1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/arch/arm/kernel/traps.c
5 * Copyright (C) 1995-2009 Russell King
6 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
8 * 'traps.c' handles hardware exceptions after we have saved some state in
9 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
10 * kill the offending process.
12 #include <linux/signal.h>
13 #include <linux/personality.h>
14 #include <linux/kallsyms.h>
15 #include <linux/spinlock.h>
16 #include <linux/uaccess.h>
17 #include <linux/hardirq.h>
18 #include <linux/kdebug.h>
19 #include <linux/kprobes.h>
20 #include <linux/module.h>
21 #include <linux/kexec.h>
22 #include <linux/bug.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/sched/signal.h>
26 #include <linux/sched/debug.h>
27 #include <linux/sched/task_stack.h>
28 #include <linux/irq.h>
30 #include <linux/atomic.h>
31 #include <asm/cacheflush.h>
32 #include <asm/exception.h>
33 #include <asm/unistd.h>
34 #include <asm/traps.h>
35 #include <asm/ptrace.h>
36 #include <asm/unwind.h>
38 #include <asm/system_misc.h>
39 #include <asm/opcodes.h>
42 static const char *handler
[]= {
47 "undefined instruction",
52 #ifdef CONFIG_DEBUG_USER
53 unsigned int user_debug
;
55 static int __init
user_debug_setup(char *str
)
57 get_option(&str
, &user_debug
);
60 __setup("user_debug=", user_debug_setup
);
63 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
65 void dump_backtrace_entry(unsigned long where
, unsigned long from
,
66 unsigned long frame
, const char *loglvl
)
68 unsigned long end
= frame
+ 4 + sizeof(struct pt_regs
);
70 #ifdef CONFIG_KALLSYMS
71 printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
72 loglvl
, where
, (void *)where
, from
, (void *)from
);
74 printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
78 if (in_entry_text(from
) && end
<= ALIGN(frame
, THREAD_SIZE
))
79 dump_mem(loglvl
, "Exception stack", frame
+ 4, end
);
82 void dump_backtrace_stm(u32
*stack
, u32 instruction
, const char *loglvl
)
88 for (reg
= 10, x
= 0, p
= str
; reg
>= 0; reg
--) {
89 if (instruction
& BIT(reg
)) {
90 p
+= sprintf(p
, " r%d:%08x", reg
, *stack
--);
94 printk("%s%s\n", loglvl
, str
);
99 printk("%s%s\n", loglvl
, str
);
102 #ifndef CONFIG_ARM_UNWIND
104 * Stack pointers should always be within the kernels view of
105 * physical memory. If it is not there, then we can't dump
106 * out any information relating to the stack.
108 static int verify_stack(unsigned long sp
)
110 if (sp
< PAGE_OFFSET
||
111 (sp
> (unsigned long)high_memory
&& high_memory
!= NULL
))
119 * Dump out the contents of some memory nicely...
121 static void dump_mem(const char *lvl
, const char *str
, unsigned long bottom
,
127 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl
, str
, bottom
, top
);
129 for (first
= bottom
& ~31; first
< top
; first
+= 32) {
131 char str
[sizeof(" 12345678") * 8 + 1];
133 memset(str
, ' ', sizeof(str
));
134 str
[sizeof(str
) - 1] = '\0';
136 for (p
= first
, i
= 0; i
< 8 && p
< top
; i
++, p
+= 4) {
137 if (p
>= bottom
&& p
< top
) {
139 if (get_kernel_nofault(val
, (unsigned long *)p
))
140 sprintf(str
+ i
* 9, " %08lx", val
);
142 sprintf(str
+ i
* 9, " ????????");
145 printk("%s%04lx:%s\n", lvl
, first
& 0xffff, str
);
149 static void dump_instr(const char *lvl
, struct pt_regs
*regs
)
151 unsigned long addr
= instruction_pointer(regs
);
152 const int thumb
= thumb_mode(regs
);
153 const int width
= thumb
? 4 : 8;
154 char str
[sizeof("00000000 ") * 5 + 2 + 1], *p
= str
;
158 * Note that we now dump the code first, just in case the backtrace
162 for (i
= -4; i
< 1 + !!thumb
; i
++) {
163 unsigned int val
, bad
;
165 if (!user_mode(regs
)) {
168 bad
= get_kernel_nofault(val16
, &((u16
*)addr
)[i
]);
171 bad
= get_kernel_nofault(val
, &((u32
*)addr
)[i
]);
175 bad
= get_user(val
, &((u16
*)addr
)[i
]);
177 bad
= get_user(val
, &((u32
*)addr
)[i
]);
181 p
+= sprintf(p
, i
== 0 ? "(%0*x) " : "%0*x ",
184 p
+= sprintf(p
, "bad PC value");
188 printk("%sCode: %s\n", lvl
, str
);
191 #ifdef CONFIG_ARM_UNWIND
192 static inline void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
,
195 unwind_backtrace(regs
, tsk
, loglvl
);
198 static void dump_backtrace(struct pt_regs
*regs
, struct task_struct
*tsk
,
201 unsigned int fp
, mode
;
204 printk("%sBacktrace: ", loglvl
);
210 fp
= frame_pointer(regs
);
211 mode
= processor_mode(regs
);
212 } else if (tsk
!= current
) {
213 fp
= thread_saved_fp(tsk
);
216 asm("mov %0, fp" : "=r" (fp
) : : "cc");
221 pr_cont("no frame pointer");
223 } else if (verify_stack(fp
)) {
224 pr_cont("invalid frame pointer 0x%08x", fp
);
226 } else if (fp
< (unsigned long)end_of_stack(tsk
))
227 pr_cont("frame pointer underflow");
231 c_backtrace(fp
, mode
, loglvl
);
235 void show_stack(struct task_struct
*tsk
, unsigned long *sp
, const char *loglvl
)
237 dump_backtrace(NULL
, tsk
, loglvl
);
241 #ifdef CONFIG_PREEMPT
242 #define S_PREEMPT " PREEMPT"
243 #elif defined(CONFIG_PREEMPT_RT)
244 #define S_PREEMPT " PREEMPT_RT"
253 #ifdef CONFIG_THUMB2_KERNEL
254 #define S_ISA " THUMB2"
259 static int __die(const char *str
, int err
, struct pt_regs
*regs
)
261 struct task_struct
*tsk
= current
;
262 static int die_counter
;
265 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA
"\n",
266 str
, err
, ++die_counter
);
268 /* trap and error numbers are mostly meaningless on ARM */
269 ret
= notify_die(DIE_OOPS
, str
, regs
, err
, tsk
->thread
.trap_no
, SIGSEGV
);
270 if (ret
== NOTIFY_STOP
)
275 __show_regs_alloc_free(regs
);
276 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
277 TASK_COMM_LEN
, tsk
->comm
, task_pid_nr(tsk
), end_of_stack(tsk
));
279 if (!user_mode(regs
) || in_interrupt()) {
280 dump_mem(KERN_EMERG
, "Stack: ", regs
->ARM_sp
,
281 THREAD_SIZE
+ (unsigned long)task_stack_page(tsk
));
282 dump_backtrace(regs
, tsk
, KERN_EMERG
);
283 dump_instr(KERN_EMERG
, regs
);
289 static arch_spinlock_t die_lock
= __ARCH_SPIN_LOCK_UNLOCKED
;
290 static int die_owner
= -1;
291 static unsigned int die_nest_count
;
293 static unsigned long oops_begin(void)
300 /* racy, but better than risking deadlock. */
301 raw_local_irq_save(flags
);
302 cpu
= smp_processor_id();
303 if (!arch_spin_trylock(&die_lock
)) {
304 if (cpu
== die_owner
)
305 /* nested oops. should stop eventually */;
307 arch_spin_lock(&die_lock
);
316 static void oops_end(unsigned long flags
, struct pt_regs
*regs
, int signr
)
318 if (regs
&& kexec_should_crash(current
))
323 add_taint(TAINT_DIE
, LOCKDEP_NOW_UNRELIABLE
);
326 /* Nest count reaches zero, release the lock. */
327 arch_spin_unlock(&die_lock
);
328 raw_local_irq_restore(flags
);
332 panic("Fatal exception in interrupt");
334 panic("Fatal exception");
340 * This function is protected against re-entrancy.
342 void die(const char *str
, struct pt_regs
*regs
, int err
)
344 enum bug_trap_type bug_type
= BUG_TRAP_TYPE_NONE
;
345 unsigned long flags
= oops_begin();
348 if (!user_mode(regs
))
349 bug_type
= report_bug(regs
->ARM_pc
, regs
);
350 if (bug_type
!= BUG_TRAP_TYPE_NONE
)
353 if (__die(str
, err
, regs
))
356 oops_end(flags
, regs
, sig
);
359 void arm_notify_die(const char *str
, struct pt_regs
*regs
,
360 int signo
, int si_code
, void __user
*addr
,
361 unsigned long err
, unsigned long trap
)
363 if (user_mode(regs
)) {
364 current
->thread
.error_code
= err
;
365 current
->thread
.trap_no
= trap
;
367 force_sig_fault(signo
, si_code
, addr
);
373 #ifdef CONFIG_GENERIC_BUG
375 int is_valid_bugaddr(unsigned long pc
)
377 #ifdef CONFIG_THUMB2_KERNEL
379 u16 insn
= __opcode_to_mem_thumb16(BUG_INSTR_VALUE
);
382 u32 insn
= __opcode_to_mem_arm(BUG_INSTR_VALUE
);
385 if (get_kernel_nofault(bkpt
, (void *)pc
))
393 static LIST_HEAD(undef_hook
);
394 static DEFINE_RAW_SPINLOCK(undef_lock
);
396 void register_undef_hook(struct undef_hook
*hook
)
400 raw_spin_lock_irqsave(&undef_lock
, flags
);
401 list_add(&hook
->node
, &undef_hook
);
402 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
405 void unregister_undef_hook(struct undef_hook
*hook
)
409 raw_spin_lock_irqsave(&undef_lock
, flags
);
410 list_del(&hook
->node
);
411 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
414 static nokprobe_inline
415 int call_undef_hook(struct pt_regs
*regs
, unsigned int instr
)
417 struct undef_hook
*hook
;
419 int (*fn
)(struct pt_regs
*regs
, unsigned int instr
) = NULL
;
421 raw_spin_lock_irqsave(&undef_lock
, flags
);
422 list_for_each_entry(hook
, &undef_hook
, node
)
423 if ((instr
& hook
->instr_mask
) == hook
->instr_val
&&
424 (regs
->ARM_cpsr
& hook
->cpsr_mask
) == hook
->cpsr_val
)
426 raw_spin_unlock_irqrestore(&undef_lock
, flags
);
428 return fn
? fn(regs
, instr
) : 1;
431 asmlinkage
void do_undefinstr(struct pt_regs
*regs
)
436 pc
= (void __user
*)instruction_pointer(regs
);
438 if (processor_mode(regs
) == SVC_MODE
) {
439 #ifdef CONFIG_THUMB2_KERNEL
440 if (thumb_mode(regs
)) {
441 instr
= __mem_to_opcode_thumb16(((u16
*)pc
)[0]);
442 if (is_wide_instruction(instr
)) {
444 inst2
= __mem_to_opcode_thumb16(((u16
*)pc
)[1]);
445 instr
= __opcode_thumb32_compose(instr
, inst2
);
449 instr
= __mem_to_opcode_arm(*(u32
*) pc
);
450 } else if (thumb_mode(regs
)) {
451 if (get_user(instr
, (u16 __user
*)pc
))
453 instr
= __mem_to_opcode_thumb16(instr
);
454 if (is_wide_instruction(instr
)) {
456 if (get_user(instr2
, (u16 __user
*)pc
+1))
458 instr2
= __mem_to_opcode_thumb16(instr2
);
459 instr
= __opcode_thumb32_compose(instr
, instr2
);
462 if (get_user(instr
, (u32 __user
*)pc
))
464 instr
= __mem_to_opcode_arm(instr
);
467 if (call_undef_hook(regs
, instr
) == 0)
471 #ifdef CONFIG_DEBUG_USER
472 if (user_debug
& UDBG_UNDEFINED
) {
473 pr_info("%s (%d): undefined instruction: pc=%p\n",
474 current
->comm
, task_pid_nr(current
), pc
);
476 dump_instr(KERN_INFO
, regs
);
479 arm_notify_die("Oops - undefined instruction", regs
,
480 SIGILL
, ILL_ILLOPC
, pc
, 0, 6);
482 NOKPROBE_SYMBOL(do_undefinstr
)
485 * Handle FIQ similarly to NMI on x86 systems.
487 * The runtime environment for NMIs is extremely restrictive
488 * (NMIs can pre-empt critical sections meaning almost all locking is
489 * forbidden) meaning this default FIQ handling must only be used in
490 * circumstances where non-maskability improves robustness, such as
491 * watchdog or debug logic.
493 * This handler is not appropriate for general purpose use in drivers
494 * platform code and can be overrideen using set_fiq_handler.
496 asmlinkage
void __exception_irq_entry
handle_fiq_as_nmi(struct pt_regs
*regs
)
498 struct pt_regs
*old_regs
= set_irq_regs(regs
);
502 /* nop. FIQ handlers for special arch/arm features can be added here. */
506 set_irq_regs(old_regs
);
510 * bad_mode handles the impossible case in the vectors. If you see one of
511 * these, then it's extremely serious, and could mean you have buggy hardware.
512 * It never returns, and never tries to sync. We hope that we can at least
513 * dump out some state information...
515 asmlinkage
void bad_mode(struct pt_regs
*regs
, int reason
)
519 pr_crit("Bad mode in %s handler detected\n", handler
[reason
]);
521 die("Oops - bad mode", regs
, 0);
526 static int bad_syscall(int n
, struct pt_regs
*regs
)
528 if ((current
->personality
& PER_MASK
) != PER_LINUX
) {
529 send_sig(SIGSEGV
, current
, 1);
533 #ifdef CONFIG_DEBUG_USER
534 if (user_debug
& UDBG_SYSCALL
) {
535 pr_err("[%d] %s: obsolete system call %08x.\n",
536 task_pid_nr(current
), current
->comm
, n
);
537 dump_instr(KERN_ERR
, regs
);
541 arm_notify_die("Oops - bad syscall", regs
, SIGILL
, ILL_ILLTRP
,
542 (void __user
*)instruction_pointer(regs
) -
543 (thumb_mode(regs
) ? 2 : 4),
550 __do_cache_op(unsigned long start
, unsigned long end
)
555 unsigned long chunk
= min(PAGE_SIZE
, end
- start
);
557 if (fatal_signal_pending(current
))
560 ret
= flush_icache_user_range(start
, start
+ chunk
);
566 } while (start
< end
);
572 do_cache_op(unsigned long start
, unsigned long end
, int flags
)
574 if (end
< start
|| flags
)
577 if (!access_ok(start
, end
- start
))
580 return __do_cache_op(start
, end
);
584 * Handle all unrecognised system calls.
585 * 0x9f0000 - 0x9fffff are some more esoteric system calls
587 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
588 asmlinkage
int arm_syscall(int no
, struct pt_regs
*regs
)
590 if ((no
>> 16) != (__ARM_NR_BASE
>> 16))
591 return bad_syscall(no
, regs
);
593 switch (no
& 0xffff) {
594 case 0: /* branch through 0 */
595 arm_notify_die("branch through zero", regs
,
596 SIGSEGV
, SEGV_MAPERR
, NULL
, 0, 0);
599 case NR(breakpoint
): /* SWI BREAK_POINT */
600 regs
->ARM_pc
-= thumb_mode(regs
) ? 2 : 4;
605 * Flush a region from virtual address 'r0' to virtual address 'r1'
606 * _exclusive_. There is no alignment requirement on either address;
607 * user space does not need to know the hardware cache layout.
609 * r2 contains flags. It should ALWAYS be passed as ZERO until it
610 * is defined to be something else. For now we ignore it, but may
611 * the fires of hell burn in your belly if you break this rule. ;)
613 * (at a later date, we may want to allow this call to not flush
614 * various aspects of the cache. Passing '0' will guarantee that
615 * everything necessary gets flushed to maintain consistency in
616 * the specified region).
619 return do_cache_op(regs
->ARM_r0
, regs
->ARM_r1
, regs
->ARM_r2
);
622 if (!(elf_hwcap
& HWCAP_26BIT
))
624 regs
->ARM_cpsr
&= ~MODE32_BIT
;
628 if (!(elf_hwcap
& HWCAP_26BIT
))
630 regs
->ARM_cpsr
|= MODE32_BIT
;
634 set_tls(regs
->ARM_r0
);
638 return current_thread_info()->tp_value
[0];
641 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
642 if not implemented, rather than raising SIGILL. This
643 way the calling program can gracefully determine whether
644 a feature is supported. */
645 if ((no
& 0xffff) <= 0x7ff)
649 #ifdef CONFIG_DEBUG_USER
651 * experience shows that these seem to indicate that
652 * something catastrophic has happened
654 if (user_debug
& UDBG_SYSCALL
) {
655 pr_err("[%d] %s: arm syscall %d\n",
656 task_pid_nr(current
), current
->comm
, no
);
657 dump_instr(KERN_ERR
, regs
);
658 if (user_mode(regs
)) {
660 c_backtrace(frame_pointer(regs
), processor_mode(regs
), KERN_ERR
);
664 arm_notify_die("Oops - bad syscall(2)", regs
, SIGILL
, ILL_ILLTRP
,
665 (void __user
*)instruction_pointer(regs
) -
666 (thumb_mode(regs
) ? 2 : 4),
671 #ifdef CONFIG_TLS_REG_EMUL
674 * We might be running on an ARMv6+ processor which should have the TLS
675 * register but for some reason we can't use it, or maybe an SMP system
676 * using a pre-ARMv6 processor (there are apparently a few prototypes like
677 * that in existence) and therefore access to that register must be
681 static int get_tp_trap(struct pt_regs
*regs
, unsigned int instr
)
683 int reg
= (instr
>> 12) & 15;
686 regs
->uregs
[reg
] = current_thread_info()->tp_value
[0];
691 static struct undef_hook arm_mrc_hook
= {
692 .instr_mask
= 0x0fff0fff,
693 .instr_val
= 0x0e1d0f70,
694 .cpsr_mask
= PSR_T_BIT
,
699 static int __init
arm_mrc_hook_init(void)
701 register_undef_hook(&arm_mrc_hook
);
705 late_initcall(arm_mrc_hook_init
);
710 * A data abort trap was taken, but we did not handle the instruction.
711 * Try to abort the user program, or panic if it was the kernel.
714 baddataabort(int code
, unsigned long instr
, struct pt_regs
*regs
)
716 unsigned long addr
= instruction_pointer(regs
);
718 #ifdef CONFIG_DEBUG_USER
719 if (user_debug
& UDBG_BADABORT
) {
720 pr_err("8<--- cut here ---\n");
721 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
722 task_pid_nr(current
), current
->comm
, code
, instr
);
723 dump_instr(KERN_ERR
, regs
);
724 show_pte(KERN_ERR
, current
->mm
, addr
);
728 arm_notify_die("unknown data abort code", regs
,
729 SIGILL
, ILL_ILLOPC
, (void __user
*)addr
, instr
, 0);
732 void __readwrite_bug(const char *fn
)
734 pr_err("%s called, but not implemented\n", fn
);
737 EXPORT_SYMBOL(__readwrite_bug
);
739 void __pte_error(const char *file
, int line
, pte_t pte
)
741 pr_err("%s:%d: bad pte %08llx.\n", file
, line
, (long long)pte_val(pte
));
744 void __pmd_error(const char *file
, int line
, pmd_t pmd
)
746 pr_err("%s:%d: bad pmd %08llx.\n", file
, line
, (long long)pmd_val(pmd
));
749 void __pgd_error(const char *file
, int line
, pgd_t pgd
)
751 pr_err("%s:%d: bad pgd %08llx.\n", file
, line
, (long long)pgd_val(pgd
));
754 asmlinkage
void __div0(void)
756 pr_err("Division by zero in kernel.\n");
759 EXPORT_SYMBOL(__div0
);
765 /* if that doesn't kill us, halt */
766 panic("Oops failed to kill thread");
769 #ifdef CONFIG_KUSER_HELPERS
770 static void __init
kuser_init(void *vectors
)
772 extern char __kuser_helper_start
[], __kuser_helper_end
[];
773 int kuser_sz
= __kuser_helper_end
- __kuser_helper_start
;
775 memcpy(vectors
+ 0x1000 - kuser_sz
, __kuser_helper_start
, kuser_sz
);
778 * vectors + 0xfe0 = __kuser_get_tls
779 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
781 if (tls_emu
|| has_tls_reg
)
782 memcpy(vectors
+ 0xfe0, vectors
+ 0xfe8, 4);
785 static inline void __init
kuser_init(void *vectors
)
790 void __init
early_trap_init(void *vectors_base
)
792 #ifndef CONFIG_CPU_V7M
793 unsigned long vectors
= (unsigned long)vectors_base
;
794 extern char __stubs_start
[], __stubs_end
[];
795 extern char __vectors_start
[], __vectors_end
[];
798 vectors_page
= vectors_base
;
801 * Poison the vectors page with an undefined instruction. This
802 * instruction is chosen to be undefined for both ARM and Thumb
803 * ISAs. The Thumb version is an undefined instruction with a
804 * branch back to the undefined instruction.
806 for (i
= 0; i
< PAGE_SIZE
/ sizeof(u32
); i
++)
807 ((u32
*)vectors_base
)[i
] = 0xe7fddef1;
810 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
811 * into the vector page, mapped at 0xffff0000, and ensure these
812 * are visible to the instruction stream.
814 memcpy((void *)vectors
, __vectors_start
, __vectors_end
- __vectors_start
);
815 memcpy((void *)vectors
+ 0x1000, __stubs_start
, __stubs_end
- __stubs_start
);
817 kuser_init(vectors_base
);
819 flush_icache_range(vectors
, vectors
+ PAGE_SIZE
* 2);
820 #else /* ifndef CONFIG_CPU_V7M */
822 * on V7-M there is no need to copy the vector table to a dedicated
823 * memory area. The address is configurable and so a table in the kernel