in Thumb mode or not.
337 * Correct this offset.
339 regs->ARM_pc -= correction;
341 pc = (void __user *)instruction_pointer(regs);
343 if (processor_mode(regs) == SVC_MODE) {
345 } else if (thumb_mode(regs)) {
346 get_user(instr, (u16 __user *)pc);
348 get_user(instr, (u32 __user *)pc);
351 if (call_undef_hook(regs, instr) == 0)
354 #ifdef CONFIG_DEBUG_USER
355 if (user_debug & UDBG_UNDEFINED) {
356 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
357 current->comm, task_pid_nr(current), pc);
358 dump_instr(KERN_INFO, regs);
362 info.si_signo = SIGILL;
364 info.si_code = ILL_ILLOPC;
367 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
370 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
372 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
373 printk("You may have a hardware problem...\n");
377 * bad_mode handles the impossible case in the vectors. If you see one of
378 * these, then it's extremely serious, and could mean you have buggy hardware.
379 * It never returns, and never tries to sync. We hope that we can at least
380 * dump out some state information...
382 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
386 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
388 die("Oops - bad mode", regs, 0);
393 static int bad_syscall(int n, struct pt_regs *regs)
395 struct thread_info *thread = current_thread_info();
398 if (current->personality != PER_LINUX &&
399 current->personality != PER_LINUX_32BIT &&
400 thread->exec_domain->handler) {
401 thread->exec_domain->handler(n, regs);
405 #ifdef CONFIG_DEBUG_USER
406 if (user_debug & UDBG_SYSCALL) {
407 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
408 task_pid_nr(current), current->comm, n);
409 dump_instr(KERN_ERR, regs);
413 info.si_signo = SIGILL;
415 info.si_code = ILL_ILLTRP;
416 info.si_addr = (void __user *)instruction_pointer(regs) -
417 (thumb_mode(regs) ? 2 : 4);
419 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
425 do_cache_op(unsigned long start, unsigned long end, int flags)
427 struct mm_struct *mm = current->active_mm;
428 struct vm_area_struct *vma;
430 if (end < start || flags)
433 down_read(&mm->mmap_sem);
434 vma = find_vma(mm, start);
435 if (vma && vma->vm_start < end) {
436 if (start < vma->vm_start)
437 start = vma->vm_start;
438 if (end > vma->vm_end)
441 flush_cache_user_range(vma, start, end);
443 up_read(&mm->mmap_sem);
447 * Handle all unrecognised system calls.
448 * 0x9f0000 - 0x9fffff are some more esoteric system calls
450 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
451 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
453 struct thread_info *thread = current_thread_info();
456 if ((no >> 16) != (__ARM_NR_BASE>> 16))
457 return bad_syscall(no, regs);
459 switch (no & 0xffff) {
460 case 0: /* branch through 0 */
461 info.si_signo = SIGSEGV;
463 info.si_code = SEGV_MAPERR;
466 arm_notify_die("branch through zero", regs, &info, 0, 0);
469 case NR(breakpoint): /* SWI BREAK_POINT */
470 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
471 ptrace_break(current, regs);
475 * Flush a region from virtual address 'r0' to virtual address 'r1'
476 * _exclusive_. There is no alignment requirement on either address;
477 * user space does not need to know the hardware cache layout.
479 * r2 contains flags. It should ALWAYS be passed as ZERO until it
480 * is defined to be something else. For now we ignore it, but may
481 * the fires of hell burn in your belly if you break this rule. ;)
483 * (at a later date, we may want to allow this call to not flush
484 * various aspects of the cache. Passing '0' will guarantee that
485 * everything necessary gets flushed to maintain consistency in
486 * the specified region).
489 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
493 if (!(elf_hwcap & HWCAP_26BIT))
495 regs->ARM_cpsr &= ~MODE32_BIT;
499 if (!(elf_hwcap & HWCAP_26BIT))
501 regs->ARM_cpsr |= MODE32_BIT;
505 thread->tp_value = regs->ARM_r0;
506 #if defined(CONFIG_HAS_TLS_REG)
507 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
508 #elif !defined(CONFIG_TLS_REG_EMUL)
510 * User space must never try to access this directly.
511 * Expect your app to break eventually if you do so.
512 * The user helper at 0xffff0fe0 must be used instead.
513 * (see entry-armv.S for details)
515 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
519 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
521 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
522 * Return zero in r0 if *MEM was changed or non-zero if no exchange
523 * happened. Also set the user C flag accordingly.
524 * If access permissions have to be fixed up then non-zero is
525 * returned and the operation has to be re-attempted.
527 * *NOTE*: This is a ghost syscall private to the kernel. Only the
528 * __kuser_cmpxchg code in entry-armv.S should be aware of its
529 * existence. Don't ever use this from user code.
533 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
534 struct pt_regs *regs);
536 unsigned long addr = regs->ARM_r2;
537 struct mm_struct *mm = current->mm;
538 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
541 regs->ARM_cpsr &= ~PSR_C_BIT;
542 down_read(&mm->mmap_sem);
543 pgd = pgd_offset(mm, addr);
544 if (!pgd_present(*pgd))
546 pmd = pmd_offset(pgd, addr);
547 if (!pmd_present(*pmd))
549 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
550 if (!pte_present(*pte) || !pte_dirty(*pte)) {
551 pte_unmap_unlock(pte, ptl);
554 val = *(unsigned long *)addr;
557 *(unsigned long *)addr = regs->ARM_r1;
558 regs->ARM_cpsr |= PSR_C_BIT;
560 pte_unmap_unlock(pte, ptl);
561 up_read(&mm->mmap_sem);
565 up_read(&mm->mmap_sem);
566 /* simulate a write access fault */
567 do_DataAbort(addr, 15 + (1 << 11), regs);
572 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
573 if not implemented, rather than raising SIGILL. This
574 way the calling program can gracefully determine whether
575 a feature is supported. */
576 if ((no & 0xffff) <= 0x7ff)
580 #ifdef CONFIG_DEBUG_USER
582 * experience shows that these seem to indicate that
583 * something catastrophic has happened
585 if (user_debug & UDBG_SYSCALL) {
586 printk("[%d] %s: arm syscall %d\n",
587 task_pid_nr(current), current->comm, no);
588 dump_instr("", regs);
589 if (user_mode(regs)) {
591 c_backtrace(regs->ARM_fp, processor_mode(regs));
595 info.si_signo = SIGILL;
597 info.si_code = ILL_ILLTRP;
598 info.si_addr = (void __user *)instruction_pointer(regs) -
599 (thumb_mode(regs) ? 2 : 4);
601 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
605 #ifdef CONFIG_TLS_REG_EMUL
608 * We might be running on an ARMv6+ processor which should have the TLS
609 * register but for some reason we can't use it, or maybe an SMP system
610 * using a pre-ARMv6 processor (there are apparently a few prototypes like
611 * that in existence) and therefore access to that register must be
615 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
617 int reg = (instr >> 12) & 15;
620 regs->uregs[reg] = current_thread_info()->tp_value;
625 static struct undef_hook arm_mrc_hook = {
626 .instr_mask = 0x0fff0fff,
627 .instr_val = 0x0e1d0f70,
628 .cpsr_mask = PSR_T_BIT,
633 static int __init arm_mrc_hook_init(void)
635 register_undef_hook(&arm_mrc_hook);
639 late_initcall(arm_mrc_hook_init);
643 void __bad_xchg(volatile void *ptr, int size)
645 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
646 __builtin_return_address(0), ptr, size);
649 EXPORT_SYMBOL(__bad_xchg);
652 * A data abort trap was taken, but we did not handle the instruction.
653 * Try to abort the user program, or panic if it was the kernel.
656 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
658 unsigned long addr = instruction_pointer(regs);
661 #ifdef CONFIG_DEBUG_USER
662 if (user_debug & UDBG_BADABORT) {
663 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
664 task_pid_nr(current), current->comm, code, instr);
665 dump_instr(KERN_ERR, regs);
666 show_pte(current->mm, addr);
670 info.si_signo = SIGILL;
672 info.si_code = ILL_ILLOPC;
673 info.si_addr = (void __user *)addr;
675 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
678 void __attribute__((noreturn)) __bug(const char *file, int line)
680 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
683 /* Avoid "noreturn function does return" */
686 EXPORT_SYMBOL(__bug);
688 void __readwrite_bug(const char *fn)
690 printk("%s called, but not implemented\n", fn);
693 EXPORT_SYMBOL(__readwrite_bug);
695 void __pte_error(const char *file, int line, unsigned long val)
697 printk("%s:%d: bad pte %08lx.\n", file, line, val);
700 void __pmd_error(const char *file, int line, unsigned long val)
702 printk("%s:%d: bad pmd %08lx.\n", file, line, val);
705 void __pgd_error(const char *file, int line, unsigned long val)
707 printk("%s:%d: bad pgd %08lx.\n", file, line, val);
710 asmlinkage void __div0(void)
712 printk("Division by zero in kernel.\n");
715 EXPORT_SYMBOL(__div0);
721 /* if that doesn't kill us, halt */
722 panic("Oops failed to kill thread");
724 EXPORT_SYMBOL(abort);
726 void __init trap_init(void)
731 void __init early_trap_init(void)
733 unsigned long vectors = CONFIG_VECTORS_BASE;
734 extern char __stubs_start[], __stubs_end[];
735 extern char __vectors_start[], __vectors_end[];
736 extern char __kuser_helper_start[], __kuser_helper_end[];
737 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
740 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
741 * into the vector page, mapped at 0xffff0000, and ensure these
742 * are visible to the instruction stream.
744 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
745 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
746 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
749 * Copy signal return handlers into the vector page, and
750 * set sigreturn to be a pointer to these.
752 memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
753 sizeof(sigreturn_codes));
754 memcpy((void *)KERN_RESTART_CODE, syscall_restart_code,
755 sizeof(syscall_restart_code));
757 flush_icache_range(vectors, vectors + PAGE_SIZE);
758 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);