1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * This function is used through-out the kernel (including mm and fs)
10 * to indicate a major problem.
12 #include <linux/debug_locks.h>
13 #include <linux/sched/debug.h>
14 #include <linux/interrupt.h>
15 #include <linux/kgdb.h>
16 #include <linux/kmsg_dump.h>
17 #include <linux/kallsyms.h>
18 #include <linux/notifier.h>
19 #include <linux/vt_kern.h>
20 #include <linux/module.h>
21 #include <linux/random.h>
22 #include <linux/ftrace.h>
23 #include <linux/reboot.h>
24 #include <linux/delay.h>
25 #include <linux/kexec.h>
26 #include <linux/panic_notifier.h>
27 #include <linux/sched.h>
28 #include <linux/sysrq.h>
29 #include <linux/init.h>
30 #include <linux/nmi.h>
31 #include <linux/console.h>
32 #include <linux/bug.h>
33 #include <linux/ratelimit.h>
34 #include <linux/debugfs.h>
35 #include <linux/sysfs.h>
36 #include <asm/sections.h>
38 #define PANIC_TIMER_STEP 100
39 #define PANIC_BLINK_SPD 18
43 * Should we dump all CPUs backtraces in an oops event?
44 * Defaults to 0, can be changed via sysctl.
46 static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
48 #define sysctl_oops_all_cpu_backtrace 0
49 #endif /* CONFIG_SMP */
51 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
52 static unsigned long tainted_mask =
53 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
54 static int pause_on_oops;
55 static int pause_on_oops_flag;
56 static DEFINE_SPINLOCK(pause_on_oops_lock);
57 bool crash_kexec_post_notifiers;
58 int panic_on_warn __read_mostly;
59 unsigned long panic_on_taint;
60 bool panic_on_taint_nousertaint = false;
61 static unsigned int warn_limit __read_mostly;
63 int panic_timeout = CONFIG_PANIC_TIMEOUT;
64 EXPORT_SYMBOL_GPL(panic_timeout);
66 #define PANIC_PRINT_TASK_INFO 0x00000001
67 #define PANIC_PRINT_MEM_INFO 0x00000002
68 #define PANIC_PRINT_TIMER_INFO 0x00000004
69 #define PANIC_PRINT_LOCK_INFO 0x00000008
70 #define PANIC_PRINT_FTRACE_INFO 0x00000010
71 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
72 unsigned long panic_print;
74 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
76 EXPORT_SYMBOL(panic_notifier_list);
79 static struct ctl_table kern_panic_table[] = {
82 .procname = "oops_all_cpu_backtrace",
83 .data = &sysctl_oops_all_cpu_backtrace,
84 .maxlen = sizeof(int),
86 .proc_handler = proc_dointvec_minmax,
87 .extra1 = SYSCTL_ZERO,
92 .procname = "warn_limit",
94 .maxlen = sizeof(warn_limit),
96 .proc_handler = proc_douintvec,
101 static __init int kernel_panic_sysctls_init(void)
103 register_sysctl_init("kernel", kern_panic_table);
106 late_initcall(kernel_panic_sysctls_init);
109 static atomic_t warn_count = ATOMIC_INIT(0);
112 static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
115 return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
118 static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
120 static __init int kernel_panic_sysfs_init(void)
122 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
125 late_initcall(kernel_panic_sysfs_init);
128 static long no_blink(int state)
133 /* Returns how long it waited in ms */
134 long (*panic_blink)(int state);
135 EXPORT_SYMBOL(panic_blink);
138 * Stop ourself in panic -- architecture code may override this
140 void __weak panic_smp_self_stop(void)
147 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
148 * may override this to prepare for crash dumping, e.g. save regs info.
150 void __weak nmi_panic_self_stop(struct pt_regs *regs)
152 panic_smp_self_stop();
156 * Stop other CPUs in panic. Architecture dependent code may override this
157 * with more suitable version. For example, if the architecture supports
158 * crash dump, it should save registers of each stopped CPU and disable
159 * per-CPU features such as virtualization extensions.
161 void __weak crash_smp_send_stop(void)
163 static int cpus_stopped;
166 * This function can be called twice in panic path, but obviously
167 * we execute this only once.
173 * Note smp_send_stop is the usual smp shutdown function, which
174 * unfortunately means it may not be hardened to work in a panic
181 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
184 * A variant of panic() called from NMI context. We return if we've already
185 * panicked on this CPU. If another CPU already panicked, loop in
186 * nmi_panic_self_stop() which can provide architecture dependent code such
187 * as saving register state for crash dump.
189 void nmi_panic(struct pt_regs *regs, const char *msg)
193 cpu = raw_smp_processor_id();
194 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
196 if (old_cpu == PANIC_CPU_INVALID)
198 else if (old_cpu != cpu)
199 nmi_panic_self_stop(regs);
201 EXPORT_SYMBOL(nmi_panic);
203 static void panic_print_sys_info(void)
205 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
206 console_flush_on_panic(CONSOLE_REPLAY_ALL);
208 if (panic_print & PANIC_PRINT_TASK_INFO)
211 if (panic_print & PANIC_PRINT_MEM_INFO)
214 if (panic_print & PANIC_PRINT_TIMER_INFO)
215 sysrq_timer_list_show();
217 if (panic_print & PANIC_PRINT_LOCK_INFO)
218 debug_show_all_locks();
220 if (panic_print & PANIC_PRINT_FTRACE_INFO)
221 ftrace_dump(DUMP_ALL);
224 void check_panic_on_warn(const char *origin)
229 panic("%s: panic_on_warn set ...\n", origin);
231 limit = READ_ONCE(warn_limit);
232 if (atomic_inc_return(&warn_count) >= limit && limit)
233 panic("%s: system warned too often (kernel.warn_limit is %d)",
238 * panic - halt the system
239 * @fmt: The text string to print
241 * Display a message, then perform cleanups.
243 * This function never returns.
245 void panic(const char *fmt, ...)
247 static char buf[1024];
249 long i, i_next = 0, len;
251 int old_cpu, this_cpu;
252 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
256 * This thread may hit another WARN() in the panic path.
257 * Resetting this prevents additional WARN() from panicking the
258 * system on this thread. Other threads are blocked by the
259 * panic_mutex in panic().
265 * Disable local interrupts. This will prevent panic_smp_self_stop
266 * from deadlocking the first cpu that invokes the panic, since
267 * there is nothing to prevent an interrupt handler (that runs
268 * after setting panic_cpu) from invoking panic() again.
271 preempt_disable_notrace();
274 * It's possible to come here directly from a panic-assertion and
275 * not have preempt disabled. Some functions called from here want
276 * preempt to be disabled. No point enabling it later though...
278 * Only one CPU is allowed to execute the panic code from here. For
279 * multiple parallel invocations of panic, all other CPUs either
280 * stop themself or will wait until they are stopped by the 1st CPU
281 * with smp_send_stop().
283 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
284 * comes here, so go ahead.
285 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
286 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
288 this_cpu = raw_smp_processor_id();
289 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
291 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
292 panic_smp_self_stop();
297 len = vscnprintf(buf, sizeof(buf), fmt, args);
300 if (len && buf[len - 1] == '\n')
303 pr_emerg("Kernel panic - not syncing: %s\n", buf);
304 #ifdef CONFIG_DEBUG_BUGVERBOSE
306 * Avoid nested stack-dumping if a panic occurs during oops processing
308 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
313 * If kgdb is enabled, give it a chance to run before we stop all
314 * the other CPUs or else we won't be able to debug processes left
320 * If we have crashed and we have a crash kernel loaded let it handle
322 * If we want to run this after calling panic_notifiers, pass
323 * the "crash_kexec_post_notifiers" option to the kernel.
325 * Bypass the panic_cpu check and call __crash_kexec directly.
327 if (!_crash_kexec_post_notifiers) {
331 * Note smp_send_stop is the usual smp shutdown function, which
332 * unfortunately means it may not be hardened to work in a
338 * If we want to do crash dump after notifier calls and
339 * kmsg_dump, we will need architecture dependent extra
340 * works in addition to stopping other CPUs.
342 crash_smp_send_stop();
346 * Run any panic handlers, including those that might need to
347 * add information to the kmsg dump output.
349 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
351 kmsg_dump(KMSG_DUMP_PANIC);
354 * If you doubt kdump always works fine in any situation,
355 * "crash_kexec_post_notifiers" offers you a chance to run
356 * panic_notifiers and dumping kmsg before kdump.
357 * Note: since some panic_notifiers can make crashed kernel
358 * more unstable, it can increase risks of the kdump failure too.
360 * Bypass the panic_cpu check and call __crash_kexec directly.
362 if (_crash_kexec_post_notifiers)
371 * We may have ended up stopping the CPU holding the lock (in
372 * smp_send_stop()) while still having some valuable data in the console
373 * buffer. Try to acquire the lock then release it regardless of the
374 * result. The release will also print the buffers out. Locks debug
375 * should be disabled to avoid reporting bad unlock balance when
376 * panic() is not being callled from OOPS.
379 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
381 panic_print_sys_info();
384 panic_blink = no_blink;
386 if (panic_timeout > 0) {
388 * Delay timeout seconds before rebooting the machine.
389 * We can't use the "normal" timers since we just panicked.
391 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
393 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
394 touch_nmi_watchdog();
396 i += panic_blink(state ^= 1);
397 i_next = i + 3600 / PANIC_BLINK_SPD;
399 mdelay(PANIC_TIMER_STEP);
402 if (panic_timeout != 0) {
404 * This will not be a clean reboot, with everything
405 * shutting down. But if there is a chance of
406 * rebooting the system it will be rebooted.
408 if (panic_reboot_mode != REBOOT_UNDEFINED)
409 reboot_mode = panic_reboot_mode;
414 extern int stop_a_enabled;
415 /* Make sure the user can actually press Stop-A (L1-A) */
417 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
418 "twice on console to return to the boot prom\n");
421 #if defined(CONFIG_S390)
424 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
426 /* Do not scroll important messages printed above */
429 for (i = 0; ; i += PANIC_TIMER_STEP) {
430 touch_softlockup_watchdog();
432 i += panic_blink(state ^= 1);
433 i_next = i + 3600 / PANIC_BLINK_SPD;
435 mdelay(PANIC_TIMER_STEP);
439 EXPORT_SYMBOL(panic);
442 * TAINT_FORCED_RMMOD could be a per-module flag but the module
443 * is being removed anyway.
445 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
446 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
447 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
448 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
449 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
450 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
451 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
452 [ TAINT_USER ] = { 'U', ' ', false },
453 [ TAINT_DIE ] = { 'D', ' ', false },
454 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
455 [ TAINT_WARN ] = { 'W', ' ', false },
456 [ TAINT_CRAP ] = { 'C', ' ', true },
457 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
458 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
459 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
460 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
461 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
462 [ TAINT_AUX ] = { 'X', ' ', true },
463 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
467 * print_tainted - return a string to represent the kernel taint state.
469 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
471 * The string is overwritten by the next call to print_tainted(),
472 * but is always NULL terminated.
474 const char *print_tainted(void)
476 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
478 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
484 s = buf + sprintf(buf, "Tainted: ");
485 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
486 const struct taint_flag *t = &taint_flags[i];
487 *s++ = test_bit(i, &tainted_mask) ?
488 t->c_true : t->c_false;
492 snprintf(buf, sizeof(buf), "Not tainted");
497 int test_taint(unsigned flag)
499 return test_bit(flag, &tainted_mask);
501 EXPORT_SYMBOL(test_taint);
503 unsigned long get_taint(void)
509 * add_taint: add a taint flag if not already set.
510 * @flag: one of the TAINT_* constants.
511 * @lockdep_ok: whether lock debugging is still OK.
513 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
514 * some notewortht-but-not-corrupting cases, it can be set to true.
516 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
518 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
519 pr_warn("Disabling lock debugging due to kernel taint\n");
521 set_bit(flag, &tainted_mask);
523 if (tainted_mask & panic_on_taint) {
525 panic("panic_on_taint set ...");
528 EXPORT_SYMBOL(add_taint);
530 static void spin_msec(int msecs)
534 for (i = 0; i < msecs; i++) {
535 touch_nmi_watchdog();
541 * It just happens that oops_enter() and oops_exit() are identically
544 static void do_oops_enter_exit(void)
547 static int spin_counter;
552 spin_lock_irqsave(&pause_on_oops_lock, flags);
553 if (pause_on_oops_flag == 0) {
554 /* This CPU may now print the oops message */
555 pause_on_oops_flag = 1;
557 /* We need to stall this CPU */
559 /* This CPU gets to do the counting */
560 spin_counter = pause_on_oops;
562 spin_unlock(&pause_on_oops_lock);
563 spin_msec(MSEC_PER_SEC);
564 spin_lock(&pause_on_oops_lock);
565 } while (--spin_counter);
566 pause_on_oops_flag = 0;
568 /* This CPU waits for a different one */
569 while (spin_counter) {
570 spin_unlock(&pause_on_oops_lock);
572 spin_lock(&pause_on_oops_lock);
576 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
580 * Return true if the calling CPU is allowed to print oops-related info.
581 * This is a bit racy..
583 bool oops_may_print(void)
585 return pause_on_oops_flag == 0;
589 * Called when the architecture enters its oops handler, before it prints
590 * anything. If this is the first CPU to oops, and it's oopsing the first
591 * time then let it proceed.
593 * This is all enabled by the pause_on_oops kernel boot option. We do all
594 * this to ensure that oopses don't scroll off the screen. It has the
595 * side-effect of preventing later-oopsing CPUs from mucking up the display,
598 * It turns out that the CPU which is allowed to print ends up pausing for
599 * the right duration, whereas all the other CPUs pause for twice as long:
600 * once in oops_enter(), once in oops_exit().
602 void oops_enter(void)
605 /* can't trust the integrity of the kernel anymore: */
607 do_oops_enter_exit();
609 if (sysctl_oops_all_cpu_backtrace)
610 trigger_all_cpu_backtrace();
614 * 64-bit random ID for oopses:
618 static int init_oops_id(void)
621 get_random_bytes(&oops_id, sizeof(oops_id));
627 late_initcall(init_oops_id);
629 static void print_oops_end_marker(void)
632 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
636 * Called when the architecture exits its oops handler, after printing
641 do_oops_enter_exit();
642 print_oops_end_marker();
643 kmsg_dump(KMSG_DUMP_OOPS);
651 void __warn(const char *file, int line, void *caller, unsigned taint,
652 struct pt_regs *regs, struct warn_args *args)
654 disable_trace_on_warning();
657 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
658 raw_smp_processor_id(), current->pid, file, line,
661 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
662 raw_smp_processor_id(), current->pid, caller);
665 vprintk(args->fmt, args->args);
672 check_panic_on_warn("kernel");
677 print_irqtrace_events(current);
679 print_oops_end_marker();
681 /* Just a warning, don't kill lockdep. */
682 add_taint(taint, LOCKDEP_STILL_OK);
686 void warn_slowpath_fmt(const char *file, int line, unsigned taint,
687 const char *fmt, ...)
689 struct warn_args args;
694 __warn(file, line, __builtin_return_address(0), taint,
700 va_start(args.args, fmt);
701 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
704 EXPORT_SYMBOL(warn_slowpath_fmt);
706 void __warn_printk(const char *fmt, ...)
716 EXPORT_SYMBOL(__warn_printk);
721 /* Support resetting WARN*_ONCE state */
723 static int clear_warn_once_set(void *data, u64 val)
725 generic_bug_clear_once();
726 memset(__start_once, 0, __end_once - __start_once);
730 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
733 static __init int register_warn_debugfs(void)
735 /* Don't care about failure */
736 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
737 &clear_warn_once_fops);
741 device_initcall(register_warn_debugfs);
744 #ifdef CONFIG_STACKPROTECTOR
747 * Called when gcc's -fstack-protector feature is used, and
748 * gcc detects corruption of the on-stack canary value
750 __visible noinstr void __stack_chk_fail(void)
752 instrumentation_begin();
753 panic("stack-protector: Kernel stack is corrupted in: %pB",
754 __builtin_return_address(0));
755 instrumentation_end();
757 EXPORT_SYMBOL(__stack_chk_fail);
761 core_param(panic, panic_timeout, int, 0644);
762 core_param(panic_print, panic_print, ulong, 0644);
763 core_param(pause_on_oops, pause_on_oops, int, 0644);
764 core_param(panic_on_warn, panic_on_warn, int, 0644);
765 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
767 static int __init oops_setup(char *s)
771 if (!strcmp(s, "panic"))
775 early_param("oops", oops_setup);
777 static int __init panic_on_taint_setup(char *s)
784 taint_str = strsep(&s, ",");
785 if (kstrtoul(taint_str, 16, &panic_on_taint))
788 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
789 panic_on_taint &= TAINT_FLAGS_MAX;
794 if (s && !strcmp(s, "nousertaint"))
795 panic_on_taint_nousertaint = true;
797 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
798 panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
802 early_param("panic_on_taint", panic_on_taint_setup);