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/interrupt.h>
13 #include <linux/kmsg_dump.h>
14 #include <linux/kallsyms.h>
15 #include <linux/notifier.h>
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/ftrace.h>
19 #include <linux/reboot.h>
20 #include <linux/delay.h>
21 #include <linux/kexec.h>
22 #include <linux/sched.h>
23 #include <linux/sysrq.h>
24 #include <linux/init.h>
25 #include <linux/nmi.h>
26 #include <linux/console.h>
27 #include <linux/bug.h>
29 #define PANIC_TIMER_STEP 100
30 #define PANIC_BLINK_SPD 18
32 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
33 static unsigned long tainted_mask;
34 static int pause_on_oops;
35 static int pause_on_oops_flag;
36 static DEFINE_SPINLOCK(pause_on_oops_lock);
37 bool crash_kexec_post_notifiers;
38 int panic_on_warn __read_mostly;
40 int panic_timeout = CONFIG_PANIC_TIMEOUT;
41 EXPORT_SYMBOL_GPL(panic_timeout);
43 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
45 EXPORT_SYMBOL(panic_notifier_list);
47 static long no_blink(int state)
52 /* Returns how long it waited in ms */
53 long (*panic_blink)(int state);
54 EXPORT_SYMBOL(panic_blink);
57 * Stop ourself in panic -- architecture code may override this
59 void __weak panic_smp_self_stop(void)
66 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
67 * may override this to prepare for crash dumping, e.g. save regs info.
69 void __weak nmi_panic_self_stop(struct pt_regs *regs)
71 panic_smp_self_stop();
74 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
77 * A variant of panic() called from NMI context. We return if we've already
78 * panicked on this CPU. If another CPU already panicked, loop in
79 * nmi_panic_self_stop() which can provide architecture dependent code such
80 * as saving register state for crash dump.
82 void nmi_panic(struct pt_regs *regs, const char *msg)
86 cpu = raw_smp_processor_id();
87 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
89 if (old_cpu == PANIC_CPU_INVALID)
91 else if (old_cpu != cpu)
92 nmi_panic_self_stop(regs);
94 EXPORT_SYMBOL(nmi_panic);
97 * panic - halt the system
98 * @fmt: The text string to print
100 * Display a message, then perform cleanups.
102 * This function never returns.
104 void panic(const char *fmt, ...)
106 static char buf[1024];
110 int old_cpu, this_cpu;
113 * Disable local interrupts. This will prevent panic_smp_self_stop
114 * from deadlocking the first cpu that invokes the panic, since
115 * there is nothing to prevent an interrupt handler (that runs
116 * after setting panic_cpu) from invoking panic() again.
121 * It's possible to come here directly from a panic-assertion and
122 * not have preempt disabled. Some functions called from here want
123 * preempt to be disabled. No point enabling it later though...
125 * Only one CPU is allowed to execute the panic code from here. For
126 * multiple parallel invocations of panic, all other CPUs either
127 * stop themself or will wait until they are stopped by the 1st CPU
128 * with smp_send_stop().
130 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
131 * comes here, so go ahead.
132 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
133 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
135 this_cpu = raw_smp_processor_id();
136 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
138 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
139 panic_smp_self_stop();
144 vsnprintf(buf, sizeof(buf), fmt, args);
146 pr_emerg("Kernel panic - not syncing: %s\n", buf);
147 #ifdef CONFIG_DEBUG_BUGVERBOSE
149 * Avoid nested stack-dumping if a panic occurs during oops processing
151 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
156 * If we have crashed and we have a crash kernel loaded let it handle
158 * If we want to run this after calling panic_notifiers, pass
159 * the "crash_kexec_post_notifiers" option to the kernel.
161 * Bypass the panic_cpu check and call __crash_kexec directly.
163 if (!crash_kexec_post_notifiers) {
164 printk_nmi_flush_on_panic();
169 * Note smp_send_stop is the usual smp shutdown function, which
170 * unfortunately means it may not be hardened to work in a panic
176 * Run any panic handlers, including those that might need to
177 * add information to the kmsg dump output.
179 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
181 /* Call flush even twice. It tries harder with a single online CPU */
182 printk_nmi_flush_on_panic();
183 kmsg_dump(KMSG_DUMP_PANIC);
186 * If you doubt kdump always works fine in any situation,
187 * "crash_kexec_post_notifiers" offers you a chance to run
188 * panic_notifiers and dumping kmsg before kdump.
189 * Note: since some panic_notifiers can make crashed kernel
190 * more unstable, it can increase risks of the kdump failure too.
192 * Bypass the panic_cpu check and call __crash_kexec directly.
194 if (crash_kexec_post_notifiers)
200 * We may have ended up stopping the CPU holding the lock (in
201 * smp_send_stop()) while still having some valuable data in the console
202 * buffer. Try to acquire the lock then release it regardless of the
203 * result. The release will also print the buffers out. Locks debug
204 * should be disabled to avoid reporting bad unlock balance when
205 * panic() is not being callled from OOPS.
208 console_flush_on_panic();
211 panic_blink = no_blink;
213 if (panic_timeout > 0) {
215 * Delay timeout seconds before rebooting the machine.
216 * We can't use the "normal" timers since we just panicked.
218 pr_emerg("Rebooting in %d seconds..", panic_timeout);
220 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
221 touch_nmi_watchdog();
223 i += panic_blink(state ^= 1);
224 i_next = i + 3600 / PANIC_BLINK_SPD;
226 mdelay(PANIC_TIMER_STEP);
229 if (panic_timeout != 0) {
231 * This will not be a clean reboot, with everything
232 * shutting down. But if there is a chance of
233 * rebooting the system it will be rebooted.
239 extern int stop_a_enabled;
240 /* Make sure the user can actually press Stop-A (L1-A) */
242 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
245 #if defined(CONFIG_S390)
247 unsigned long caller;
249 caller = (unsigned long)__builtin_return_address(0);
250 disabled_wait(caller);
253 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
255 for (i = 0; ; i += PANIC_TIMER_STEP) {
256 touch_softlockup_watchdog();
258 i += panic_blink(state ^= 1);
259 i_next = i + 3600 / PANIC_BLINK_SPD;
261 mdelay(PANIC_TIMER_STEP);
265 EXPORT_SYMBOL(panic);
274 static const struct tnt tnts[] = {
275 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
276 { TAINT_FORCED_MODULE, 'F', ' ' },
277 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
278 { TAINT_FORCED_RMMOD, 'R', ' ' },
279 { TAINT_MACHINE_CHECK, 'M', ' ' },
280 { TAINT_BAD_PAGE, 'B', ' ' },
281 { TAINT_USER, 'U', ' ' },
282 { TAINT_DIE, 'D', ' ' },
283 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
284 { TAINT_WARN, 'W', ' ' },
285 { TAINT_CRAP, 'C', ' ' },
286 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
287 { TAINT_OOT_MODULE, 'O', ' ' },
288 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
289 { TAINT_SOFTLOCKUP, 'L', ' ' },
290 { TAINT_LIVEPATCH, 'K', ' ' },
294 * print_tainted - return a string to represent the kernel taint state.
296 * 'P' - Proprietary module has been loaded.
297 * 'F' - Module has been forcibly loaded.
298 * 'S' - SMP with CPUs not designed for SMP.
299 * 'R' - User forced a module unload.
300 * 'M' - System experienced a machine check exception.
301 * 'B' - System has hit bad_page.
302 * 'U' - Userspace-defined naughtiness.
303 * 'D' - Kernel has oopsed before
304 * 'A' - ACPI table overridden.
305 * 'W' - Taint on warning.
306 * 'C' - modules from drivers/staging are loaded.
307 * 'I' - Working around severe firmware bug.
308 * 'O' - Out-of-tree module has been loaded.
309 * 'E' - Unsigned module has been loaded.
310 * 'L' - A soft lockup has previously occurred.
311 * 'K' - Kernel has been live patched.
313 * The string is overwritten by the next call to print_tainted().
315 const char *print_tainted(void)
317 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
323 s = buf + sprintf(buf, "Tainted: ");
324 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
325 const struct tnt *t = &tnts[i];
326 *s++ = test_bit(t->bit, &tainted_mask) ?
331 snprintf(buf, sizeof(buf), "Not tainted");
336 int test_taint(unsigned flag)
338 return test_bit(flag, &tainted_mask);
340 EXPORT_SYMBOL(test_taint);
342 unsigned long get_taint(void)
348 * add_taint: add a taint flag if not already set.
349 * @flag: one of the TAINT_* constants.
350 * @lockdep_ok: whether lock debugging is still OK.
352 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
353 * some notewortht-but-not-corrupting cases, it can be set to true.
355 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
357 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
358 pr_warn("Disabling lock debugging due to kernel taint\n");
360 set_bit(flag, &tainted_mask);
362 EXPORT_SYMBOL(add_taint);
364 static void spin_msec(int msecs)
368 for (i = 0; i < msecs; i++) {
369 touch_nmi_watchdog();
375 * It just happens that oops_enter() and oops_exit() are identically
378 static void do_oops_enter_exit(void)
381 static int spin_counter;
386 spin_lock_irqsave(&pause_on_oops_lock, flags);
387 if (pause_on_oops_flag == 0) {
388 /* This CPU may now print the oops message */
389 pause_on_oops_flag = 1;
391 /* We need to stall this CPU */
393 /* This CPU gets to do the counting */
394 spin_counter = pause_on_oops;
396 spin_unlock(&pause_on_oops_lock);
397 spin_msec(MSEC_PER_SEC);
398 spin_lock(&pause_on_oops_lock);
399 } while (--spin_counter);
400 pause_on_oops_flag = 0;
402 /* This CPU waits for a different one */
403 while (spin_counter) {
404 spin_unlock(&pause_on_oops_lock);
406 spin_lock(&pause_on_oops_lock);
410 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
414 * Return true if the calling CPU is allowed to print oops-related info.
415 * This is a bit racy..
417 int oops_may_print(void)
419 return pause_on_oops_flag == 0;
423 * Called when the architecture enters its oops handler, before it prints
424 * anything. If this is the first CPU to oops, and it's oopsing the first
425 * time then let it proceed.
427 * This is all enabled by the pause_on_oops kernel boot option. We do all
428 * this to ensure that oopses don't scroll off the screen. It has the
429 * side-effect of preventing later-oopsing CPUs from mucking up the display,
432 * It turns out that the CPU which is allowed to print ends up pausing for
433 * the right duration, whereas all the other CPUs pause for twice as long:
434 * once in oops_enter(), once in oops_exit().
436 void oops_enter(void)
439 /* can't trust the integrity of the kernel anymore: */
441 do_oops_enter_exit();
445 * 64-bit random ID for oopses:
449 static int init_oops_id(void)
452 get_random_bytes(&oops_id, sizeof(oops_id));
458 late_initcall(init_oops_id);
460 void print_oops_end_marker(void)
463 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
467 * Called when the architecture exits its oops handler, after printing
472 do_oops_enter_exit();
473 print_oops_end_marker();
474 kmsg_dump(KMSG_DUMP_OOPS);
482 void __warn(const char *file, int line, void *caller, unsigned taint,
483 struct pt_regs *regs, struct warn_args *args)
485 disable_trace_on_warning();
487 pr_warn("------------[ cut here ]------------\n");
490 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
491 raw_smp_processor_id(), current->pid, file, line,
494 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
495 raw_smp_processor_id(), current->pid, caller);
498 vprintk(args->fmt, args->args);
502 * This thread may hit another WARN() in the panic path.
503 * Resetting this prevents additional WARN() from panicking the
504 * system on this thread. Other threads are blocked by the
505 * panic_mutex in panic().
508 panic("panic_on_warn set ...\n");
518 print_oops_end_marker();
520 /* Just a warning, don't kill lockdep. */
521 add_taint(taint, LOCKDEP_STILL_OK);
524 #ifdef WANT_WARN_ON_SLOWPATH
525 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
527 struct warn_args args;
530 va_start(args.args, fmt);
531 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
535 EXPORT_SYMBOL(warn_slowpath_fmt);
537 void warn_slowpath_fmt_taint(const char *file, int line,
538 unsigned taint, const char *fmt, ...)
540 struct warn_args args;
543 va_start(args.args, fmt);
544 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
547 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
549 void warn_slowpath_null(const char *file, int line)
551 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
553 EXPORT_SYMBOL(warn_slowpath_null);
556 #ifdef CONFIG_CC_STACKPROTECTOR
559 * Called when gcc's -fstack-protector feature is used, and
560 * gcc detects corruption of the on-stack canary value
562 __visible void __stack_chk_fail(void)
564 panic("stack-protector: Kernel stack is corrupted in: %p\n",
565 __builtin_return_address(0));
567 EXPORT_SYMBOL(__stack_chk_fail);
571 core_param(panic, panic_timeout, int, 0644);
572 core_param(pause_on_oops, pause_on_oops, int, 0644);
573 core_param(panic_on_warn, panic_on_warn, int, 0644);
575 static int __init setup_crash_kexec_post_notifiers(char *s)
577 crash_kexec_post_notifiers = true;
580 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
582 static int __init oops_setup(char *s)
586 if (!strcmp(s, "panic"))
590 early_param("oops", oops_setup);