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 unsigned long end = frame + 4 + sizeof(struct pt_regs);
73 #ifdef CONFIG_KALLSYMS
74 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
76 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
79 if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
80 dump_mem("", "Exception stack", frame + 4, end);
83 void dump_backtrace_stm(u32 *stack, u32 instruction)
89 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
90 if (instruction & BIT(reg)) {
91 p += sprintf(p, " r%d:%08x", reg, *stack--);
103 #ifndef CONFIG_ARM_UNWIND
105 * Stack pointers should always be within the kernels view of
106 * physical memory. If it is not there, then we can't dump
107 * out any information relating to the stack.
109 static int verify_stack(unsigned long sp)
111 if (sp < PAGE_OFFSET ||
112 (sp > (unsigned long)high_memory && high_memory != NULL))
120 * Dump out the contents of some memory nicely...
122 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
130 * We need to switch to kernel mode so that we can use __get_user
131 * to safely read from kernel space. Note that we now dump the
132 * code first, just in case the backtrace kills us.
137 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
139 for (first = bottom & ~31; first < top; first += 32) {
141 char str[sizeof(" 12345678") * 8 + 1];
143 memset(str, ' ', sizeof(str));
144 str[sizeof(str) - 1] = '\0';
146 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
147 if (p >= bottom && p < top) {
149 if (__get_user(val, (unsigned long *)p) == 0)
150 sprintf(str + i * 9, " %08lx", val);
152 sprintf(str + i * 9, " ????????");
155 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
161 static void __dump_instr(const char *lvl, struct pt_regs *regs)
163 unsigned long addr = instruction_pointer(regs);
164 const int thumb = thumb_mode(regs);
165 const int width = thumb ? 4 : 8;
166 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
170 * Note that we now dump the code first, just in case the backtrace
174 for (i = -4; i < 1 + !!thumb; i++) {
175 unsigned int val, bad;
178 bad = get_user(val, &((u16 *)addr)[i]);
180 bad = get_user(val, &((u32 *)addr)[i]);
183 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
186 p += sprintf(p, "bad PC value");
190 printk("%sCode: %s\n", lvl, str);
193 static void dump_instr(const char *lvl, struct pt_regs *regs)
197 if (!user_mode(regs)) {
200 __dump_instr(lvl, regs);
203 __dump_instr(lvl, regs);
207 #ifdef CONFIG_ARM_UNWIND
208 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
210 unwind_backtrace(regs, tsk);
213 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
215 unsigned int fp, mode;
218 printk("Backtrace: ");
224 fp = frame_pointer(regs);
225 mode = processor_mode(regs);
226 } else if (tsk != current) {
227 fp = thread_saved_fp(tsk);
230 asm("mov %0, fp" : "=r" (fp) : : "cc");
235 pr_cont("no frame pointer");
237 } else if (verify_stack(fp)) {
238 pr_cont("invalid frame pointer 0x%08x", fp);
240 } else if (fp < (unsigned long)end_of_stack(tsk))
241 pr_cont("frame pointer underflow");
245 c_backtrace(fp, mode);
249 void show_stack(struct task_struct *tsk, unsigned long *sp)
251 dump_backtrace(NULL, tsk);
255 #ifdef CONFIG_PREEMPT
256 #define S_PREEMPT " PREEMPT"
265 #ifdef CONFIG_THUMB2_KERNEL
266 #define S_ISA " THUMB2"
271 static int __die(const char *str, int err, struct pt_regs *regs)
273 struct task_struct *tsk = current;
274 static int die_counter;
277 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
278 str, err, ++die_counter);
280 /* trap and error numbers are mostly meaningless on ARM */
281 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
282 if (ret == NOTIFY_STOP)
287 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
288 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
290 if (!user_mode(regs) || in_interrupt()) {
291 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
292 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
293 dump_backtrace(regs, tsk);
294 dump_instr(KERN_EMERG, regs);
300 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
301 static int die_owner = -1;
302 static unsigned int die_nest_count;
304 static unsigned long oops_begin(void)
311 /* racy, but better than risking deadlock. */
312 raw_local_irq_save(flags);
313 cpu = smp_processor_id();
314 if (!arch_spin_trylock(&die_lock)) {
315 if (cpu == die_owner)
316 /* nested oops. should stop eventually */;
318 arch_spin_lock(&die_lock);
327 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
329 if (regs && kexec_should_crash(current))
334 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
337 /* Nest count reaches zero, release the lock. */
338 arch_spin_unlock(&die_lock);
339 raw_local_irq_restore(flags);
343 panic("Fatal exception in interrupt");
345 panic("Fatal exception");
347 make_task_dead(signr);
351 * This function is protected against re-entrancy.
353 void die(const char *str, struct pt_regs *regs, int err)
355 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
356 unsigned long flags = oops_begin();
359 if (!user_mode(regs))
360 bug_type = report_bug(regs->ARM_pc, regs);
361 if (bug_type != BUG_TRAP_TYPE_NONE)
364 if (__die(str, err, regs))
367 oops_end(flags, regs, sig);
370 void arm_notify_die(const char *str, struct pt_regs *regs,
371 struct siginfo *info, unsigned long err, unsigned long trap)
373 if (user_mode(regs)) {
374 current->thread.error_code = err;
375 current->thread.trap_no = trap;
377 force_sig_info(info->si_signo, info, current);
383 #ifdef CONFIG_GENERIC_BUG
385 int is_valid_bugaddr(unsigned long pc)
387 #ifdef CONFIG_THUMB2_KERNEL
389 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
392 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
395 if (probe_kernel_address((unsigned *)pc, bkpt))
403 static LIST_HEAD(undef_hook);
404 static DEFINE_RAW_SPINLOCK(undef_lock);
406 void register_undef_hook(struct undef_hook *hook)
410 raw_spin_lock_irqsave(&undef_lock, flags);
411 list_add(&hook->node, &undef_hook);
412 raw_spin_unlock_irqrestore(&undef_lock, flags);
415 void unregister_undef_hook(struct undef_hook *hook)
419 raw_spin_lock_irqsave(&undef_lock, flags);
420 list_del(&hook->node);
421 raw_spin_unlock_irqrestore(&undef_lock, flags);
424 static nokprobe_inline
425 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
427 struct undef_hook *hook;
429 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
431 raw_spin_lock_irqsave(&undef_lock, flags);
432 list_for_each_entry(hook, &undef_hook, node)
433 if ((instr & hook->instr_mask) == hook->instr_val &&
434 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
436 raw_spin_unlock_irqrestore(&undef_lock, flags);
438 return fn ? fn(regs, instr) : 1;
441 asmlinkage void do_undefinstr(struct pt_regs *regs)
447 clear_siginfo(&info);
448 pc = (void __user *)instruction_pointer(regs);
450 if (processor_mode(regs) == SVC_MODE) {
451 #ifdef CONFIG_THUMB2_KERNEL
452 if (thumb_mode(regs)) {
453 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
454 if (is_wide_instruction(instr)) {
456 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
457 instr = __opcode_thumb32_compose(instr, inst2);
461 instr = __mem_to_opcode_arm(*(u32 *) pc);
462 } else if (thumb_mode(regs)) {
463 if (get_user(instr, (u16 __user *)pc))
465 instr = __mem_to_opcode_thumb16(instr);
466 if (is_wide_instruction(instr)) {
468 if (get_user(instr2, (u16 __user *)pc+1))
470 instr2 = __mem_to_opcode_thumb16(instr2);
471 instr = __opcode_thumb32_compose(instr, instr2);
474 if (get_user(instr, (u32 __user *)pc))
476 instr = __mem_to_opcode_arm(instr);
479 if (call_undef_hook(regs, instr) == 0)
483 #ifdef CONFIG_DEBUG_USER
484 if (user_debug & UDBG_UNDEFINED) {
485 pr_info("%s (%d): undefined instruction: pc=%p\n",
486 current->comm, task_pid_nr(current), pc);
488 dump_instr(KERN_INFO, regs);
492 info.si_signo = SIGILL;
494 info.si_code = ILL_ILLOPC;
497 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
499 NOKPROBE_SYMBOL(do_undefinstr)
502 * Handle FIQ similarly to NMI on x86 systems.
504 * The runtime environment for NMIs is extremely restrictive
505 * (NMIs can pre-empt critical sections meaning almost all locking is
506 * forbidden) meaning this default FIQ handling must only be used in
507 * circumstances where non-maskability improves robustness, such as
508 * watchdog or debug logic.
510 * This handler is not appropriate for general purpose use in drivers
511 * platform code and can be overrideen using set_fiq_handler.
513 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
515 struct pt_regs *old_regs = set_irq_regs(regs);
519 /* nop. FIQ handlers for special arch/arm features can be added here. */
523 set_irq_regs(old_regs);
527 * bad_mode handles the impossible case in the vectors. If you see one of
528 * these, then it's extremely serious, and could mean you have buggy hardware.
529 * It never returns, and never tries to sync. We hope that we can at least
530 * dump out some state information...
532 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
536 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
538 die("Oops - bad mode", regs, 0);
543 static int bad_syscall(int n, struct pt_regs *regs)
547 clear_siginfo(&info);
548 if ((current->personality & PER_MASK) != PER_LINUX) {
549 send_sig(SIGSEGV, current, 1);
553 #ifdef CONFIG_DEBUG_USER
554 if (user_debug & UDBG_SYSCALL) {
555 pr_err("[%d] %s: obsolete system call %08x.\n",
556 task_pid_nr(current), current->comm, n);
557 dump_instr(KERN_ERR, regs);
561 info.si_signo = SIGILL;
563 info.si_code = ILL_ILLTRP;
564 info.si_addr = (void __user *)instruction_pointer(regs) -
565 (thumb_mode(regs) ? 2 : 4);
567 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
573 __do_cache_op(unsigned long start, unsigned long end)
578 unsigned long chunk = min(PAGE_SIZE, end - start);
580 if (fatal_signal_pending(current))
583 ret = flush_cache_user_range(start, start + chunk);
589 } while (start < end);
595 do_cache_op(unsigned long start, unsigned long end, int flags)
597 if (end < start || flags)
600 if (!access_ok(VERIFY_READ, start, end - start))
603 return __do_cache_op(start, end);
607 * Handle all unrecognised system calls.
608 * 0x9f0000 - 0x9fffff are some more esoteric system calls
610 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
611 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
615 clear_siginfo(&info);
616 if ((no >> 16) != (__ARM_NR_BASE>> 16))
617 return bad_syscall(no, regs);
619 switch (no & 0xffff) {
620 case 0: /* branch through 0 */
621 info.si_signo = SIGSEGV;
623 info.si_code = SEGV_MAPERR;
626 arm_notify_die("branch through zero", regs, &info, 0, 0);
629 case NR(breakpoint): /* SWI BREAK_POINT */
630 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
631 ptrace_break(current, regs);
635 * Flush a region from virtual address 'r0' to virtual address 'r1'
636 * _exclusive_. There is no alignment requirement on either address;
637 * user space does not need to know the hardware cache layout.
639 * r2 contains flags. It should ALWAYS be passed as ZERO until it
640 * is defined to be something else. For now we ignore it, but may
641 * the fires of hell burn in your belly if you break this rule. ;)
643 * (at a later date, we may want to allow this call to not flush
644 * various aspects of the cache. Passing '0' will guarantee that
645 * everything necessary gets flushed to maintain consistency in
646 * the specified region).
649 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
652 if (!(elf_hwcap & HWCAP_26BIT))
654 regs->ARM_cpsr &= ~MODE32_BIT;
658 if (!(elf_hwcap & HWCAP_26BIT))
660 regs->ARM_cpsr |= MODE32_BIT;
664 set_tls(regs->ARM_r0);
668 return current_thread_info()->tp_value[0];
671 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
672 if not implemented, rather than raising SIGILL. This
673 way the calling program can gracefully determine whether
674 a feature is supported. */
675 if ((no & 0xffff) <= 0x7ff)
679 #ifdef CONFIG_DEBUG_USER
681 * experience shows that these seem to indicate that
682 * something catastrophic has happened
684 if (user_debug & UDBG_SYSCALL) {
685 pr_err("[%d] %s: arm syscall %d\n",
686 task_pid_nr(current), current->comm, no);
687 dump_instr("", regs);
688 if (user_mode(regs)) {
690 c_backtrace(frame_pointer(regs), processor_mode(regs));
694 info.si_signo = SIGILL;
696 info.si_code = ILL_ILLTRP;
697 info.si_addr = (void __user *)instruction_pointer(regs) -
698 (thumb_mode(regs) ? 2 : 4);
700 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
704 #ifdef CONFIG_TLS_REG_EMUL
707 * We might be running on an ARMv6+ processor which should have the TLS
708 * register but for some reason we can't use it, or maybe an SMP system
709 * using a pre-ARMv6 processor (there are apparently a few prototypes like
710 * that in existence) and therefore access to that register must be
714 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
716 int reg = (instr >> 12) & 15;
719 regs->uregs[reg] = current_thread_info()->tp_value[0];
724 static struct undef_hook arm_mrc_hook = {
725 .instr_mask = 0x0fff0fff,
726 .instr_val = 0x0e1d0f70,
727 .cpsr_mask = PSR_T_BIT,
732 static int __init arm_mrc_hook_init(void)
734 register_undef_hook(&arm_mrc_hook);
738 late_initcall(arm_mrc_hook_init);
743 * A data abort trap was taken, but we did not handle the instruction.
744 * Try to abort the user program, or panic if it was the kernel.
747 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
749 unsigned long addr = instruction_pointer(regs);
752 clear_siginfo(&info);
754 #ifdef CONFIG_DEBUG_USER
755 if (user_debug & UDBG_BADABORT) {
756 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
757 task_pid_nr(current), current->comm, code, instr);
758 dump_instr(KERN_ERR, regs);
759 show_pte(current->mm, addr);
763 info.si_signo = SIGILL;
765 info.si_code = ILL_ILLOPC;
766 info.si_addr = (void __user *)addr;
768 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
771 void __readwrite_bug(const char *fn)
773 pr_err("%s called, but not implemented\n", fn);
776 EXPORT_SYMBOL(__readwrite_bug);
778 void __pte_error(const char *file, int line, pte_t pte)
780 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
783 void __pmd_error(const char *file, int line, pmd_t pmd)
785 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
788 void __pgd_error(const char *file, int line, pgd_t pgd)
790 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
793 asmlinkage void __div0(void)
795 pr_err("Division by zero in kernel.\n");
798 EXPORT_SYMBOL(__div0);
804 /* if that doesn't kill us, halt */
805 panic("Oops failed to kill thread");
808 void __init trap_init(void)
813 #ifdef CONFIG_KUSER_HELPERS
814 static void __init kuser_init(void *vectors)
816 extern char __kuser_helper_start[], __kuser_helper_end[];
817 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
819 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
822 * vectors + 0xfe0 = __kuser_get_tls
823 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
825 if (tls_emu || has_tls_reg)
826 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
829 static inline void __init kuser_init(void *vectors)
834 #ifndef CONFIG_CPU_V7M
835 static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
837 memcpy(vma, lma_start, lma_end - lma_start);
840 static void flush_vectors(void *vma, size_t offset, size_t size)
842 unsigned long start = (unsigned long)vma + offset;
843 unsigned long end = start + size;
845 flush_icache_range(start, end);
848 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
849 int spectre_bhb_update_vectors(unsigned int method)
851 extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
852 extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
853 void *vec_start, *vec_end;
855 if (system_state > SYSTEM_SCHEDULING) {
856 pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
858 return SPECTRE_VULNERABLE;
862 case SPECTRE_V2_METHOD_LOOP8:
863 vec_start = __vectors_bhb_loop8_start;
864 vec_end = __vectors_bhb_loop8_end;
867 case SPECTRE_V2_METHOD_BPIALL:
868 vec_start = __vectors_bhb_bpiall_start;
869 vec_end = __vectors_bhb_bpiall_end;
873 pr_err("CPU%u: unknown Spectre BHB state %d\n",
874 smp_processor_id(), method);
875 return SPECTRE_VULNERABLE;
878 copy_from_lma(vectors_page, vec_start, vec_end);
879 flush_vectors(vectors_page, 0, vec_end - vec_start);
881 return SPECTRE_MITIGATED;
885 void __init early_trap_init(void *vectors_base)
887 extern char __stubs_start[], __stubs_end[];
888 extern char __vectors_start[], __vectors_end[];
891 vectors_page = vectors_base;
894 * Poison the vectors page with an undefined instruction. This
895 * instruction is chosen to be undefined for both ARM and Thumb
896 * ISAs. The Thumb version is an undefined instruction with a
897 * branch back to the undefined instruction.
899 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
900 ((u32 *)vectors_base)[i] = 0xe7fddef1;
903 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
904 * into the vector page, mapped at 0xffff0000, and ensure these
905 * are visible to the instruction stream.
907 copy_from_lma(vectors_base, __vectors_start, __vectors_end);
908 copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
910 kuser_init(vectors_base);
912 flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
914 #else /* ifndef CONFIG_CPU_V7M */
915 void __init early_trap_init(void *vectors_base)
918 * on V7-M there is no need to copy the vector table to a dedicated
919 * memory area. The address is configurable and so a table in the kernel