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>
27 #define PANIC_TIMER_STEP 100
28 #define PANIC_BLINK_SPD 18
30 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
31 static unsigned long tainted_mask;
32 static int pause_on_oops;
33 static int pause_on_oops_flag;
34 static DEFINE_SPINLOCK(pause_on_oops_lock);
35 static bool crash_kexec_post_notifiers;
37 int panic_timeout = CONFIG_PANIC_TIMEOUT;
38 EXPORT_SYMBOL_GPL(panic_timeout);
40 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
42 EXPORT_SYMBOL(panic_notifier_list);
44 static long no_blink(int state)
49 /* Returns how long it waited in ms */
50 long (*panic_blink)(int state);
51 EXPORT_SYMBOL(panic_blink);
54 * Stop ourself in panic -- architecture code may override this
56 void __weak panic_smp_self_stop(void)
63 * panic - halt the system
64 * @fmt: The text string to print
66 * Display a message, then perform cleanups.
68 * This function never returns.
70 void panic(const char *fmt, ...)
72 static DEFINE_SPINLOCK(panic_lock);
73 static char buf[1024];
79 * Disable local interrupts. This will prevent panic_smp_self_stop
80 * from deadlocking the first cpu that invokes the panic, since
81 * there is nothing to prevent an interrupt handler (that runs
82 * after the panic_lock is acquired) from invoking panic again.
87 * It's possible to come here directly from a panic-assertion and
88 * not have preempt disabled. Some functions called from here want
89 * preempt to be disabled. No point enabling it later though...
91 * Only one CPU is allowed to execute the panic code from here. For
92 * multiple parallel invocations of panic, all other CPUs either
93 * stop themself or will wait until they are stopped by the 1st CPU
94 * with smp_send_stop().
96 if (!spin_trylock(&panic_lock))
97 panic_smp_self_stop();
102 vsnprintf(buf, sizeof(buf), fmt, args);
104 pr_emerg("Kernel panic - not syncing: %s\n", buf);
105 #ifdef CONFIG_DEBUG_BUGVERBOSE
107 * Avoid nested stack-dumping if a panic occurs during oops processing
109 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
114 * If we have crashed and we have a crash kernel loaded let it handle
116 * If we want to run this after calling panic_notifiers, pass
117 * the "crash_kexec_post_notifiers" option to the kernel.
119 if (!crash_kexec_post_notifiers)
123 * Note smp_send_stop is the usual smp shutdown function, which
124 * unfortunately means it may not be hardened to work in a panic
130 * Run any panic handlers, including those that might need to
131 * add information to the kmsg dump output.
133 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
135 kmsg_dump(KMSG_DUMP_PANIC);
138 * If you doubt kdump always works fine in any situation,
139 * "crash_kexec_post_notifiers" offers you a chance to run
140 * panic_notifiers and dumping kmsg before kdump.
141 * Note: since some panic_notifiers can make crashed kernel
142 * more unstable, it can increase risks of the kdump failure too.
149 panic_blink = no_blink;
151 if (panic_timeout > 0) {
153 * Delay timeout seconds before rebooting the machine.
154 * We can't use the "normal" timers since we just panicked.
156 pr_emerg("Rebooting in %d seconds..", panic_timeout);
158 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
159 touch_nmi_watchdog();
161 i += panic_blink(state ^= 1);
162 i_next = i + 3600 / PANIC_BLINK_SPD;
164 mdelay(PANIC_TIMER_STEP);
167 if (panic_timeout != 0) {
169 * This will not be a clean reboot, with everything
170 * shutting down. But if there is a chance of
171 * rebooting the system it will be rebooted.
177 extern int stop_a_enabled;
178 /* Make sure the user can actually press Stop-A (L1-A) */
180 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
183 #if defined(CONFIG_S390)
185 unsigned long caller;
187 caller = (unsigned long)__builtin_return_address(0);
188 disabled_wait(caller);
191 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
193 for (i = 0; ; i += PANIC_TIMER_STEP) {
194 touch_softlockup_watchdog();
196 i += panic_blink(state ^= 1);
197 i_next = i + 3600 / PANIC_BLINK_SPD;
199 mdelay(PANIC_TIMER_STEP);
203 EXPORT_SYMBOL(panic);
212 static const struct tnt tnts[] = {
213 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
214 { TAINT_FORCED_MODULE, 'F', ' ' },
215 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
216 { TAINT_FORCED_RMMOD, 'R', ' ' },
217 { TAINT_MACHINE_CHECK, 'M', ' ' },
218 { TAINT_BAD_PAGE, 'B', ' ' },
219 { TAINT_USER, 'U', ' ' },
220 { TAINT_DIE, 'D', ' ' },
221 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
222 { TAINT_WARN, 'W', ' ' },
223 { TAINT_CRAP, 'C', ' ' },
224 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
225 { TAINT_OOT_MODULE, 'O', ' ' },
226 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
227 { TAINT_SOFTLOCKUP, 'L', ' ' },
231 * print_tainted - return a string to represent the kernel taint state.
233 * 'P' - Proprietary module has been loaded.
234 * 'F' - Module has been forcibly loaded.
235 * 'S' - SMP with CPUs not designed for SMP.
236 * 'R' - User forced a module unload.
237 * 'M' - System experienced a machine check exception.
238 * 'B' - System has hit bad_page.
239 * 'U' - Userspace-defined naughtiness.
240 * 'D' - Kernel has oopsed before
241 * 'A' - ACPI table overridden.
242 * 'W' - Taint on warning.
243 * 'C' - modules from drivers/staging are loaded.
244 * 'I' - Working around severe firmware bug.
245 * 'O' - Out-of-tree module has been loaded.
246 * 'E' - Unsigned module has been loaded.
248 * The string is overwritten by the next call to print_tainted().
250 const char *print_tainted(void)
252 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
258 s = buf + sprintf(buf, "Tainted: ");
259 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
260 const struct tnt *t = &tnts[i];
261 *s++ = test_bit(t->bit, &tainted_mask) ?
266 snprintf(buf, sizeof(buf), "Not tainted");
271 int test_taint(unsigned flag)
273 return test_bit(flag, &tainted_mask);
275 EXPORT_SYMBOL(test_taint);
277 unsigned long get_taint(void)
283 * add_taint: add a taint flag if not already set.
284 * @flag: one of the TAINT_* constants.
285 * @lockdep_ok: whether lock debugging is still OK.
287 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
288 * some notewortht-but-not-corrupting cases, it can be set to true.
290 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
292 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
293 pr_warn("Disabling lock debugging due to kernel taint\n");
295 set_bit(flag, &tainted_mask);
297 EXPORT_SYMBOL(add_taint);
299 static void spin_msec(int msecs)
303 for (i = 0; i < msecs; i++) {
304 touch_nmi_watchdog();
310 * It just happens that oops_enter() and oops_exit() are identically
313 static void do_oops_enter_exit(void)
316 static int spin_counter;
321 spin_lock_irqsave(&pause_on_oops_lock, flags);
322 if (pause_on_oops_flag == 0) {
323 /* This CPU may now print the oops message */
324 pause_on_oops_flag = 1;
326 /* We need to stall this CPU */
328 /* This CPU gets to do the counting */
329 spin_counter = pause_on_oops;
331 spin_unlock(&pause_on_oops_lock);
332 spin_msec(MSEC_PER_SEC);
333 spin_lock(&pause_on_oops_lock);
334 } while (--spin_counter);
335 pause_on_oops_flag = 0;
337 /* This CPU waits for a different one */
338 while (spin_counter) {
339 spin_unlock(&pause_on_oops_lock);
341 spin_lock(&pause_on_oops_lock);
345 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
349 * Return true if the calling CPU is allowed to print oops-related info.
350 * This is a bit racy..
352 int oops_may_print(void)
354 return pause_on_oops_flag == 0;
358 * Called when the architecture enters its oops handler, before it prints
359 * anything. If this is the first CPU to oops, and it's oopsing the first
360 * time then let it proceed.
362 * This is all enabled by the pause_on_oops kernel boot option. We do all
363 * this to ensure that oopses don't scroll off the screen. It has the
364 * side-effect of preventing later-oopsing CPUs from mucking up the display,
367 * It turns out that the CPU which is allowed to print ends up pausing for
368 * the right duration, whereas all the other CPUs pause for twice as long:
369 * once in oops_enter(), once in oops_exit().
371 void oops_enter(void)
374 /* can't trust the integrity of the kernel anymore: */
376 do_oops_enter_exit();
380 * 64-bit random ID for oopses:
384 static int init_oops_id(void)
387 get_random_bytes(&oops_id, sizeof(oops_id));
393 late_initcall(init_oops_id);
395 void print_oops_end_marker(void)
398 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
402 * Called when the architecture exits its oops handler, after printing
407 do_oops_enter_exit();
408 print_oops_end_marker();
409 kmsg_dump(KMSG_DUMP_OOPS);
412 #ifdef WANT_WARN_ON_SLOWPATH
413 struct slowpath_args {
418 static void warn_slowpath_common(const char *file, int line, void *caller,
419 unsigned taint, struct slowpath_args *args)
421 disable_trace_on_warning();
423 pr_warn("------------[ cut here ]------------\n");
424 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
425 raw_smp_processor_id(), current->pid, file, line, caller);
428 vprintk(args->fmt, args->args);
432 print_oops_end_marker();
433 /* Just a warning, don't kill lockdep. */
434 add_taint(taint, LOCKDEP_STILL_OK);
437 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
439 struct slowpath_args args;
442 va_start(args.args, fmt);
443 warn_slowpath_common(file, line, __builtin_return_address(0),
447 EXPORT_SYMBOL(warn_slowpath_fmt);
449 void warn_slowpath_fmt_taint(const char *file, int line,
450 unsigned taint, const char *fmt, ...)
452 struct slowpath_args args;
455 va_start(args.args, fmt);
456 warn_slowpath_common(file, line, __builtin_return_address(0),
460 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
462 void warn_slowpath_null(const char *file, int line)
464 warn_slowpath_common(file, line, __builtin_return_address(0),
467 EXPORT_SYMBOL(warn_slowpath_null);
470 #ifdef CONFIG_CC_STACKPROTECTOR
473 * Called when gcc's -fstack-protector feature is used, and
474 * gcc detects corruption of the on-stack canary value
476 __visible void __stack_chk_fail(void)
478 panic("stack-protector: Kernel stack is corrupted in: %p\n",
479 __builtin_return_address(0));
481 EXPORT_SYMBOL(__stack_chk_fail);
485 core_param(panic, panic_timeout, int, 0644);
486 core_param(pause_on_oops, pause_on_oops, int, 0644);
488 static int __init setup_crash_kexec_post_notifiers(char *s)
490 crash_kexec_post_notifiers = true;
493 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
495 static int __init oops_setup(char *s)
499 if (!strcmp(s, "panic"))
503 early_param("oops", oops_setup);