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/init.h>
23 #include <asm/atomic.h>
24 #include <asm/cacheflush.h>
25 #include <asm/system.h>
26 #include <asm/uaccess.h>
27 #include <asm/unistd.h>
28 #include <asm/traps.h>
34 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
36 #ifdef CONFIG_DEBUG_USER
37 unsigned int user_debug;
39 static int __init user_debug_setup(char *str)
41 get_option(&str, &user_debug);
44 __setup("user_debug=", user_debug_setup);
47 static void dump_mem(const char *str, unsigned long bottom, unsigned long top);
49 static inline int in_exception_text(unsigned long ptr)
51 extern char __exception_text_start[];
52 extern char __exception_text_end[];
54 return ptr >= (unsigned long)&__exception_text_start &&
55 ptr < (unsigned long)&__exception_text_end;
58 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
60 #ifdef CONFIG_KALLSYMS
61 printk("[<%08lx>] ", where);
62 print_symbol("(%s) ", where);
63 printk("from [<%08lx>] ", from);
64 print_symbol("(%s)\n", from);
66 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
69 if (in_exception_text(where))
70 dump_mem("Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
74 * Stack pointers should always be within the kernels view of
75 * physical memory. If it is not there, then we can't dump
76 * out any information relating to the stack.
78 static int verify_stack(unsigned long sp)
80 if (sp < PAGE_OFFSET || (sp > (unsigned long)high_memory && high_memory != 0))
87 * Dump out the contents of some memory nicely...
89 static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
91 unsigned long p = bottom & ~31;
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(0x%08lx to 0x%08lx)\n", str, bottom, top);
105 for (p = bottom & ~31; p < top;) {
106 printk("%04lx: ", p & 0xffff);
108 for (i = 0; i < 8; i++, p += 4) {
111 if (p < bottom || p >= top)
114 __get_user(val, (unsigned long *)p);
115 printk("%08x ", val);
124 static void dump_instr(struct pt_regs *regs)
126 unsigned long addr = instruction_pointer(regs);
127 const int thumb = thumb_mode(regs);
128 const int width = thumb ? 4 : 8;
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.
141 for (i = -4; i < 1; i++) {
142 unsigned int val, bad;
145 bad = __get_user(val, &((u16 *)addr)[i]);
147 bad = __get_user(val, &((u32 *)addr)[i]);
150 printk(i == 0 ? "(%0*x) " : "%0*x ", width, val);
152 printk("bad PC value.");
161 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
166 printk("Backtrace: ");
169 printk("no frame pointer");
171 } else if (verify_stack(fp)) {
172 printk("invalid frame pointer 0x%08x", fp);
174 } else if (fp < (unsigned long)end_of_stack(tsk))
175 printk("frame pointer underflow");
179 c_backtrace(fp, processor_mode(regs));
182 void dump_stack(void)
184 #ifdef CONFIG_DEBUG_ERRORS
189 EXPORT_SYMBOL(dump_stack);
191 void show_stack(struct task_struct *tsk, unsigned long *sp)
199 fp = thread_saved_fp(tsk);
201 asm("mov %0, fp" : "=r" (fp) : : "cc");
203 c_backtrace(fp, 0x10);
207 static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
209 struct task_struct *tsk = thread->task;
210 static int die_counter;
212 printk("Internal error: %s: %x [#%d]\n", str, err, ++die_counter);
215 printk("Process %s (pid: %d, stack limit = 0x%p)\n",
216 tsk->comm, tsk->pid, thread + 1);
218 if (!user_mode(regs) || in_interrupt()) {
219 dump_mem("Stack: ", regs->ARM_sp,
220 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
221 dump_backtrace(regs, tsk);
226 DEFINE_SPINLOCK(die_lock);
229 * This function is protected against re-entrancy.
231 NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
233 struct thread_info *thread = current_thread_info();
236 spin_lock_irq(&die_lock);
238 __die(str, err, thread, regs);
240 spin_unlock_irq(&die_lock);
243 panic("Fatal exception");
248 void notify_die(const char *str, struct pt_regs *regs, struct siginfo *info,
249 unsigned long err, unsigned long trap)
251 if (user_mode(regs)) {
252 current->thread.error_code = err;
253 current->thread.trap_no = trap;
255 force_sig_info(info->si_signo, info, current);
261 static LIST_HEAD(undef_hook);
262 static DEFINE_SPINLOCK(undef_lock);
264 void register_undef_hook(struct undef_hook *hook)
268 spin_lock_irqsave(&undef_lock, flags);
269 list_add(&hook->node, &undef_hook);
270 spin_unlock_irqrestore(&undef_lock, flags);
273 void unregister_undef_hook(struct undef_hook *hook)
277 spin_lock_irqsave(&undef_lock, flags);
278 list_del(&hook->node);
279 spin_unlock_irqrestore(&undef_lock, flags);
282 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
284 unsigned int correction = thumb_mode(regs) ? 2 : 4;
286 struct undef_hook *hook;
291 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
292 * depending whether we're in Thumb mode or not.
293 * Correct this offset.
295 regs->ARM_pc -= correction;
297 pc = (void __user *)instruction_pointer(regs);
299 if (processor_mode(regs) == SVC_MODE) {
301 } else if (thumb_mode(regs)) {
302 get_user(instr, (u16 __user *)pc);
304 get_user(instr, (u32 __user *)pc);
307 spin_lock_irq(&undef_lock);
308 list_for_each_entry(hook, &undef_hook, node) {
309 if ((instr & hook->instr_mask) == hook->instr_val &&
310 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val) {
311 if (hook->fn(regs, instr) == 0) {
312 spin_unlock_irq(&undef_lock);
317 spin_unlock_irq(&undef_lock);
319 #ifdef CONFIG_DEBUG_USER
320 if (user_debug & UDBG_UNDEFINED) {
321 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
322 current->comm, current->pid, pc);
327 info.si_signo = SIGILL;
329 info.si_code = ILL_ILLOPC;
332 notify_die("Oops - undefined instruction", regs, &info, 0, 6);
335 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
337 #ifndef CONFIG_IGNORE_FIQ
338 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
339 printk("You may have a hardware problem...\n");
344 * bad_mode handles the impossible case in the vectors. If you see one of
345 * these, then it's extremely serious, and could mean you have buggy hardware.
346 * It never returns, and never tries to sync. We hope that we can at least
347 * dump out some state information...
349 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
353 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
355 die("Oops - bad mode", regs, 0);
360 static int bad_syscall(int n, struct pt_regs *regs)
362 struct thread_info *thread = current_thread_info();
365 if (current->personality != PER_LINUX &&
366 current->personality != PER_LINUX_32BIT &&
367 thread->exec_domain->handler) {
368 thread->exec_domain->handler(n, regs);
372 #ifdef CONFIG_DEBUG_USER
373 if (user_debug & UDBG_SYSCALL) {
374 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
375 current->pid, current->comm, n);
380 info.si_signo = SIGILL;
382 info.si_code = ILL_ILLTRP;
383 info.si_addr = (void __user *)instruction_pointer(regs) -
384 (thumb_mode(regs) ? 2 : 4);
386 notify_die("Oops - bad syscall", regs, &info, n, 0);
392 do_cache_op(unsigned long start, unsigned long end, int flags)
394 struct vm_area_struct *vma;
396 if (end < start || flags)
399 vma = find_vma(current->active_mm, start);
400 if (vma && vma->vm_start < end) {
401 if (start < vma->vm_start)
402 start = vma->vm_start;
403 if (end > vma->vm_end)
406 flush_cache_user_range(vma, start, end);
411 * Handle all unrecognised system calls.
412 * 0x9f0000 - 0x9fffff are some more esoteric system calls
414 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
415 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
417 struct thread_info *thread = current_thread_info();
420 if ((no >> 16) != (__ARM_NR_BASE>> 16))
421 return bad_syscall(no, regs);
423 switch (no & 0xffff) {
424 case 0: /* branch through 0 */
425 info.si_signo = SIGSEGV;
427 info.si_code = SEGV_MAPERR;
430 notify_die("branch through zero", regs, &info, 0, 0);
433 case NR(breakpoint): /* SWI BREAK_POINT */
434 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
435 ptrace_break(current, regs);
439 * Flush a region from virtual address 'r0' to virtual address 'r1'
440 * _exclusive_. There is no alignment requirement on either address;
441 * user space does not need to know the hardware cache layout.
443 * r2 contains flags. It should ALWAYS be passed as ZERO until it
444 * is defined to be something else. For now we ignore it, but may
445 * the fires of hell burn in your belly if you break this rule. ;)
447 * (at a later date, we may want to allow this call to not flush
448 * various aspects of the cache. Passing '0' will guarantee that
449 * everything necessary gets flushed to maintain consistency in
450 * the specified region).
453 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
457 if (!(elf_hwcap & HWCAP_26BIT))
459 regs->ARM_cpsr &= ~MODE32_BIT;
463 if (!(elf_hwcap & HWCAP_26BIT))
465 regs->ARM_cpsr |= MODE32_BIT;
469 thread->tp_value = regs->ARM_r0;
470 #if defined(CONFIG_HAS_TLS_REG)
471 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
472 #elif !defined(CONFIG_TLS_REG_EMUL)
474 * User space must never try to access this directly.
475 * Expect your app to break eventually if you do so.
476 * The user helper at 0xffff0fe0 must be used instead.
477 * (see entry-armv.S for details)
479 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
483 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
485 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
486 * Return zero in r0 if *MEM was changed or non-zero if no exchange
487 * happened. Also set the user C flag accordingly.
488 * If access permissions have to be fixed up then non-zero is
489 * returned and the operation has to be re-attempted.
491 * *NOTE*: This is a ghost syscall private to the kernel. Only the
492 * __kuser_cmpxchg code in entry-armv.S should be aware of its
493 * existence. Don't ever use this from user code.
497 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
498 struct pt_regs *regs);
500 unsigned long addr = regs->ARM_r2;
501 struct mm_struct *mm = current->mm;
502 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
505 regs->ARM_cpsr &= ~PSR_C_BIT;
506 down_read(&mm->mmap_sem);
507 pgd = pgd_offset(mm, addr);
508 if (!pgd_present(*pgd))
510 pmd = pmd_offset(pgd, addr);
511 if (!pmd_present(*pmd))
513 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
514 if (!pte_present(*pte) || !pte_dirty(*pte)) {
515 pte_unmap_unlock(pte, ptl);
518 val = *(unsigned long *)addr;
521 *(unsigned long *)addr = regs->ARM_r1;
522 regs->ARM_cpsr |= PSR_C_BIT;
524 pte_unmap_unlock(pte, ptl);
525 up_read(&mm->mmap_sem);
529 up_read(&mm->mmap_sem);
530 /* simulate a write access fault */
531 do_DataAbort(addr, 15 + (1 << 11), regs);
537 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
538 if not implemented, rather than raising SIGILL. This
539 way the calling program can gracefully determine whether
540 a feature is supported. */
545 #ifdef CONFIG_DEBUG_USER
547 * experience shows that these seem to indicate that
548 * something catastrophic has happened
550 if (user_debug & UDBG_SYSCALL) {
551 printk("[%d] %s: arm syscall %d\n",
552 current->pid, current->comm, no);
554 if (user_mode(regs)) {
556 c_backtrace(regs->ARM_fp, processor_mode(regs));
560 info.si_signo = SIGILL;
562 info.si_code = ILL_ILLTRP;
563 info.si_addr = (void __user *)instruction_pointer(regs) -
564 (thumb_mode(regs) ? 2 : 4);
566 notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
570 #ifdef CONFIG_TLS_REG_EMUL
573 * We might be running on an ARMv6+ processor which should have the TLS
574 * register but for some reason we can't use it, or maybe an SMP system
575 * using a pre-ARMv6 processor (there are apparently a few prototypes like
576 * that in existence) and therefore access to that register must be
580 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
582 int reg = (instr >> 12) & 15;
585 regs->uregs[reg] = current_thread_info()->tp_value;
590 static struct undef_hook arm_mrc_hook = {
591 .instr_mask = 0x0fff0fff,
592 .instr_val = 0x0e1d0f70,
593 .cpsr_mask = PSR_T_BIT,
598 static int __init arm_mrc_hook_init(void)
600 register_undef_hook(&arm_mrc_hook);
604 late_initcall(arm_mrc_hook_init);
608 void __bad_xchg(volatile void *ptr, int size)
610 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
611 __builtin_return_address(0), ptr, size);
614 EXPORT_SYMBOL(__bad_xchg);
617 * A data abort trap was taken, but we did not handle the instruction.
618 * Try to abort the user program, or panic if it was the kernel.
621 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
623 unsigned long addr = instruction_pointer(regs);
626 #ifdef CONFIG_DEBUG_USER
627 if (user_debug & UDBG_BADABORT) {
628 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
629 current->pid, current->comm, code, instr);
631 show_pte(current->mm, addr);
635 info.si_signo = SIGILL;
637 info.si_code = ILL_ILLOPC;
638 info.si_addr = (void __user *)addr;
640 notify_die("unknown data abort code", regs, &info, instr, 0);
643 void __attribute__((noreturn)) __bug(const char *file, int line)
645 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
648 /* Avoid "noreturn function does return" */
651 EXPORT_SYMBOL(__bug);
653 void __readwrite_bug(const char *fn)
655 printk("%s called, but not implemented\n", fn);
658 EXPORT_SYMBOL(__readwrite_bug);
660 void __pte_error(const char *file, int line, unsigned long val)
662 printk("%s:%d: bad pte %08lx.\n", file, line, val);
665 void __pmd_error(const char *file, int line, unsigned long val)
667 printk("%s:%d: bad pmd %08lx.\n", file, line, val);
670 void __pgd_error(const char *file, int line, unsigned long val)
672 printk("%s:%d: bad pgd %08lx.\n", file, line, val);
675 asmlinkage void __div0(void)
677 printk("Division by zero in kernel.\n");
680 EXPORT_SYMBOL(__div0);
686 /* if that doesn't kill us, halt */
687 panic("Oops failed to kill thread");
689 EXPORT_SYMBOL(abort);
691 void __init trap_init(void)
693 unsigned long vectors = CONFIG_VECTORS_BASE;
694 extern char __stubs_start[], __stubs_end[];
695 extern char __vectors_start[], __vectors_end[];
696 extern char __kuser_helper_start[], __kuser_helper_end[];
697 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
700 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
701 * into the vector page, mapped at 0xffff0000, and ensure these
702 * are visible to the instruction stream.
704 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
705 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
706 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
709 * Copy signal return handlers into the vector page, and
710 * set sigreturn to be a pointer to these.
712 memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
713 sizeof(sigreturn_codes));
715 flush_icache_range(vectors, vectors + PAGE_SIZE);
716 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);