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.h>
29 #include <linux/irq.h>
31 #include <linux/atomic.h>
32 #include <asm/cacheflush.h>
33 #include <asm/exception.h>
34 #include <asm/spectre.h>
35 #include <asm/unistd.h>
36 #include <asm/traps.h>
37 #include <asm/ptrace.h>
38 #include <asm/unwind.h>
40 #include <asm/system_misc.h>
41 #include <asm/opcodes.h>
44 static const char *handler[]= {
49 "undefined instruction",
54 #ifdef CONFIG_DEBUG_USER
55 unsigned int user_debug;
57 static int __init user_debug_setup(char *str)
59 get_option(&str, &user_debug);
62 __setup("user_debug=", user_debug_setup);
65 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
67 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
69 #ifdef CONFIG_KALLSYMS
70 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
72 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
75 if (in_exception_text(where))
76 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
79 void dump_backtrace_stm(u32 *stack, u32 instruction)
85 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
86 if (instruction & BIT(reg)) {
87 p += sprintf(p, " r%d:%08x", reg, *stack--);
99 #ifndef CONFIG_ARM_UNWIND
101 * Stack pointers should always be within the kernels view of
102 * physical memory. If it is not there, then we can't dump
103 * out any information relating to the stack.
105 static int verify_stack(unsigned long sp)
107 if (sp < PAGE_OFFSET ||
108 (sp > (unsigned long)high_memory && high_memory != NULL))
116 * Dump out the contents of some memory nicely...
118 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
126 * We need to switch to kernel mode so that we can use __get_user
127 * to safely read from kernel space. Note that we now dump the
128 * code first, just in case the backtrace kills us.
133 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
135 for (first = bottom & ~31; first < top; first += 32) {
137 char str[sizeof(" 12345678") * 8 + 1];
139 memset(str, ' ', sizeof(str));
140 str[sizeof(str) - 1] = '\0';
142 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
143 if (p >= bottom && p < top) {
145 if (__get_user(val, (unsigned long *)p) == 0)
146 sprintf(str + i * 9, " %08lx", val);
148 sprintf(str + i * 9, " ????????");
151 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
157 static void __dump_instr(const char *lvl, struct pt_regs *regs)
159 unsigned long addr = instruction_pointer(regs);
160 const int thumb = thumb_mode(regs);
161 const int width = thumb ? 4 : 8;
162 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
166 * Note that we now dump the code first, just in case the backtrace
170 for (i = -4; i < 1 + !!thumb; i++) {
171 unsigned int val, bad;
174 bad = get_user(val, &((u16 *)addr)[i]);
176 bad = get_user(val, &((u32 *)addr)[i]);
179 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
182 p += sprintf(p, "bad PC value");
186 printk("%sCode: %s\n", lvl, str);
189 static void dump_instr(const char *lvl, struct pt_regs *regs)
193 if (!user_mode(regs)) {
196 __dump_instr(lvl, regs);
199 __dump_instr(lvl, regs);
203 #ifdef CONFIG_ARM_UNWIND
204 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
206 unwind_backtrace(regs, tsk);
209 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
211 unsigned int fp, mode;
214 printk("Backtrace: ");
220 fp = frame_pointer(regs);
221 mode = processor_mode(regs);
222 } else if (tsk != current) {
223 fp = thread_saved_fp(tsk);
226 asm("mov %0, fp" : "=r" (fp) : : "cc");
231 pr_cont("no frame pointer");
233 } else if (verify_stack(fp)) {
234 pr_cont("invalid frame pointer 0x%08x", fp);
236 } else if (fp < (unsigned long)end_of_stack(tsk))
237 pr_cont("frame pointer underflow");
241 c_backtrace(fp, mode);
245 void show_stack(struct task_struct *tsk, unsigned long *sp)
247 dump_backtrace(NULL, tsk);
251 #ifdef CONFIG_PREEMPT
252 #define S_PREEMPT " PREEMPT"
261 #ifdef CONFIG_THUMB2_KERNEL
262 #define S_ISA " THUMB2"
267 static int __die(const char *str, int err, struct pt_regs *regs)
269 struct task_struct *tsk = current;
270 static int die_counter;
273 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
274 str, err, ++die_counter);
276 /* trap and error numbers are mostly meaningless on ARM */
277 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
278 if (ret == NOTIFY_STOP)
283 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
284 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
286 if (!user_mode(regs) || in_interrupt()) {
287 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
288 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
289 dump_backtrace(regs, tsk);
290 dump_instr(KERN_EMERG, regs);
296 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
297 static int die_owner = -1;
298 static unsigned int die_nest_count;
300 static unsigned long oops_begin(void)
307 /* racy, but better than risking deadlock. */
308 raw_local_irq_save(flags);
309 cpu = smp_processor_id();
310 if (!arch_spin_trylock(&die_lock)) {
311 if (cpu == die_owner)
312 /* nested oops. should stop eventually */;
314 arch_spin_lock(&die_lock);
323 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
325 if (regs && kexec_should_crash(current))
330 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
333 /* Nest count reaches zero, release the lock. */
334 arch_spin_unlock(&die_lock);
335 raw_local_irq_restore(flags);
339 panic("Fatal exception in interrupt");
341 panic("Fatal exception");
347 * This function is protected against re-entrancy.
349 void die(const char *str, struct pt_regs *regs, int err)
351 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
352 unsigned long flags = oops_begin();
355 if (!user_mode(regs))
356 bug_type = report_bug(regs->ARM_pc, regs);
357 if (bug_type != BUG_TRAP_TYPE_NONE)
360 if (__die(str, err, regs))
363 oops_end(flags, regs, sig);
366 void arm_notify_die(const char *str, struct pt_regs *regs,
367 struct siginfo *info, unsigned long err, unsigned long trap)
369 if (user_mode(regs)) {
370 current->thread.error_code = err;
371 current->thread.trap_no = trap;
373 force_sig_info(info->si_signo, info, current);
379 #ifdef CONFIG_GENERIC_BUG
381 int is_valid_bugaddr(unsigned long pc)
383 #ifdef CONFIG_THUMB2_KERNEL
385 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
388 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
391 if (probe_kernel_address((unsigned *)pc, bkpt))
399 static LIST_HEAD(undef_hook);
400 static DEFINE_RAW_SPINLOCK(undef_lock);
402 void register_undef_hook(struct undef_hook *hook)
406 raw_spin_lock_irqsave(&undef_lock, flags);
407 list_add(&hook->node, &undef_hook);
408 raw_spin_unlock_irqrestore(&undef_lock, flags);
411 void unregister_undef_hook(struct undef_hook *hook)
415 raw_spin_lock_irqsave(&undef_lock, flags);
416 list_del(&hook->node);
417 raw_spin_unlock_irqrestore(&undef_lock, flags);
420 static nokprobe_inline
421 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
423 struct undef_hook *hook;
425 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
427 raw_spin_lock_irqsave(&undef_lock, flags);
428 list_for_each_entry(hook, &undef_hook, node)
429 if ((instr & hook->instr_mask) == hook->instr_val &&
430 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
432 raw_spin_unlock_irqrestore(&undef_lock, flags);
434 return fn ? fn(regs, instr) : 1;
437 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
443 pc = (void __user *)instruction_pointer(regs);
445 if (processor_mode(regs) == SVC_MODE) {
446 #ifdef CONFIG_THUMB2_KERNEL
447 if (thumb_mode(regs)) {
448 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
449 if (is_wide_instruction(instr)) {
451 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
452 instr = __opcode_thumb32_compose(instr, inst2);
456 instr = __mem_to_opcode_arm(*(u32 *) pc);
457 } else if (thumb_mode(regs)) {
458 if (get_user(instr, (u16 __user *)pc))
460 instr = __mem_to_opcode_thumb16(instr);
461 if (is_wide_instruction(instr)) {
463 if (get_user(instr2, (u16 __user *)pc+1))
465 instr2 = __mem_to_opcode_thumb16(instr2);
466 instr = __opcode_thumb32_compose(instr, instr2);
469 if (get_user(instr, (u32 __user *)pc))
471 instr = __mem_to_opcode_arm(instr);
474 if (call_undef_hook(regs, instr) == 0)
478 #ifdef CONFIG_DEBUG_USER
479 if (user_debug & UDBG_UNDEFINED) {
480 pr_info("%s (%d): undefined instruction: pc=%p\n",
481 current->comm, task_pid_nr(current), pc);
483 dump_instr(KERN_INFO, regs);
487 info.si_signo = SIGILL;
489 info.si_code = ILL_ILLOPC;
492 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
494 NOKPROBE_SYMBOL(do_undefinstr)
497 * Handle FIQ similarly to NMI on x86 systems.
499 * The runtime environment for NMIs is extremely restrictive
500 * (NMIs can pre-empt critical sections meaning almost all locking is
501 * forbidden) meaning this default FIQ handling must only be used in
502 * circumstances where non-maskability improves robustness, such as
503 * watchdog or debug logic.
505 * This handler is not appropriate for general purpose use in drivers
506 * platform code and can be overrideen using set_fiq_handler.
508 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
510 struct pt_regs *old_regs = set_irq_regs(regs);
514 /* nop. FIQ handlers for special arch/arm features can be added here. */
518 set_irq_regs(old_regs);
522 * bad_mode handles the impossible case in the vectors. If you see one of
523 * these, then it's extremely serious, and could mean you have buggy hardware.
524 * It never returns, and never tries to sync. We hope that we can at least
525 * dump out some state information...
527 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
531 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
533 die("Oops - bad mode", regs, 0);
538 static int bad_syscall(int n, struct pt_regs *regs)
542 if ((current->personality & PER_MASK) != PER_LINUX) {
543 send_sig(SIGSEGV, current, 1);
547 #ifdef CONFIG_DEBUG_USER
548 if (user_debug & UDBG_SYSCALL) {
549 pr_err("[%d] %s: obsolete system call %08x.\n",
550 task_pid_nr(current), current->comm, n);
551 dump_instr(KERN_ERR, regs);
555 info.si_signo = SIGILL;
557 info.si_code = ILL_ILLTRP;
558 info.si_addr = (void __user *)instruction_pointer(regs) -
559 (thumb_mode(regs) ? 2 : 4);
561 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
567 __do_cache_op(unsigned long start, unsigned long end)
572 unsigned long chunk = min(PAGE_SIZE, end - start);
574 if (fatal_signal_pending(current))
577 ret = flush_cache_user_range(start, start + chunk);
583 } while (start < end);
589 do_cache_op(unsigned long start, unsigned long end, int flags)
591 if (end < start || flags)
594 if (!access_ok(VERIFY_READ, start, end - start))
597 return __do_cache_op(start, end);
601 * Handle all unrecognised system calls.
602 * 0x9f0000 - 0x9fffff are some more esoteric system calls
604 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
605 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
609 if ((no >> 16) != (__ARM_NR_BASE>> 16))
610 return bad_syscall(no, regs);
612 switch (no & 0xffff) {
613 case 0: /* branch through 0 */
614 info.si_signo = SIGSEGV;
616 info.si_code = SEGV_MAPERR;
619 arm_notify_die("branch through zero", regs, &info, 0, 0);
622 case NR(breakpoint): /* SWI BREAK_POINT */
623 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
624 ptrace_break(current, regs);
628 * Flush a region from virtual address 'r0' to virtual address 'r1'
629 * _exclusive_. There is no alignment requirement on either address;
630 * user space does not need to know the hardware cache layout.
632 * r2 contains flags. It should ALWAYS be passed as ZERO until it
633 * is defined to be something else. For now we ignore it, but may
634 * the fires of hell burn in your belly if you break this rule. ;)
636 * (at a later date, we may want to allow this call to not flush
637 * various aspects of the cache. Passing '0' will guarantee that
638 * everything necessary gets flushed to maintain consistency in
639 * the specified region).
642 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
645 if (!(elf_hwcap & HWCAP_26BIT))
647 regs->ARM_cpsr &= ~MODE32_BIT;
651 if (!(elf_hwcap & HWCAP_26BIT))
653 regs->ARM_cpsr |= MODE32_BIT;
657 set_tls(regs->ARM_r0);
661 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
662 if not implemented, rather than raising SIGILL. This
663 way the calling program can gracefully determine whether
664 a feature is supported. */
665 if ((no & 0xffff) <= 0x7ff)
669 #ifdef CONFIG_DEBUG_USER
671 * experience shows that these seem to indicate that
672 * something catastrophic has happened
674 if (user_debug & UDBG_SYSCALL) {
675 pr_err("[%d] %s: arm syscall %d\n",
676 task_pid_nr(current), current->comm, no);
677 dump_instr("", regs);
678 if (user_mode(regs)) {
680 c_backtrace(frame_pointer(regs), processor_mode(regs));
684 info.si_signo = SIGILL;
686 info.si_code = ILL_ILLTRP;
687 info.si_addr = (void __user *)instruction_pointer(regs) -
688 (thumb_mode(regs) ? 2 : 4);
690 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
694 #ifdef CONFIG_TLS_REG_EMUL
697 * We might be running on an ARMv6+ processor which should have the TLS
698 * register but for some reason we can't use it, or maybe an SMP system
699 * using a pre-ARMv6 processor (there are apparently a few prototypes like
700 * that in existence) and therefore access to that register must be
704 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
706 int reg = (instr >> 12) & 15;
709 regs->uregs[reg] = current_thread_info()->tp_value[0];
714 static struct undef_hook arm_mrc_hook = {
715 .instr_mask = 0x0fff0fff,
716 .instr_val = 0x0e1d0f70,
717 .cpsr_mask = PSR_T_BIT,
722 static int __init arm_mrc_hook_init(void)
724 register_undef_hook(&arm_mrc_hook);
728 late_initcall(arm_mrc_hook_init);
733 * A data abort trap was taken, but we did not handle the instruction.
734 * Try to abort the user program, or panic if it was the kernel.
737 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
739 unsigned long addr = instruction_pointer(regs);
742 #ifdef CONFIG_DEBUG_USER
743 if (user_debug & UDBG_BADABORT) {
744 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
745 task_pid_nr(current), current->comm, code, instr);
746 dump_instr(KERN_ERR, regs);
747 show_pte(current->mm, addr);
751 info.si_signo = SIGILL;
753 info.si_code = ILL_ILLOPC;
754 info.si_addr = (void __user *)addr;
756 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
759 void __readwrite_bug(const char *fn)
761 pr_err("%s called, but not implemented\n", fn);
764 EXPORT_SYMBOL(__readwrite_bug);
766 void __pte_error(const char *file, int line, pte_t pte)
768 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
771 void __pmd_error(const char *file, int line, pmd_t pmd)
773 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
776 void __pgd_error(const char *file, int line, pgd_t pgd)
778 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
781 asmlinkage void __div0(void)
783 pr_err("Division by zero in kernel.\n");
786 EXPORT_SYMBOL(__div0);
792 /* if that doesn't kill us, halt */
793 panic("Oops failed to kill thread");
795 EXPORT_SYMBOL(abort);
797 void __init trap_init(void)
802 #ifdef CONFIG_KUSER_HELPERS
803 static void __init kuser_init(void *vectors)
805 extern char __kuser_helper_start[], __kuser_helper_end[];
806 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
808 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
811 * vectors + 0xfe0 = __kuser_get_tls
812 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
814 if (tls_emu || has_tls_reg)
815 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
818 static inline void __init kuser_init(void *vectors)
823 #ifndef CONFIG_CPU_V7M
824 static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
826 memcpy(vma, lma_start, lma_end - lma_start);
829 static void flush_vectors(void *vma, size_t offset, size_t size)
831 unsigned long start = (unsigned long)vma + offset;
832 unsigned long end = start + size;
834 flush_icache_range(start, end);
837 #ifdef CONFIG_HARDEN_BRANCH_HISTORY
838 int spectre_bhb_update_vectors(unsigned int method)
840 extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
841 extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
842 void *vec_start, *vec_end;
844 if (system_state >= SYSTEM_RUNNING) {
845 pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
847 return SPECTRE_VULNERABLE;
851 case SPECTRE_V2_METHOD_LOOP8:
852 vec_start = __vectors_bhb_loop8_start;
853 vec_end = __vectors_bhb_loop8_end;
856 case SPECTRE_V2_METHOD_BPIALL:
857 vec_start = __vectors_bhb_bpiall_start;
858 vec_end = __vectors_bhb_bpiall_end;
862 pr_err("CPU%u: unknown Spectre BHB state %d\n",
863 smp_processor_id(), method);
864 return SPECTRE_VULNERABLE;
867 copy_from_lma(vectors_page, vec_start, vec_end);
868 flush_vectors(vectors_page, 0, vec_end - vec_start);
870 return SPECTRE_MITIGATED;
874 void __init early_trap_init(void *vectors_base)
876 extern char __stubs_start[], __stubs_end[];
877 extern char __vectors_start[], __vectors_end[];
880 vectors_page = vectors_base;
883 * Poison the vectors page with an undefined instruction. This
884 * instruction is chosen to be undefined for both ARM and Thumb
885 * ISAs. The Thumb version is an undefined instruction with a
886 * branch back to the undefined instruction.
888 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
889 ((u32 *)vectors_base)[i] = 0xe7fddef1;
892 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
893 * into the vector page, mapped at 0xffff0000, and ensure these
894 * are visible to the instruction stream.
896 copy_from_lma(vectors_base, __vectors_start, __vectors_end);
897 copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
899 kuser_init(vectors_base);
901 flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
903 #else /* ifndef CONFIG_CPU_V7M */
904 void __init early_trap_init(void *vectors_base)
907 * on V7-M there is no need to copy the vector table to a dedicated
908 * memory area. The address is configurable and so a table in the kernel