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/kprobes.h>
23 #include <linux/module.h>
24 #include <linux/kexec.h>
25 #include <linux/bug.h>
26 #include <linux/delay.h>
27 #include <linux/init.h>
28 #include <linux/sched/signal.h>
29 #include <linux/sched/debug.h>
30 #include <linux/sched/task_stack.h>
31 #include <linux/irq.h>
33 #include <linux/atomic.h>
34 #include <asm/cacheflush.h>
35 #include <asm/exception.h>
36 #include <asm/spectre.h>
37 #include <asm/unistd.h>
38 #include <asm/traps.h>
39 #include <asm/ptrace.h>
40 #include <asm/unwind.h>
42 #include <asm/system_misc.h>
43 #include <asm/opcodes.h>
46 static const char *handler[]= {
51 "undefined instruction",
56 #ifdef CONFIG_DEBUG_USER
57 unsigned int user_debug;
59 static int __init user_debug_setup(char *str)
61 get_option(&str, &user_debug);
64 __setup("user_debug=", user_debug_setup);
67 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
69 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
71 #ifdef CONFIG_KALLSYMS
72 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
74 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
77 if (in_exception_text(where))
78 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
81 void dump_backtrace_stm(u32 *stack, u32 instruction)
87 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
88 if (instruction & BIT(reg)) {
89 p += sprintf(p, " r%d:%08x", reg, *stack--);
101 #ifndef CONFIG_ARM_UNWIND
103 * Stack pointers should always be within the kernels view of
104 * physical memory. If it is not there, then we can't dump
105 * out any information relating to the stack.
107 static int verify_stack(unsigned long sp)
109 if (sp < PAGE_OFFSET ||
110 (sp > (unsigned long)high_memory && high_memory != NULL))
118 * Dump out the contents of some memory nicely...
120 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
128 * We need to switch to kernel mode so that we can use __get_user
129 * to safely read from kernel space. Note that we now dump the
130 * code first, just in case the backtrace kills us.
135 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
137 for (first = bottom & ~31; first < top; first += 32) {
139 char str[sizeof(" 12345678") * 8 + 1];
141 memset(str, ' ', sizeof(str));
142 str[sizeof(str) - 1] = '\0';
144 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
145 if (p >= bottom && p < top) {
147 if (__get_user(val, (unsigned long *)p) == 0)
148 sprintf(str + i * 9, " %08lx", val);
150 sprintf(str + i * 9, " ????????");
153 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
159 static void __dump_instr(const char *lvl, struct pt_regs *regs)
161 unsigned long addr = instruction_pointer(regs);
162 const int thumb = thumb_mode(regs);
163 const int width = thumb ? 4 : 8;
164 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
168 * Note that we now dump the code first, just in case the backtrace
172 for (i = -4; i < 1 + !!thumb; i++) {
173 unsigned int val, bad;
176 bad = get_user(val, &((u16 *)addr)[i]);
178 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 static void dump_instr(const char *lvl, struct pt_regs *regs)
195 if (!user_mode(regs)) {
198 __dump_instr(lvl, regs);
201 __dump_instr(lvl, regs);
205 #ifdef CONFIG_ARM_UNWIND
206 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
208 unwind_backtrace(regs, tsk);
211 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
213 unsigned int fp, mode;
216 printk("Backtrace: ");
222 fp = frame_pointer(regs);
223 mode = processor_mode(regs);
224 } else if (tsk != current) {
225 fp = thread_saved_fp(tsk);
228 asm("mov %0, fp" : "=r" (fp) : : "cc");
233 pr_cont("no frame pointer");
235 } else if (verify_stack(fp)) {
236 pr_cont("invalid frame pointer 0x%08x", fp);
238 } else if (fp < (unsigned long)end_of_stack(tsk))
239 pr_cont("frame pointer underflow");
243 c_backtrace(fp, mode);
247 void show_stack(struct task_struct *tsk, unsigned long *sp)
249 dump_backtrace(NULL, tsk);
253 #ifdef CONFIG_PREEMPT
254 #define S_PREEMPT " PREEMPT"
263 #ifdef CONFIG_THUMB2_KERNEL
264 #define S_ISA " THUMB2"
269 static int __die(const char *str, int err, struct pt_regs *regs)
271 struct task_struct *tsk = current;
272 static int die_counter;
275 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
276 str, err, ++die_counter);
278 /* trap and error numbers are mostly meaningless on ARM */
279 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
280 if (ret == NOTIFY_STOP)
285 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
286 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
288 if (!user_mode(regs) || in_interrupt()) {
289 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
290 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
291 dump_backtrace(regs, tsk);
292 dump_instr(KERN_EMERG, regs);
298 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
299 static int die_owner = -1;
300 static unsigned int die_nest_count;
302 static unsigned long oops_begin(void)
309 /* racy, but better than risking deadlock. */
310 raw_local_irq_save(flags);
311 cpu = smp_processor_id();
312 if (!arch_spin_trylock(&die_lock)) {
313 if (cpu == die_owner)
314 /* nested oops. should stop eventually */;
316 arch_spin_lock(&die_lock);
325 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
327 if (regs && kexec_should_crash(current))
332 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
335 /* Nest count reaches zero, release the lock. */
336 arch_spin_unlock(&die_lock);
337 raw_local_irq_restore(flags);
341 panic("Fatal exception in interrupt");
343 panic("Fatal exception");
345 make_task_dead(signr);
349 * This function is protected against re-entrancy.
351 void die(const char *str, struct pt_regs *regs, int err)
353 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
354 unsigned long flags = oops_begin();
357 if (!user_mode(regs))
358 bug_type = report_bug(regs->ARM_pc, regs);
359 if (bug_type != BUG_TRAP_TYPE_NONE)
362 if (__die(str, err, regs))
365 oops_end(flags, regs, sig);
368 void arm_notify_die(const char *str, struct pt_regs *regs,
369 struct siginfo *info, unsigned long err, unsigned long trap)
371 if (user_mode(regs)) {
372 current->thread.error_code = err;
373 current->thread.trap_no = trap;
375 force_sig_info(info->si_signo, info, current);
381 #ifdef CONFIG_GENERIC_BUG
383 int is_valid_bugaddr(unsigned long pc)
385 #ifdef CONFIG_THUMB2_KERNEL
387 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
390 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
393 if (probe_kernel_address((unsigned *)pc, bkpt))
401 static LIST_HEAD(undef_hook);
402 static DEFINE_RAW_SPINLOCK(undef_lock);
404 void register_undef_hook(struct undef_hook *hook)
408 raw_spin_lock_irqsave(&undef_lock, flags);
409 list_add(&hook->node, &undef_hook);
410 raw_spin_unlock_irqrestore(&undef_lock, flags);
413 void unregister_undef_hook(struct undef_hook *hook)
417 raw_spin_lock_irqsave(&undef_lock, flags);
418 list_del(&hook->node);
419 raw_spin_unlock_irqrestore(&undef_lock, flags);
422 static nokprobe_inline
423 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
425 struct undef_hook *hook;
427 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
429 raw_spin_lock_irqsave(&undef_lock, flags);
430 list_for_each_entry(hook, &undef_hook, node)
431 if ((instr & hook->instr_mask) == hook->instr_val &&
432 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
434 raw_spin_unlock_irqrestore(&undef_lock, flags);
436 return fn ? fn(regs, instr) : 1;
439 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
445 pc = (void __user *)instruction_pointer(regs);
447 if (processor_mode(regs) == SVC_MODE) {
448 #ifdef CONFIG_THUMB2_KERNEL
449 if (thumb_mode(regs)) {
450 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
451 if (is_wide_instruction(instr)) {
453 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
454 instr = __opcode_thumb32_compose(instr, inst2);
458 instr = __mem_to_opcode_arm(*(u32 *) pc);
459 } else if (thumb_mode(regs)) {
460 if (get_user(instr, (u16 __user *)pc))
462 instr = __mem_to_opcode_thumb16(instr);
463 if (is_wide_instruction(instr)) {
465 if (get_user(instr2, (u16 __user *)pc+1))
467 instr2 = __mem_to_opcode_thumb16(instr2);
468 instr = __opcode_thumb32_compose(instr, instr2);
471 if (get_user(instr, (u32 __user *)pc))
473 instr = __mem_to_opcode_arm(instr);
476 if (call_undef_hook(regs, instr) == 0)
480 #ifdef CONFIG_DEBUG_USER
481 if (user_debug & UDBG_UNDEFINED) {
482 pr_info("%s (%d): undefined instruction: pc=%p\n",
483 current->comm, task_pid_nr(current), pc);
485 dump_instr(KERN_INFO, regs);
489 info.si_signo = SIGILL;
491 info.si_code = ILL_ILLOPC;
494 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
496 NOKPROBE_SYMBOL(do_undefinstr)
499 * Handle FIQ similarly to NMI on x86 systems.
501 * The runtime environment for NMIs is extremely restrictive
502 * (NMIs can pre-empt critical sections meaning almost all locking is
503 * forbidden) meaning this default FIQ handling must only be used in
504 * circumstances where non-maskability improves robustness, such as
505 * watchdog or debug logic.
507 * This handler is not appropriate for general purpose use in drivers
508 * platform code and can be overrideen using set_fiq_handler.
510 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
512 struct pt_regs *old_regs = set_irq_regs(regs);
516 /* nop. FIQ handlers for special arch/arm features can be added here. */
520 set_irq_regs(old_regs);
524 * bad_mode handles the impossible case in the vectors. If you see one of
525 * these, then it's extremely serious, and could mean you have buggy hardware.
526 * It never returns, and never tries to sync. We hope that we can at least
527 * dump out some state information...
529 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
533 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
535 die("Oops - bad mode", regs, 0);
540 static int bad_syscall(int n, struct pt_regs *regs)
544 if ((current->personality & PER_MASK) != PER_LINUX) {
545 send_sig(SIGSEGV, current, 1);
549 #ifdef CONFIG_DEBUG_USER
550 if (user_debug & UDBG_SYSCALL) {
551 pr_err("[%d] %s: obsolete system call %08x.\n",
552 task_pid_nr(current), current->comm, n);
553 dump_instr(KERN_ERR, regs);
557 info.si_signo = SIGILL;
559 info.si_code = ILL_ILLTRP;
560 info.si_addr = (void __user *)instruction_pointer(regs) -
561 (thumb_mode(regs) ? 2 : 4);
563 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
569 __do_cache_op(unsigned long start, unsigned long end)
574 unsigned long chunk = min(PAGE_SIZE, end - start);
576 if (fatal_signal_pending(current))
579 ret = flush_cache_user_range(start, start + chunk);
585 } while (start < end);
591 do_cache_op(unsigned long start, unsigned long end, int flags)
593 if (end < start || flags)
596 if (!access_ok(VERIFY_READ, start, end - start))
599 return __do_cache_op(start, end);
603 * Handle all unrecognised system calls.
604 * 0x9f0000 - 0x9fffff are some more esoteric system calls
606 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
607 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
611 if ((no >> 16) != (__ARM_NR_BASE>> 16))
612 return bad_syscall(no, regs);
614 switch (no & 0xffff) {
615 case 0: /* branch through 0 */
616 info.si_signo = SIGSEGV;
618 info.si_code = SEGV_MAPERR;
621 arm_notify_die("branch through zero", regs, &info, 0, 0);
624 case NR(breakpoint): /* SWI BREAK_POINT */
625 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
626 ptrace_break(current, regs);
630 * Flush a region from virtual address 'r0' to virtual address 'r1'
631 * _exclusive_. There is no alignment requirement on either address;
632 * user space does not need to know the hardware cache layout.
634 * r2 contains flags. It should ALWAYS be passed as ZERO until it
635 * is defined to be something else. For now we ignore it, but may
636 * the fires of hell burn in your belly if you break this rule. ;)
638 * (at a later date, we may want to allow this call to not flush
639 * various aspects of the cache. Passing '0' will guarantee that
640 * everything necessary gets flushed to maintain consistency in
641 * the specified region).
644 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
647 if (!(elf_hwcap & HWCAP_26BIT))
649 regs->ARM_cpsr &= ~MODE32_BIT;
653 if (!(elf_hwcap & HWCAP_26BIT))
655 regs->ARM_cpsr |= MODE32_BIT;
659 set_tls(regs->ARM_r0);
663 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
664 if not implemented, rather than raising SIGILL. This
665 way the calling program can gracefully determine whether
666 a feature is supported. */
667 if ((no & 0xffff) <= 0x7ff)
671 #ifdef CONFIG_DEBUG_USER
673 * experience shows that these seem to indicate that
674 * something catastrophic has happened
676 if (user_debug & UDBG_SYSCALL) {
677 pr_err("[%d] %s: arm syscall %d\n",
678 task_pid_nr(current), current->comm, no);
679 dump_instr("", regs);
680 if (user_mode(regs)) {
682 c_backtrace(frame_pointer(regs), processor_mode(regs));
686 info.si_signo = SIGILL;
688 info.si_code = ILL_ILLTRP;
689 info.si_addr = (void __user *)instruction_pointer(regs) -
690 (thumb_mode(regs) ? 2 : 4);
692 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
696 #ifdef CONFIG_TLS_REG_EMUL
699 * We might be running on an ARMv6+ processor which should have the TLS
700 * register but for some reason we can't use it, or maybe an SMP system
701 * using a pre-ARMv6 processor (there are apparently a few prototypes like
702 * that in existence) and therefore access to that register must be
706 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
708 int reg = (instr >> 12) & 15;
711 regs->uregs[reg] = current_thread_info()->tp_value[0];
716 static struct undef_hook arm_mrc_hook = {
717 .instr_mask = 0x0fff0fff,
718 .instr_val = 0x0e1d0f70,
719 .cpsr_mask = PSR_T_BIT,
724 static int __init arm_mrc_hook_init(void)
726 register_undef_hook(&arm_mrc_hook);
730 late_initcall(arm_mrc_hook_init);
735 * A data abort trap was taken, but we did not handle the instruction.
736 * Try to abort the user program, or panic if it was the kernel.
739 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
741 unsigned long addr = instruction_pointer(regs);
744 #ifdef CONFIG_DEBUG_USER
745 if (user_debug & UDBG_BADABORT) {
746 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
747 task_pid_nr(current), current->comm, code, instr);
748 dump_instr(KERN_ERR, regs);
749 show_pte(current->mm, addr);
753 info.si_signo = SIGILL;
755 info.si_code = ILL_ILLOPC;
756 info.si_addr = (void __user *)addr;
758 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
761 void __readwrite_bug(const char *fn)
763 pr_err("%s called, but not implemented\n", fn);
766 EXPORT_SYMBOL(__readwrite_bug);
768 void __pte_error(const char *file, int line, pte_t pte)
770 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
773 void __pmd_error(const char *file, int line, pmd_t pmd)
775 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
778 void __pgd_error(const char *file, int line, pgd_t pgd)
780 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
783 asmlinkage void __div0(void)
785 pr_err("Division by zero in kernel.\n");
788 EXPORT_SYMBOL(__div0);
794 /* if that doesn't kill us, halt */
795 panic("Oops failed to kill thread");
798 void __init trap_init(void)
803 #ifdef CONFIG_KUSER_HELPERS
804 static void __init kuser_init(void *vectors)
806 extern char __kuser_helper_start[], __kuser_helper_end[];
807 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
809 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
812 * vectors + 0xfe0 = __kuser_get_tls
813 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
815 if (tls_emu || has_tls_reg)
816 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
819 static inline void __init kuser_init(void *vectors)
824 #ifndef CONFIG_CPU_V7M
825 static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
827 memcpy(vma, lma_start, lma_end - lma_start);
830 static void flush_vectors(void *vma, size_t offset, size_t size)
832 unsigned long start = (unsigned long)vma + offset;
833 unsigned long end = start + size;
835 flush_icache_range(start, end);
838 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
839 int spectre_bhb_update_vectors(unsigned int method)
841 extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
842 extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
843 void *vec_start, *vec_end;
845 if (system_state > SYSTEM_SCHEDULING) {
846 pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
848 return SPECTRE_VULNERABLE;
852 case SPECTRE_V2_METHOD_LOOP8:
853 vec_start = __vectors_bhb_loop8_start;
854 vec_end = __vectors_bhb_loop8_end;
857 case SPECTRE_V2_METHOD_BPIALL:
858 vec_start = __vectors_bhb_bpiall_start;
859 vec_end = __vectors_bhb_bpiall_end;
863 pr_err("CPU%u: unknown Spectre BHB state %d\n",
864 smp_processor_id(), method);
865 return SPECTRE_VULNERABLE;
868 copy_from_lma(vectors_page, vec_start, vec_end);
869 flush_vectors(vectors_page, 0, vec_end - vec_start);
871 return SPECTRE_MITIGATED;
875 void __init early_trap_init(void *vectors_base)
877 extern char __stubs_start[], __stubs_end[];
878 extern char __vectors_start[], __vectors_end[];
881 vectors_page = vectors_base;
884 * Poison the vectors page with an undefined instruction. This
885 * instruction is chosen to be undefined for both ARM and Thumb
886 * ISAs. The Thumb version is an undefined instruction with a
887 * branch back to the undefined instruction.
889 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
890 ((u32 *)vectors_base)[i] = 0xe7fddef1;
893 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
894 * into the vector page, mapped at 0xffff0000, and ensure these
895 * are visible to the instruction stream.
897 copy_from_lma(vectors_base, __vectors_start, __vectors_end);
898 copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
900 kuser_init(vectors_base);
902 flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
904 #else /* ifndef CONFIG_CPU_V7M */
905 void __init early_trap_init(void *vectors_base)
908 * on V7-M there is no need to copy the vector table to a dedicated
909 * memory area. The address is configurable and so a table in the kernel