2 * linux/arch/arm/kernel/traps.c
4 * Copyright (C) 1995-2002 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 *str, unsigned long bottom, unsigned long top);
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 *str, unsigned long bottom, unsigned long top)
91 * We need to switch to kernel mode so that we can use __get_user
92 * to safely read from kernel space. Note that we now dump the
93 * code first, just in case the backtrace kills us.
98 printk("%s(0x%08lx to 0x%08lx)\n", str, bottom, top);
100 for (first = bottom & ~31; first < top; first += 32) {
102 char str[sizeof(" 12345678") * 8 + 1];
104 memset(str, ' ', sizeof(str));
105 str[sizeof(str) - 1] = '\0';
107 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
108 if (p >= bottom && p < top) {
110 if (__get_user(val, (unsigned long *)p) == 0)
111 sprintf(str + i * 9, " %08lx", val);
113 sprintf(str + i * 9, " ????????");
116 printk("%04lx:%s\n", first & 0xffff, str);
122 static void dump_instr(struct pt_regs *regs)
124 unsigned long addr = instruction_pointer(regs);
125 const int thumb = thumb_mode(regs);
126 const int width = thumb ? 4 : 8;
128 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
132 * We need to switch to kernel mode so that we can use __get_user
133 * to safely read from kernel space. Note that we now dump the
134 * code first, just in case the backtrace kills us.
139 for (i = -4; i < 1; i++) {
140 unsigned int val, bad;
143 bad = __get_user(val, &((u16 *)addr)[i]);
145 bad = __get_user(val, &((u32 *)addr)[i]);
148 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
151 p += sprintf(p, "bad PC value");
155 printk("Code: %s\n", str);
160 #ifdef CONFIG_ARM_UNWIND
161 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
163 unwind_backtrace(regs, tsk);
166 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
168 unsigned int fp, mode;
171 printk("Backtrace: ");
178 mode = processor_mode(regs);
179 } else if (tsk != current) {
180 fp = thread_saved_fp(tsk);
183 asm("mov %0, fp" : "=r" (fp) : : "cc");
188 printk("no frame pointer");
190 } else if (verify_stack(fp)) {
191 printk("invalid frame pointer 0x%08x", fp);
193 } else if (fp < (unsigned long)end_of_stack(tsk))
194 printk("frame pointer underflow");
198 c_backtrace(fp, mode);
202 void dump_stack(void)
204 dump_backtrace(NULL, NULL);
207 EXPORT_SYMBOL(dump_stack);
209 void show_stack(struct task_struct *tsk, unsigned long *sp)
211 dump_backtrace(NULL, tsk);
215 #ifdef CONFIG_PREEMPT
216 #define S_PREEMPT " PREEMPT"
226 static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
228 struct task_struct *tsk = thread->task;
229 static int die_counter;
231 printk("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
232 str, err, ++die_counter);
235 printk("Process %s (pid: %d, stack limit = 0x%p)\n",
236 tsk->comm, task_pid_nr(tsk), thread + 1);
238 if (!user_mode(regs) || in_interrupt()) {
239 dump_mem("Stack: ", regs->ARM_sp,
240 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
241 dump_backtrace(regs, tsk);
246 DEFINE_SPINLOCK(die_lock);
249 * This function is protected against re-entrancy.
251 NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
253 struct thread_info *thread = current_thread_info();
258 spin_lock_irq(&die_lock);
260 __die(str, err, thread, regs);
262 add_taint(TAINT_DIE);
263 spin_unlock_irq(&die_lock);
266 panic("Fatal exception in interrupt");
269 panic("Fatal exception");
275 void arm_notify_die(const char *str, struct pt_regs *regs,
276 struct siginfo *info, unsigned long err, unsigned long trap)
278 if (user_mode(regs)) {
279 current->thread.error_code = err;
280 current->thread.trap_no = trap;
282 force_sig_info(info->si_signo, info, current);
288 static LIST_HEAD(undef_hook);
289 static DEFINE_SPINLOCK(undef_lock);
291 void register_undef_hook(struct undef_hook *hook)
295 spin_lock_irqsave(&undef_lock, flags);
296 list_add(&hook->node, &undef_hook);
297 spin_unlock_irqrestore(&undef_lock, flags);
300 void unregister_undef_hook(struct undef_hook *hook)
304 spin_lock_irqsave(&undef_lock, flags);
305 list_del(&hook->node);
306 spin_unlock_irqrestore(&undef_lock, flags);
309 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
311 struct undef_hook *hook;
313 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
315 spin_lock_irqsave(&undef_lock, flags);
316 list_for_each_entry(hook, &undef_hook, node)
317 if ((instr & hook->instr_mask) == hook->instr_val &&
318 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
320 spin_unlock_irqrestore(&undef_lock, flags);
322 return fn ? fn(regs, instr) : 1;
325 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
327 unsigned int correction = thumb_mode(regs) ? 2 : 4;
333 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
334 * depending whether we're in Thumb mode or not.
335 * Correct this offset.
337 regs->ARM_pc -= correction;
339 pc = (void __user *)instruction_pointer(regs);
341 if (processor_mode(regs) == SVC_MODE) {
343 } else if (thumb_mode(regs)) {
344 get_user(instr, (u16 __user *)pc);
346 get_user(instr, (u32 __user *)pc);
349 if (call_undef_hook(regs, instr) == 0)
352 #ifdef CONFIG_DEBUG_USER
353 if (user_debug & UDBG_UNDEFINED) {
354 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
355 current->comm, task_pid_nr(current), pc);
360 info.si_signo = SIGILL;
362 info.si_code = ILL_ILLOPC;
365 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
368 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
370 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
371 printk("You may have a hardware problem...\n");
375 * bad_mode handles the impossible case in the vectors. If you see one of
376 * these, then it's extremely serious, and could mean you have buggy hardware.
377 * It never returns, and never tries to sync. We hope that we can at least
378 * dump out some state information...
380 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
384 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
386 die("Oops - bad mode", regs, 0);
391 static int bad_syscall(int n, struct pt_regs *regs)
393 struct thread_info *thread = current_thread_info();
396 if (current->personality != PER_LINUX &&
397 current->personality != PER_LINUX_32BIT &&
398 thread->exec_domain->handler) {
399 thread->exec_domain->handler(n, regs);
403 #ifdef CONFIG_DEBUG_USER
404 if (user_debug & UDBG_SYSCALL) {
405 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
406 task_pid_nr(current), current->comm, n);
411 info.si_signo = SIGILL;
413 info.si_code = ILL_ILLTRP;
414 info.si_addr = (void __user *)instruction_pointer(regs) -
415 (thumb_mode(regs) ? 2 : 4);
417 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
423 do_cache_op(unsigned long start, unsigned long end, int flags)
425 struct mm_struct *mm = current->active_mm;
426 struct vm_area_struct *vma;
428 if (end < start || flags)
431 down_read(&mm->mmap_sem);
432 vma = find_vma(mm, start);
433 if (vma && vma->vm_start < end) {
434 if (start < vma->vm_start)
435 start = vma->vm_start;
436 if (end > vma->vm_end)
439 flush_cache_user_range(vma, start, end);
441 up_read(&mm->mmap_sem);
445 * Handle all unrecognised system calls.
446 * 0x9f0000 - 0x9fffff are some more esoteric system calls
448 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
449 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
451 struct thread_info *thread = current_thread_info();
454 if ((no >> 16) != (__ARM_NR_BASE>> 16))
455 return bad_syscall(no, regs);
457 switch (no & 0xffff) {
458 case 0: /* branch through 0 */
459 info.si_signo = SIGSEGV;
461 info.si_code = SEGV_MAPERR;
464 arm_notify_die("branch through zero", regs, &info, 0, 0);
467 case NR(breakpoint): /* SWI BREAK_POINT */
468 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
469 ptrace_break(current, regs);
473 * Flush a region from virtual address 'r0' to virtual address 'r1'
474 * _exclusive_. There is no alignment requirement on either address;
475 * user space does not need to know the hardware cache layout.
477 * r2 contains flags. It should ALWAYS be passed as ZERO until it
478 * is defined to be something else. For now we ignore it, but may
479 * the fires of hell burn in your belly if you break this rule. ;)
481 * (at a later date, we may want to allow this call to not flush
482 * various aspects of the cache. Passing '0' will guarantee that
483 * everything necessary gets flushed to maintain consistency in
484 * the specified region).
487 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
491 if (!(elf_hwcap & HWCAP_26BIT))
493 regs->ARM_cpsr &= ~MODE32_BIT;
497 if (!(elf_hwcap & HWCAP_26BIT))
499 regs->ARM_cpsr |= MODE32_BIT;
503 thread->tp_value = regs->ARM_r0;
504 #if defined(CONFIG_HAS_TLS_REG)
505 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
506 #elif !defined(CONFIG_TLS_REG_EMUL)
508 * User space must never try to access this directly.
509 * Expect your app to break eventually if you do so.
510 * The user helper at 0xffff0fe0 must be used instead.
511 * (see entry-armv.S for details)
513 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
517 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
519 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
520 * Return zero in r0 if *MEM was changed or non-zero if no exchange
521 * happened. Also set the user C flag accordingly.
522 * If access permissions have to be fixed up then non-zero is
523 * returned and the operation has to be re-attempted.
525 * *NOTE*: This is a ghost syscall private to the kernel. Only the
526 * __kuser_cmpxchg code in entry-armv.S should be aware of its
527 * existence. Don't ever use this from user code.
531 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
532 struct pt_regs *regs);
534 unsigned long addr = regs->ARM_r2;
535 struct mm_struct *mm = current->mm;
536 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
539 regs->ARM_cpsr &= ~PSR_C_BIT;
540 down_read(&mm->mmap_sem);
541 pgd = pgd_offset(mm, addr);
542 if (!pgd_present(*pgd))
544 pmd = pmd_offset(pgd, addr);
545 if (!pmd_present(*pmd))
547 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
548 if (!pte_present(*pte) || !pte_dirty(*pte)) {
549 pte_unmap_unlock(pte, ptl);
552 val = *(unsigned long *)addr;
555 *(unsigned long *)addr = regs->ARM_r1;
556 regs->ARM_cpsr |= PSR_C_BIT;
558 pte_unmap_unlock(pte, ptl);
559 up_read(&mm->mmap_sem);
563 up_read(&mm->mmap_sem);
564 /* simulate a write access fault */
565 do_DataAbort(addr, 15 + (1 << 11), regs);
570 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
571 if not implemented, rather than raising SIGILL. This
572 way the calling program can gracefully determine whether
573 a feature is supported. */
578 #ifdef CONFIG_DEBUG_USER
580 * experience shows that these seem to indicate that
581 * something catastrophic has happened
583 if (user_debug & UDBG_SYSCALL) {
584 printk("[%d] %s: arm syscall %d\n",
585 task_pid_nr(current), current->comm, no);
587 if (user_mode(regs)) {
589 c_backtrace(regs->ARM_fp, processor_mode(regs));
593 info.si_signo = SIGILL;
595 info.si_code = ILL_ILLTRP;
596 info.si_addr = (void __user *)instruction_pointer(regs) -
597 (thumb_mode(regs) ? 2 : 4);
599 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
603 #ifdef CONFIG_TLS_REG_EMUL
606 * We might be running on an ARMv6+ processor which should have the TLS
607 * register but for some reason we can't use it, or maybe an SMP system
608 * using a pre-ARMv6 processor (there are apparently a few prototypes like
609 * that in existence) and therefore access to that register must be
613 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
615 int reg = (instr >> 12) & 15;
618 regs->uregs[reg] = current_thread_info()->tp_value;
623 static struct undef_hook arm_mrc_hook = {
624 .instr_mask = 0x0fff0fff,
625 .instr_val = 0x0e1d0f70,
626 .cpsr_mask = PSR_T_BIT,
631 static int __init arm_mrc_hook_init(void)
633 register_undef_hook(&arm_mrc_hook);
637 late_initcall(arm_mrc_hook_init);
641 void __bad_xchg(volatile void *ptr, int size)
643 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
644 __builtin_return_address(0), ptr, size);
647 EXPORT_SYMBOL(__bad_xchg);
650 * A data abort trap was taken, but we did not handle the instruction.
651 * Try to abort the user program, or panic if it was the kernel.
654 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
656 unsigned long addr = instruction_pointer(regs);
659 #ifdef CONFIG_DEBUG_USER
660 if (user_debug & UDBG_BADABORT) {
661 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
662 task_pid_nr(current), current->comm, code, instr);
664 show_pte(current->mm, addr);
668 info.si_signo = SIGILL;
670 info.si_code = ILL_ILLOPC;
671 info.si_addr = (void __user *)addr;
673 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
676 void __attribute__((noreturn)) __bug(const char *file, int line)
678 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
681 /* Avoid "noreturn function does return" */
684 EXPORT_SYMBOL(__bug);
686 void __readwrite_bug(const char *fn)
688 printk("%s called, but not implemented\n", fn);
691 EXPORT_SYMBOL(__readwrite_bug);
693 void __pte_error(const char *file, int line, unsigned long val)
695 printk("%s:%d: bad pte %08lx.\n", file, line, val);
698 void __pmd_error(const char *file, int line, unsigned long val)
700 printk("%s:%d: bad pmd %08lx.\n", file, line, val);
703 void __pgd_error(const char *file, int line, unsigned long val)
705 printk("%s:%d: bad pgd %08lx.\n", file, line, val);
708 asmlinkage void __div0(void)
710 printk("Division by zero in kernel.\n");
713 EXPORT_SYMBOL(__div0);
719 /* if that doesn't kill us, halt */
720 panic("Oops failed to kill thread");
722 EXPORT_SYMBOL(abort);
724 void __init trap_init(void)
729 void __init early_trap_init(void)
731 unsigned long vectors = CONFIG_VECTORS_BASE;
732 extern char __stubs_start[], __stubs_end[];
733 extern char __vectors_start[], __vectors_end[];
734 extern char __kuser_helper_start[], __kuser_helper_end[];
735 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
738 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
739 * into the vector page, mapped at 0xffff0000, and ensure these
740 * are visible to the instruction stream.
742 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
743 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
744 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
747 * Copy signal return handlers into the vector page, and
748 * set sigreturn to be a pointer to these.
750 memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
751 sizeof(sigreturn_codes));
753 flush_icache_range(vectors, vectors + PAGE_SIZE);
754 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);