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/bug.h>
25 #include <linux/delay.h>
26 #include <linux/init.h>
27 #include <linux/sched.h>
29 #include <linux/atomic.h>
30 #include <asm/cacheflush.h>
31 #include <asm/exception.h>
32 #include <asm/unistd.h>
33 #include <asm/traps.h>
34 #include <asm/unwind.h>
36 #include <asm/system_misc.h>
40 static const char *handler
[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
44 #ifdef CONFIG_DEBUG_USER
45 unsigned int user_debug
;
47 static int __init
user_debug_setup(char *str
)
49 get_option(&str
, &user_debug
);
52 __setup("user_debug=", user_debug_setup
);
55 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
57 void dump_backtrace_entry(unsigned long where
, unsigned long from
, unsigned long frame
)
59 #ifdef CONFIG_KALLSYMS
60 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where
, (void *)where
, from
, (void *)from
);
62 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where
, from
);
65 if (in_exception_text(where
))
66 dump_mem("", "Exception stack", frame
+ 4, frame
+ 4 + sizeof(struct pt_regs
));
69 #ifndef CONFIG_ARM_UNWIND
71 * Stack pointers should always be within the kernels view of
72 * physical memory. If it is not there, then we can't dump
73 * out any information relating to the stack.
75 static int verify_stack(unsigned long sp
)
77 if (sp
< PAGE_OFFSET
||
78 (sp
> (unsigned long)high_memory
&& high_memory
!= NULL
))
86 * Dump out the contents of some memory nicely...
88 static void dump_mem(const char *lvl
, const char *str
, unsigned long bottom
,
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%s(0x%08lx to 0x%08lx)\n", lvl
, str
, bottom
, top
);
105 for (first
= bottom
& ~31; first
< top
; first
+= 32) {
107 char str
[sizeof(" 12345678") * 8 + 1];
109 memset(str
, ' ', sizeof(str
));
110 str
[sizeof(str
) - 1] = '\0';
112 for (p
= first
, i
= 0; i
< 8 && p
< top
; i
++, p
+= 4) {
113 if (p
>= bottom
&& p
< top
) {
115 if (__get_user(val
, (unsigned long *)p
) == 0)
116 sprintf(str
+ i
* 9, " %08lx", val
);
118 sprintf(str
+ i
* 9, " ????????");
121 printk("%s%04lx:%s\n", lvl
, first
& 0xffff, str
);
127 static void dump_instr(const char *lvl
, struct pt_regs
*regs
)
129 unsigned long addr
= instruction_pointer(regs
);
130 const int thumb
= thumb_mode(regs
);
131 const int width
= thumb
? 4 : 8;
133 char str
[sizeof("00000000 ") * 5 + 2 + 1], *p
= str
;
137 * We need to switch to kernel mode so that we can use __get_user
138 * to safely read from kernel space. Note that we now dump the
139 * code first, just in case the backtrace kills us.
144 for (i
= -4; i
< 1 + !!thumb
; i
++) {
145 unsigned int val
, bad
;
148 bad
= __get_user(val
, &((u16
*)addr
)[i
]);
150 bad
= __get_user(val
, &((u32
*)addr
)[i
]);
153 p
+= sprintf(p
, i
== 0 ? "(%0*x) " : "%0*x ",
156 p
+= sprintf(p
, "bad PC value");
160 printk("%sCode: %s\n", lvl
, str
);
165 #ifdef CONFIG_ARM_UNWIND
166 static inline void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
)
168 unwind_backtrace(regs
, tsk
);
171 static void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
)
173 unsigned int fp
, mode
;
176 printk("Backtrace: ");
183 mode
= processor_mode(regs
);
184 } else if (tsk
!= current
) {
185 fp
= thread_saved_fp(tsk
);
188 asm("mov %0, fp" : "=r" (fp
) : : "cc");
193 printk("no frame pointer");
195 } else if (verify_stack(fp
)) {
196 printk("invalid frame pointer 0x%08x", fp
);
198 } else if (fp
< (unsigned long)end_of_stack(tsk
))
199 printk("frame pointer underflow");
203 c_backtrace(fp
, mode
);
207 void dump_stack(void)
209 dump_backtrace(NULL
, NULL
);
212 EXPORT_SYMBOL(dump_stack
);
214 void show_stack(struct task_struct
*tsk
, unsigned long *sp
)
216 dump_backtrace(NULL
, tsk
);
220 #ifdef CONFIG_PREEMPT
221 #define S_PREEMPT " PREEMPT"
230 #ifdef CONFIG_THUMB2_KERNEL
231 #define S_ISA " THUMB2"
236 static int __die(const char *str
, int err
, struct thread_info
*thread
, struct pt_regs
*regs
)
238 struct task_struct
*tsk
= thread
->task
;
239 static int die_counter
;
242 printk(KERN_EMERG
"Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
243 S_ISA
"\n", str
, err
, ++die_counter
);
245 /* trap and error numbers are mostly meaningless on ARM */
246 ret
= notify_die(DIE_OOPS
, str
, regs
, err
, tsk
->thread
.trap_no
, SIGSEGV
);
247 if (ret
== NOTIFY_STOP
)
252 printk(KERN_EMERG
"Process %.*s (pid: %d, stack limit = 0x%p)\n",
253 TASK_COMM_LEN
, tsk
->comm
, task_pid_nr(tsk
), thread
+ 1);
255 if (!user_mode(regs
) || in_interrupt()) {
256 dump_mem(KERN_EMERG
, "Stack: ", regs
->ARM_sp
,
257 THREAD_SIZE
+ (unsigned long)task_stack_page(tsk
));
258 dump_backtrace(regs
, tsk
);
259 dump_instr(KERN_EMERG
, regs
);
265 static DEFINE_RAW_SPINLOCK(die_lock
);
268 * This function is protected against re-entrancy.
270 void die(const char *str
, struct pt_regs
*regs
, int err
)
272 struct thread_info
*thread
= current_thread_info();
274 enum bug_trap_type bug_type
= BUG_TRAP_TYPE_NONE
;
278 raw_spin_lock_irq(&die_lock
);
281 if (!user_mode(regs
))
282 bug_type
= report_bug(regs
->ARM_pc
, regs
);
283 if (bug_type
!= BUG_TRAP_TYPE_NONE
)
285 ret
= __die(str
, err
, thread
, regs
);
287 if (regs
&& kexec_should_crash(thread
->task
))
291 add_taint(TAINT_DIE
);
292 raw_spin_unlock_irq(&die_lock
);
296 panic("Fatal exception in interrupt");
298 panic("Fatal exception");
299 if (ret
!= NOTIFY_STOP
)
303 void arm_notify_die(const char *str
, struct pt_regs
*regs
,
304 struct siginfo
*info
, unsigned long err
, unsigned long trap
)
306 if (user_mode(regs
)) {
307 current
->thread
.error_code
= err
;
308 current
->thread
.trap_no
= trap
;
310 force_sig_info(info
->si_signo
, info
, current
);
316 #ifdef CONFIG_GENERIC_BUG
318 int is_valid_bugaddr(unsigned long pc
)
320 #ifdef CONFIG_THUMB2_KERNEL
326 if (probe_kernel_address((unsigned *)pc
, bkpt
))
329 return bkpt
== BUG_INSTR_VALUE
;
334 static LIST_HEAD(undef_hook
);
335 static DEFINE_RAW_SPINLOCK(undef_lock
);
337 void register_undef_hook(struct undef_hook
*hook
)
341 raw_spin_lock_irqsave(&undef_lock
, flags
);
342 list_add(&hook
->node
, &undef_hook
);
343 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
346 void unregister_undef_hook(struct undef_hook
*hook
)
350 raw_spin_lock_irqsave(&undef_lock
, flags
);
351 list_del(&hook
->node
);
352 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
355 static int call_undef_hook(struct pt_regs
*regs
, unsigned int instr
)
357 struct undef_hook
*hook
;
359 int (*fn
)(struct pt_regs
*regs
, unsigned int instr
) = NULL
;
361 raw_spin_lock_irqsave(&undef_lock
, flags
);
362 list_for_each_entry(hook
, &undef_hook
, node
)
363 if ((instr
& hook
->instr_mask
) == hook
->instr_val
&&
364 (regs
->ARM_cpsr
& hook
->cpsr_mask
) == hook
->cpsr_val
)
366 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
368 return fn
? fn(regs
, instr
) : 1;
371 asmlinkage
void __exception
do_undefinstr(struct pt_regs
*regs
)
373 unsigned int correction
= thumb_mode(regs
) ? 2 : 4;
379 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
380 * depending whether we're in Thumb mode or not.
381 * Correct this offset.
383 regs
->ARM_pc
-= correction
;
385 pc
= (void __user
*)instruction_pointer(regs
);
387 if (processor_mode(regs
) == SVC_MODE
) {
388 #ifdef CONFIG_THUMB2_KERNEL
389 if (thumb_mode(regs
)) {
390 instr
= ((u16
*)pc
)[0];
391 if (is_wide_instruction(instr
)) {
393 instr
|= ((u16
*)pc
)[1];
398 } else if (thumb_mode(regs
)) {
399 get_user(instr
, (u16 __user
*)pc
);
400 if (is_wide_instruction(instr
)) {
402 get_user(instr2
, (u16 __user
*)pc
+1);
407 get_user(instr
, (u32 __user
*)pc
);
410 if (call_undef_hook(regs
, instr
) == 0)
413 #ifdef CONFIG_DEBUG_USER
414 if (user_debug
& UDBG_UNDEFINED
) {
415 printk(KERN_INFO
"%s (%d): undefined instruction: pc=%p\n",
416 current
->comm
, task_pid_nr(current
), pc
);
417 dump_instr(KERN_INFO
, regs
);
421 info
.si_signo
= SIGILL
;
423 info
.si_code
= ILL_ILLOPC
;
426 arm_notify_die("Oops - undefined instruction", regs
, &info
, 0, 6);
429 asmlinkage
void do_unexp_fiq (struct pt_regs
*regs
)
431 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
432 printk("You may have a hardware problem...\n");
436 * bad_mode handles the impossible case in the vectors. If you see one of
437 * these, then it's extremely serious, and could mean you have buggy hardware.
438 * It never returns, and never tries to sync. We hope that we can at least
439 * dump out some state information...
441 asmlinkage
void bad_mode(struct pt_regs
*regs
, int reason
)
445 printk(KERN_CRIT
"Bad mode in %s handler detected\n", handler
[reason
]);
447 die("Oops - bad mode", regs
, 0);
452 static int bad_syscall(int n
, struct pt_regs
*regs
)
454 struct thread_info
*thread
= current_thread_info();
457 if ((current
->personality
& PER_MASK
) != PER_LINUX
&&
458 thread
->exec_domain
->handler
) {
459 thread
->exec_domain
->handler(n
, regs
);
463 #ifdef CONFIG_DEBUG_USER
464 if (user_debug
& UDBG_SYSCALL
) {
465 printk(KERN_ERR
"[%d] %s: obsolete system call %08x.\n",
466 task_pid_nr(current
), current
->comm
, n
);
467 dump_instr(KERN_ERR
, regs
);
471 info
.si_signo
= SIGILL
;
473 info
.si_code
= ILL_ILLTRP
;
474 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
475 (thumb_mode(regs
) ? 2 : 4);
477 arm_notify_die("Oops - bad syscall", regs
, &info
, n
, 0);
483 do_cache_op(unsigned long start
, unsigned long end
, int flags
)
485 struct mm_struct
*mm
= current
->active_mm
;
486 struct vm_area_struct
*vma
;
488 if (end
< start
|| flags
)
491 down_read(&mm
->mmap_sem
);
492 vma
= find_vma(mm
, start
);
493 if (vma
&& vma
->vm_start
< end
) {
494 if (start
< vma
->vm_start
)
495 start
= vma
->vm_start
;
496 if (end
> vma
->vm_end
)
499 up_read(&mm
->mmap_sem
);
500 return flush_cache_user_range(start
, end
);
502 up_read(&mm
->mmap_sem
);
507 * Handle all unrecognised system calls.
508 * 0x9f0000 - 0x9fffff are some more esoteric system calls
510 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
511 asmlinkage
int arm_syscall(int no
, struct pt_regs
*regs
)
513 struct thread_info
*thread
= current_thread_info();
516 if ((no
>> 16) != (__ARM_NR_BASE
>> 16))
517 return bad_syscall(no
, regs
);
519 switch (no
& 0xffff) {
520 case 0: /* branch through 0 */
521 info
.si_signo
= SIGSEGV
;
523 info
.si_code
= SEGV_MAPERR
;
526 arm_notify_die("branch through zero", regs
, &info
, 0, 0);
529 case NR(breakpoint
): /* SWI BREAK_POINT */
530 regs
->ARM_pc
-= thumb_mode(regs
) ? 2 : 4;
531 ptrace_break(current
, regs
);
535 * Flush a region from virtual address 'r0' to virtual address 'r1'
536 * _exclusive_. There is no alignment requirement on either address;
537 * user space does not need to know the hardware cache layout.
539 * r2 contains flags. It should ALWAYS be passed as ZERO until it
540 * is defined to be something else. For now we ignore it, but may
541 * the fires of hell burn in your belly if you break this rule. ;)
543 * (at a later date, we may want to allow this call to not flush
544 * various aspects of the cache. Passing '0' will guarantee that
545 * everything necessary gets flushed to maintain consistency in
546 * the specified region).
549 return do_cache_op(regs
->ARM_r0
, regs
->ARM_r1
, regs
->ARM_r2
);
552 if (!(elf_hwcap
& HWCAP_26BIT
))
554 regs
->ARM_cpsr
&= ~MODE32_BIT
;
558 if (!(elf_hwcap
& HWCAP_26BIT
))
560 regs
->ARM_cpsr
|= MODE32_BIT
;
564 thread
->tp_value
= regs
->ARM_r0
;
568 asm ("mcr p15, 0, %0, c13, c0, 3"
569 : : "r" (regs
->ARM_r0
));
572 * User space must never try to access this directly.
573 * Expect your app to break eventually if you do so.
574 * The user helper at 0xffff0fe0 must be used instead.
575 * (see entry-armv.S for details)
577 *((unsigned int *)0xffff0ff0) = regs
->ARM_r0
;
581 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
583 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
584 * Return zero in r0 if *MEM was changed or non-zero if no exchange
585 * happened. Also set the user C flag accordingly.
586 * If access permissions have to be fixed up then non-zero is
587 * returned and the operation has to be re-attempted.
589 * *NOTE*: This is a ghost syscall private to the kernel. Only the
590 * __kuser_cmpxchg code in entry-armv.S should be aware of its
591 * existence. Don't ever use this from user code.
595 extern void do_DataAbort(unsigned long addr
, unsigned int fsr
,
596 struct pt_regs
*regs
);
598 unsigned long addr
= regs
->ARM_r2
;
599 struct mm_struct
*mm
= current
->mm
;
600 pgd_t
*pgd
; pmd_t
*pmd
; pte_t
*pte
;
603 regs
->ARM_cpsr
&= ~PSR_C_BIT
;
604 down_read(&mm
->mmap_sem
);
605 pgd
= pgd_offset(mm
, addr
);
606 if (!pgd_present(*pgd
))
608 pmd
= pmd_offset(pgd
, addr
);
609 if (!pmd_present(*pmd
))
611 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
612 if (!pte_present(*pte
) || !pte_write(*pte
) || !pte_dirty(*pte
)) {
613 pte_unmap_unlock(pte
, ptl
);
616 val
= *(unsigned long *)addr
;
619 *(unsigned long *)addr
= regs
->ARM_r1
;
620 regs
->ARM_cpsr
|= PSR_C_BIT
;
622 pte_unmap_unlock(pte
, ptl
);
623 up_read(&mm
->mmap_sem
);
627 up_read(&mm
->mmap_sem
);
628 /* simulate a write access fault */
629 do_DataAbort(addr
, 15 + (1 << 11), regs
);
634 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
635 if not implemented, rather than raising SIGILL. This
636 way the calling program can gracefully determine whether
637 a feature is supported. */
638 if ((no
& 0xffff) <= 0x7ff)
642 #ifdef CONFIG_DEBUG_USER
644 * experience shows that these seem to indicate that
645 * something catastrophic has happened
647 if (user_debug
& UDBG_SYSCALL
) {
648 printk("[%d] %s: arm syscall %d\n",
649 task_pid_nr(current
), current
->comm
, no
);
650 dump_instr("", regs
);
651 if (user_mode(regs
)) {
653 c_backtrace(regs
->ARM_fp
, processor_mode(regs
));
657 info
.si_signo
= SIGILL
;
659 info
.si_code
= ILL_ILLTRP
;
660 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
661 (thumb_mode(regs
) ? 2 : 4);
663 arm_notify_die("Oops - bad syscall(2)", regs
, &info
, no
, 0);
667 #ifdef CONFIG_TLS_REG_EMUL
670 * We might be running on an ARMv6+ processor which should have the TLS
671 * register but for some reason we can't use it, or maybe an SMP system
672 * using a pre-ARMv6 processor (there are apparently a few prototypes like
673 * that in existence) and therefore access to that register must be
677 static int get_tp_trap(struct pt_regs
*regs
, unsigned int instr
)
679 int reg
= (instr
>> 12) & 15;
682 regs
->uregs
[reg
] = current_thread_info()->tp_value
;
687 static struct undef_hook arm_mrc_hook
= {
688 .instr_mask
= 0x0fff0fff,
689 .instr_val
= 0x0e1d0f70,
690 .cpsr_mask
= PSR_T_BIT
,
695 static int __init
arm_mrc_hook_init(void)
697 register_undef_hook(&arm_mrc_hook
);
701 late_initcall(arm_mrc_hook_init
);
705 void __bad_xchg(volatile void *ptr
, int size
)
707 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
708 __builtin_return_address(0), ptr
, size
);
711 EXPORT_SYMBOL(__bad_xchg
);
714 * A data abort trap was taken, but we did not handle the instruction.
715 * Try to abort the user program, or panic if it was the kernel.
718 baddataabort(int code
, unsigned long instr
, struct pt_regs
*regs
)
720 unsigned long addr
= instruction_pointer(regs
);
723 #ifdef CONFIG_DEBUG_USER
724 if (user_debug
& UDBG_BADABORT
) {
725 printk(KERN_ERR
"[%d] %s: bad data abort: code %d instr 0x%08lx\n",
726 task_pid_nr(current
), current
->comm
, code
, instr
);
727 dump_instr(KERN_ERR
, regs
);
728 show_pte(current
->mm
, addr
);
732 info
.si_signo
= SIGILL
;
734 info
.si_code
= ILL_ILLOPC
;
735 info
.si_addr
= (void __user
*)addr
;
737 arm_notify_die("unknown data abort code", regs
, &info
, instr
, 0);
740 void __readwrite_bug(const char *fn
)
742 printk("%s called, but not implemented\n", fn
);
745 EXPORT_SYMBOL(__readwrite_bug
);
747 void __pte_error(const char *file
, int line
, pte_t pte
)
749 printk("%s:%d: bad pte %08llx.\n", file
, line
, (long long)pte_val(pte
));
752 void __pmd_error(const char *file
, int line
, pmd_t pmd
)
754 printk("%s:%d: bad pmd %08llx.\n", file
, line
, (long long)pmd_val(pmd
));
757 void __pgd_error(const char *file
, int line
, pgd_t pgd
)
759 printk("%s:%d: bad pgd %08llx.\n", file
, line
, (long long)pgd_val(pgd
));
762 asmlinkage
void __div0(void)
764 printk("Division by zero in kernel.\n");
767 EXPORT_SYMBOL(__div0
);
773 /* if that doesn't kill us, halt */
774 panic("Oops failed to kill thread");
776 EXPORT_SYMBOL(abort
);
778 void __init
trap_init(void)
783 static void __init
kuser_get_tls_init(unsigned long vectors
)
786 * vectors + 0xfe0 = __kuser_get_tls
787 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
789 if (tls_emu
|| has_tls_reg
)
790 memcpy((void *)vectors
+ 0xfe0, (void *)vectors
+ 0xfe8, 4);
793 void __init
early_trap_init(void *vectors_base
)
795 unsigned long vectors
= (unsigned long)vectors_base
;
796 extern char __stubs_start
[], __stubs_end
[];
797 extern char __vectors_start
[], __vectors_end
[];
798 extern char __kuser_helper_start
[], __kuser_helper_end
[];
799 int kuser_sz
= __kuser_helper_end
- __kuser_helper_start
;
801 vectors_page
= vectors_base
;
804 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
805 * into the vector page, mapped at 0xffff0000, and ensure these
806 * are visible to the instruction stream.
808 memcpy((void *)vectors
, __vectors_start
, __vectors_end
- __vectors_start
);
809 memcpy((void *)vectors
+ 0x200, __stubs_start
, __stubs_end
- __stubs_start
);
810 memcpy((void *)vectors
+ 0x1000 - kuser_sz
, __kuser_helper_start
, kuser_sz
);
813 * Do processor specific fixups for the kuser helpers
815 kuser_get_tls_init(vectors
);
818 * Copy signal return handlers into the vector page, and
819 * set sigreturn to be a pointer to these.
821 memcpy((void *)(vectors
+ KERN_SIGRETURN_CODE
- CONFIG_VECTORS_BASE
),
822 sigreturn_codes
, sizeof(sigreturn_codes
));
824 flush_icache_range(vectors
, vectors
+ PAGE_SIZE
);
825 modify_domain(DOMAIN_USER
, DOMAIN_CLIENT
);
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