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/sched.h>
27 #include <linux/sysrq.h>
28 #include <linux/init.h>
29 #include <linux/nmi.h>
30 #include <linux/console.h>
31 #include <linux/bug.h>
32 #include <linux/ratelimit.h>
33 #include <linux/debugfs.h>
34 #include <asm/sections.h>
36 #define PANIC_TIMER_STEP 100
37 #define PANIC_BLINK_SPD 18
41 * Should we dump all CPUs backtraces in an oops event?
42 * Defaults to 0, can be changed via sysctl.
44 unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
45 #endif /* CONFIG_SMP */
47 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
48 static unsigned long tainted_mask =
49 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
50 static int pause_on_oops;
51 static int pause_on_oops_flag;
52 static DEFINE_SPINLOCK(pause_on_oops_lock);
53 bool crash_kexec_post_notifiers;
54 int panic_on_warn __read_mostly;
55 unsigned long panic_on_taint;
56 bool panic_on_taint_nousertaint = false;
58 int panic_timeout = CONFIG_PANIC_TIMEOUT;
59 EXPORT_SYMBOL_GPL(panic_timeout);
61 #define PANIC_PRINT_TASK_INFO 0x00000001
62 #define PANIC_PRINT_MEM_INFO 0x00000002
63 #define PANIC_PRINT_TIMER_INFO 0x00000004
64 #define PANIC_PRINT_LOCK_INFO 0x00000008
65 #define PANIC_PRINT_FTRACE_INFO 0x00000010
66 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
67 unsigned long panic_print;
69 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
71 EXPORT_SYMBOL(panic_notifier_list);
73 static long no_blink(int state)
78 /* Returns how long it waited in ms */
79 long (*panic_blink)(int state);
80 EXPORT_SYMBOL(panic_blink);
83 * Stop ourself in panic -- architecture code may override this
85 void __weak panic_smp_self_stop(void)
92 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
93 * may override this to prepare for crash dumping, e.g. save regs info.
95 void __weak nmi_panic_self_stop(struct pt_regs *regs)
97 panic_smp_self_stop();
101 * Stop other CPUs in panic. Architecture dependent code may override this
102 * with more suitable version. For example, if the architecture supports
103 * crash dump, it should save registers of each stopped CPU and disable
104 * per-CPU features such as virtualization extensions.
106 void __weak crash_smp_send_stop(void)
108 static int cpus_stopped;
111 * This function can be called twice in panic path, but obviously
112 * we execute this only once.
118 * Note smp_send_stop is the usual smp shutdown function, which
119 * unfortunately means it may not be hardened to work in a panic
126 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
129 * A variant of panic() called from NMI context. We return if we've already
130 * panicked on this CPU. If another CPU already panicked, loop in
131 * nmi_panic_self_stop() which can provide architecture dependent code such
132 * as saving register state for crash dump.
134 void nmi_panic(struct pt_regs *regs, const char *msg)
138 cpu = raw_smp_processor_id();
139 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
141 if (old_cpu == PANIC_CPU_INVALID)
143 else if (old_cpu != cpu)
144 nmi_panic_self_stop(regs);
146 EXPORT_SYMBOL(nmi_panic);
148 static void panic_print_sys_info(void)
150 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
151 console_flush_on_panic(CONSOLE_REPLAY_ALL);
153 if (panic_print & PANIC_PRINT_TASK_INFO)
156 if (panic_print & PANIC_PRINT_MEM_INFO)
159 if (panic_print & PANIC_PRINT_TIMER_INFO)
160 sysrq_timer_list_show();
162 if (panic_print & PANIC_PRINT_LOCK_INFO)
163 debug_show_all_locks();
165 if (panic_print & PANIC_PRINT_FTRACE_INFO)
166 ftrace_dump(DUMP_ALL);
170 * panic - halt the system
171 * @fmt: The text string to print
173 * Display a message, then perform cleanups.
175 * This function never returns.
177 void panic(const char *fmt, ...)
179 static char buf[1024];
181 long i, i_next = 0, len;
183 int old_cpu, this_cpu;
184 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
187 * Disable local interrupts. This will prevent panic_smp_self_stop
188 * from deadlocking the first cpu that invokes the panic, since
189 * there is nothing to prevent an interrupt handler (that runs
190 * after setting panic_cpu) from invoking panic() again.
193 preempt_disable_notrace();
196 * It's possible to come here directly from a panic-assertion and
197 * not have preempt disabled. Some functions called from here want
198 * preempt to be disabled. No point enabling it later though...
200 * Only one CPU is allowed to execute the panic code from here. For
201 * multiple parallel invocations of panic, all other CPUs either
202 * stop themself or will wait until they are stopped by the 1st CPU
203 * with smp_send_stop().
205 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
206 * comes here, so go ahead.
207 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
208 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
210 this_cpu = raw_smp_processor_id();
211 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
213 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
214 panic_smp_self_stop();
219 len = vscnprintf(buf, sizeof(buf), fmt, args);
222 if (len && buf[len - 1] == '\n')
225 pr_emerg("Kernel panic - not syncing: %s\n", buf);
226 #ifdef CONFIG_DEBUG_BUGVERBOSE
228 * Avoid nested stack-dumping if a panic occurs during oops processing
230 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
235 * If kgdb is enabled, give it a chance to run before we stop all
236 * the other CPUs or else we won't be able to debug processes left
242 * If we have crashed and we have a crash kernel loaded let it handle
244 * If we want to run this after calling panic_notifiers, pass
245 * the "crash_kexec_post_notifiers" option to the kernel.
247 * Bypass the panic_cpu check and call __crash_kexec directly.
249 if (!_crash_kexec_post_notifiers) {
250 printk_safe_flush_on_panic();
254 * Note smp_send_stop is the usual smp shutdown function, which
255 * unfortunately means it may not be hardened to work in a
261 * If we want to do crash dump after notifier calls and
262 * kmsg_dump, we will need architecture dependent extra
263 * works in addition to stopping other CPUs.
265 crash_smp_send_stop();
269 * Run any panic handlers, including those that might need to
270 * add information to the kmsg dump output.
272 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
274 /* Call flush even twice. It tries harder with a single online CPU */
275 printk_safe_flush_on_panic();
276 kmsg_dump(KMSG_DUMP_PANIC);
279 * If you doubt kdump always works fine in any situation,
280 * "crash_kexec_post_notifiers" offers you a chance to run
281 * panic_notifiers and dumping kmsg before kdump.
282 * Note: since some panic_notifiers can make crashed kernel
283 * more unstable, it can increase risks of the kdump failure too.
285 * Bypass the panic_cpu check and call __crash_kexec directly.
287 if (_crash_kexec_post_notifiers)
296 * We may have ended up stopping the CPU holding the lock (in
297 * smp_send_stop()) while still having some valuable data in the console
298 * buffer. Try to acquire the lock then release it regardless of the
299 * result. The release will also print the buffers out. Locks debug
300 * should be disabled to avoid reporting bad unlock balance when
301 * panic() is not being callled from OOPS.
304 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
306 panic_print_sys_info();
309 panic_blink = no_blink;
311 if (panic_timeout > 0) {
313 * Delay timeout seconds before rebooting the machine.
314 * We can't use the "normal" timers since we just panicked.
316 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
318 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
319 touch_nmi_watchdog();
321 i += panic_blink(state ^= 1);
322 i_next = i + 3600 / PANIC_BLINK_SPD;
324 mdelay(PANIC_TIMER_STEP);
327 if (panic_timeout != 0) {
329 * This will not be a clean reboot, with everything
330 * shutting down. But if there is a chance of
331 * rebooting the system it will be rebooted.
333 if (panic_reboot_mode != REBOOT_UNDEFINED)
334 reboot_mode = panic_reboot_mode;
339 extern int stop_a_enabled;
340 /* Make sure the user can actually press Stop-A (L1-A) */
342 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
343 "twice on console to return to the boot prom\n");
346 #if defined(CONFIG_S390)
349 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
351 /* Do not scroll important messages printed above */
354 for (i = 0; ; i += PANIC_TIMER_STEP) {
355 touch_softlockup_watchdog();
357 i += panic_blink(state ^= 1);
358 i_next = i + 3600 / PANIC_BLINK_SPD;
360 mdelay(PANIC_TIMER_STEP);
364 EXPORT_SYMBOL(panic);
367 * TAINT_FORCED_RMMOD could be a per-module flag but the module
368 * is being removed anyway.
370 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
371 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
372 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
373 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
374 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
375 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
376 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
377 [ TAINT_USER ] = { 'U', ' ', false },
378 [ TAINT_DIE ] = { 'D', ' ', false },
379 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
380 [ TAINT_WARN ] = { 'W', ' ', false },
381 [ TAINT_CRAP ] = { 'C', ' ', true },
382 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
383 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
384 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
385 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
386 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
387 [ TAINT_AUX ] = { 'X', ' ', true },
388 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
392 * print_tainted - return a string to represent the kernel taint state.
394 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
396 * The string is overwritten by the next call to print_tainted(),
397 * but is always NULL terminated.
399 const char *print_tainted(void)
401 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
403 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
409 s = buf + sprintf(buf, "Tainted: ");
410 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
411 const struct taint_flag *t = &taint_flags[i];
412 *s++ = test_bit(i, &tainted_mask) ?
413 t->c_true : t->c_false;
417 snprintf(buf, sizeof(buf), "Not tainted");
422 int test_taint(unsigned flag)
424 return test_bit(flag, &tainted_mask);
426 EXPORT_SYMBOL(test_taint);
428 unsigned long get_taint(void)
434 * add_taint: add a taint flag if not already set.
435 * @flag: one of the TAINT_* constants.
436 * @lockdep_ok: whether lock debugging is still OK.
438 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
439 * some notewortht-but-not-corrupting cases, it can be set to true.
441 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
443 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
444 pr_warn("Disabling lock debugging due to kernel taint\n");
446 set_bit(flag, &tainted_mask);
448 if (tainted_mask & panic_on_taint) {
450 panic("panic_on_taint set ...");
453 EXPORT_SYMBOL(add_taint);
455 static void spin_msec(int msecs)
459 for (i = 0; i < msecs; i++) {
460 touch_nmi_watchdog();
466 * It just happens that oops_enter() and oops_exit() are identically
469 static void do_oops_enter_exit(void)
472 static int spin_counter;
477 spin_lock_irqsave(&pause_on_oops_lock, flags);
478 if (pause_on_oops_flag == 0) {
479 /* This CPU may now print the oops message */
480 pause_on_oops_flag = 1;
482 /* We need to stall this CPU */
484 /* This CPU gets to do the counting */
485 spin_counter = pause_on_oops;
487 spin_unlock(&pause_on_oops_lock);
488 spin_msec(MSEC_PER_SEC);
489 spin_lock(&pause_on_oops_lock);
490 } while (--spin_counter);
491 pause_on_oops_flag = 0;
493 /* This CPU waits for a different one */
494 while (spin_counter) {
495 spin_unlock(&pause_on_oops_lock);
497 spin_lock(&pause_on_oops_lock);
501 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
505 * Return true if the calling CPU is allowed to print oops-related info.
506 * This is a bit racy..
508 bool oops_may_print(void)
510 return pause_on_oops_flag == 0;
514 * Called when the architecture enters its oops handler, before it prints
515 * anything. If this is the first CPU to oops, and it's oopsing the first
516 * time then let it proceed.
518 * This is all enabled by the pause_on_oops kernel boot option. We do all
519 * this to ensure that oopses don't scroll off the screen. It has the
520 * side-effect of preventing later-oopsing CPUs from mucking up the display,
523 * It turns out that the CPU which is allowed to print ends up pausing for
524 * the right duration, whereas all the other CPUs pause for twice as long:
525 * once in oops_enter(), once in oops_exit().
527 void oops_enter(void)
530 /* can't trust the integrity of the kernel anymore: */
532 do_oops_enter_exit();
534 if (sysctl_oops_all_cpu_backtrace)
535 trigger_all_cpu_backtrace();
539 * 64-bit random ID for oopses:
543 static int init_oops_id(void)
546 get_random_bytes(&oops_id, sizeof(oops_id));
552 late_initcall(init_oops_id);
554 static void print_oops_end_marker(void)
557 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
561 * Called when the architecture exits its oops handler, after printing
566 do_oops_enter_exit();
567 print_oops_end_marker();
568 kmsg_dump(KMSG_DUMP_OOPS);
576 void __warn(const char *file, int line, void *caller, unsigned taint,
577 struct pt_regs *regs, struct warn_args *args)
579 disable_trace_on_warning();
582 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
583 raw_smp_processor_id(), current->pid, file, line,
586 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
587 raw_smp_processor_id(), current->pid, caller);
590 vprintk(args->fmt, args->args);
599 * This thread may hit another WARN() in the panic path.
600 * Resetting this prevents additional WARN() from panicking the
601 * system on this thread. Other threads are blocked by the
602 * panic_mutex in panic().
605 panic("panic_on_warn set ...\n");
610 print_irqtrace_events(current);
612 print_oops_end_marker();
614 /* Just a warning, don't kill lockdep. */
615 add_taint(taint, LOCKDEP_STILL_OK);
619 void warn_slowpath_fmt(const char *file, int line, unsigned taint,
620 const char *fmt, ...)
622 struct warn_args args;
627 __warn(file, line, __builtin_return_address(0), taint,
633 va_start(args.args, fmt);
634 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
637 EXPORT_SYMBOL(warn_slowpath_fmt);
639 void __warn_printk(const char *fmt, ...)
649 EXPORT_SYMBOL(__warn_printk);
654 /* Support resetting WARN*_ONCE state */
656 static int clear_warn_once_set(void *data, u64 val)
658 generic_bug_clear_once();
659 memset(__start_once, 0, __end_once - __start_once);
663 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
666 static __init int register_warn_debugfs(void)
668 /* Don't care about failure */
669 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
670 &clear_warn_once_fops);
674 device_initcall(register_warn_debugfs);
677 #ifdef CONFIG_STACKPROTECTOR
680 * Called when gcc's -fstack-protector feature is used, and
681 * gcc detects corruption of the on-stack canary value
683 __visible noinstr void __stack_chk_fail(void)
685 instrumentation_begin();
686 panic("stack-protector: Kernel stack is corrupted in: %pB",
687 __builtin_return_address(0));
688 instrumentation_end();
690 EXPORT_SYMBOL(__stack_chk_fail);
694 core_param(panic, panic_timeout, int, 0644);
695 core_param(panic_print, panic_print, ulong, 0644);
696 core_param(pause_on_oops, pause_on_oops, int, 0644);
697 core_param(panic_on_warn, panic_on_warn, int, 0644);
698 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
700 static int __init oops_setup(char *s)
704 if (!strcmp(s, "panic"))
708 early_param("oops", oops_setup);
710 static int __init panic_on_taint_setup(char *s)
717 taint_str = strsep(&s, ",");
718 if (kstrtoul(taint_str, 16, &panic_on_taint))
721 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
722 panic_on_taint &= TAINT_FLAGS_MAX;
727 if (s && !strcmp(s, "nousertaint"))
728 panic_on_taint_nousertaint = true;
730 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
731 panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
735 early_param("panic_on_taint", panic_on_taint_setup);