4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * This function is used through-out the kernel (including mm and fs)
9 * to indicate a major problem.
11 #include <linux/debug_locks.h>
12 #include <linux/sched/debug.h>
13 #include <linux/interrupt.h>
14 #include <linux/kmsg_dump.h>
15 #include <linux/kallsyms.h>
16 #include <linux/notifier.h>
17 #include <linux/vt_kern.h>
18 #include <linux/module.h>
19 #include <linux/random.h>
20 #include <linux/ftrace.h>
21 #include <linux/reboot.h>
22 #include <linux/delay.h>
23 #include <linux/kexec.h>
24 #include <linux/sched.h>
25 #include <linux/sysrq.h>
26 #include <linux/init.h>
27 #include <linux/nmi.h>
28 #include <linux/console.h>
29 #include <linux/bug.h>
30 #include <linux/ratelimit.h>
31 #include <linux/debugfs.h>
32 #include <asm/sections.h>
34 #define PANIC_TIMER_STEP 100
35 #define PANIC_BLINK_SPD 18
37 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
38 static unsigned long tainted_mask =
39 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
40 static int pause_on_oops;
41 static int pause_on_oops_flag;
42 static DEFINE_SPINLOCK(pause_on_oops_lock);
43 bool crash_kexec_post_notifiers;
44 int panic_on_warn __read_mostly;
46 int panic_timeout = CONFIG_PANIC_TIMEOUT;
47 EXPORT_SYMBOL_GPL(panic_timeout);
49 #define PANIC_PRINT_TASK_INFO 0x00000001
50 #define PANIC_PRINT_MEM_INFO 0x00000002
51 #define PANIC_PRINT_TIMER_INFO 0x00000004
52 #define PANIC_PRINT_LOCK_INFO 0x00000008
53 #define PANIC_PRINT_FTRACE_INFO 0x00000010
54 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
55 unsigned long panic_print;
57 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
59 EXPORT_SYMBOL(panic_notifier_list);
61 static long no_blink(int state)
66 /* Returns how long it waited in ms */
67 long (*panic_blink)(int state);
68 EXPORT_SYMBOL(panic_blink);
71 * Stop ourself in panic -- architecture code may override this
73 void __weak panic_smp_self_stop(void)
80 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
81 * may override this to prepare for crash dumping, e.g. save regs info.
83 void __weak nmi_panic_self_stop(struct pt_regs *regs)
85 panic_smp_self_stop();
89 * Stop other CPUs in panic. Architecture dependent code may override this
90 * with more suitable version. For example, if the architecture supports
91 * crash dump, it should save registers of each stopped CPU and disable
92 * per-CPU features such as virtualization extensions.
94 void __weak crash_smp_send_stop(void)
96 static int cpus_stopped;
99 * This function can be called twice in panic path, but obviously
100 * we execute this only once.
106 * Note smp_send_stop is the usual smp shutdown function, which
107 * unfortunately means it may not be hardened to work in a panic
114 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
117 * A variant of panic() called from NMI context. We return if we've already
118 * panicked on this CPU. If another CPU already panicked, loop in
119 * nmi_panic_self_stop() which can provide architecture dependent code such
120 * as saving register state for crash dump.
122 void nmi_panic(struct pt_regs *regs, const char *msg)
126 cpu = raw_smp_processor_id();
127 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
129 if (old_cpu == PANIC_CPU_INVALID)
131 else if (old_cpu != cpu)
132 nmi_panic_self_stop(regs);
134 EXPORT_SYMBOL(nmi_panic);
136 static void panic_print_sys_info(void)
138 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
139 console_flush_on_panic(CONSOLE_REPLAY_ALL);
141 if (panic_print & PANIC_PRINT_TASK_INFO)
144 if (panic_print & PANIC_PRINT_MEM_INFO)
147 if (panic_print & PANIC_PRINT_TIMER_INFO)
148 sysrq_timer_list_show();
150 if (panic_print & PANIC_PRINT_LOCK_INFO)
151 debug_show_all_locks();
153 if (panic_print & PANIC_PRINT_FTRACE_INFO)
154 ftrace_dump(DUMP_ALL);
158 * panic - halt the system
159 * @fmt: The text string to print
161 * Display a message, then perform cleanups.
163 * This function never returns.
165 void panic(const char *fmt, ...)
167 static char buf[1024];
169 long i, i_next = 0, len;
171 int old_cpu, this_cpu;
172 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
175 * Disable local interrupts. This will prevent panic_smp_self_stop
176 * from deadlocking the first cpu that invokes the panic, since
177 * there is nothing to prevent an interrupt handler (that runs
178 * after setting panic_cpu) from invoking panic() again.
183 * It's possible to come here directly from a panic-assertion and
184 * not have preempt disabled. Some functions called from here want
185 * preempt to be disabled. No point enabling it later though...
187 * Only one CPU is allowed to execute the panic code from here. For
188 * multiple parallel invocations of panic, all other CPUs either
189 * stop themself or will wait until they are stopped by the 1st CPU
190 * with smp_send_stop().
192 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
193 * comes here, so go ahead.
194 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
195 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
197 this_cpu = raw_smp_processor_id();
198 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
200 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
201 panic_smp_self_stop();
206 len = vscnprintf(buf, sizeof(buf), fmt, args);
209 if (len && buf[len - 1] == '\n')
212 pr_emerg("Kernel panic - not syncing: %s\n", buf);
213 #ifdef CONFIG_DEBUG_BUGVERBOSE
215 * Avoid nested stack-dumping if a panic occurs during oops processing
217 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
222 * If we have crashed and we have a crash kernel loaded let it handle
224 * If we want to run this after calling panic_notifiers, pass
225 * the "crash_kexec_post_notifiers" option to the kernel.
227 * Bypass the panic_cpu check and call __crash_kexec directly.
229 if (!_crash_kexec_post_notifiers) {
230 printk_safe_flush_on_panic();
234 * Note smp_send_stop is the usual smp shutdown function, which
235 * unfortunately means it may not be hardened to work in a
241 * If we want to do crash dump after notifier calls and
242 * kmsg_dump, we will need architecture dependent extra
243 * works in addition to stopping other CPUs.
245 crash_smp_send_stop();
249 * Run any panic handlers, including those that might need to
250 * add information to the kmsg dump output.
252 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
254 /* Call flush even twice. It tries harder with a single online CPU */
255 printk_safe_flush_on_panic();
256 kmsg_dump(KMSG_DUMP_PANIC);
259 * If you doubt kdump always works fine in any situation,
260 * "crash_kexec_post_notifiers" offers you a chance to run
261 * panic_notifiers and dumping kmsg before kdump.
262 * Note: since some panic_notifiers can make crashed kernel
263 * more unstable, it can increase risks of the kdump failure too.
265 * Bypass the panic_cpu check and call __crash_kexec directly.
267 if (_crash_kexec_post_notifiers)
276 * We may have ended up stopping the CPU holding the lock (in
277 * smp_send_stop()) while still having some valuable data in the console
278 * buffer. Try to acquire the lock then release it regardless of the
279 * result. The release will also print the buffers out. Locks debug
280 * should be disabled to avoid reporting bad unlock balance when
281 * panic() is not being callled from OOPS.
284 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
286 panic_print_sys_info();
289 panic_blink = no_blink;
291 if (panic_timeout > 0) {
293 * Delay timeout seconds before rebooting the machine.
294 * We can't use the "normal" timers since we just panicked.
296 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
298 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
299 touch_nmi_watchdog();
301 i += panic_blink(state ^= 1);
302 i_next = i + 3600 / PANIC_BLINK_SPD;
304 mdelay(PANIC_TIMER_STEP);
307 if (panic_timeout != 0) {
309 * This will not be a clean reboot, with everything
310 * shutting down. But if there is a chance of
311 * rebooting the system it will be rebooted.
313 if (panic_reboot_mode != REBOOT_UNDEFINED)
314 reboot_mode = panic_reboot_mode;
319 extern int stop_a_enabled;
320 /* Make sure the user can actually press Stop-A (L1-A) */
322 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
323 "twice on console to return to the boot prom\n");
326 #if defined(CONFIG_S390)
329 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
331 /* Do not scroll important messages printed above */
334 for (i = 0; ; i += PANIC_TIMER_STEP) {
335 touch_softlockup_watchdog();
337 i += panic_blink(state ^= 1);
338 i_next = i + 3600 / PANIC_BLINK_SPD;
340 mdelay(PANIC_TIMER_STEP);
344 EXPORT_SYMBOL(panic);
347 * TAINT_FORCED_RMMOD could be a per-module flag but the module
348 * is being removed anyway.
350 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
351 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
352 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
353 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
354 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
355 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
356 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
357 [ TAINT_USER ] = { 'U', ' ', false },
358 [ TAINT_DIE ] = { 'D', ' ', false },
359 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
360 [ TAINT_WARN ] = { 'W', ' ', false },
361 [ TAINT_CRAP ] = { 'C', ' ', true },
362 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
363 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
364 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
365 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
366 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
367 [ TAINT_AUX ] = { 'X', ' ', true },
368 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
372 * print_tainted - return a string to represent the kernel taint state.
374 * For individual taint flag meanings, see Documentation/sysctl/kernel.txt
376 * The string is overwritten by the next call to print_tainted(),
377 * but is always NULL terminated.
379 const char *print_tainted(void)
381 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
383 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
389 s = buf + sprintf(buf, "Tainted: ");
390 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
391 const struct taint_flag *t = &taint_flags[i];
392 *s++ = test_bit(i, &tainted_mask) ?
393 t->c_true : t->c_false;
397 snprintf(buf, sizeof(buf), "Not tainted");
402 int test_taint(unsigned flag)
404 return test_bit(flag, &tainted_mask);
406 EXPORT_SYMBOL(test_taint);
408 unsigned long get_taint(void)
414 * add_taint: add a taint flag if not already set.
415 * @flag: one of the TAINT_* constants.
416 * @lockdep_ok: whether lock debugging is still OK.
418 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
419 * some notewortht-but-not-corrupting cases, it can be set to true.
421 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
423 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
424 pr_warn("Disabling lock debugging due to kernel taint\n");
426 set_bit(flag, &tainted_mask);
428 EXPORT_SYMBOL(add_taint);
430 static void spin_msec(int msecs)
434 for (i = 0; i < msecs; i++) {
435 touch_nmi_watchdog();
441 * It just happens that oops_enter() and oops_exit() are identically
444 static void do_oops_enter_exit(void)
447 static int spin_counter;
452 spin_lock_irqsave(&pause_on_oops_lock, flags);
453 if (pause_on_oops_flag == 0) {
454 /* This CPU may now print the oops message */
455 pause_on_oops_flag = 1;
457 /* We need to stall this CPU */
459 /* This CPU gets to do the counting */
460 spin_counter = pause_on_oops;
462 spin_unlock(&pause_on_oops_lock);
463 spin_msec(MSEC_PER_SEC);
464 spin_lock(&pause_on_oops_lock);
465 } while (--spin_counter);
466 pause_on_oops_flag = 0;
468 /* This CPU waits for a different one */
469 while (spin_counter) {
470 spin_unlock(&pause_on_oops_lock);
472 spin_lock(&pause_on_oops_lock);
476 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
480 * Return true if the calling CPU is allowed to print oops-related info.
481 * This is a bit racy..
483 int oops_may_print(void)
485 return pause_on_oops_flag == 0;
489 * Called when the architecture enters its oops handler, before it prints
490 * anything. If this is the first CPU to oops, and it's oopsing the first
491 * time then let it proceed.
493 * This is all enabled by the pause_on_oops kernel boot option. We do all
494 * this to ensure that oopses don't scroll off the screen. It has the
495 * side-effect of preventing later-oopsing CPUs from mucking up the display,
498 * It turns out that the CPU which is allowed to print ends up pausing for
499 * the right duration, whereas all the other CPUs pause for twice as long:
500 * once in oops_enter(), once in oops_exit().
502 void oops_enter(void)
505 /* can't trust the integrity of the kernel anymore: */
507 do_oops_enter_exit();
511 * 64-bit random ID for oopses:
515 static int init_oops_id(void)
518 get_random_bytes(&oops_id, sizeof(oops_id));
524 late_initcall(init_oops_id);
526 void print_oops_end_marker(void)
529 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
533 * Called when the architecture exits its oops handler, after printing
538 do_oops_enter_exit();
539 print_oops_end_marker();
540 kmsg_dump(KMSG_DUMP_OOPS);
548 void __warn(const char *file, int line, void *caller, unsigned taint,
549 struct pt_regs *regs, struct warn_args *args)
551 disable_trace_on_warning();
557 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
558 raw_smp_processor_id(), current->pid, file, line,
561 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
562 raw_smp_processor_id(), current->pid, caller);
565 vprintk(args->fmt, args->args);
569 * This thread may hit another WARN() in the panic path.
570 * Resetting this prevents additional WARN() from panicking the
571 * system on this thread. Other threads are blocked by the
572 * panic_mutex in panic().
575 panic("panic_on_warn set ...\n");
585 print_irqtrace_events(current);
587 print_oops_end_marker();
589 /* Just a warning, don't kill lockdep. */
590 add_taint(taint, LOCKDEP_STILL_OK);
593 #ifdef WANT_WARN_ON_SLOWPATH
594 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
596 struct warn_args args;
599 va_start(args.args, fmt);
600 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
604 EXPORT_SYMBOL(warn_slowpath_fmt);
606 void warn_slowpath_fmt_taint(const char *file, int line,
607 unsigned taint, const char *fmt, ...)
609 struct warn_args args;
612 va_start(args.args, fmt);
613 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
616 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
618 void warn_slowpath_null(const char *file, int line)
621 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
623 EXPORT_SYMBOL(warn_slowpath_null);
625 void __warn_printk(const char *fmt, ...)
635 EXPORT_SYMBOL(__warn_printk);
640 /* Support resetting WARN*_ONCE state */
642 static int clear_warn_once_set(void *data, u64 val)
644 generic_bug_clear_once();
645 memset(__start_once, 0, __end_once - __start_once);
649 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
652 static __init int register_warn_debugfs(void)
654 /* Don't care about failure */
655 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
656 &clear_warn_once_fops);
660 device_initcall(register_warn_debugfs);
663 #ifdef CONFIG_STACKPROTECTOR
666 * Called when gcc's -fstack-protector feature is used, and
667 * gcc detects corruption of the on-stack canary value
669 __visible void __stack_chk_fail(void)
671 panic("stack-protector: Kernel stack is corrupted in: %pB",
672 __builtin_return_address(0));
674 EXPORT_SYMBOL(__stack_chk_fail);
678 #ifdef CONFIG_ARCH_HAS_REFCOUNT
679 void refcount_error_report(struct pt_regs *regs, const char *err)
681 WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
682 err, (void *)instruction_pointer(regs),
683 current->comm, task_pid_nr(current),
684 from_kuid_munged(&init_user_ns, current_uid()),
685 from_kuid_munged(&init_user_ns, current_euid()));
689 core_param(panic, panic_timeout, int, 0644);
690 core_param(panic_print, panic_print, ulong, 0644);
691 core_param(pause_on_oops, pause_on_oops, int, 0644);
692 core_param(panic_on_warn, panic_on_warn, int, 0644);
693 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
695 static int __init oops_setup(char *s)
699 if (!strcmp(s, "panic"))
703 early_param("oops", oops_setup);