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 /* Machine specific panic information string */
32 char *mach_panic_string;
34 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
35 static unsigned long tainted_mask;
36 static int pause_on_oops;
37 static int pause_on_oops_flag;
38 static DEFINE_SPINLOCK(pause_on_oops_lock);
39 bool crash_kexec_post_notifiers;
40 int panic_on_warn __read_mostly;
42 int panic_timeout = CONFIG_PANIC_TIMEOUT;
43 EXPORT_SYMBOL_GPL(panic_timeout);
45 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
47 EXPORT_SYMBOL(panic_notifier_list);
49 static long no_blink(int state)
54 /* Returns how long it waited in ms */
55 long (*panic_blink)(int state);
56 EXPORT_SYMBOL(panic_blink);
59 * Stop ourself in panic -- architecture code may override this
61 void __weak panic_smp_self_stop(void)
68 * panic - halt the system
69 * @fmt: The text string to print
71 * Display a message, then perform cleanups.
73 * This function never returns.
75 void panic(const char *fmt, ...)
77 static DEFINE_SPINLOCK(panic_lock);
78 static char buf[1024];
84 * Disable local interrupts. This will prevent panic_smp_self_stop
85 * from deadlocking the first cpu that invokes the panic, since
86 * there is nothing to prevent an interrupt handler (that runs
87 * after the panic_lock is acquired) from invoking panic again.
92 * It's possible to come here directly from a panic-assertion and
93 * not have preempt disabled. Some functions called from here want
94 * preempt to be disabled. No point enabling it later though...
96 * Only one CPU is allowed to execute the panic code from here. For
97 * multiple parallel invocations of panic, all other CPUs either
98 * stop themself or will wait until they are stopped by the 1st CPU
99 * with smp_send_stop().
101 if (!spin_trylock(&panic_lock))
102 panic_smp_self_stop();
107 vsnprintf(buf, sizeof(buf), fmt, args);
109 pr_emerg("Kernel panic - not syncing: %s\n", buf);
110 #ifdef CONFIG_DEBUG_BUGVERBOSE
112 * Avoid nested stack-dumping if a panic occurs during oops processing
114 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
119 * If we have crashed and we have a crash kernel loaded let it handle
121 * If we want to run this after calling panic_notifiers, pass
122 * the "crash_kexec_post_notifiers" option to the kernel.
124 if (!crash_kexec_post_notifiers)
128 * Note smp_send_stop is the usual smp shutdown function, which
129 * unfortunately means it may not be hardened to work in a panic
135 * Run any panic handlers, including those that might need to
136 * add information to the kmsg dump output.
138 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
140 kmsg_dump(KMSG_DUMP_PANIC);
143 * If you doubt kdump always works fine in any situation,
144 * "crash_kexec_post_notifiers" offers you a chance to run
145 * panic_notifiers and dumping kmsg before kdump.
146 * Note: since some panic_notifiers can make crashed kernel
147 * more unstable, it can increase risks of the kdump failure too.
149 if (crash_kexec_post_notifiers)
155 * We may have ended up stopping the CPU holding the lock (in
156 * smp_send_stop()) while still having some valuable data in the console
157 * buffer. Try to acquire the lock then release it regardless of the
158 * result. The release will also print the buffers out. Locks debug
159 * should be disabled to avoid reporting bad unlock balance when
160 * panic() is not being callled from OOPS.
163 console_flush_on_panic();
166 panic_blink = no_blink;
168 if (panic_timeout > 0) {
170 * Delay timeout seconds before rebooting the machine.
171 * We can't use the "normal" timers since we just panicked.
173 pr_emerg("Rebooting in %d seconds..", panic_timeout);
175 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
176 touch_nmi_watchdog();
178 i += panic_blink(state ^= 1);
179 i_next = i + 3600 / PANIC_BLINK_SPD;
181 mdelay(PANIC_TIMER_STEP);
184 if (panic_timeout != 0) {
186 * This will not be a clean reboot, with everything
187 * shutting down. But if there is a chance of
188 * rebooting the system it will be rebooted.
194 extern int stop_a_enabled;
195 /* Make sure the user can actually press Stop-A (L1-A) */
197 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
200 #if defined(CONFIG_S390)
202 unsigned long caller;
204 caller = (unsigned long)__builtin_return_address(0);
205 disabled_wait(caller);
208 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
210 for (i = 0; ; i += PANIC_TIMER_STEP) {
211 touch_softlockup_watchdog();
213 i += panic_blink(state ^= 1);
214 i_next = i + 3600 / PANIC_BLINK_SPD;
216 mdelay(PANIC_TIMER_STEP);
220 EXPORT_SYMBOL(panic);
229 static const struct tnt tnts[] = {
230 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
231 { TAINT_FORCED_MODULE, 'F', ' ' },
232 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
233 { TAINT_FORCED_RMMOD, 'R', ' ' },
234 { TAINT_MACHINE_CHECK, 'M', ' ' },
235 { TAINT_BAD_PAGE, 'B', ' ' },
236 { TAINT_USER, 'U', ' ' },
237 { TAINT_DIE, 'D', ' ' },
238 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
239 { TAINT_WARN, 'W', ' ' },
240 { TAINT_CRAP, 'C', ' ' },
241 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
242 { TAINT_OOT_MODULE, 'O', ' ' },
243 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
244 { TAINT_SOFTLOCKUP, 'L', ' ' },
245 { TAINT_LIVEPATCH, 'K', ' ' },
249 * print_tainted - return a string to represent the kernel taint state.
251 * 'P' - Proprietary module has been loaded.
252 * 'F' - Module has been forcibly loaded.
253 * 'S' - SMP with CPUs not designed for SMP.
254 * 'R' - User forced a module unload.
255 * 'M' - System experienced a machine check exception.
256 * 'B' - System has hit bad_page.
257 * 'U' - Userspace-defined naughtiness.
258 * 'D' - Kernel has oopsed before
259 * 'A' - ACPI table overridden.
260 * 'W' - Taint on warning.
261 * 'C' - modules from drivers/staging are loaded.
262 * 'I' - Working around severe firmware bug.
263 * 'O' - Out-of-tree module has been loaded.
264 * 'E' - Unsigned module has been loaded.
265 * 'L' - A soft lockup has previously occurred.
266 * 'K' - Kernel has been live patched.
268 * The string is overwritten by the next call to print_tainted().
270 const char *print_tainted(void)
272 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
278 s = buf + sprintf(buf, "Tainted: ");
279 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
280 const struct tnt *t = &tnts[i];
281 *s++ = test_bit(t->bit, &tainted_mask) ?
286 snprintf(buf, sizeof(buf), "Not tainted");
291 int test_taint(unsigned flag)
293 return test_bit(flag, &tainted_mask);
295 EXPORT_SYMBOL(test_taint);
297 unsigned long get_taint(void)
303 * add_taint: add a taint flag if not already set.
304 * @flag: one of the TAINT_* constants.
305 * @lockdep_ok: whether lock debugging is still OK.
307 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
308 * some notewortht-but-not-corrupting cases, it can be set to true.
310 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
312 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
313 pr_warn("Disabling lock debugging due to kernel taint\n");
315 set_bit(flag, &tainted_mask);
317 EXPORT_SYMBOL(add_taint);
319 static void spin_msec(int msecs)
323 for (i = 0; i < msecs; i++) {
324 touch_nmi_watchdog();
330 * It just happens that oops_enter() and oops_exit() are identically
333 static void do_oops_enter_exit(void)
336 static int spin_counter;
341 spin_lock_irqsave(&pause_on_oops_lock, flags);
342 if (pause_on_oops_flag == 0) {
343 /* This CPU may now print the oops message */
344 pause_on_oops_flag = 1;
346 /* We need to stall this CPU */
348 /* This CPU gets to do the counting */
349 spin_counter = pause_on_oops;
351 spin_unlock(&pause_on_oops_lock);
352 spin_msec(MSEC_PER_SEC);
353 spin_lock(&pause_on_oops_lock);
354 } while (--spin_counter);
355 pause_on_oops_flag = 0;
357 /* This CPU waits for a different one */
358 while (spin_counter) {
359 spin_unlock(&pause_on_oops_lock);
361 spin_lock(&pause_on_oops_lock);
365 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
369 * Return true if the calling CPU is allowed to print oops-related info.
370 * This is a bit racy..
372 int oops_may_print(void)
374 return pause_on_oops_flag == 0;
378 * Called when the architecture enters its oops handler, before it prints
379 * anything. If this is the first CPU to oops, and it's oopsing the first
380 * time then let it proceed.
382 * This is all enabled by the pause_on_oops kernel boot option. We do all
383 * this to ensure that oopses don't scroll off the screen. It has the
384 * side-effect of preventing later-oopsing CPUs from mucking up the display,
387 * It turns out that the CPU which is allowed to print ends up pausing for
388 * the right duration, whereas all the other CPUs pause for twice as long:
389 * once in oops_enter(), once in oops_exit().
391 void oops_enter(void)
394 /* can't trust the integrity of the kernel anymore: */
396 do_oops_enter_exit();
400 * 64-bit random ID for oopses:
404 static int init_oops_id(void)
407 get_random_bytes(&oops_id, sizeof(oops_id));
413 late_initcall(init_oops_id);
415 void print_oops_end_marker(void)
419 if (mach_panic_string)
420 printk(KERN_WARNING "Board Information: %s\n",
423 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
427 * Called when the architecture exits its oops handler, after printing
432 do_oops_enter_exit();
433 print_oops_end_marker();
434 kmsg_dump(KMSG_DUMP_OOPS);
437 #ifdef WANT_WARN_ON_SLOWPATH
438 struct slowpath_args {
443 static void warn_slowpath_common(const char *file, int line, void *caller,
444 unsigned taint, struct slowpath_args *args)
446 disable_trace_on_warning();
448 pr_warn("------------[ cut here ]------------\n");
449 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
450 raw_smp_processor_id(), current->pid, file, line, caller);
453 vprintk(args->fmt, args->args);
457 * This thread may hit another WARN() in the panic path.
458 * Resetting this prevents additional WARN() from panicking the
459 * system on this thread. Other threads are blocked by the
460 * panic_mutex in panic().
463 panic("panic_on_warn set ...\n");
468 print_oops_end_marker();
469 /* Just a warning, don't kill lockdep. */
470 add_taint(taint, LOCKDEP_STILL_OK);
473 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
475 struct slowpath_args args;
478 va_start(args.args, fmt);
479 warn_slowpath_common(file, line, __builtin_return_address(0),
483 EXPORT_SYMBOL(warn_slowpath_fmt);
485 void warn_slowpath_fmt_taint(const char *file, int line,
486 unsigned taint, const char *fmt, ...)
488 struct slowpath_args args;
491 va_start(args.args, fmt);
492 warn_slowpath_common(file, line, __builtin_return_address(0),
496 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
498 void warn_slowpath_null(const char *file, int line)
500 warn_slowpath_common(file, line, __builtin_return_address(0),
503 EXPORT_SYMBOL(warn_slowpath_null);
506 #ifdef CONFIG_CC_STACKPROTECTOR
509 * Called when gcc's -fstack-protector feature is used, and
510 * gcc detects corruption of the on-stack canary value
512 __visible void __stack_chk_fail(void)
514 panic("stack-protector: Kernel stack is corrupted in: %p\n",
515 __builtin_return_address(0));
517 EXPORT_SYMBOL(__stack_chk_fail);
521 core_param(panic, panic_timeout, int, 0644);
522 core_param(pause_on_oops, pause_on_oops, int, 0644);
523 core_param(panic_on_warn, panic_on_warn, int, 0644);
525 static int __init setup_crash_kexec_post_notifiers(char *s)
527 crash_kexec_post_notifiers = true;
530 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
532 static int __init oops_setup(char *s)
536 if (!strcmp(s, "panic"))
540 early_param("oops", oops_setup);