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, unsigned long frame)
67 #ifdef CONFIG_KALLSYMS
68 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
70 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
73 if (in_entry_text(from))
74 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
77 void dump_backtrace_stm(u32 *stack, u32 instruction)
83 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
84 if (instruction & BIT(reg)) {
85 p += sprintf(p, " r%d:%08x", reg, *stack--);
97 #ifndef CONFIG_ARM_UNWIND
99 * Stack pointers should always be within the kernels view of
100 * physical memory. If it is not there, then we can't dump
101 * out any information relating to the stack.
103 static int verify_stack(unsigned long sp)
105 if (sp < PAGE_OFFSET ||
106 (sp > (unsigned long)high_memory && high_memory != NULL))
114 * Dump out the contents of some memory nicely...
116 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
124 * We need to switch to kernel mode so that we can use __get_user
125 * to safely read from kernel space. Note that we now dump the
126 * code first, just in case the backtrace kills us.
131 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
133 for (first = bottom & ~31; first < top; first += 32) {
135 char str[sizeof(" 12345678") * 8 + 1];
137 memset(str, ' ', sizeof(str));
138 str[sizeof(str) - 1] = '\0';
140 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
141 if (p >= bottom && p < top) {
143 if (__get_user(val, (unsigned long *)p) == 0)
144 sprintf(str + i * 9, " %08lx", val);
146 sprintf(str + i * 9, " ????????");
149 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
155 static void __dump_instr(const char *lvl, struct pt_regs *regs)
157 unsigned long addr = instruction_pointer(regs);
158 const int thumb = thumb_mode(regs);
159 const int width = thumb ? 4 : 8;
160 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
164 * Note that we now dump the code first, just in case the backtrace
168 for (i = -4; i < 1 + !!thumb; i++) {
169 unsigned int val, bad;
172 bad = get_user(val, &((u16 *)addr)[i]);
174 bad = get_user(val, &((u32 *)addr)[i]);
177 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
180 p += sprintf(p, "bad PC value");
184 printk("%sCode: %s\n", lvl, str);
187 static void dump_instr(const char *lvl, struct pt_regs *regs)
191 if (!user_mode(regs)) {
194 __dump_instr(lvl, regs);
197 __dump_instr(lvl, regs);
201 #ifdef CONFIG_ARM_UNWIND
202 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
204 unwind_backtrace(regs, tsk);
207 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
209 unsigned int fp, mode;
212 printk("Backtrace: ");
218 fp = frame_pointer(regs);
219 mode = processor_mode(regs);
220 } else if (tsk != current) {
221 fp = thread_saved_fp(tsk);
224 asm("mov %0, fp" : "=r" (fp) : : "cc");
229 pr_cont("no frame pointer");
231 } else if (verify_stack(fp)) {
232 pr_cont("invalid frame pointer 0x%08x", fp);
234 } else if (fp < (unsigned long)end_of_stack(tsk))
235 pr_cont("frame pointer underflow");
239 c_backtrace(fp, mode);
243 void show_stack(struct task_struct *tsk, unsigned long *sp)
245 dump_backtrace(NULL, tsk);
249 #ifdef CONFIG_PREEMPT
250 #define S_PREEMPT " PREEMPT"
259 #ifdef CONFIG_THUMB2_KERNEL
260 #define S_ISA " THUMB2"
265 static int __die(const char *str, int err, struct pt_regs *regs)
267 struct task_struct *tsk = current;
268 static int die_counter;
271 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
272 str, err, ++die_counter);
274 /* trap and error numbers are mostly meaningless on ARM */
275 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
276 if (ret == NOTIFY_STOP)
281 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
282 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
284 if (!user_mode(regs) || in_interrupt()) {
285 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
286 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
287 dump_backtrace(regs, tsk);
288 dump_instr(KERN_EMERG, regs);
294 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
295 static int die_owner = -1;
296 static unsigned int die_nest_count;
298 static unsigned long oops_begin(void)
305 /* racy, but better than risking deadlock. */
306 raw_local_irq_save(flags);
307 cpu = smp_processor_id();
308 if (!arch_spin_trylock(&die_lock)) {
309 if (cpu == die_owner)
310 /* nested oops. should stop eventually */;
312 arch_spin_lock(&die_lock);
321 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
323 if (regs && kexec_should_crash(current))
328 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
331 /* Nest count reaches zero, release the lock. */
332 arch_spin_unlock(&die_lock);
333 raw_local_irq_restore(flags);
337 panic("Fatal exception in interrupt");
339 panic("Fatal exception");
345 * This function is protected against re-entrancy.
347 void die(const char *str, struct pt_regs *regs, int err)
349 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
350 unsigned long flags = oops_begin();
353 if (!user_mode(regs))
354 bug_type = report_bug(regs->ARM_pc, regs);
355 if (bug_type != BUG_TRAP_TYPE_NONE)
358 if (__die(str, err, regs))
361 oops_end(flags, regs, sig);
364 void arm_notify_die(const char *str, struct pt_regs *regs,
365 int signo, int si_code, void __user *addr,
366 unsigned long err, unsigned long trap)
368 if (user_mode(regs)) {
369 current->thread.error_code = err;
370 current->thread.trap_no = trap;
372 force_sig_fault(signo, si_code, addr);
378 #ifdef CONFIG_GENERIC_BUG
380 int is_valid_bugaddr(unsigned long pc)
382 #ifdef CONFIG_THUMB2_KERNEL
384 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
387 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
390 if (probe_kernel_address((unsigned *)pc, bkpt))
398 static LIST_HEAD(undef_hook);
399 static DEFINE_RAW_SPINLOCK(undef_lock);
401 void register_undef_hook(struct undef_hook *hook)
405 raw_spin_lock_irqsave(&undef_lock, flags);
406 list_add(&hook->node, &undef_hook);
407 raw_spin_unlock_irqrestore(&undef_lock, flags);
410 void unregister_undef_hook(struct undef_hook *hook)
414 raw_spin_lock_irqsave(&undef_lock, flags);
415 list_del(&hook->node);
416 raw_spin_unlock_irqrestore(&undef_lock, flags);
419 static nokprobe_inline
420 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
422 struct undef_hook *hook;
424 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
426 raw_spin_lock_irqsave(&undef_lock, flags);
427 list_for_each_entry(hook, &undef_hook, node)
428 if ((instr & hook->instr_mask) == hook->instr_val &&
429 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
431 raw_spin_unlock_irqrestore(&undef_lock, flags);
433 return fn ? fn(regs, instr) : 1;
436 asmlinkage void do_undefinstr(struct pt_regs *regs)
441 pc = (void __user *)instruction_pointer(regs);
443 if (processor_mode(regs) == SVC_MODE) {
444 #ifdef CONFIG_THUMB2_KERNEL
445 if (thumb_mode(regs)) {
446 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
447 if (is_wide_instruction(instr)) {
449 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
450 instr = __opcode_thumb32_compose(instr, inst2);
454 instr = __mem_to_opcode_arm(*(u32 *) pc);
455 } else if (thumb_mode(regs)) {
456 if (get_user(instr, (u16 __user *)pc))
458 instr = __mem_to_opcode_thumb16(instr);
459 if (is_wide_instruction(instr)) {
461 if (get_user(instr2, (u16 __user *)pc+1))
463 instr2 = __mem_to_opcode_thumb16(instr2);
464 instr = __opcode_thumb32_compose(instr, instr2);
467 if (get_user(instr, (u32 __user *)pc))
469 instr = __mem_to_opcode_arm(instr);
472 if (call_undef_hook(regs, instr) == 0)
476 #ifdef CONFIG_DEBUG_USER
477 if (user_debug & UDBG_UNDEFINED) {
478 pr_info("%s (%d): undefined instruction: pc=%p\n",
479 current->comm, task_pid_nr(current), pc);
481 dump_instr(KERN_INFO, regs);
484 arm_notify_die("Oops - undefined instruction", regs,
485 SIGILL, ILL_ILLOPC, pc, 0, 6);
487 NOKPROBE_SYMBOL(do_undefinstr)
490 * Handle FIQ similarly to NMI on x86 systems.
492 * The runtime environment for NMIs is extremely restrictive
493 * (NMIs can pre-empt critical sections meaning almost all locking is
494 * forbidden) meaning this default FIQ handling must only be used in
495 * circumstances where non-maskability improves robustness, such as
496 * watchdog or debug logic.
498 * This handler is not appropriate for general purpose use in drivers
499 * platform code and can be overrideen using set_fiq_handler.
501 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
503 struct pt_regs *old_regs = set_irq_regs(regs);
507 /* nop. FIQ handlers for special arch/arm features can be added here. */
511 set_irq_regs(old_regs);
515 * bad_mode handles the impossible case in the vectors. If you see one of
516 * these, then it's extremely serious, and could mean you have buggy hardware.
517 * It never returns, and never tries to sync. We hope that we can at least
518 * dump out some state information...
520 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
524 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
526 die("Oops - bad mode", regs, 0);
531 static int bad_syscall(int n, struct pt_regs *regs)
533 if ((current->personality & PER_MASK) != PER_LINUX) {
534 send_sig(SIGSEGV, current, 1);
538 #ifdef CONFIG_DEBUG_USER
539 if (user_debug & UDBG_SYSCALL) {
540 pr_err("[%d] %s: obsolete system call %08x.\n",
541 task_pid_nr(current), current->comm, n);
542 dump_instr(KERN_ERR, regs);
546 arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
547 (void __user *)instruction_pointer(regs) -
548 (thumb_mode(regs) ? 2 : 4),
555 __do_cache_op(unsigned long start, unsigned long end)
560 unsigned long chunk = min(PAGE_SIZE, end - start);
562 if (fatal_signal_pending(current))
565 ret = flush_cache_user_range(start, start + chunk);
571 } while (start < end);
577 do_cache_op(unsigned long start, unsigned long end, int flags)
579 if (end < start || flags)
582 if (!access_ok(start, end - start))
585 return __do_cache_op(start, end);
589 * Handle all unrecognised system calls.
590 * 0x9f0000 - 0x9fffff are some more esoteric system calls
592 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
593 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
595 if ((no >> 16) != (__ARM_NR_BASE>> 16))
596 return bad_syscall(no, regs);
598 switch (no & 0xffff) {
599 case 0: /* branch through 0 */
600 arm_notify_die("branch through zero", regs,
601 SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
604 case NR(breakpoint): /* SWI BREAK_POINT */
605 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
610 * Flush a region from virtual address 'r0' to virtual address 'r1'
611 * _exclusive_. There is no alignment requirement on either address;
612 * user space does not need to know the hardware cache layout.
614 * r2 contains flags. It should ALWAYS be passed as ZERO until it
615 * is defined to be something else. For now we ignore it, but may
616 * the fires of hell burn in your belly if you break this rule. ;)
618 * (at a later date, we may want to allow this call to not flush
619 * various aspects of the cache. Passing '0' will guarantee that
620 * everything necessary gets flushed to maintain consistency in
621 * the specified region).
624 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
627 if (!(elf_hwcap & HWCAP_26BIT))
629 regs->ARM_cpsr &= ~MODE32_BIT;
633 if (!(elf_hwcap & HWCAP_26BIT))
635 regs->ARM_cpsr |= MODE32_BIT;
639 set_tls(regs->ARM_r0);
643 return current_thread_info()->tp_value[0];
646 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
647 if not implemented, rather than raising SIGILL. This
648 way the calling program can gracefully determine whether
649 a feature is supported. */
650 if ((no & 0xffff) <= 0x7ff)
654 #ifdef CONFIG_DEBUG_USER
656 * experience shows that these seem to indicate that
657 * something catastrophic has happened
659 if (user_debug & UDBG_SYSCALL) {
660 pr_err("[%d] %s: arm syscall %d\n",
661 task_pid_nr(current), current->comm, no);
662 dump_instr("", regs);
663 if (user_mode(regs)) {
665 c_backtrace(frame_pointer(regs), processor_mode(regs));
669 arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
670 (void __user *)instruction_pointer(regs) -
671 (thumb_mode(regs) ? 2 : 4),
676 #ifdef CONFIG_TLS_REG_EMUL
679 * We might be running on an ARMv6+ processor which should have the TLS
680 * register but for some reason we can't use it, or maybe an SMP system
681 * using a pre-ARMv6 processor (there are apparently a few prototypes like
682 * that in existence) and therefore access to that register must be
686 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
688 int reg = (instr >> 12) & 15;
691 regs->uregs[reg] = current_thread_info()->tp_value[0];
696 static struct undef_hook arm_mrc_hook = {
697 .instr_mask = 0x0fff0fff,
698 .instr_val = 0x0e1d0f70,
699 .cpsr_mask = PSR_T_BIT,
704 static int __init arm_mrc_hook_init(void)
706 register_undef_hook(&arm_mrc_hook);
710 late_initcall(arm_mrc_hook_init);
715 * A data abort trap was taken, but we did not handle the instruction.
716 * Try to abort the user program, or panic if it was the kernel.
719 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
721 unsigned long addr = instruction_pointer(regs);
723 #ifdef CONFIG_DEBUG_USER
724 if (user_debug & UDBG_BADABORT) {
725 pr_err("8<--- cut here ---\n");
726 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
727 task_pid_nr(current), current->comm, code, instr);
728 dump_instr(KERN_ERR, regs);
729 show_pte(KERN_ERR, current->mm, addr);
733 arm_notify_die("unknown data abort code", regs,
734 SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
737 void __readwrite_bug(const char *fn)
739 pr_err("%s called, but not implemented\n", fn);
742 EXPORT_SYMBOL(__readwrite_bug);
744 void __pte_error(const char *file, int line, pte_t pte)
746 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
749 void __pmd_error(const char *file, int line, pmd_t pmd)
751 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
754 void __pgd_error(const char *file, int line, pgd_t pgd)
756 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
759 asmlinkage void __div0(void)
761 pr_err("Division by zero in kernel.\n");
764 EXPORT_SYMBOL(__div0);
770 /* if that doesn't kill us, halt */
771 panic("Oops failed to kill thread");
774 void __init trap_init(void)
779 #ifdef CONFIG_KUSER_HELPERS
780 static void __init kuser_init(void *vectors)
782 extern char __kuser_helper_start[], __kuser_helper_end[];
783 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
785 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
788 * vectors + 0xfe0 = __kuser_get_tls
789 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
791 if (tls_emu || has_tls_reg)
792 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
795 static inline void __init kuser_init(void *vectors)
800 void __init early_trap_init(void *vectors_base)
802 #ifndef CONFIG_CPU_V7M
803 unsigned long vectors = (unsigned long)vectors_base;
804 extern char __stubs_start[], __stubs_end[];
805 extern char __vectors_start[], __vectors_end[];
808 vectors_page = vectors_base;
811 * Poison the vectors page with an undefined instruction. This
812 * instruction is chosen to be undefined for both ARM and Thumb
813 * ISAs. The Thumb version is an undefined instruction with a
814 * branch back to the undefined instruction.
816 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
817 ((u32 *)vectors_base)[i] = 0xe7fddef1;
820 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
821 * into the vector page, mapped at 0xffff0000, and ensure these
822 * are visible to the instruction stream.
824 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
825 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
827 kuser_init(vectors_base);
829 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
830 #else /* ifndef CONFIG_CPU_V7M */
832 * on V7-M there is no need to copy the vector table to a dedicated
833 * memory area. The address is configurable and so a table in the kernel