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/reboot.h>
19 #include <linux/delay.h>
20 #include <linux/kexec.h>
21 #include <linux/sched.h>
22 #include <linux/sysrq.h>
23 #include <linux/init.h>
24 #include <linux/nmi.h>
25 #include <linux/dmi.h>
28 #define PANIC_TIMER_STEP 100
29 #define PANIC_BLINK_SPD 18
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);
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 printk(KERN_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 * Do we want to call this before we try to display a message?
120 kmsg_dump(KMSG_DUMP_PANIC);
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
129 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
134 panic_blink = no_blink;
136 if (panic_timeout > 0) {
138 * Delay timeout seconds before rebooting the machine.
139 * We can't use the "normal" timers since we just panicked.
141 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
143 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
144 touch_nmi_watchdog();
146 i += panic_blink(state ^= 1);
147 i_next = i + 3600 / PANIC_BLINK_SPD;
149 mdelay(PANIC_TIMER_STEP);
152 if (panic_timeout != 0) {
154 * This will not be a clean reboot, with everything
155 * shutting down. But if there is a chance of
156 * rebooting the system it will be rebooted.
162 extern int stop_a_enabled;
163 /* Make sure the user can actually press Stop-A (L1-A) */
165 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
168 #if defined(CONFIG_S390)
170 unsigned long caller;
172 caller = (unsigned long)__builtin_return_address(0);
173 disabled_wait(caller);
177 for (i = 0; ; i += PANIC_TIMER_STEP) {
178 touch_softlockup_watchdog();
180 i += panic_blink(state ^= 1);
181 i_next = i + 3600 / PANIC_BLINK_SPD;
183 mdelay(PANIC_TIMER_STEP);
187 EXPORT_SYMBOL(panic);
196 static const struct tnt tnts[] = {
197 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
198 { TAINT_FORCED_MODULE, 'F', ' ' },
199 { TAINT_UNSAFE_SMP, 'S', ' ' },
200 { TAINT_FORCED_RMMOD, 'R', ' ' },
201 { TAINT_MACHINE_CHECK, 'M', ' ' },
202 { TAINT_BAD_PAGE, 'B', ' ' },
203 { TAINT_USER, 'U', ' ' },
204 { TAINT_DIE, 'D', ' ' },
205 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
206 { TAINT_WARN, 'W', ' ' },
207 { TAINT_CRAP, 'C', ' ' },
208 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
209 { TAINT_OOT_MODULE, 'O', ' ' },
213 * print_tainted - return a string to represent the kernel taint state.
215 * 'P' - Proprietary module has been loaded.
216 * 'F' - Module has been forcibly loaded.
217 * 'S' - SMP with CPUs not designed for SMP.
218 * 'R' - User forced a module unload.
219 * 'M' - System experienced a machine check exception.
220 * 'B' - System has hit bad_page.
221 * 'U' - Userspace-defined naughtiness.
222 * 'D' - Kernel has oopsed before
223 * 'A' - ACPI table overridden.
224 * 'W' - Taint on warning.
225 * 'C' - modules from drivers/staging are loaded.
226 * 'I' - Working around severe firmware bug.
227 * 'O' - Out-of-tree module has been loaded.
229 * The string is overwritten by the next call to print_tainted().
231 const char *print_tainted(void)
233 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
239 s = buf + sprintf(buf, "Tainted: ");
240 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
241 const struct tnt *t = &tnts[i];
242 *s++ = test_bit(t->bit, &tainted_mask) ?
247 snprintf(buf, sizeof(buf), "Not tainted");
252 int test_taint(unsigned flag)
254 return test_bit(flag, &tainted_mask);
256 EXPORT_SYMBOL(test_taint);
258 unsigned long get_taint(void)
263 void add_taint(unsigned flag)
266 * Can't trust the integrity of the kernel anymore.
267 * We don't call directly debug_locks_off() because the issue
268 * is not necessarily serious enough to set oops_in_progress to 1
269 * Also we want to keep up lockdep for staging/out-of-tree
270 * development and post-warning case.
274 case TAINT_OOT_MODULE:
276 case TAINT_FIRMWARE_WORKAROUND:
280 if (__debug_locks_off())
281 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
284 set_bit(flag, &tainted_mask);
286 EXPORT_SYMBOL(add_taint);
288 static void spin_msec(int msecs)
292 for (i = 0; i < msecs; i++) {
293 touch_nmi_watchdog();
299 * It just happens that oops_enter() and oops_exit() are identically
302 static void do_oops_enter_exit(void)
305 static int spin_counter;
310 spin_lock_irqsave(&pause_on_oops_lock, flags);
311 if (pause_on_oops_flag == 0) {
312 /* This CPU may now print the oops message */
313 pause_on_oops_flag = 1;
315 /* We need to stall this CPU */
317 /* This CPU gets to do the counting */
318 spin_counter = pause_on_oops;
320 spin_unlock(&pause_on_oops_lock);
321 spin_msec(MSEC_PER_SEC);
322 spin_lock(&pause_on_oops_lock);
323 } while (--spin_counter);
324 pause_on_oops_flag = 0;
326 /* This CPU waits for a different one */
327 while (spin_counter) {
328 spin_unlock(&pause_on_oops_lock);
330 spin_lock(&pause_on_oops_lock);
334 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
338 * Return true if the calling CPU is allowed to print oops-related info.
339 * This is a bit racy..
341 int oops_may_print(void)
343 return pause_on_oops_flag == 0;
347 * Called when the architecture enters its oops handler, before it prints
348 * anything. If this is the first CPU to oops, and it's oopsing the first
349 * time then let it proceed.
351 * This is all enabled by the pause_on_oops kernel boot option. We do all
352 * this to ensure that oopses don't scroll off the screen. It has the
353 * side-effect of preventing later-oopsing CPUs from mucking up the display,
356 * It turns out that the CPU which is allowed to print ends up pausing for
357 * the right duration, whereas all the other CPUs pause for twice as long:
358 * once in oops_enter(), once in oops_exit().
360 void oops_enter(void)
363 /* can't trust the integrity of the kernel anymore: */
365 do_oops_enter_exit();
369 * 64-bit random ID for oopses:
371 static u64 __suspend_volatile_bss oops_id;
373 static int init_oops_id(void)
376 get_random_bytes(&oops_id, sizeof(oops_id));
382 late_initcall(init_oops_id);
384 void print_oops_end_marker(void)
387 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
388 (unsigned long long)oops_id);
392 * Called when the architecture exits its oops handler, after printing
397 do_oops_enter_exit();
398 print_oops_end_marker();
399 kmsg_dump(KMSG_DUMP_OOPS);
402 #ifdef WANT_WARN_ON_SLOWPATH
403 struct slowpath_args {
408 static void warn_slowpath_common(const char *file, int line, void *caller,
409 unsigned taint, struct slowpath_args *args)
413 printk(KERN_WARNING "------------[ cut here ]------------\n");
414 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
415 board = dmi_get_system_info(DMI_PRODUCT_NAME);
417 printk(KERN_WARNING "Hardware name: %s\n", board);
420 vprintk(args->fmt, args->args);
424 print_oops_end_marker();
428 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
430 struct slowpath_args args;
433 va_start(args.args, fmt);
434 warn_slowpath_common(file, line, __builtin_return_address(0),
438 EXPORT_SYMBOL(warn_slowpath_fmt);
440 void warn_slowpath_fmt_taint(const char *file, int line,
441 unsigned taint, const char *fmt, ...)
443 struct slowpath_args args;
446 va_start(args.args, fmt);
447 warn_slowpath_common(file, line, __builtin_return_address(0),
451 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
453 void warn_slowpath_null(const char *file, int line)
455 warn_slowpath_common(file, line, __builtin_return_address(0),
458 EXPORT_SYMBOL(warn_slowpath_null);
461 #ifdef CONFIG_CC_STACKPROTECTOR
464 * Called when gcc's -fstack-protector feature is used, and
465 * gcc detects corruption of the on-stack canary value
467 void __stack_chk_fail(void)
469 panic("stack-protector: Kernel stack is corrupted in: %p\n",
470 __builtin_return_address(0));
472 EXPORT_SYMBOL(__stack_chk_fail);
476 core_param(panic, panic_timeout, int, 0644);
477 core_param(pause_on_oops, pause_on_oops, int, 0644);
479 static int __init oops_setup(char *s)
483 if (!strcmp(s, "panic"))
487 early_param("oops", oops_setup);