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>
29 #define PANIC_TIMER_STEP 100
30 #define PANIC_BLINK_SPD 18
32 /* Machine specific panic information string */
33 char *mach_panic_string;
35 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
36 static unsigned long tainted_mask;
37 static int pause_on_oops;
38 static int pause_on_oops_flag;
39 static DEFINE_SPINLOCK(pause_on_oops_lock);
40 bool crash_kexec_post_notifiers;
41 int panic_on_warn __read_mostly;
43 int panic_timeout = CONFIG_PANIC_TIMEOUT;
44 EXPORT_SYMBOL_GPL(panic_timeout);
46 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
48 EXPORT_SYMBOL(panic_notifier_list);
50 static long no_blink(int state)
55 /* Returns how long it waited in ms */
56 long (*panic_blink)(int state);
57 EXPORT_SYMBOL(panic_blink);
60 * Stop ourself in panic -- architecture code may override this
62 void __weak panic_smp_self_stop(void)
69 * panic - halt the system
70 * @fmt: The text string to print
72 * Display a message, then perform cleanups.
74 * This function never returns.
76 void panic(const char *fmt, ...)
78 static DEFINE_SPINLOCK(panic_lock);
79 static char buf[1024];
85 * Disable local interrupts. This will prevent panic_smp_self_stop
86 * from deadlocking the first cpu that invokes the panic, since
87 * there is nothing to prevent an interrupt handler (that runs
88 * after the panic_lock is acquired) from invoking panic again.
93 * It's possible to come here directly from a panic-assertion and
94 * not have preempt disabled. Some functions called from here want
95 * preempt to be disabled. No point enabling it later though...
97 * Only one CPU is allowed to execute the panic code from here. For
98 * multiple parallel invocations of panic, all other CPUs either
99 * stop themself or will wait until they are stopped by the 1st CPU
100 * with smp_send_stop().
102 if (!spin_trylock(&panic_lock))
103 panic_smp_self_stop();
108 vsnprintf(buf, sizeof(buf), fmt, args);
110 pr_emerg("Kernel panic - not syncing: %s\n", buf);
111 #ifdef CONFIG_DEBUG_BUGVERBOSE
113 * Avoid nested stack-dumping if a panic occurs during oops processing
115 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
120 * If we have crashed and we have a crash kernel loaded let it handle
122 * If we want to run this after calling panic_notifiers, pass
123 * the "crash_kexec_post_notifiers" option to the kernel.
125 if (!crash_kexec_post_notifiers)
129 * Note smp_send_stop is the usual smp shutdown function, which
130 * unfortunately means it may not be hardened to work in a panic
136 * Run any panic handlers, including those that might need to
137 * add information to the kmsg dump output.
139 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
141 kmsg_dump(KMSG_DUMP_PANIC);
144 * If you doubt kdump always works fine in any situation,
145 * "crash_kexec_post_notifiers" offers you a chance to run
146 * panic_notifiers and dumping kmsg before kdump.
147 * Note: since some panic_notifiers can make crashed kernel
148 * more unstable, it can increase risks of the kdump failure too.
150 if (crash_kexec_post_notifiers)
156 * We may have ended up stopping the CPU holding the lock (in
157 * smp_send_stop()) while still having some valuable data in the console
158 * buffer. Try to acquire the lock then release it regardless of the
159 * result. The release will also print the buffers out. Locks debug
160 * should be disabled to avoid reporting bad unlock balance when
161 * panic() is not being callled from OOPS.
164 console_flush_on_panic();
167 panic_blink = no_blink;
169 if (panic_timeout > 0) {
171 * Delay timeout seconds before rebooting the machine.
172 * We can't use the "normal" timers since we just panicked.
174 pr_emerg("Rebooting in %d seconds..", panic_timeout);
176 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
177 touch_nmi_watchdog();
179 i += panic_blink(state ^= 1);
180 i_next = i + 3600 / PANIC_BLINK_SPD;
182 mdelay(PANIC_TIMER_STEP);
185 if (panic_timeout != 0) {
187 * This will not be a clean reboot, with everything
188 * shutting down. But if there is a chance of
189 * rebooting the system it will be rebooted.
195 extern int stop_a_enabled;
196 /* Make sure the user can actually press Stop-A (L1-A) */
198 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
201 #if defined(CONFIG_S390)
203 unsigned long caller;
205 caller = (unsigned long)__builtin_return_address(0);
206 disabled_wait(caller);
209 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
211 for (i = 0; ; i += PANIC_TIMER_STEP) {
212 touch_softlockup_watchdog();
214 i += panic_blink(state ^= 1);
215 i_next = i + 3600 / PANIC_BLINK_SPD;
217 mdelay(PANIC_TIMER_STEP);
221 EXPORT_SYMBOL(panic);
230 static const struct tnt tnts[] = {
231 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
232 { TAINT_FORCED_MODULE, 'F', ' ' },
233 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
234 { TAINT_FORCED_RMMOD, 'R', ' ' },
235 { TAINT_MACHINE_CHECK, 'M', ' ' },
236 { TAINT_BAD_PAGE, 'B', ' ' },
237 { TAINT_USER, 'U', ' ' },
238 { TAINT_DIE, 'D', ' ' },
239 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
240 { TAINT_WARN, 'W', ' ' },
241 { TAINT_CRAP, 'C', ' ' },
242 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
243 { TAINT_OOT_MODULE, 'O', ' ' },
244 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
245 { TAINT_SOFTLOCKUP, 'L', ' ' },
246 { TAINT_LIVEPATCH, 'K', ' ' },
250 * print_tainted - return a string to represent the kernel taint state.
252 * 'P' - Proprietary module has been loaded.
253 * 'F' - Module has been forcibly loaded.
254 * 'S' - SMP with CPUs not designed for SMP.
255 * 'R' - User forced a module unload.
256 * 'M' - System experienced a machine check exception.
257 * 'B' - System has hit bad_page.
258 * 'U' - Userspace-defined naughtiness.
259 * 'D' - Kernel has oopsed before
260 * 'A' - ACPI table overridden.
261 * 'W' - Taint on warning.
262 * 'C' - modules from drivers/staging are loaded.
263 * 'I' - Working around severe firmware bug.
264 * 'O' - Out-of-tree module has been loaded.
265 * 'E' - Unsigned module has been loaded.
266 * 'L' - A soft lockup has previously occurred.
267 * 'K' - Kernel has been live patched.
269 * The string is overwritten by the next call to print_tainted().
271 const char *print_tainted(void)
273 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
279 s = buf + sprintf(buf, "Tainted: ");
280 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
281 const struct tnt *t = &tnts[i];
282 *s++ = test_bit(t->bit, &tainted_mask) ?
287 snprintf(buf, sizeof(buf), "Not tainted");
292 int test_taint(unsigned flag)
294 return test_bit(flag, &tainted_mask);
296 EXPORT_SYMBOL(test_taint);
298 unsigned long get_taint(void)
304 * add_taint: add a taint flag if not already set.
305 * @flag: one of the TAINT_* constants.
306 * @lockdep_ok: whether lock debugging is still OK.
308 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
309 * some notewortht-but-not-corrupting cases, it can be set to true.
311 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
313 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
314 pr_warn("Disabling lock debugging due to kernel taint\n");
316 set_bit(flag, &tainted_mask);
318 EXPORT_SYMBOL(add_taint);
320 static void spin_msec(int msecs)
324 for (i = 0; i < msecs; i++) {
325 touch_nmi_watchdog();
331 * It just happens that oops_enter() and oops_exit() are identically
334 static void do_oops_enter_exit(void)
337 static int spin_counter;
342 spin_lock_irqsave(&pause_on_oops_lock, flags);
343 if (pause_on_oops_flag == 0) {
344 /* This CPU may now print the oops message */
345 pause_on_oops_flag = 1;
347 /* We need to stall this CPU */
349 /* This CPU gets to do the counting */
350 spin_counter = pause_on_oops;
352 spin_unlock(&pause_on_oops_lock);
353 spin_msec(MSEC_PER_SEC);
354 spin_lock(&pause_on_oops_lock);
355 } while (--spin_counter);
356 pause_on_oops_flag = 0;
358 /* This CPU waits for a different one */
359 while (spin_counter) {
360 spin_unlock(&pause_on_oops_lock);
362 spin_lock(&pause_on_oops_lock);
366 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
370 * Return true if the calling CPU is allowed to print oops-related info.
371 * This is a bit racy..
373 int oops_may_print(void)
375 return pause_on_oops_flag == 0;
379 * Called when the architecture enters its oops handler, before it prints
380 * anything. If this is the first CPU to oops, and it's oopsing the first
381 * time then let it proceed.
383 * This is all enabled by the pause_on_oops kernel boot option. We do all
384 * this to ensure that oopses don't scroll off the screen. It has the
385 * side-effect of preventing later-oopsing CPUs from mucking up the display,
388 * It turns out that the CPU which is allowed to print ends up pausing for
389 * the right duration, whereas all the other CPUs pause for twice as long:
390 * once in oops_enter(), once in oops_exit().
392 void oops_enter(void)
395 /* can't trust the integrity of the kernel anymore: */
397 do_oops_enter_exit();
401 * 64-bit random ID for oopses:
405 static int init_oops_id(void)
407 struct device_node *np;
409 np = of_find_node_by_name(NULL, "panic_timeout");
411 of_property_read_u32(np, "panic-timeout-value", &panic_timeout);
414 get_random_bytes(&oops_id, sizeof(oops_id));
420 late_initcall(init_oops_id);
422 void print_oops_end_marker(void)
426 if (mach_panic_string)
427 printk(KERN_WARNING "Board Information: %s\n",
430 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
434 * Called when the architecture exits its oops handler, after printing
439 do_oops_enter_exit();
440 print_oops_end_marker();
441 kmsg_dump(KMSG_DUMP_OOPS);
444 #ifdef WANT_WARN_ON_SLOWPATH
445 struct slowpath_args {
450 static void warn_slowpath_common(const char *file, int line, void *caller,
451 unsigned taint, struct slowpath_args *args)
453 disable_trace_on_warning();
455 pr_warn("------------[ cut here ]------------\n");
456 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
457 raw_smp_processor_id(), current->pid, file, line, caller);
460 vprintk(args->fmt, args->args);
464 * This thread may hit another WARN() in the panic path.
465 * Resetting this prevents additional WARN() from panicking the
466 * system on this thread. Other threads are blocked by the
467 * panic_mutex in panic().
470 panic("panic_on_warn set ...\n");
475 print_oops_end_marker();
476 /* Just a warning, don't kill lockdep. */
477 add_taint(taint, LOCKDEP_STILL_OK);
480 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
482 struct slowpath_args args;
485 va_start(args.args, fmt);
486 warn_slowpath_common(file, line, __builtin_return_address(0),
490 EXPORT_SYMBOL(warn_slowpath_fmt);
492 void warn_slowpath_fmt_taint(const char *file, int line,
493 unsigned taint, const char *fmt, ...)
495 struct slowpath_args args;
498 va_start(args.args, fmt);
499 warn_slowpath_common(file, line, __builtin_return_address(0),
503 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
505 void warn_slowpath_null(const char *file, int line)
507 warn_slowpath_common(file, line, __builtin_return_address(0),
510 EXPORT_SYMBOL(warn_slowpath_null);
513 #ifdef CONFIG_CC_STACKPROTECTOR
516 * Called when gcc's -fstack-protector feature is used, and
517 * gcc detects corruption of the on-stack canary value
519 __visible void __stack_chk_fail(void)
521 panic("stack-protector: Kernel stack is corrupted in: %p\n",
522 __builtin_return_address(0));
524 EXPORT_SYMBOL(__stack_chk_fail);
528 core_param(panic, panic_timeout, int, 0644);
529 core_param(pause_on_oops, pause_on_oops, int, 0644);
530 core_param(panic_on_warn, panic_on_warn, int, 0644);
532 static int __init setup_crash_kexec_post_notifiers(char *s)
534 crash_kexec_post_notifiers = true;
537 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
539 static int __init oops_setup(char *s)
543 if (!strcmp(s, "panic"))
547 early_param("oops", oops_setup);