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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/panic.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * This function is used through-out the kernel (including mm and fs)
9 * to indicate a major problem.
10 */
Andrew Morton657b3012006-08-13 23:24:19 -070011#include <linux/debug_locks.h>
Ingo Molnarc95dbf22009-03-13 11:14:06 +010012#include <linux/interrupt.h>
Arjan van de Ven79b4cc52008-01-30 13:32:50 +010013#include <linux/kallsyms.h>
Ingo Molnarc95dbf22009-03-13 11:14:06 +010014#include <linux/notifier.h>
15#include <linux/module.h>
16#include <linux/random.h>
17#include <linux/reboot.h>
18#include <linux/delay.h>
19#include <linux/kexec.h>
20#include <linux/sched.h>
21#include <linux/sysrq.h>
22#include <linux/init.h>
23#include <linux/nmi.h>
Arjan van de Venbd89bb22008-11-28 08:36:09 -080024#include <linux/dmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
Linus Torvalds1da177e2005-04-16 15:20:36 -070026int panic_on_oops;
Andi Kleen25ddbb12008-10-15 22:01:41 -070027static unsigned long tainted_mask;
Andrew Mortondd287792006-03-23 03:00:57 -080028static int pause_on_oops;
29static int pause_on_oops_flag;
30static DEFINE_SPINLOCK(pause_on_oops_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Andrew Mortondd287792006-03-23 03:00:57 -080032int panic_timeout;
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
Alan Sterne041c682006-03-27 01:16:30 -080034ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36EXPORT_SYMBOL(panic_notifier_list);
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038static long no_blink(long time)
39{
40 return 0;
41}
42
43/* Returns how long it waited in ms */
44long (*panic_blink)(long time);
45EXPORT_SYMBOL(panic_blink);
46
47/**
48 * panic - halt the system
49 * @fmt: The text string to print
50 *
51 * Display a message, then perform cleanups.
52 *
53 * This function never returns.
54 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070055NORET_TYPE void panic(const char * fmt, ...)
56{
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 static char buf[1024];
58 va_list args;
Ingo Molnarc95dbf22009-03-13 11:14:06 +010059 long i;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Eric W. Biedermandc009d92005-06-25 14:57:52 -070061 /*
Ingo Molnarc95dbf22009-03-13 11:14:06 +010062 * It's possible to come here directly from a panic-assertion and
63 * not have preempt disabled. Some functions called from here want
Eric W. Biedermandc009d92005-06-25 14:57:52 -070064 * preempt to be disabled. No point enabling it later though...
65 */
66 preempt_disable();
67
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 bust_spinlocks(1);
69 va_start(args, fmt);
70 vsnprintf(buf, sizeof(buf), fmt, args);
71 va_end(args);
72 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
Ingo Molnar5cb27302008-02-14 09:07:01 +010073#ifdef CONFIG_DEBUG_BUGVERBOSE
74 dump_stack();
75#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
Eric W. Biedermandc009d92005-06-25 14:57:52 -070077 /*
78 * If we have crashed and we have a crash kernel loaded let it handle
79 * everything else.
80 * Do we want to call this before we try to display a message?
81 */
Alexander Nyberg6e274d12005-06-25 14:58:26 -070082 crash_kexec(NULL);
Eric W. Biedermandc009d92005-06-25 14:57:52 -070083
Eric W. Biedermandc009d92005-06-25 14:57:52 -070084 /*
85 * Note smp_send_stop is the usual smp shutdown function, which
86 * unfortunately means it may not be hardened to work in a panic
87 * situation.
88 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 smp_send_stop();
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Alan Sterne041c682006-03-27 01:16:30 -080091 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -070092
93 if (!panic_blink)
94 panic_blink = no_blink;
95
Eric W. Biedermandc009d92005-06-25 14:57:52 -070096 if (panic_timeout > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 /*
Ingo Molnarc95dbf22009-03-13 11:14:06 +010098 * Delay timeout seconds before rebooting the machine.
99 * We can't use the "normal" timers since we just panicked.
100 */
101 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
102
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 for (i = 0; i < panic_timeout*1000; ) {
104 touch_nmi_watchdog();
105 i += panic_blink(i);
106 mdelay(1);
107 i++;
108 }
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100109 /*
110 * This will not be a clean reboot, with everything
111 * shutting down. But if there is a chance of
112 * rebooting the system it will be rebooted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 */
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600114 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 }
116#ifdef __sparc__
117 {
118 extern int stop_a_enabled;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700119 /* Make sure the user can actually press Stop-A (L1-A) */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 stop_a_enabled = 1;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700121 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 }
123#endif
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -0800124#if defined(CONFIG_S390)
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100125 {
126 unsigned long caller;
127
128 caller = (unsigned long)__builtin_return_address(0);
129 disabled_wait(caller);
130 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131#endif
132 local_irq_enable();
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100133 for (i = 0; ; ) {
Jan Beulichc22db942006-02-10 01:51:11 -0800134 touch_softlockup_watchdog();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 i += panic_blink(i);
136 mdelay(1);
137 i++;
138 }
Ingo Molnarffd71da2009-03-13 10:54:24 +0100139 bust_spinlocks(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140}
141
142EXPORT_SYMBOL(panic);
143
Daniel Walkerc277e632007-10-18 03:06:08 -0700144
Andi Kleen25ddbb12008-10-15 22:01:41 -0700145struct tnt {
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100146 u8 bit;
147 char true;
148 char false;
Andi Kleen25ddbb12008-10-15 22:01:41 -0700149};
150
151static const struct tnt tnts[] = {
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100152 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
153 { TAINT_FORCED_MODULE, 'F', ' ' },
154 { TAINT_UNSAFE_SMP, 'S', ' ' },
155 { TAINT_FORCED_RMMOD, 'R', ' ' },
156 { TAINT_MACHINE_CHECK, 'M', ' ' },
157 { TAINT_BAD_PAGE, 'B', ' ' },
158 { TAINT_USER, 'U', ' ' },
159 { TAINT_DIE, 'D', ' ' },
160 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
161 { TAINT_WARN, 'W', ' ' },
162 { TAINT_CRAP, 'C', ' ' },
Andi Kleen25ddbb12008-10-15 22:01:41 -0700163};
164
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165/**
166 * print_tainted - return a string to represent the kernel taint state.
167 *
168 * 'P' - Proprietary module has been loaded.
169 * 'F' - Module has been forcibly loaded.
170 * 'S' - SMP with CPUs not designed for SMP.
171 * 'R' - User forced a module unload.
172 * 'M' - System experienced a machine check exception.
173 * 'B' - System has hit bad_page.
174 * 'U' - Userspace-defined naughtiness.
Arjan van de Vena8005992008-12-01 13:14:00 -0800175 * 'D' - Kernel has oopsed before
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 * 'A' - ACPI table overridden.
Theodore Ts'o34f5a392007-02-10 01:45:24 -0800177 * 'W' - Taint on warning.
Greg Kroah-Hartman061b1bd2008-09-24 14:46:44 -0700178 * 'C' - modules from drivers/staging are loaded.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 *
180 * The string is overwritten by the next call to print_taint().
181 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182const char *print_tainted(void)
183{
Andi Kleen25ddbb12008-10-15 22:01:41 -0700184 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
185
186 if (tainted_mask) {
187 char *s;
188 int i;
189
190 s = buf + sprintf(buf, "Tainted: ");
191 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
192 const struct tnt *t = &tnts[i];
193 *s++ = test_bit(t->bit, &tainted_mask) ?
194 t->true : t->false;
195 }
196 *s = 0;
197 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 snprintf(buf, sizeof(buf), "Not tainted");
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100199
200 return buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
Andi Kleen25ddbb12008-10-15 22:01:41 -0700203int test_taint(unsigned flag)
204{
205 return test_bit(flag, &tainted_mask);
206}
207EXPORT_SYMBOL(test_taint);
208
209unsigned long get_taint(void)
210{
211 return tainted_mask;
212}
213
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214void add_taint(unsigned flag)
215{
Frederic Weisbecker9eeba612009-04-11 03:17:17 +0200216 /*
217 * Can't trust the integrity of the kernel anymore.
218 * We don't call directly debug_locks_off() because the issue
219 * is not necessarily serious enough to set oops_in_progress to 1
Frederic Weisbecker574bbe72009-04-11 03:17:18 +0200220 * Also we want to keep up lockdep for staging development and
221 * post-warning case.
Frederic Weisbecker9eeba612009-04-11 03:17:17 +0200222 */
Frederic Weisbecker574bbe72009-04-11 03:17:18 +0200223 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
Ingo Molnarb48ccb02009-04-23 09:36:52 +0200224 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
Frederic Weisbecker9eeba612009-04-11 03:17:17 +0200225
Andi Kleen25ddbb12008-10-15 22:01:41 -0700226 set_bit(flag, &tainted_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227}
228EXPORT_SYMBOL(add_taint);
Andrew Mortondd287792006-03-23 03:00:57 -0800229
Andrew Mortondd287792006-03-23 03:00:57 -0800230static void spin_msec(int msecs)
231{
232 int i;
233
234 for (i = 0; i < msecs; i++) {
235 touch_nmi_watchdog();
236 mdelay(1);
237 }
238}
239
240/*
241 * It just happens that oops_enter() and oops_exit() are identically
242 * implemented...
243 */
244static void do_oops_enter_exit(void)
245{
246 unsigned long flags;
247 static int spin_counter;
248
249 if (!pause_on_oops)
250 return;
251
252 spin_lock_irqsave(&pause_on_oops_lock, flags);
253 if (pause_on_oops_flag == 0) {
254 /* This CPU may now print the oops message */
255 pause_on_oops_flag = 1;
256 } else {
257 /* We need to stall this CPU */
258 if (!spin_counter) {
259 /* This CPU gets to do the counting */
260 spin_counter = pause_on_oops;
261 do {
262 spin_unlock(&pause_on_oops_lock);
263 spin_msec(MSEC_PER_SEC);
264 spin_lock(&pause_on_oops_lock);
265 } while (--spin_counter);
266 pause_on_oops_flag = 0;
267 } else {
268 /* This CPU waits for a different one */
269 while (spin_counter) {
270 spin_unlock(&pause_on_oops_lock);
271 spin_msec(1);
272 spin_lock(&pause_on_oops_lock);
273 }
274 }
275 }
276 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
277}
278
279/*
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100280 * Return true if the calling CPU is allowed to print oops-related info.
281 * This is a bit racy..
Andrew Mortondd287792006-03-23 03:00:57 -0800282 */
283int oops_may_print(void)
284{
285 return pause_on_oops_flag == 0;
286}
287
288/*
289 * Called when the architecture enters its oops handler, before it prints
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100290 * anything. If this is the first CPU to oops, and it's oopsing the first
291 * time then let it proceed.
Andrew Mortondd287792006-03-23 03:00:57 -0800292 *
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100293 * This is all enabled by the pause_on_oops kernel boot option. We do all
294 * this to ensure that oopses don't scroll off the screen. It has the
295 * side-effect of preventing later-oopsing CPUs from mucking up the display,
296 * too.
Andrew Mortondd287792006-03-23 03:00:57 -0800297 *
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100298 * It turns out that the CPU which is allowed to print ends up pausing for
299 * the right duration, whereas all the other CPUs pause for twice as long:
300 * once in oops_enter(), once in oops_exit().
Andrew Mortondd287792006-03-23 03:00:57 -0800301 */
302void oops_enter(void)
303{
Thomas Gleixnerbdff7872009-07-24 15:30:45 -0400304 tracing_off();
Ingo Molnarc95dbf22009-03-13 11:14:06 +0100305 /* can't trust the integrity of the kernel anymore: */
306 debug_locks_off();
Andrew Mortondd287792006-03-23 03:00:57 -0800307 do_oops_enter_exit();
308}
309
310/*
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +0100311 * 64-bit random ID for oopses:
312 */
313static u64 oops_id;
314
315static int init_oops_id(void)
316{
317 if (!oops_id)
318 get_random_bytes(&oops_id, sizeof(oops_id));
Arjan van de Vend6624f92009-01-06 14:40:54 -0800319 else
320 oops_id++;
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +0100321
322 return 0;
323}
324late_initcall(init_oops_id);
325
Arjan van de Ven71c33912008-01-30 13:32:50 +0100326static void print_oops_end_marker(void)
327{
328 init_oops_id();
329 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
330 (unsigned long long)oops_id);
331}
332
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +0100333/*
Andrew Mortondd287792006-03-23 03:00:57 -0800334 * Called when the architecture exits its oops handler, after printing
335 * everything.
336 */
337void oops_exit(void)
338{
339 do_oops_enter_exit();
Arjan van de Ven71c33912008-01-30 13:32:50 +0100340 print_oops_end_marker();
Andrew Mortondd287792006-03-23 03:00:57 -0800341}
Arjan van de Ven3162f752006-09-26 10:52:39 +0200342
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100343#ifdef WANT_WARN_ON_SLOWPATH
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700344struct slowpath_args {
345 const char *fmt;
Arjan van de Vena8f18b92008-07-25 01:45:53 -0700346 va_list args;
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700347};
348
349static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
350{
Arjan van de Venbd89bb22008-11-28 08:36:09 -0800351 const char *board;
352
Arjan van de Vena8f18b92008-07-25 01:45:53 -0700353 printk(KERN_WARNING "------------[ cut here ]------------\n");
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700354 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
Arjan van de Venbd89bb22008-11-28 08:36:09 -0800355 board = dmi_get_system_info(DMI_PRODUCT_NAME);
356 if (board)
357 printk(KERN_WARNING "Hardware name: %s\n", board);
Arjan van de Ven74853db2008-11-28 08:35:25 -0800358
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700359 if (args)
360 vprintk(args->fmt, args->args);
Arjan van de Vena8f18b92008-07-25 01:45:53 -0700361
362 print_modules();
363 dump_stack();
364 print_oops_end_marker();
365 add_taint(TAINT_WARN);
366}
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700367
368void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
369{
370 struct slowpath_args args;
371
372 args.fmt = fmt;
373 va_start(args.args, fmt);
374 warn_slowpath_common(file, line, __builtin_return_address(0), &args);
375 va_end(args.args);
376}
Andi Kleen57adc4d2009-05-06 16:02:53 -0700377EXPORT_SYMBOL(warn_slowpath_fmt);
378
379void warn_slowpath_null(const char *file, int line)
380{
Linus Torvalds0f6f49a2009-05-16 13:41:28 -0700381 warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
Andi Kleen57adc4d2009-05-06 16:02:53 -0700382}
383EXPORT_SYMBOL(warn_slowpath_null);
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100384#endif
385
Arjan van de Ven3162f752006-09-26 10:52:39 +0200386#ifdef CONFIG_CC_STACKPROTECTOR
Arjan van de Ven54371a42008-02-15 15:33:12 -0800387
Arjan van de Ven3162f752006-09-26 10:52:39 +0200388/*
389 * Called when gcc's -fstack-protector feature is used, and
390 * gcc detects corruption of the on-stack canary value
391 */
392void __stack_chk_fail(void)
393{
Ingo Molnar517a92c2008-02-14 09:02:13 +0100394 panic("stack-protector: Kernel stack is corrupted in: %p\n",
395 __builtin_return_address(0));
Arjan van de Ven3162f752006-09-26 10:52:39 +0200396}
397EXPORT_SYMBOL(__stack_chk_fail);
Arjan van de Ven54371a42008-02-15 15:33:12 -0800398
Arjan van de Ven3162f752006-09-26 10:52:39 +0200399#endif
Rusty Russellf44dd162008-10-22 10:00:24 -0500400
401core_param(panic, panic_timeout, int, 0644);
402core_param(pause_on_oops, pause_on_oops, int, 0644);