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 printk("[<%08lx>] ", where);
54 print_symbol("(%s) ", where);
55 printk("from [<%08lx>] ", from);
56 print_symbol("(%s)\n", from);
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)
86 unsigned long p = bottom & ~31;
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 (p = bottom & ~31; p < top;) {
101 printk("%04lx: ", p & 0xffff);
103 for (i = 0; i < 8; i++, p += 4) {
106 if (p < bottom || p >= top)
109 __get_user(val, (unsigned long *)p);
110 printk("%08x ", val);
119 static void dump_instr(struct pt_regs *regs)
121 unsigned long addr = instruction_pointer(regs);
122 const int thumb = thumb_mode(regs);
123 const int width = thumb ? 4 : 8;
128 * We need to switch to kernel mode so that we can use __get_user
129 * to safely read from kernel space. Note that we now dump the
130 * code first, just in case the backtrace kills us.
136 for (i = -4; i < 1; i++) {
137 unsigned int val, bad;
140 bad = __get_user(val, &((u16 *)addr)[i]);
142 bad = __get_user(val, &((u32 *)addr)[i]);
145 printk(i == 0 ? "(%0*x) " : "%0*x ", width, val);
147 printk("bad PC value.");
156 #ifdef CONFIG_ARM_UNWIND
157 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
159 unwind_backtrace(regs, tsk);
162 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
164 unsigned int fp, mode;
167 printk("Backtrace: ");
174 mode = processor_mode(regs);
175 } else if (tsk != current) {
176 fp = thread_saved_fp(tsk);
179 asm("mov %0, fp" : "=r" (fp) : : "cc");
184 printk("no frame pointer");
186 } else if (verify_stack(fp)) {
187 printk("invalid frame pointer 0x%08x", fp);
189 } else if (fp < (unsigned long)end_of_stack(tsk))
190 printk("frame pointer underflow");
194 c_backtrace(fp, mode);
198 void dump_stack(void)
200 dump_backtrace(NULL, NULL);
203 EXPORT_SYMBOL(dump_stack);
205 void show_stack(struct task_struct *tsk, unsigned long *sp)
207 dump_backtrace(NULL, tsk);
211 #ifdef CONFIG_PREEMPT
212 #define S_PREEMPT " PREEMPT"
222 static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
224 struct task_struct *tsk = thread->task;
225 static int die_counter;
227 printk("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
228 str, err, ++die_counter);
231 printk("Process %s (pid: %d, stack limit = 0x%p)\n",
232 tsk->comm, task_pid_nr(tsk), thread + 1);
234 if (!user_mode(regs) || in_interrupt()) {
235 dump_mem("Stack: ", regs->ARM_sp,
236 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
237 dump_backtrace(regs, tsk);
242 DEFINE_SPINLOCK(die_lock);
245 * This function is protected against re-entrancy.
247 NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
249 struct thread_info *thread = current_thread_info();
254 spin_lock_irq(&die_lock);
256 __die(str, err, thread, regs);
258 add_taint(TAINT_DIE);
259 spin_unlock_irq(&die_lock);
262 panic("Fatal exception in interrupt");
265 panic("Fatal exception");
271 void arm_notify_die(const char *str, struct pt_regs *regs,
272 struct siginfo *info, unsigned long err, unsigned long trap)
274 if (user_mode(regs)) {
275 current->thread.error_code = err;
276 current->thread.trap_no = trap;
278 force_sig_info(info->si_signo, info, current);
284 static LIST_HEAD(undef_hook);
285 static DEFINE_SPINLOCK(undef_lock);
287 void register_undef_hook(struct undef_hook *hook)
291 spin_lock_irqsave(&undef_lock, flags);
292 list_add(&hook->node, &undef_hook);
293 spin_unlock_irqrestore(&undef_lock, flags);
296 void unregister_undef_hook(struct undef_hook *hook)
300 spin_lock_irqsave(&undef_lock, flags);
301 list_del(&hook->node);
302 spin_unlock_irqrestore(&undef_lock, flags);
305 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
307 struct undef_hook *hook;
309 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
311 spin_lock_irqsave(&undef_lock, flags);
312 list_for_each_entry(hook, &undef_hook, node)
313 if ((instr & hook->instr_mask) == hook->instr_val &&
314 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
316 spin_unlock_irqrestore(&undef_lock, flags);
318 return fn ? fn(regs, instr) : 1;
321 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
323 unsigned int correction = thumb_mode(regs) ? 2 : 4;
329 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
330 * depending whether we're in Thumb mode or not.
331 * Correct this offset.
333 regs->ARM_pc -= correction;
335 pc = (void __user *)instruction_pointer(regs);
337 if (processor_mode(regs) == SVC_MODE) {
339 } else if (thumb_mode(regs)) {
340 get_user(instr, (u16 __user *)pc);
342 get_user(instr, (u32 __user *)pc);
345 if (call_undef_hook(regs, instr) == 0)
348 #ifdef CONFIG_DEBUG_USER
349 if (user_debug & UDBG_UNDEFINED) {
350 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
351 current->comm, task_pid_nr(current), pc);
356 info.si_signo = SIGILL;
358 info.si_code = ILL_ILLOPC;
361 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
364 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
366 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
367 printk("You may have a hardware problem...\n");
371 * bad_mode handles the impossible case in the vectors. If you see one of
372 * these, then it's extremely serious, and could mean you have buggy hardware.
373 * It never returns, and never tries to sync. We hope that we can at least
374 * dump out some state information...
376 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
380 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
382 die("Oops - bad mode", regs, 0);
387 static int bad_syscall(int n, struct pt_regs *regs)
389 struct thread_info *thread = current_thread_info();
392 if (current->personality != PER_LINUX &&
393 current->personality != PER_LINUX_32BIT &&
394 thread->exec_domain->handler) {
395 thread->exec_domain->handler(n, regs);
399 #ifdef CONFIG_DEBUG_USER
400 if (user_debug & UDBG_SYSCALL) {
401 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
402 task_pid_nr(current), current->comm, n);
407 info.si_signo = SIGILL;
409 info.si_code = ILL_ILLTRP;
410 info.si_addr = (void __user *)instruction_pointer(regs) -
411 (thumb_mode(regs) ? 2 : 4);
413 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
419 do_cache_op(unsigned long start, unsigned long end, int flags)
421 struct vm_area_struct *vma;
423 if (end < start || flags)
426 vma = find_vma(current->active_mm, start);
427 if (vma && vma->vm_start < end) {
428 if (start < vma->vm_start)
429 start = vma->vm_start;
430 if (end > vma->vm_end)
433 flush_cache_user_range(vma, start, end);
438 * Handle all unrecognised system calls.
439 * 0x9f0000 - 0x9fffff are some more esoteric system calls
441 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
442 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
444 struct thread_info *thread = current_thread_info();
447 if ((no >> 16) != (__ARM_NR_BASE>> 16))
448 return bad_syscall(no, regs);
450 switch (no & 0xffff) {
451 case 0: /* branch through 0 */
452 info.si_signo = SIGSEGV;
454 info.si_code = SEGV_MAPERR;
457 arm_notify_die("branch through zero", regs, &info, 0, 0);
460 case NR(breakpoint): /* SWI BREAK_POINT */
461 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
462 ptrace_break(current, regs);
466 * Flush a region from virtual address 'r0' to virtual address 'r1'
467 * _exclusive_. There is no alignment requirement on either address;
468 * user space does not need to know the hardware cache layout.
470 * r2 contains flags. It should ALWAYS be passed as ZERO until it
471 * is defined to be something else. For now we ignore it, but may
472 * the fires of hell burn in your belly if you break this rule. ;)
474 * (at a later date, we may want to allow this call to not flush
475 * various aspects of the cache. Passing '0' will guarantee that
476 * everything necessary gets flushed to maintain consistency in
477 * the specified region).
480 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
484 if (!(elf_hwcap & HWCAP_26BIT))
486 regs->ARM_cpsr &= ~MODE32_BIT;
490 if (!(elf_hwcap & HWCAP_26BIT))
492 regs->ARM_cpsr |= MODE32_BIT;
496 thread->tp_value = regs->ARM_r0;
497 #if defined(CONFIG_HAS_TLS_REG)
498 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
499 #elif !defined(CONFIG_TLS_REG_EMUL)
501 * User space must never try to access this directly.
502 * Expect your app to break eventually if you do so.
503 * The user helper at 0xffff0fe0 must be used instead.
504 * (see entry-armv.S for details)
506 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
510 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
512 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
513 * Return zero in r0 if *MEM was changed or non-zero if no exchange
514 * happened. Also set the user C flag accordingly.
515 * If access permissions have to be fixed up then non-zero is
516 * returned and the operation has to be re-attempted.
518 * *NOTE*: This is a ghost syscall private to the kernel. Only the
519 * __kuser_cmpxchg code in entry-armv.S should be aware of its
520 * existence. Don't ever use this from user code.
524 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
525 struct pt_regs *regs);
527 unsigned long addr = regs->ARM_r2;
528 struct mm_struct *mm = current->mm;
529 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
532 regs->ARM_cpsr &= ~PSR_C_BIT;
533 down_read(&mm->mmap_sem);
534 pgd = pgd_offset(mm, addr);
535 if (!pgd_present(*pgd))
537 pmd = pmd_offset(pgd, addr);
538 if (!pmd_present(*pmd))
540 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
541 if (!pte_present(*pte) || !pte_dirty(*pte)) {
542 pte_unmap_unlock(pte, ptl);
545 val = *(unsigned long *)addr;
548 *(unsigned long *)addr = regs->ARM_r1;
549 regs->ARM_cpsr |= PSR_C_BIT;
551 pte_unmap_unlock(pte, ptl);
552 up_read(&mm->mmap_sem);
556 up_read(&mm->mmap_sem);
557 /* simulate a write access fault */
558 do_DataAbort(addr, 15 + (1 << 11), regs);
563 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
564 if not implemented, rather than raising SIGILL. This
565 way the calling program can gracefully determine whether
566 a feature is supported. */
571 #ifdef CONFIG_DEBUG_USER
573 * experience shows that these seem to indicate that
574 * something catastrophic has happened
576 if (user_debug & UDBG_SYSCALL) {
577 printk("[%d] %s: arm syscall %d\n",
578 task_pid_nr(current), current->comm, no);
580 if (user_mode(regs)) {
582 c_backtrace(regs->ARM_fp, processor_mode(regs));
586 info.si_signo = SIGILL;
588 info.si_code = ILL_ILLTRP;
589 info.si_addr = (void __user *)instruction_pointer(regs) -
590 (thumb_mode(regs) ? 2 : 4);
592 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
596 #ifdef CONFIG_TLS_REG_EMUL
599 * We might be running on an ARMv6+ processor which should have the TLS
600 * register but for some reason we can't use it, or maybe an SMP system
601 * using a pre-ARMv6 processor (there are apparently a few prototypes like
602 * that in existence) and therefore access to that register must be
606 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
608 int reg = (instr >> 12) & 15;
611 regs->uregs[reg] = current_thread_info()->tp_value;
616 static struct undef_hook arm_mrc_hook = {
617 .instr_mask = 0x0fff0fff,
618 .instr_val = 0x0e1d0f70,
619 .cpsr_mask = PSR_T_BIT,
624 static int __init arm_mrc_hook_init(void)
626 register_undef_hook(&arm_mrc_hook);
630 late_initcall(arm_mrc_hook_init);
634 void __bad_xchg(volatile void *ptr, int size)
636 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
637 __builtin_return_address(0), ptr, size);
640 EXPORT_SYMBOL(__bad_xchg);
643 * A data abort trap was taken, but we did not handle the instruction.
644 * Try to abort the user program, or panic if it was the kernel.
647 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
649 unsigned long addr = instruction_pointer(regs);
652 #ifdef CONFIG_DEBUG_USER
653 if (user_debug & UDBG_BADABORT) {
654 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
655 task_pid_nr(current), current->comm, code, instr);
657 show_pte(current->mm, addr);
661 info.si_signo = SIGILL;
663 info.si_code = ILL_ILLOPC;
664 info.si_addr = (void __user *)addr;
666 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
669 void __attribute__((noreturn)) __bug(const char *file, int line)
671 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
674 /* Avoid "noreturn function does return" */
677 EXPORT_SYMBOL(__bug);
679 void __readwrite_bug(const char *fn)
681 printk("%s called, but not implemented\n", fn);
684 EXPORT_SYMBOL(__readwrite_bug);
686 void __pte_error(const char *file, int line, unsigned long val)
688 printk("%s:%d: bad pte %08lx.\n", file, line, val);
691 void __pmd_error(const char *file, int line, unsigned long val)
693 printk("%s:%d: bad pmd %08lx.\n", file, line, val);
696 void __pgd_error(const char *file, int line, unsigned long val)
698 printk("%s:%d: bad pgd %08lx.\n", file, line, val);
701 asmlinkage void __div0(void)
703 printk("Division by zero in kernel.\n");
706 EXPORT_SYMBOL(__div0);
712 /* if that doesn't kill us, halt */
713 panic("Oops failed to kill thread");
715 EXPORT_SYMBOL(abort);
717 void __init trap_init(void)
722 void __init early_trap_init(void)
724 unsigned long vectors = CONFIG_VECTORS_BASE;
725 extern char __stubs_start[], __stubs_end[];
726 extern char __vectors_start[], __vectors_end[];
727 extern char __kuser_helper_start[], __kuser_helper_end[];
728 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
731 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
732 * into the vector page, mapped at 0xffff0000, and ensure these
733 * are visible to the instruction stream.
735 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
736 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
737 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
740 * Copy signal return handlers into the vector page, and
741 * set sigreturn to be a pointer to these.
743 memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
744 sizeof(sigreturn_codes));
746 flush_icache_range(vectors, vectors + PAGE_SIZE);
747 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);