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 <asm/atomic.h>
29 #include <asm/cacheflush.h>
30 #include <asm/system.h>
31 #include <asm/unistd.h>
32 #include <asm/traps.h>
33 #include <asm/unwind.h>
38 static const char *handler
[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
42 #ifdef CONFIG_DEBUG_USER
43 unsigned int user_debug
;
45 static int __init
user_debug_setup(char *str
)
47 get_option(&str
, &user_debug
);
50 __setup("user_debug=", user_debug_setup
);
53 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
55 void dump_backtrace_entry(unsigned long where
, unsigned long from
, unsigned long frame
)
57 #ifdef CONFIG_KALLSYMS
58 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where
, (void *)where
, from
, (void *)from
);
60 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where
, from
);
63 if (in_exception_text(where
))
64 dump_mem("", "Exception stack", frame
+ 4, frame
+ 4 + sizeof(struct pt_regs
));
67 #ifndef CONFIG_ARM_UNWIND
69 * Stack pointers should always be within the kernels view of
70 * physical memory. If it is not there, then we can't dump
71 * out any information relating to the stack.
73 static int verify_stack(unsigned long sp
)
75 if (sp
< PAGE_OFFSET
||
76 (sp
> (unsigned long)high_memory
&& high_memory
!= NULL
))
84 * Dump out the contents of some memory nicely...
86 static void dump_mem(const char *lvl
, const char *str
, unsigned long bottom
,
94 * We need to switch to kernel mode so that we can use __get_user
95 * to safely read from kernel space. Note that we now dump the
96 * code first, just in case the backtrace kills us.
101 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl
, str
, bottom
, top
);
103 for (first
= bottom
& ~31; first
< top
; first
+= 32) {
105 char str
[sizeof(" 12345678") * 8 + 1];
107 memset(str
, ' ', sizeof(str
));
108 str
[sizeof(str
) - 1] = '\0';
110 for (p
= first
, i
= 0; i
< 8 && p
< top
; i
++, p
+= 4) {
111 if (p
>= bottom
&& p
< top
) {
113 if (__get_user(val
, (unsigned long *)p
) == 0)
114 sprintf(str
+ i
* 9, " %08lx", val
);
116 sprintf(str
+ i
* 9, " ????????");
119 printk("%s%04lx:%s\n", lvl
, first
& 0xffff, str
);
125 static void dump_instr(const char *lvl
, struct pt_regs
*regs
)
127 unsigned long addr
= instruction_pointer(regs
);
128 const int thumb
= thumb_mode(regs
);
129 const int width
= thumb
? 4 : 8;
131 char str
[sizeof("00000000 ") * 5 + 2 + 1], *p
= str
;
135 * We need to switch to kernel mode so that we can use __get_user
136 * to safely read from kernel space. Note that we now dump the
137 * code first, just in case the backtrace kills us.
142 for (i
= -4; i
< 1; i
++) {
143 unsigned int val
, bad
;
146 bad
= __get_user(val
, &((u16
*)addr
)[i
]);
148 bad
= __get_user(val
, &((u32
*)addr
)[i
]);
151 p
+= sprintf(p
, i
== 0 ? "(%0*x) " : "%0*x ",
154 p
+= sprintf(p
, "bad PC value");
158 printk("%sCode: %s\n", lvl
, str
);
163 #ifdef CONFIG_ARM_UNWIND
164 static inline void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
)
166 unwind_backtrace(regs
, tsk
);
169 static void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
)
171 unsigned int fp
, mode
;
174 printk("Backtrace: ");
181 mode
= processor_mode(regs
);
182 } else if (tsk
!= current
) {
183 fp
= thread_saved_fp(tsk
);
186 asm("mov %0, fp" : "=r" (fp
) : : "cc");
191 printk("no frame pointer");
193 } else if (verify_stack(fp
)) {
194 printk("invalid frame pointer 0x%08x", fp
);
196 } else if (fp
< (unsigned long)end_of_stack(tsk
))
197 printk("frame pointer underflow");
201 c_backtrace(fp
, mode
);
205 void dump_stack(void)
207 dump_backtrace(NULL
, NULL
);
210 EXPORT_SYMBOL(dump_stack
);
212 void show_stack(struct task_struct
*tsk
, unsigned long *sp
)
214 dump_backtrace(NULL
, tsk
);
218 #ifdef CONFIG_PREEMPT
219 #define S_PREEMPT " PREEMPT"
229 static int __die(const char *str
, int err
, struct thread_info
*thread
, struct pt_regs
*regs
)
231 struct task_struct
*tsk
= thread
->task
;
232 static int die_counter
;
235 printk(KERN_EMERG
"Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
"\n",
236 str
, err
, ++die_counter
);
237 sysfs_printk_last_file();
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
) {
360 } else if (thumb_mode(regs
)) {
361 get_user(instr
, (u16 __user
*)pc
);
363 get_user(instr
, (u32 __user
*)pc
);
366 if (call_undef_hook(regs
, instr
) == 0)
369 #ifdef CONFIG_DEBUG_USER
370 if (user_debug
& UDBG_UNDEFINED
) {
371 printk(KERN_INFO
"%s (%d): undefined instruction: pc=%p\n",
372 current
->comm
, task_pid_nr(current
), pc
);
373 dump_instr(KERN_INFO
, regs
);
377 info
.si_signo
= SIGILL
;
379 info
.si_code
= ILL_ILLOPC
;
382 arm_notify_die("Oops - undefined instruction", regs
, &info
, 0, 6);
385 asmlinkage
void do_unexp_fiq (struct pt_regs
*regs
)
387 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
388 printk("You may have a hardware problem...\n");
392 * bad_mode handles the impossible case in the vectors. If you see one of
393 * these, then it's extremely serious, and could mean you have buggy hardware.
394 * It never returns, and never tries to sync. We hope that we can at least
395 * dump out some state information...
397 asmlinkage
void bad_mode(struct pt_regs
*regs
, int reason
)
401 printk(KERN_CRIT
"Bad mode in %s handler detected\n", handler
[reason
]);
403 die("Oops - bad mode", regs
, 0);
408 static int bad_syscall(int n
, struct pt_regs
*regs
)
410 struct thread_info
*thread
= current_thread_info();
413 if (current
->personality
!= PER_LINUX
&&
414 current
->personality
!= PER_LINUX_32BIT
&&
415 thread
->exec_domain
->handler
) {
416 thread
->exec_domain
->handler(n
, regs
);
420 #ifdef CONFIG_DEBUG_USER
421 if (user_debug
& UDBG_SYSCALL
) {
422 printk(KERN_ERR
"[%d] %s: obsolete system call %08x.\n",
423 task_pid_nr(current
), current
->comm
, n
);
424 dump_instr(KERN_ERR
, regs
);
428 info
.si_signo
= SIGILL
;
430 info
.si_code
= ILL_ILLTRP
;
431 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
432 (thumb_mode(regs
) ? 2 : 4);
434 arm_notify_die("Oops - bad syscall", regs
, &info
, n
, 0);
440 do_cache_op(unsigned long start
, unsigned long end
, int flags
)
442 struct mm_struct
*mm
= current
->active_mm
;
443 struct vm_area_struct
*vma
;
445 if (end
< start
|| flags
)
448 down_read(&mm
->mmap_sem
);
449 vma
= find_vma(mm
, start
);
450 if (vma
&& vma
->vm_start
< end
) {
451 if (start
< vma
->vm_start
)
452 start
= vma
->vm_start
;
453 if (end
> vma
->vm_end
)
456 flush_cache_user_range(vma
, start
, end
);
458 up_read(&mm
->mmap_sem
);
462 * Handle all unrecognised system calls.
463 * 0x9f0000 - 0x9fffff are some more esoteric system calls
465 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
466 asmlinkage
int arm_syscall(int no
, struct pt_regs
*regs
)
468 struct thread_info
*thread
= current_thread_info();
471 if ((no
>> 16) != (__ARM_NR_BASE
>> 16))
472 return bad_syscall(no
, regs
);
474 switch (no
& 0xffff) {
475 case 0: /* branch through 0 */
476 info
.si_signo
= SIGSEGV
;
478 info
.si_code
= SEGV_MAPERR
;
481 arm_notify_die("branch through zero", regs
, &info
, 0, 0);
484 case NR(breakpoint
): /* SWI BREAK_POINT */
485 regs
->ARM_pc
-= thumb_mode(regs
) ? 2 : 4;
486 ptrace_break(current
, regs
);
490 * Flush a region from virtual address 'r0' to virtual address 'r1'
491 * _exclusive_. There is no alignment requirement on either address;
492 * user space does not need to know the hardware cache layout.
494 * r2 contains flags. It should ALWAYS be passed as ZERO until it
495 * is defined to be something else. For now we ignore it, but may
496 * the fires of hell burn in your belly if you break this rule. ;)
498 * (at a later date, we may want to allow this call to not flush
499 * various aspects of the cache. Passing '0' will guarantee that
500 * everything necessary gets flushed to maintain consistency in
501 * the specified region).
504 do_cache_op(regs
->ARM_r0
, regs
->ARM_r1
, regs
->ARM_r2
);
508 if (!(elf_hwcap
& HWCAP_26BIT
))
510 regs
->ARM_cpsr
&= ~MODE32_BIT
;
514 if (!(elf_hwcap
& HWCAP_26BIT
))
516 regs
->ARM_cpsr
|= MODE32_BIT
;
520 thread
->tp_value
= regs
->ARM_r0
;
524 asm ("mcr p15, 0, %0, c13, c0, 3"
525 : : "r" (regs
->ARM_r0
));
528 * User space must never try to access this directly.
529 * Expect your app to break eventually if you do so.
530 * The user helper at 0xffff0fe0 must be used instead.
531 * (see entry-armv.S for details)
533 *((unsigned int *)0xffff0ff0) = regs
->ARM_r0
;
537 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
539 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
540 * Return zero in r0 if *MEM was changed or non-zero if no exchange
541 * happened. Also set the user C flag accordingly.
542 * If access permissions have to be fixed up then non-zero is
543 * returned and the operation has to be re-attempted.
545 * *NOTE*: This is a ghost syscall private to the kernel. Only the
546 * __kuser_cmpxchg code in entry-armv.S should be aware of its
547 * existence. Don't ever use this from user code.
551 extern void do_DataAbort(unsigned long addr
, unsigned int fsr
,
552 struct pt_regs
*regs
);
554 unsigned long addr
= regs
->ARM_r2
;
555 struct mm_struct
*mm
= current
->mm
;
556 pgd_t
*pgd
; pmd_t
*pmd
; pte_t
*pte
;
559 regs
->ARM_cpsr
&= ~PSR_C_BIT
;
560 down_read(&mm
->mmap_sem
);
561 pgd
= pgd_offset(mm
, addr
);
562 if (!pgd_present(*pgd
))
564 pmd
= pmd_offset(pgd
, addr
);
565 if (!pmd_present(*pmd
))
567 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
568 if (!pte_present(*pte
) || !pte_dirty(*pte
)) {
569 pte_unmap_unlock(pte
, ptl
);
572 val
= *(unsigned long *)addr
;
575 *(unsigned long *)addr
= regs
->ARM_r1
;
576 regs
->ARM_cpsr
|= PSR_C_BIT
;
578 pte_unmap_unlock(pte
, ptl
);
579 up_read(&mm
->mmap_sem
);
583 up_read(&mm
->mmap_sem
);
584 /* simulate a write access fault */
585 do_DataAbort(addr
, 15 + (1 << 11), regs
);
590 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
591 if not implemented, rather than raising SIGILL. This
592 way the calling program can gracefully determine whether
593 a feature is supported. */
594 if ((no
& 0xffff) <= 0x7ff)
598 #ifdef CONFIG_DEBUG_USER
600 * experience shows that these seem to indicate that
601 * something catastrophic has happened
603 if (user_debug
& UDBG_SYSCALL
) {
604 printk("[%d] %s: arm syscall %d\n",
605 task_pid_nr(current
), current
->comm
, no
);
606 dump_instr("", regs
);
607 if (user_mode(regs
)) {
609 c_backtrace(regs
->ARM_fp
, processor_mode(regs
));
613 info
.si_signo
= SIGILL
;
615 info
.si_code
= ILL_ILLTRP
;
616 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
617 (thumb_mode(regs
) ? 2 : 4);
619 arm_notify_die("Oops - bad syscall(2)", regs
, &info
, no
, 0);
623 #ifdef CONFIG_TLS_REG_EMUL
626 * We might be running on an ARMv6+ processor which should have the TLS
627 * register but for some reason we can't use it, or maybe an SMP system
628 * using a pre-ARMv6 processor (there are apparently a few prototypes like
629 * that in existence) and therefore access to that register must be
633 static int get_tp_trap(struct pt_regs
*regs
, unsigned int instr
)
635 int reg
= (instr
>> 12) & 15;
638 regs
->uregs
[reg
] = current_thread_info()->tp_value
;
643 static struct undef_hook arm_mrc_hook
= {
644 .instr_mask
= 0x0fff0fff,
645 .instr_val
= 0x0e1d0f70,
646 .cpsr_mask
= PSR_T_BIT
,
651 static int __init
arm_mrc_hook_init(void)
653 register_undef_hook(&arm_mrc_hook
);
657 late_initcall(arm_mrc_hook_init
);
661 void __bad_xchg(volatile void *ptr
, int size
)
663 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
664 __builtin_return_address(0), ptr
, size
);
667 EXPORT_SYMBOL(__bad_xchg
);
670 * A data abort trap was taken, but we did not handle the instruction.
671 * Try to abort the user program, or panic if it was the kernel.
674 baddataabort(int code
, unsigned long instr
, struct pt_regs
*regs
)
676 unsigned long addr
= instruction_pointer(regs
);
679 #ifdef CONFIG_DEBUG_USER
680 if (user_debug
& UDBG_BADABORT
) {
681 printk(KERN_ERR
"[%d] %s: bad data abort: code %d instr 0x%08lx\n",
682 task_pid_nr(current
), current
->comm
, code
, instr
);
683 dump_instr(KERN_ERR
, regs
);
684 show_pte(current
->mm
, addr
);
688 info
.si_signo
= SIGILL
;
690 info
.si_code
= ILL_ILLOPC
;
691 info
.si_addr
= (void __user
*)addr
;
693 arm_notify_die("unknown data abort code", regs
, &info
, instr
, 0);
696 void __attribute__((noreturn
)) __bug(const char *file
, int line
)
698 printk(KERN_CRIT
"kernel BUG at %s:%d!\n", file
, line
);
701 /* Avoid "noreturn function does return" */
704 EXPORT_SYMBOL(__bug
);
706 void __readwrite_bug(const char *fn
)
708 printk("%s called, but not implemented\n", fn
);
711 EXPORT_SYMBOL(__readwrite_bug
);
713 void __pte_error(const char *file
, int line
, pte_t pte
)
715 printk("%s:%d: bad pte %08llx.\n", file
, line
, (long long)pte_val(pte
));
718 void __pmd_error(const char *file
, int line
, pmd_t pmd
)
720 printk("%s:%d: bad pmd %08llx.\n", file
, line
, (long long)pmd_val(pmd
));
723 void __pgd_error(const char *file
, int line
, pgd_t pgd
)
725 printk("%s:%d: bad pgd %08llx.\n", file
, line
, (long long)pgd_val(pgd
));
728 asmlinkage
void __div0(void)
730 printk("Division by zero in kernel.\n");
733 EXPORT_SYMBOL(__div0
);
739 /* if that doesn't kill us, halt */
740 panic("Oops failed to kill thread");
742 EXPORT_SYMBOL(abort
);
744 void __init
trap_init(void)
749 static void __init
kuser_get_tls_init(unsigned long vectors
)
752 * vectors + 0xfe0 = __kuser_get_tls
753 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
755 if (tls_emu
|| has_tls_reg
)
756 memcpy((void *)vectors
+ 0xfe0, (void *)vectors
+ 0xfe8, 4);
759 void __init
early_trap_init(void)
761 #if defined(CONFIG_CPU_USE_DOMAINS)
762 unsigned long vectors
= CONFIG_VECTORS_BASE
;
764 unsigned long vectors
= (unsigned long)vectors_page
;
766 extern char __stubs_start
[], __stubs_end
[];
767 extern char __vectors_start
[], __vectors_end
[];
768 extern char __kuser_helper_start
[], __kuser_helper_end
[];
769 int kuser_sz
= __kuser_helper_end
- __kuser_helper_start
;
772 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
773 * into the vector page, mapped at 0xffff0000, and ensure these
774 * are visible to the instruction stream.
776 memcpy((void *)vectors
, __vectors_start
, __vectors_end
- __vectors_start
);
777 memcpy((void *)vectors
+ 0x200, __stubs_start
, __stubs_end
- __stubs_start
);
778 memcpy((void *)vectors
+ 0x1000 - kuser_sz
, __kuser_helper_start
, kuser_sz
);
781 * Do processor specific fixups for the kuser helpers
783 kuser_get_tls_init(vectors
);
786 * Copy signal return handlers into the vector page, and
787 * set sigreturn to be a pointer to these.
789 memcpy((void *)(vectors
+ KERN_SIGRETURN_CODE
- CONFIG_VECTORS_BASE
),
790 sigreturn_codes
, sizeof(sigreturn_codes
));
791 memcpy((void *)(vectors
+ KERN_RESTART_CODE
- CONFIG_VECTORS_BASE
),
792 syscall_restart_code
, sizeof(syscall_restart_code
));
794 flush_icache_range(vectors
, vectors
+ PAGE_SIZE
);
795 modify_domain(DOMAIN_USER
, DOMAIN_CLIENT
);