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