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>
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 + !!thumb
; 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 show_stack(struct task_struct
*tsk
, unsigned long *sp
)
207 dump_backtrace(NULL
, tsk
);
211 #ifdef CONFIG_PREEMPT
212 #define S_PREEMPT " PREEMPT"
221 #ifdef CONFIG_THUMB2_KERNEL
222 #define S_ISA " THUMB2"
227 static int __die(const char *str
, int err
, struct pt_regs
*regs
)
229 struct task_struct
*tsk
= current
;
230 static int die_counter
;
233 printk(KERN_EMERG
"Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
234 S_ISA
"\n", str
, err
, ++die_counter
);
236 /* trap and error numbers are mostly meaningless on ARM */
237 ret
= notify_die(DIE_OOPS
, str
, regs
, err
, tsk
->thread
.trap_no
, SIGSEGV
);
238 if (ret
== NOTIFY_STOP
)
243 printk(KERN_EMERG
"Process %.*s (pid: %d, stack limit = 0x%p)\n",
244 TASK_COMM_LEN
, tsk
->comm
, task_pid_nr(tsk
), end_of_stack(tsk
));
246 if (!user_mode(regs
) || in_interrupt()) {
247 dump_mem(KERN_EMERG
, "Stack: ", regs
->ARM_sp
,
248 THREAD_SIZE
+ (unsigned long)task_stack_page(tsk
));
249 dump_backtrace(regs
, tsk
);
250 dump_instr(KERN_EMERG
, regs
);
256 static arch_spinlock_t die_lock
= __ARCH_SPIN_LOCK_UNLOCKED
;
257 static int die_owner
= -1;
258 static unsigned int die_nest_count
;
260 static unsigned long oops_begin(void)
267 /* racy, but better than risking deadlock. */
268 raw_local_irq_save(flags
);
269 cpu
= smp_processor_id();
270 if (!arch_spin_trylock(&die_lock
)) {
271 if (cpu
== die_owner
)
272 /* nested oops. should stop eventually */;
274 arch_spin_lock(&die_lock
);
283 static void oops_end(unsigned long flags
, struct pt_regs
*regs
, int signr
)
285 if (regs
&& kexec_should_crash(current
))
290 add_taint(TAINT_DIE
, LOCKDEP_NOW_UNRELIABLE
);
293 /* Nest count reaches zero, release the lock. */
294 arch_spin_unlock(&die_lock
);
295 raw_local_irq_restore(flags
);
299 panic("Fatal exception in interrupt");
301 panic("Fatal exception");
307 * This function is protected against re-entrancy.
309 void die(const char *str
, struct pt_regs
*regs
, int err
)
311 enum bug_trap_type bug_type
= BUG_TRAP_TYPE_NONE
;
312 unsigned long flags
= oops_begin();
315 if (!user_mode(regs
))
316 bug_type
= report_bug(regs
->ARM_pc
, regs
);
317 if (bug_type
!= BUG_TRAP_TYPE_NONE
)
320 if (__die(str
, err
, regs
))
323 oops_end(flags
, regs
, sig
);
326 void arm_notify_die(const char *str
, struct pt_regs
*regs
,
327 struct siginfo
*info
, unsigned long err
, unsigned long trap
)
329 if (user_mode(regs
)) {
330 current
->thread
.error_code
= err
;
331 current
->thread
.trap_no
= trap
;
333 force_sig_info(info
->si_signo
, info
, current
);
339 #ifdef CONFIG_GENERIC_BUG
341 int is_valid_bugaddr(unsigned long pc
)
343 #ifdef CONFIG_THUMB2_KERNEL
349 if (probe_kernel_address((unsigned *)pc
, bkpt
))
352 return bkpt
== BUG_INSTR_VALUE
;
357 static LIST_HEAD(undef_hook
);
358 static DEFINE_RAW_SPINLOCK(undef_lock
);
360 void register_undef_hook(struct undef_hook
*hook
)
364 raw_spin_lock_irqsave(&undef_lock
, flags
);
365 list_add(&hook
->node
, &undef_hook
);
366 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
369 void unregister_undef_hook(struct undef_hook
*hook
)
373 raw_spin_lock_irqsave(&undef_lock
, flags
);
374 list_del(&hook
->node
);
375 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
378 static int call_undef_hook(struct pt_regs
*regs
, unsigned int instr
)
380 struct undef_hook
*hook
;
382 int (*fn
)(struct pt_regs
*regs
, unsigned int instr
) = NULL
;
384 raw_spin_lock_irqsave(&undef_lock
, flags
);
385 list_for_each_entry(hook
, &undef_hook
, node
)
386 if ((instr
& hook
->instr_mask
) == hook
->instr_val
&&
387 (regs
->ARM_cpsr
& hook
->cpsr_mask
) == hook
->cpsr_val
)
389 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
391 return fn
? fn(regs
, instr
) : 1;
394 asmlinkage
void __exception
do_undefinstr(struct pt_regs
*regs
)
400 pc
= (void __user
*)instruction_pointer(regs
);
402 if (processor_mode(regs
) == SVC_MODE
) {
403 #ifdef CONFIG_THUMB2_KERNEL
404 if (thumb_mode(regs
)) {
405 instr
= ((u16
*)pc
)[0];
406 if (is_wide_instruction(instr
)) {
408 instr
|= ((u16
*)pc
)[1];
413 } else if (thumb_mode(regs
)) {
414 if (get_user(instr
, (u16 __user
*)pc
))
416 if (is_wide_instruction(instr
)) {
418 if (get_user(instr2
, (u16 __user
*)pc
+1))
423 } else if (get_user(instr
, (u32 __user
*)pc
)) {
427 if (call_undef_hook(regs
, instr
) == 0)
431 #ifdef CONFIG_DEBUG_USER
432 if (user_debug
& UDBG_UNDEFINED
) {
433 printk(KERN_INFO
"%s (%d): undefined instruction: pc=%p\n",
434 current
->comm
, task_pid_nr(current
), pc
);
435 dump_instr(KERN_INFO
, regs
);
439 info
.si_signo
= SIGILL
;
441 info
.si_code
= ILL_ILLOPC
;
444 arm_notify_die("Oops - undefined instruction", regs
, &info
, 0, 6);
447 asmlinkage
void do_unexp_fiq (struct pt_regs
*regs
)
449 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
450 printk("You may have a hardware problem...\n");
454 * bad_mode handles the impossible case in the vectors. If you see one of
455 * these, then it's extremely serious, and could mean you have buggy hardware.
456 * It never returns, and never tries to sync. We hope that we can at least
457 * dump out some state information...
459 asmlinkage
void bad_mode(struct pt_regs
*regs
, int reason
)
463 printk(KERN_CRIT
"Bad mode in %s handler detected\n", handler
[reason
]);
465 die("Oops - bad mode", regs
, 0);
470 static int bad_syscall(int n
, struct pt_regs
*regs
)
472 struct thread_info
*thread
= current_thread_info();
475 if ((current
->personality
& PER_MASK
) != PER_LINUX
&&
476 thread
->exec_domain
->handler
) {
477 thread
->exec_domain
->handler(n
, regs
);
481 #ifdef CONFIG_DEBUG_USER
482 if (user_debug
& UDBG_SYSCALL
) {
483 printk(KERN_ERR
"[%d] %s: obsolete system call %08x.\n",
484 task_pid_nr(current
), current
->comm
, n
);
485 dump_instr(KERN_ERR
, regs
);
489 info
.si_signo
= SIGILL
;
491 info
.si_code
= ILL_ILLTRP
;
492 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
493 (thumb_mode(regs
) ? 2 : 4);
495 arm_notify_die("Oops - bad syscall", regs
, &info
, n
, 0);
501 do_cache_op(unsigned long start
, unsigned long end
, int flags
)
503 struct mm_struct
*mm
= current
->active_mm
;
504 struct vm_area_struct
*vma
;
506 if (end
< start
|| flags
)
509 down_read(&mm
->mmap_sem
);
510 vma
= find_vma(mm
, start
);
511 if (vma
&& vma
->vm_start
< end
) {
512 if (start
< vma
->vm_start
)
513 start
= vma
->vm_start
;
514 if (end
> vma
->vm_end
)
517 up_read(&mm
->mmap_sem
);
518 return flush_cache_user_range(start
, end
);
520 up_read(&mm
->mmap_sem
);
525 * Handle all unrecognised system calls.
526 * 0x9f0000 - 0x9fffff are some more esoteric system calls
528 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
529 asmlinkage
int arm_syscall(int no
, struct pt_regs
*regs
)
531 struct thread_info
*thread
= current_thread_info();
534 if ((no
>> 16) != (__ARM_NR_BASE
>> 16))
535 return bad_syscall(no
, regs
);
537 switch (no
& 0xffff) {
538 case 0: /* branch through 0 */
539 info
.si_signo
= SIGSEGV
;
541 info
.si_code
= SEGV_MAPERR
;
544 arm_notify_die("branch through zero", regs
, &info
, 0, 0);
547 case NR(breakpoint
): /* SWI BREAK_POINT */
548 regs
->ARM_pc
-= thumb_mode(regs
) ? 2 : 4;
549 ptrace_break(current
, regs
);
553 * Flush a region from virtual address 'r0' to virtual address 'r1'
554 * _exclusive_. There is no alignment requirement on either address;
555 * user space does not need to know the hardware cache layout.
557 * r2 contains flags. It should ALWAYS be passed as ZERO until it
558 * is defined to be something else. For now we ignore it, but may
559 * the fires of hell burn in your belly if you break this rule. ;)
561 * (at a later date, we may want to allow this call to not flush
562 * various aspects of the cache. Passing '0' will guarantee that
563 * everything necessary gets flushed to maintain consistency in
564 * the specified region).
567 return do_cache_op(regs
->ARM_r0
, regs
->ARM_r1
, regs
->ARM_r2
);
570 if (!(elf_hwcap
& HWCAP_26BIT
))
572 regs
->ARM_cpsr
&= ~MODE32_BIT
;
576 if (!(elf_hwcap
& HWCAP_26BIT
))
578 regs
->ARM_cpsr
|= MODE32_BIT
;
582 thread
->tp_value
= regs
->ARM_r0
;
586 asm ("mcr p15, 0, %0, c13, c0, 3"
587 : : "r" (regs
->ARM_r0
));
590 * User space must never try to access this directly.
591 * Expect your app to break eventually if you do so.
592 * The user helper at 0xffff0fe0 must be used instead.
593 * (see entry-armv.S for details)
595 *((unsigned int *)0xffff0ff0) = regs
->ARM_r0
;
599 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
601 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
602 * Return zero in r0 if *MEM was changed or non-zero if no exchange
603 * happened. Also set the user C flag accordingly.
604 * If access permissions have to be fixed up then non-zero is
605 * returned and the operation has to be re-attempted.
607 * *NOTE*: This is a ghost syscall private to the kernel. Only the
608 * __kuser_cmpxchg code in entry-armv.S should be aware of its
609 * existence. Don't ever use this from user code.
613 extern void do_DataAbort(unsigned long addr
, unsigned int fsr
,
614 struct pt_regs
*regs
);
616 unsigned long addr
= regs
->ARM_r2
;
617 struct mm_struct
*mm
= current
->mm
;
618 pgd_t
*pgd
; pmd_t
*pmd
; pte_t
*pte
;
621 regs
->ARM_cpsr
&= ~PSR_C_BIT
;
622 down_read(&mm
->mmap_sem
);
623 pgd
= pgd_offset(mm
, addr
);
624 if (!pgd_present(*pgd
))
626 pmd
= pmd_offset(pgd
, addr
);
627 if (!pmd_present(*pmd
))
629 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
630 if (!pte_present(*pte
) || !pte_write(*pte
) || !pte_dirty(*pte
)) {
631 pte_unmap_unlock(pte
, ptl
);
634 val
= *(unsigned long *)addr
;
637 *(unsigned long *)addr
= regs
->ARM_r1
;
638 regs
->ARM_cpsr
|= PSR_C_BIT
;
640 pte_unmap_unlock(pte
, ptl
);
641 up_read(&mm
->mmap_sem
);
645 up_read(&mm
->mmap_sem
);
646 /* simulate a write access fault */
647 do_DataAbort(addr
, 15 + (1 << 11), regs
);
652 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
653 if not implemented, rather than raising SIGILL. This
654 way the calling program can gracefully determine whether
655 a feature is supported. */
656 if ((no
& 0xffff) <= 0x7ff)
660 #ifdef CONFIG_DEBUG_USER
662 * experience shows that these seem to indicate that
663 * something catastrophic has happened
665 if (user_debug
& UDBG_SYSCALL
) {
666 printk("[%d] %s: arm syscall %d\n",
667 task_pid_nr(current
), current
->comm
, no
);
668 dump_instr("", regs
);
669 if (user_mode(regs
)) {
671 c_backtrace(regs
->ARM_fp
, processor_mode(regs
));
675 info
.si_signo
= SIGILL
;
677 info
.si_code
= ILL_ILLTRP
;
678 info
.si_addr
= (void __user
*)instruction_pointer(regs
) -
679 (thumb_mode(regs
) ? 2 : 4);
681 arm_notify_die("Oops - bad syscall(2)", regs
, &info
, no
, 0);
685 #ifdef CONFIG_TLS_REG_EMUL
688 * We might be running on an ARMv6+ processor which should have the TLS
689 * register but for some reason we can't use it, or maybe an SMP system
690 * using a pre-ARMv6 processor (there are apparently a few prototypes like
691 * that in existence) and therefore access to that register must be
695 static int get_tp_trap(struct pt_regs
*regs
, unsigned int instr
)
697 int reg
= (instr
>> 12) & 15;
700 regs
->uregs
[reg
] = current_thread_info()->tp_value
;
705 static struct undef_hook arm_mrc_hook
= {
706 .instr_mask
= 0x0fff0fff,
707 .instr_val
= 0x0e1d0f70,
708 .cpsr_mask
= PSR_T_BIT
,
713 static int __init
arm_mrc_hook_init(void)
715 register_undef_hook(&arm_mrc_hook
);
719 late_initcall(arm_mrc_hook_init
);
723 void __bad_xchg(volatile void *ptr
, int size
)
725 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
726 __builtin_return_address(0), ptr
, size
);
729 EXPORT_SYMBOL(__bad_xchg
);
732 * A data abort trap was taken, but we did not handle the instruction.
733 * Try to abort the user program, or panic if it was the kernel.
736 baddataabort(int code
, unsigned long instr
, struct pt_regs
*regs
)
738 unsigned long addr
= instruction_pointer(regs
);
741 #ifdef CONFIG_DEBUG_USER
742 if (user_debug
& UDBG_BADABORT
) {
743 printk(KERN_ERR
"[%d] %s: bad data abort: code %d instr 0x%08lx\n",
744 task_pid_nr(current
), current
->comm
, code
, instr
);
745 dump_instr(KERN_ERR
, regs
);
746 show_pte(current
->mm
, addr
);
750 info
.si_signo
= SIGILL
;
752 info
.si_code
= ILL_ILLOPC
;
753 info
.si_addr
= (void __user
*)addr
;
755 arm_notify_die("unknown data abort code", regs
, &info
, instr
, 0);
758 void __readwrite_bug(const char *fn
)
760 printk("%s called, but not implemented\n", fn
);
763 EXPORT_SYMBOL(__readwrite_bug
);
765 void __pte_error(const char *file
, int line
, pte_t pte
)
767 printk("%s:%d: bad pte %08llx.\n", file
, line
, (long long)pte_val(pte
));
770 void __pmd_error(const char *file
, int line
, pmd_t pmd
)
772 printk("%s:%d: bad pmd %08llx.\n", file
, line
, (long long)pmd_val(pmd
));
775 void __pgd_error(const char *file
, int line
, pgd_t pgd
)
777 printk("%s:%d: bad pgd %08llx.\n", file
, line
, (long long)pgd_val(pgd
));
780 asmlinkage
void __div0(void)
782 printk("Division by zero in kernel.\n");
785 EXPORT_SYMBOL(__div0
);
791 /* if that doesn't kill us, halt */
792 panic("Oops failed to kill thread");
794 EXPORT_SYMBOL(abort
);
796 void __init
trap_init(void)
801 #ifdef CONFIG_KUSER_HELPERS
802 static void __init
kuser_init(void *vectors
)
804 extern char __kuser_helper_start
[], __kuser_helper_end
[];
805 int kuser_sz
= __kuser_helper_end
- __kuser_helper_start
;
807 memcpy(vectors
+ 0x1000 - kuser_sz
, __kuser_helper_start
, kuser_sz
);
810 * vectors + 0xfe0 = __kuser_get_tls
811 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
813 if (tls_emu
|| has_tls_reg
)
814 memcpy(vectors
+ 0xfe0, vectors
+ 0xfe8, 4);
817 static void __init
kuser_init(void *vectors
)
822 void __init
early_trap_init(void *vectors_base
)
824 unsigned long vectors
= (unsigned long)vectors_base
;
825 extern char __stubs_start
[], __stubs_end
[];
826 extern char __vectors_start
[], __vectors_end
[];
829 vectors_page
= vectors_base
;
832 * Poison the vectors page with an undefined instruction. This
833 * instruction is chosen to be undefined for both ARM and Thumb
834 * ISAs. The Thumb version is an undefined instruction with a
835 * branch back to the undefined instruction.
837 for (i
= 0; i
< PAGE_SIZE
/ sizeof(u32
); i
++)
838 ((u32
*)vectors_base
)[i
] = 0xe7fddef1;
841 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
842 * into the vector page, mapped at 0xffff0000, and ensure these
843 * are visible to the instruction stream.
845 memcpy((void *)vectors
, __vectors_start
, __vectors_end
- __vectors_start
);
846 memcpy((void *)vectors
+ 0x1000, __stubs_start
, __stubs_end
- __stubs_start
);
848 kuser_init(vectors_base
);
850 flush_icache_range(vectors
, vectors
+ PAGE_SIZE
* 2);
851 modify_domain(DOMAIN_USER
, DOMAIN_CLIENT
);