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 unsigned long panic_print;
56 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
58 EXPORT_SYMBOL(panic_notifier_list);
60 static long no_blink(int state)
65 /* Returns how long it waited in ms */
66 long (*panic_blink)(int state);
67 EXPORT_SYMBOL(panic_blink);
70 * Stop ourself in panic -- architecture code may override this
72 void __weak panic_smp_self_stop(void)
79 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
80 * may override this to prepare for crash dumping, e.g. save regs info.
82 void __weak nmi_panic_self_stop(struct pt_regs *regs)
84 panic_smp_self_stop();
88 * Stop other CPUs in panic. Architecture dependent code may override this
89 * with more suitable version. For example, if the architecture supports
90 * crash dump, it should save registers of each stopped CPU and disable
91 * per-CPU features such as virtualization extensions.
93 void __weak crash_smp_send_stop(void)
95 static int cpus_stopped;
98 * This function can be called twice in panic path, but obviously
99 * we execute this only once.
105 * Note smp_send_stop is the usual smp shutdown function, which
106 * unfortunately means it may not be hardened to work in a panic
113 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
116 * A variant of panic() called from NMI context. We return if we've already
117 * panicked on this CPU. If another CPU already panicked, loop in
118 * nmi_panic_self_stop() which can provide architecture dependent code such
119 * as saving register state for crash dump.
121 void nmi_panic(struct pt_regs *regs, const char *msg)
125 cpu = raw_smp_processor_id();
126 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
128 if (old_cpu == PANIC_CPU_INVALID)
130 else if (old_cpu != cpu)
131 nmi_panic_self_stop(regs);
133 EXPORT_SYMBOL(nmi_panic);
135 static void panic_print_sys_info(void)
137 if (panic_print & PANIC_PRINT_TASK_INFO)
140 if (panic_print & PANIC_PRINT_MEM_INFO)
143 if (panic_print & PANIC_PRINT_TIMER_INFO)
144 sysrq_timer_list_show();
146 if (panic_print & PANIC_PRINT_LOCK_INFO)
147 debug_show_all_locks();
149 if (panic_print & PANIC_PRINT_FTRACE_INFO)
150 ftrace_dump(DUMP_ALL);
154 * panic - halt the system
155 * @fmt: The text string to print
157 * Display a message, then perform cleanups.
159 * This function never returns.
161 void panic(const char *fmt, ...)
163 static char buf[1024];
165 long i, i_next = 0, len;
167 int old_cpu, this_cpu;
168 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
171 * Disable local interrupts. This will prevent panic_smp_self_stop
172 * from deadlocking the first cpu that invokes the panic, since
173 * there is nothing to prevent an interrupt handler (that runs
174 * after setting panic_cpu) from invoking panic() again.
179 * It's possible to come here directly from a panic-assertion and
180 * not have preempt disabled. Some functions called from here want
181 * preempt to be disabled. No point enabling it later though...
183 * Only one CPU is allowed to execute the panic code from here. For
184 * multiple parallel invocations of panic, all other CPUs either
185 * stop themself or will wait until they are stopped by the 1st CPU
186 * with smp_send_stop().
188 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
189 * comes here, so go ahead.
190 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
191 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
193 this_cpu = raw_smp_processor_id();
194 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
196 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
197 panic_smp_self_stop();
202 len = vscnprintf(buf, sizeof(buf), fmt, args);
205 if (len && buf[len - 1] == '\n')
208 pr_emerg("Kernel panic - not syncing: %s\n", buf);
209 #ifdef CONFIG_DEBUG_BUGVERBOSE
211 * Avoid nested stack-dumping if a panic occurs during oops processing
213 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
218 * If we have crashed and we have a crash kernel loaded let it handle
220 * If we want to run this after calling panic_notifiers, pass
221 * the "crash_kexec_post_notifiers" option to the kernel.
223 * Bypass the panic_cpu check and call __crash_kexec directly.
225 if (!_crash_kexec_post_notifiers) {
226 printk_safe_flush_on_panic();
230 * Note smp_send_stop is the usual smp shutdown function, which
231 * unfortunately means it may not be hardened to work in a
237 * If we want to do crash dump after notifier calls and
238 * kmsg_dump, we will need architecture dependent extra
239 * works in addition to stopping other CPUs.
241 crash_smp_send_stop();
245 * Run any panic handlers, including those that might need to
246 * add information to the kmsg dump output.
248 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
250 /* Call flush even twice. It tries harder with a single online CPU */
251 printk_safe_flush_on_panic();
252 kmsg_dump(KMSG_DUMP_PANIC);
255 * If you doubt kdump always works fine in any situation,
256 * "crash_kexec_post_notifiers" offers you a chance to run
257 * panic_notifiers and dumping kmsg before kdump.
258 * Note: since some panic_notifiers can make crashed kernel
259 * more unstable, it can increase risks of the kdump failure too.
261 * Bypass the panic_cpu check and call __crash_kexec directly.
263 if (_crash_kexec_post_notifiers)
272 * We may have ended up stopping the CPU holding the lock (in
273 * smp_send_stop()) while still having some valuable data in the console
274 * buffer. Try to acquire the lock then release it regardless of the
275 * result. The release will also print the buffers out. Locks debug
276 * should be disabled to avoid reporting bad unlock balance when
277 * panic() is not being callled from OOPS.
280 console_flush_on_panic();
282 panic_print_sys_info();
285 panic_blink = no_blink;
287 if (panic_timeout > 0) {
289 * Delay timeout seconds before rebooting the machine.
290 * We can't use the "normal" timers since we just panicked.
292 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
294 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
295 touch_nmi_watchdog();
297 i += panic_blink(state ^= 1);
298 i_next = i + 3600 / PANIC_BLINK_SPD;
300 mdelay(PANIC_TIMER_STEP);
303 if (panic_timeout != 0) {
305 * This will not be a clean reboot, with everything
306 * shutting down. But if there is a chance of
307 * rebooting the system it will be rebooted.
313 extern int stop_a_enabled;
314 /* Make sure the user can actually press Stop-A (L1-A) */
316 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
317 "twice on console to return to the boot prom\n");
320 #if defined(CONFIG_S390)
323 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
325 for (i = 0; ; i += PANIC_TIMER_STEP) {
326 touch_softlockup_watchdog();
328 i += panic_blink(state ^= 1);
329 i_next = i + 3600 / PANIC_BLINK_SPD;
331 mdelay(PANIC_TIMER_STEP);
335 EXPORT_SYMBOL(panic);
338 * TAINT_FORCED_RMMOD could be a per-module flag but the module
339 * is being removed anyway.
341 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
342 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
343 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
344 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
345 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
346 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
347 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
348 [ TAINT_USER ] = { 'U', ' ', false },
349 [ TAINT_DIE ] = { 'D', ' ', false },
350 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
351 [ TAINT_WARN ] = { 'W', ' ', false },
352 [ TAINT_CRAP ] = { 'C', ' ', true },
353 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
354 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
355 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
356 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
357 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
358 [ TAINT_AUX ] = { 'X', ' ', true },
359 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
363 * print_tainted - return a string to represent the kernel taint state.
365 * For individual taint flag meanings, see Documentation/sysctl/kernel.txt
367 * The string is overwritten by the next call to print_tainted(),
368 * but is always NULL terminated.
370 const char *print_tainted(void)
372 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
374 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
380 s = buf + sprintf(buf, "Tainted: ");
381 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
382 const struct taint_flag *t = &taint_flags[i];
383 *s++ = test_bit(i, &tainted_mask) ?
384 t->c_true : t->c_false;
388 snprintf(buf, sizeof(buf), "Not tainted");
393 int test_taint(unsigned flag)
395 return test_bit(flag, &tainted_mask);
397 EXPORT_SYMBOL(test_taint);
399 unsigned long get_taint(void)
405 * add_taint: add a taint flag if not already set.
406 * @flag: one of the TAINT_* constants.
407 * @lockdep_ok: whether lock debugging is still OK.
409 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
410 * some notewortht-but-not-corrupting cases, it can be set to true.
412 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
414 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
415 pr_warn("Disabling lock debugging due to kernel taint\n");
417 set_bit(flag, &tainted_mask);
419 EXPORT_SYMBOL(add_taint);
421 static void spin_msec(int msecs)
425 for (i = 0; i < msecs; i++) {
426 touch_nmi_watchdog();
432 * It just happens that oops_enter() and oops_exit() are identically
435 static void do_oops_enter_exit(void)
438 static int spin_counter;
443 spin_lock_irqsave(&pause_on_oops_lock, flags);
444 if (pause_on_oops_flag == 0) {
445 /* This CPU may now print the oops message */
446 pause_on_oops_flag = 1;
448 /* We need to stall this CPU */
450 /* This CPU gets to do the counting */
451 spin_counter = pause_on_oops;
453 spin_unlock(&pause_on_oops_lock);
454 spin_msec(MSEC_PER_SEC);
455 spin_lock(&pause_on_oops_lock);
456 } while (--spin_counter);
457 pause_on_oops_flag = 0;
459 /* This CPU waits for a different one */
460 while (spin_counter) {
461 spin_unlock(&pause_on_oops_lock);
463 spin_lock(&pause_on_oops_lock);
467 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
471 * Return true if the calling CPU is allowed to print oops-related info.
472 * This is a bit racy..
474 int oops_may_print(void)
476 return pause_on_oops_flag == 0;
480 * Called when the architecture enters its oops handler, before it prints
481 * anything. If this is the first CPU to oops, and it's oopsing the first
482 * time then let it proceed.
484 * This is all enabled by the pause_on_oops kernel boot option. We do all
485 * this to ensure that oopses don't scroll off the screen. It has the
486 * side-effect of preventing later-oopsing CPUs from mucking up the display,
489 * It turns out that the CPU which is allowed to print ends up pausing for
490 * the right duration, whereas all the other CPUs pause for twice as long:
491 * once in oops_enter(), once in oops_exit().
493 void oops_enter(void)
496 /* can't trust the integrity of the kernel anymore: */
498 do_oops_enter_exit();
502 * 64-bit random ID for oopses:
506 static int init_oops_id(void)
509 get_random_bytes(&oops_id, sizeof(oops_id));
515 late_initcall(init_oops_id);
517 void print_oops_end_marker(void)
520 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
524 * Called when the architecture exits its oops handler, after printing
529 do_oops_enter_exit();
530 print_oops_end_marker();
531 kmsg_dump(KMSG_DUMP_OOPS);
539 void __warn(const char *file, int line, void *caller, unsigned taint,
540 struct pt_regs *regs, struct warn_args *args)
542 disable_trace_on_warning();
548 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
549 raw_smp_processor_id(), current->pid, file, line,
552 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
553 raw_smp_processor_id(), current->pid, caller);
556 vprintk(args->fmt, args->args);
560 * This thread may hit another WARN() in the panic path.
561 * Resetting this prevents additional WARN() from panicking the
562 * system on this thread. Other threads are blocked by the
563 * panic_mutex in panic().
566 panic("panic_on_warn set ...\n");
576 print_irqtrace_events(current);
578 print_oops_end_marker();
580 /* Just a warning, don't kill lockdep. */
581 add_taint(taint, LOCKDEP_STILL_OK);
584 #ifdef WANT_WARN_ON_SLOWPATH
585 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
587 struct warn_args args;
590 va_start(args.args, fmt);
591 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
595 EXPORT_SYMBOL(warn_slowpath_fmt);
597 void warn_slowpath_fmt_taint(const char *file, int line,
598 unsigned taint, const char *fmt, ...)
600 struct warn_args args;
603 va_start(args.args, fmt);
604 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
607 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
609 void warn_slowpath_null(const char *file, int line)
612 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
614 EXPORT_SYMBOL(warn_slowpath_null);
616 void __warn_printk(const char *fmt, ...)
626 EXPORT_SYMBOL(__warn_printk);
631 /* Support resetting WARN*_ONCE state */
633 static int clear_warn_once_set(void *data, u64 val)
635 generic_bug_clear_once();
636 memset(__start_once, 0, __end_once - __start_once);
640 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
643 static __init int register_warn_debugfs(void)
645 /* Don't care about failure */
646 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
647 &clear_warn_once_fops);
651 device_initcall(register_warn_debugfs);
654 #ifdef CONFIG_STACKPROTECTOR
657 * Called when gcc's -fstack-protector feature is used, and
658 * gcc detects corruption of the on-stack canary value
660 __visible void __stack_chk_fail(void)
662 panic("stack-protector: Kernel stack is corrupted in: %pB",
663 __builtin_return_address(0));
665 EXPORT_SYMBOL(__stack_chk_fail);
669 #ifdef CONFIG_ARCH_HAS_REFCOUNT
670 void refcount_error_report(struct pt_regs *regs, const char *err)
672 WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
673 err, (void *)instruction_pointer(regs),
674 current->comm, task_pid_nr(current),
675 from_kuid_munged(&init_user_ns, current_uid()),
676 from_kuid_munged(&init_user_ns, current_euid()));
680 core_param(panic, panic_timeout, int, 0644);
681 core_param(panic_print, panic_print, ulong, 0644);
682 core_param(pause_on_oops, pause_on_oops, int, 0644);
683 core_param(panic_on_warn, panic_on_warn, int, 0644);
684 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
686 static int __init oops_setup(char *s)
690 if (!strcmp(s, "panic"))
694 early_param("oops", oops_setup);