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 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
51 EXPORT_SYMBOL(panic_notifier_list);
53 static long no_blink(int state)
58 /* Returns how long it waited in ms */
59 long (*panic_blink)(int state);
60 EXPORT_SYMBOL(panic_blink);
63 * Stop ourself in panic -- architecture code may override this
65 void __weak panic_smp_self_stop(void)
72 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
73 * may override this to prepare for crash dumping, e.g. save regs info.
75 void __weak nmi_panic_self_stop(struct pt_regs *regs)
77 panic_smp_self_stop();
81 * Stop other CPUs in panic. Architecture dependent code may override this
82 * with more suitable version. For example, if the architecture supports
83 * crash dump, it should save registers of each stopped CPU and disable
84 * per-CPU features such as virtualization extensions.
86 void __weak crash_smp_send_stop(void)
88 static int cpus_stopped;
91 * This function can be called twice in panic path, but obviously
92 * we execute this only once.
98 * Note smp_send_stop is the usual smp shutdown function, which
99 * unfortunately means it may not be hardened to work in a panic
106 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
109 * A variant of panic() called from NMI context. We return if we've already
110 * panicked on this CPU. If another CPU already panicked, loop in
111 * nmi_panic_self_stop() which can provide architecture dependent code such
112 * as saving register state for crash dump.
114 void nmi_panic(struct pt_regs *regs, const char *msg)
118 cpu = raw_smp_processor_id();
119 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
121 if (old_cpu == PANIC_CPU_INVALID)
123 else if (old_cpu != cpu)
124 nmi_panic_self_stop(regs);
126 EXPORT_SYMBOL(nmi_panic);
129 * panic - halt the system
130 * @fmt: The text string to print
132 * Display a message, then perform cleanups.
134 * This function never returns.
136 void panic(const char *fmt, ...)
138 static char buf[1024];
142 int old_cpu, this_cpu;
143 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
146 * Disable local interrupts. This will prevent panic_smp_self_stop
147 * from deadlocking the first cpu that invokes the panic, since
148 * there is nothing to prevent an interrupt handler (that runs
149 * after setting panic_cpu) from invoking panic() again.
152 preempt_disable_notrace();
155 * It's possible to come here directly from a panic-assertion and
156 * not have preempt disabled. Some functions called from here want
157 * preempt to be disabled. No point enabling it later though...
159 * Only one CPU is allowed to execute the panic code from here. For
160 * multiple parallel invocations of panic, all other CPUs either
161 * stop themself or will wait until they are stopped by the 1st CPU
162 * with smp_send_stop().
164 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
165 * comes here, so go ahead.
166 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
167 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
169 this_cpu = raw_smp_processor_id();
170 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
172 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
173 panic_smp_self_stop();
178 vsnprintf(buf, sizeof(buf), fmt, args);
180 pr_emerg("Kernel panic - not syncing: %s\n", buf);
181 #ifdef CONFIG_DEBUG_BUGVERBOSE
183 * Avoid nested stack-dumping if a panic occurs during oops processing
185 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
190 * If we have crashed and we have a crash kernel loaded let it handle
192 * If we want to run this after calling panic_notifiers, pass
193 * the "crash_kexec_post_notifiers" option to the kernel.
195 * Bypass the panic_cpu check and call __crash_kexec directly.
197 if (!_crash_kexec_post_notifiers) {
198 printk_safe_flush_on_panic();
202 * Note smp_send_stop is the usual smp shutdown function, which
203 * unfortunately means it may not be hardened to work in a
209 * If we want to do crash dump after notifier calls and
210 * kmsg_dump, we will need architecture dependent extra
211 * works in addition to stopping other CPUs.
213 crash_smp_send_stop();
217 * Run any panic handlers, including those that might need to
218 * add information to the kmsg dump output.
220 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
222 /* Call flush even twice. It tries harder with a single online CPU */
223 printk_safe_flush_on_panic();
224 kmsg_dump(KMSG_DUMP_PANIC);
227 * If you doubt kdump always works fine in any situation,
228 * "crash_kexec_post_notifiers" offers you a chance to run
229 * panic_notifiers and dumping kmsg before kdump.
230 * Note: since some panic_notifiers can make crashed kernel
231 * more unstable, it can increase risks of the kdump failure too.
233 * Bypass the panic_cpu check and call __crash_kexec directly.
235 if (_crash_kexec_post_notifiers)
244 * We may have ended up stopping the CPU holding the lock (in
245 * smp_send_stop()) while still having some valuable data in the console
246 * buffer. Try to acquire the lock then release it regardless of the
247 * result. The release will also print the buffers out. Locks debug
248 * should be disabled to avoid reporting bad unlock balance when
249 * panic() is not being callled from OOPS.
252 console_flush_on_panic();
255 panic_blink = no_blink;
257 if (panic_timeout > 0) {
259 * Delay timeout seconds before rebooting the machine.
260 * We can't use the "normal" timers since we just panicked.
262 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
264 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
265 touch_nmi_watchdog();
267 i += panic_blink(state ^= 1);
268 i_next = i + 3600 / PANIC_BLINK_SPD;
270 mdelay(PANIC_TIMER_STEP);
273 if (panic_timeout != 0) {
275 * This will not be a clean reboot, with everything
276 * shutting down. But if there is a chance of
277 * rebooting the system it will be rebooted.
283 extern int stop_a_enabled;
284 /* Make sure the user can actually press Stop-A (L1-A) */
286 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
287 "twice on console to return to the boot prom\n");
290 #if defined(CONFIG_S390)
292 unsigned long caller;
294 caller = (unsigned long)__builtin_return_address(0);
295 disabled_wait(caller);
298 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
300 for (i = 0; ; i += PANIC_TIMER_STEP) {
301 touch_softlockup_watchdog();
303 i += panic_blink(state ^= 1);
304 i_next = i + 3600 / PANIC_BLINK_SPD;
306 mdelay(PANIC_TIMER_STEP);
310 EXPORT_SYMBOL(panic);
313 * TAINT_FORCED_RMMOD could be a per-module flag but the module
314 * is being removed anyway.
316 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
317 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
318 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
319 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
320 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
321 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
322 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
323 [ TAINT_USER ] = { 'U', ' ', false },
324 [ TAINT_DIE ] = { 'D', ' ', false },
325 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
326 [ TAINT_WARN ] = { 'W', ' ', false },
327 [ TAINT_CRAP ] = { 'C', ' ', true },
328 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
329 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
330 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
331 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
332 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
333 [ TAINT_AUX ] = { 'X', ' ', true },
334 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
338 * print_tainted - return a string to represent the kernel taint state.
340 * For individual taint flag meanings, see Documentation/sysctl/kernel.txt
342 * The string is overwritten by the next call to print_tainted(),
343 * but is always NULL terminated.
345 const char *print_tainted(void)
347 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
349 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
355 s = buf + sprintf(buf, "Tainted: ");
356 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
357 const struct taint_flag *t = &taint_flags[i];
358 *s++ = test_bit(i, &tainted_mask) ?
359 t->c_true : t->c_false;
363 snprintf(buf, sizeof(buf), "Not tainted");
368 int test_taint(unsigned flag)
370 return test_bit(flag, &tainted_mask);
372 EXPORT_SYMBOL(test_taint);
374 unsigned long get_taint(void)
380 * add_taint: add a taint flag if not already set.
381 * @flag: one of the TAINT_* constants.
382 * @lockdep_ok: whether lock debugging is still OK.
384 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
385 * some notewortht-but-not-corrupting cases, it can be set to true.
387 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
389 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
390 pr_warn("Disabling lock debugging due to kernel taint\n");
392 set_bit(flag, &tainted_mask);
394 EXPORT_SYMBOL(add_taint);
396 static void spin_msec(int msecs)
400 for (i = 0; i < msecs; i++) {
401 touch_nmi_watchdog();
407 * It just happens that oops_enter() and oops_exit() are identically
410 static void do_oops_enter_exit(void)
413 static int spin_counter;
418 spin_lock_irqsave(&pause_on_oops_lock, flags);
419 if (pause_on_oops_flag == 0) {
420 /* This CPU may now print the oops message */
421 pause_on_oops_flag = 1;
423 /* We need to stall this CPU */
425 /* This CPU gets to do the counting */
426 spin_counter = pause_on_oops;
428 spin_unlock(&pause_on_oops_lock);
429 spin_msec(MSEC_PER_SEC);
430 spin_lock(&pause_on_oops_lock);
431 } while (--spin_counter);
432 pause_on_oops_flag = 0;
434 /* This CPU waits for a different one */
435 while (spin_counter) {
436 spin_unlock(&pause_on_oops_lock);
438 spin_lock(&pause_on_oops_lock);
442 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
446 * Return true if the calling CPU is allowed to print oops-related info.
447 * This is a bit racy..
449 int oops_may_print(void)
451 return pause_on_oops_flag == 0;
455 * Called when the architecture enters its oops handler, before it prints
456 * anything. If this is the first CPU to oops, and it's oopsing the first
457 * time then let it proceed.
459 * This is all enabled by the pause_on_oops kernel boot option. We do all
460 * this to ensure that oopses don't scroll off the screen. It has the
461 * side-effect of preventing later-oopsing CPUs from mucking up the display,
464 * It turns out that the CPU which is allowed to print ends up pausing for
465 * the right duration, whereas all the other CPUs pause for twice as long:
466 * once in oops_enter(), once in oops_exit().
468 void oops_enter(void)
471 /* can't trust the integrity of the kernel anymore: */
473 do_oops_enter_exit();
477 * 64-bit random ID for oopses:
481 static int init_oops_id(void)
484 get_random_bytes(&oops_id, sizeof(oops_id));
490 late_initcall(init_oops_id);
492 void print_oops_end_marker(void)
495 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
499 * Called when the architecture exits its oops handler, after printing
504 do_oops_enter_exit();
505 print_oops_end_marker();
506 kmsg_dump(KMSG_DUMP_OOPS);
514 void __warn(const char *file, int line, void *caller, unsigned taint,
515 struct pt_regs *regs, struct warn_args *args)
517 disable_trace_on_warning();
523 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
524 raw_smp_processor_id(), current->pid, file, line,
527 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
528 raw_smp_processor_id(), current->pid, caller);
531 vprintk(args->fmt, args->args);
535 * This thread may hit another WARN() in the panic path.
536 * Resetting this prevents additional WARN() from panicking the
537 * system on this thread. Other threads are blocked by the
538 * panic_mutex in panic().
541 panic("panic_on_warn set ...\n");
551 print_irqtrace_events(current);
553 print_oops_end_marker();
555 /* Just a warning, don't kill lockdep. */
556 add_taint(taint, LOCKDEP_STILL_OK);
559 #ifdef WANT_WARN_ON_SLOWPATH
560 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
562 struct warn_args args;
565 va_start(args.args, fmt);
566 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
570 EXPORT_SYMBOL(warn_slowpath_fmt);
572 void warn_slowpath_fmt_taint(const char *file, int line,
573 unsigned taint, const char *fmt, ...)
575 struct warn_args args;
578 va_start(args.args, fmt);
579 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
582 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
584 void warn_slowpath_null(const char *file, int line)
587 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
589 EXPORT_SYMBOL(warn_slowpath_null);
591 void __warn_printk(const char *fmt, ...)
601 EXPORT_SYMBOL(__warn_printk);
606 /* Support resetting WARN*_ONCE state */
608 static int clear_warn_once_set(void *data, u64 val)
610 generic_bug_clear_once();
611 memset(__start_once, 0, __end_once - __start_once);
615 DEFINE_SIMPLE_ATTRIBUTE(clear_warn_once_fops,
620 static __init int register_warn_debugfs(void)
622 /* Don't care about failure */
623 debugfs_create_file("clear_warn_once", 0200, NULL,
624 NULL, &clear_warn_once_fops);
628 device_initcall(register_warn_debugfs);
631 #ifdef CONFIG_STACKPROTECTOR
634 * Called when gcc's -fstack-protector feature is used, and
635 * gcc detects corruption of the on-stack canary value
637 __visible void __stack_chk_fail(void)
639 panic("stack-protector: Kernel stack is corrupted in: %pB",
640 __builtin_return_address(0));
642 EXPORT_SYMBOL(__stack_chk_fail);
646 #ifdef CONFIG_ARCH_HAS_REFCOUNT
647 void refcount_error_report(struct pt_regs *regs, const char *err)
649 WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
650 err, (void *)instruction_pointer(regs),
651 current->comm, task_pid_nr(current),
652 from_kuid_munged(&init_user_ns, current_uid()),
653 from_kuid_munged(&init_user_ns, current_euid()));
657 core_param(panic, panic_timeout, int, 0644);
658 core_param(pause_on_oops, pause_on_oops, int, 0644);
659 core_param(panic_on_warn, panic_on_warn, int, 0644);
660 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
662 static int __init oops_setup(char *s)
666 if (!strcmp(s, "panic"))
670 early_param("oops", oops_setup);