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>
28 #define PANIC_TIMER_STEP 100
29 #define PANIC_BLINK_SPD 18
31 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
32 static unsigned long tainted_mask;
33 static int pause_on_oops;
34 static int pause_on_oops_flag;
35 static DEFINE_SPINLOCK(pause_on_oops_lock);
36 bool crash_kexec_post_notifiers;
37 int panic_on_warn __read_mostly;
39 int panic_timeout = CONFIG_PANIC_TIMEOUT;
40 EXPORT_SYMBOL_GPL(panic_timeout);
42 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
44 EXPORT_SYMBOL(panic_notifier_list);
46 static long no_blink(int state)
51 /* Returns how long it waited in ms */
52 long (*panic_blink)(int state);
53 EXPORT_SYMBOL(panic_blink);
56 * Stop ourself in panic -- architecture code may override this
58 void __weak panic_smp_self_stop(void)
65 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
66 * may override this to prepare for crash dumping, e.g. save regs info.
68 void __weak nmi_panic_self_stop(struct pt_regs *regs)
70 panic_smp_self_stop();
73 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
76 * panic - halt the system
77 * @fmt: The text string to print
79 * Display a message, then perform cleanups.
81 * This function never returns.
83 void panic(const char *fmt, ...)
85 static char buf[1024];
89 int old_cpu, this_cpu;
92 * Disable local interrupts. This will prevent panic_smp_self_stop
93 * from deadlocking the first cpu that invokes the panic, since
94 * there is nothing to prevent an interrupt handler (that runs
95 * after setting panic_cpu) from invoking panic() again.
100 * It's possible to come here directly from a panic-assertion and
101 * not have preempt disabled. Some functions called from here want
102 * preempt to be disabled. No point enabling it later though...
104 * Only one CPU is allowed to execute the panic code from here. For
105 * multiple parallel invocations of panic, all other CPUs either
106 * stop themself or will wait until they are stopped by the 1st CPU
107 * with smp_send_stop().
109 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
110 * comes here, so go ahead.
111 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
112 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
114 this_cpu = raw_smp_processor_id();
115 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
117 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
118 panic_smp_self_stop();
123 vsnprintf(buf, sizeof(buf), fmt, args);
125 pr_emerg("Kernel panic - not syncing: %s\n", buf);
126 #ifdef CONFIG_DEBUG_BUGVERBOSE
128 * Avoid nested stack-dumping if a panic occurs during oops processing
130 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
135 * If we have crashed and we have a crash kernel loaded let it handle
137 * If we want to run this after calling panic_notifiers, pass
138 * the "crash_kexec_post_notifiers" option to the kernel.
140 if (!crash_kexec_post_notifiers)
144 * Note smp_send_stop is the usual smp shutdown function, which
145 * unfortunately means it may not be hardened to work in a panic
151 * Run any panic handlers, including those that might need to
152 * add information to the kmsg dump output.
154 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
156 kmsg_dump(KMSG_DUMP_PANIC);
159 * If you doubt kdump always works fine in any situation,
160 * "crash_kexec_post_notifiers" offers you a chance to run
161 * panic_notifiers and dumping kmsg before kdump.
162 * Note: since some panic_notifiers can make crashed kernel
163 * more unstable, it can increase risks of the kdump failure too.
165 if (crash_kexec_post_notifiers)
171 * We may have ended up stopping the CPU holding the lock (in
172 * smp_send_stop()) while still having some valuable data in the console
173 * buffer. Try to acquire the lock then release it regardless of the
174 * result. The release will also print the buffers out. Locks debug
175 * should be disabled to avoid reporting bad unlock balance when
176 * panic() is not being callled from OOPS.
183 panic_blink = no_blink;
185 if (panic_timeout > 0) {
187 * Delay timeout seconds before rebooting the machine.
188 * We can't use the "normal" timers since we just panicked.
190 pr_emerg("Rebooting in %d seconds..", panic_timeout);
192 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
193 touch_nmi_watchdog();
195 i += panic_blink(state ^= 1);
196 i_next = i + 3600 / PANIC_BLINK_SPD;
198 mdelay(PANIC_TIMER_STEP);
201 if (panic_timeout != 0) {
203 * This will not be a clean reboot, with everything
204 * shutting down. But if there is a chance of
205 * rebooting the system it will be rebooted.
211 extern int stop_a_enabled;
212 /* Make sure the user can actually press Stop-A (L1-A) */
214 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
217 #if defined(CONFIG_S390)
219 unsigned long caller;
221 caller = (unsigned long)__builtin_return_address(0);
222 disabled_wait(caller);
225 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
227 for (i = 0; ; i += PANIC_TIMER_STEP) {
228 touch_softlockup_watchdog();
230 i += panic_blink(state ^= 1);
231 i_next = i + 3600 / PANIC_BLINK_SPD;
233 mdelay(PANIC_TIMER_STEP);
237 EXPORT_SYMBOL(panic);
246 static const struct tnt tnts[] = {
247 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
248 { TAINT_FORCED_MODULE, 'F', ' ' },
249 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
250 { TAINT_FORCED_RMMOD, 'R', ' ' },
251 { TAINT_MACHINE_CHECK, 'M', ' ' },
252 { TAINT_BAD_PAGE, 'B', ' ' },
253 { TAINT_USER, 'U', ' ' },
254 { TAINT_DIE, 'D', ' ' },
255 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
256 { TAINT_WARN, 'W', ' ' },
257 { TAINT_CRAP, 'C', ' ' },
258 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
259 { TAINT_OOT_MODULE, 'O', ' ' },
260 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
261 { TAINT_SOFTLOCKUP, 'L', ' ' },
262 { TAINT_LIVEPATCH, 'K', ' ' },
266 * print_tainted - return a string to represent the kernel taint state.
268 * 'P' - Proprietary module has been loaded.
269 * 'F' - Module has been forcibly loaded.
270 * 'S' - SMP with CPUs not designed for SMP.
271 * 'R' - User forced a module unload.
272 * 'M' - System experienced a machine check exception.
273 * 'B' - System has hit bad_page.
274 * 'U' - Userspace-defined naughtiness.
275 * 'D' - Kernel has oopsed before
276 * 'A' - ACPI table overridden.
277 * 'W' - Taint on warning.
278 * 'C' - modules from drivers/staging are loaded.
279 * 'I' - Working around severe firmware bug.
280 * 'O' - Out-of-tree module has been loaded.
281 * 'E' - Unsigned module has been loaded.
282 * 'L' - A soft lockup has previously occurred.
283 * 'K' - Kernel has been live patched.
285 * The string is overwritten by the next call to print_tainted().
287 const char *print_tainted(void)
289 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
295 s = buf + sprintf(buf, "Tainted: ");
296 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
297 const struct tnt *t = &tnts[i];
298 *s++ = test_bit(t->bit, &tainted_mask) ?
303 snprintf(buf, sizeof(buf), "Not tainted");
308 int test_taint(unsigned flag)
310 return test_bit(flag, &tainted_mask);
312 EXPORT_SYMBOL(test_taint);
314 unsigned long get_taint(void)
320 * add_taint: add a taint flag if not already set.
321 * @flag: one of the TAINT_* constants.
322 * @lockdep_ok: whether lock debugging is still OK.
324 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
325 * some notewortht-but-not-corrupting cases, it can be set to true.
327 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
329 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
330 pr_warn("Disabling lock debugging due to kernel taint\n");
332 set_bit(flag, &tainted_mask);
334 EXPORT_SYMBOL(add_taint);
336 static void spin_msec(int msecs)
340 for (i = 0; i < msecs; i++) {
341 touch_nmi_watchdog();
347 * It just happens that oops_enter() and oops_exit() are identically
350 static void do_oops_enter_exit(void)
353 static int spin_counter;
358 spin_lock_irqsave(&pause_on_oops_lock, flags);
359 if (pause_on_oops_flag == 0) {
360 /* This CPU may now print the oops message */
361 pause_on_oops_flag = 1;
363 /* We need to stall this CPU */
365 /* This CPU gets to do the counting */
366 spin_counter = pause_on_oops;
368 spin_unlock(&pause_on_oops_lock);
369 spin_msec(MSEC_PER_SEC);
370 spin_lock(&pause_on_oops_lock);
371 } while (--spin_counter);
372 pause_on_oops_flag = 0;
374 /* This CPU waits for a different one */
375 while (spin_counter) {
376 spin_unlock(&pause_on_oops_lock);
378 spin_lock(&pause_on_oops_lock);
382 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
386 * Return true if the calling CPU is allowed to print oops-related info.
387 * This is a bit racy..
389 int oops_may_print(void)
391 return pause_on_oops_flag == 0;
395 * Called when the architecture enters its oops handler, before it prints
396 * anything. If this is the first CPU to oops, and it's oopsing the first
397 * time then let it proceed.
399 * This is all enabled by the pause_on_oops kernel boot option. We do all
400 * this to ensure that oopses don't scroll off the screen. It has the
401 * side-effect of preventing later-oopsing CPUs from mucking up the display,
404 * It turns out that the CPU which is allowed to print ends up pausing for
405 * the right duration, whereas all the other CPUs pause for twice as long:
406 * once in oops_enter(), once in oops_exit().
408 void oops_enter(void)
411 /* can't trust the integrity of the kernel anymore: */
413 do_oops_enter_exit();
417 * 64-bit random ID for oopses:
421 static int init_oops_id(void)
424 get_random_bytes(&oops_id, sizeof(oops_id));
430 late_initcall(init_oops_id);
432 void print_oops_end_marker(void)
435 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
439 * Called when the architecture exits its oops handler, after printing
444 do_oops_enter_exit();
445 print_oops_end_marker();
446 kmsg_dump(KMSG_DUMP_OOPS);
449 #ifdef WANT_WARN_ON_SLOWPATH
450 struct slowpath_args {
455 static void warn_slowpath_common(const char *file, int line, void *caller,
456 unsigned taint, struct slowpath_args *args)
458 disable_trace_on_warning();
460 pr_warn("------------[ cut here ]------------\n");
461 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
462 raw_smp_processor_id(), current->pid, file, line, caller);
465 vprintk(args->fmt, args->args);
469 * This thread may hit another WARN() in the panic path.
470 * Resetting this prevents additional WARN() from panicking the
471 * system on this thread. Other threads are blocked by the
472 * panic_mutex in panic().
475 panic("panic_on_warn set ...\n");
480 print_oops_end_marker();
481 /* Just a warning, don't kill lockdep. */
482 add_taint(taint, LOCKDEP_STILL_OK);
485 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
487 struct slowpath_args args;
490 va_start(args.args, fmt);
491 warn_slowpath_common(file, line, __builtin_return_address(0),
495 EXPORT_SYMBOL(warn_slowpath_fmt);
497 void warn_slowpath_fmt_taint(const char *file, int line,
498 unsigned taint, const char *fmt, ...)
500 struct slowpath_args args;
503 va_start(args.args, fmt);
504 warn_slowpath_common(file, line, __builtin_return_address(0),
508 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
510 void warn_slowpath_null(const char *file, int line)
512 warn_slowpath_common(file, line, __builtin_return_address(0),
515 EXPORT_SYMBOL(warn_slowpath_null);
518 #ifdef CONFIG_CC_STACKPROTECTOR
521 * Called when gcc's -fstack-protector feature is used, and
522 * gcc detects corruption of the on-stack canary value
524 __visible void __stack_chk_fail(void)
526 panic("stack-protector: Kernel stack is corrupted in: %p\n",
527 __builtin_return_address(0));
529 EXPORT_SYMBOL(__stack_chk_fail);
533 core_param(panic, panic_timeout, int, 0644);
534 core_param(pause_on_oops, pause_on_oops, int, 0644);
535 core_param(panic_on_warn, panic_on_warn, int, 0644);
537 static int __init setup_crash_kexec_post_notifiers(char *s)
539 crash_kexec_post_notifiers = true;
542 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
544 static int __init oops_setup(char *s)
548 if (!strcmp(s, "panic"))
552 early_param("oops", oops_setup);