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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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/module.h>
12#include <linux/sched.h>
13#include <linux/delay.h>
14#include <linux/reboot.h>
15#include <linux/notifier.h>
16#include <linux/init.h>
17#include <linux/sysrq.h>
18#include <linux/interrupt.h>
19#include <linux/nmi.h>
Eric W. Biedermandc009d92005-06-25 14:57:52 -070020#include <linux/kexec.h>
Andrew Morton657b3012006-08-13 23:24:19 -070021#include <linux/debug_locks.h>
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +010022#include <linux/random.h>
Arjan van de Ven79b4cc52008-01-30 13:32:50 +010023#include <linux/kallsyms.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Linus Torvalds1da177e2005-04-16 15:20:36 -070025int panic_on_oops;
Andi Kleen25ddbb12008-10-15 22:01:41 -070026static unsigned long tainted_mask;
Andrew Mortondd287792006-03-23 03:00:57 -080027static int pause_on_oops;
28static int pause_on_oops_flag;
29static DEFINE_SPINLOCK(pause_on_oops_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Andrew Mortondd287792006-03-23 03:00:57 -080031int panic_timeout;
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
Alan Sterne041c682006-03-27 01:16:30 -080033ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35EXPORT_SYMBOL(panic_notifier_list);
36
37static int __init panic_setup(char *str)
38{
39 panic_timeout = simple_strtoul(str, NULL, 0);
40 return 1;
41}
42__setup("panic=", panic_setup);
43
44static long no_blink(long time)
45{
46 return 0;
47}
48
49/* Returns how long it waited in ms */
50long (*panic_blink)(long time);
51EXPORT_SYMBOL(panic_blink);
52
53/**
54 * panic - halt the system
55 * @fmt: The text string to print
56 *
57 * Display a message, then perform cleanups.
58 *
59 * This function never returns.
60 */
Daniel Walkerc277e632007-10-18 03:06:08 -070061
Linus Torvalds1da177e2005-04-16 15:20:36 -070062NORET_TYPE void panic(const char * fmt, ...)
63{
64 long i;
65 static char buf[1024];
66 va_list args;
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -080067#if defined(CONFIG_S390)
Daniel Walkerc277e632007-10-18 03:06:08 -070068 unsigned long caller = (unsigned long) __builtin_return_address(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070069#endif
70
Eric W. Biedermandc009d92005-06-25 14:57:52 -070071 /*
72 * It's possible to come here directly from a panic-assertion and not
73 * have preempt disabled. Some functions called from here want
74 * preempt to be disabled. No point enabling it later though...
75 */
76 preempt_disable();
77
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 bust_spinlocks(1);
79 va_start(args, fmt);
80 vsnprintf(buf, sizeof(buf), fmt, args);
81 va_end(args);
82 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
83 bust_spinlocks(0);
84
Eric W. Biedermandc009d92005-06-25 14:57:52 -070085 /*
86 * If we have crashed and we have a crash kernel loaded let it handle
87 * everything else.
88 * Do we want to call this before we try to display a message?
89 */
Alexander Nyberg6e274d12005-06-25 14:58:26 -070090 crash_kexec(NULL);
Eric W. Biedermandc009d92005-06-25 14:57:52 -070091
Linus Torvalds1da177e2005-04-16 15:20:36 -070092#ifdef CONFIG_SMP
Eric W. Biedermandc009d92005-06-25 14:57:52 -070093 /*
94 * Note smp_send_stop is the usual smp shutdown function, which
95 * unfortunately means it may not be hardened to work in a panic
96 * situation.
97 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 smp_send_stop();
99#endif
100
Alan Sterne041c682006-03-27 01:16:30 -0800101 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
103 if (!panic_blink)
104 panic_blink = no_blink;
105
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700106 if (panic_timeout > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 /*
108 * Delay timeout seconds before rebooting the machine.
109 * We can't use the "normal" timers since we just panicked..
110 */
111 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
112 for (i = 0; i < panic_timeout*1000; ) {
113 touch_nmi_watchdog();
114 i += panic_blink(i);
115 mdelay(1);
116 i++;
117 }
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600118 /* This will not be a clean reboot, with everything
119 * shutting down. But if there is a chance of
120 * rebooting the system it will be rebooted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 */
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600122 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 }
124#ifdef __sparc__
125 {
126 extern int stop_a_enabled;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700127 /* Make sure the user can actually press Stop-A (L1-A) */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 stop_a_enabled = 1;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700129 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
131#endif
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -0800132#if defined(CONFIG_S390)
Daniel Walkerc277e632007-10-18 03:06:08 -0700133 disabled_wait(caller);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134#endif
135 local_irq_enable();
136 for (i = 0;;) {
Jan Beulichc22db942006-02-10 01:51:11 -0800137 touch_softlockup_watchdog();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 i += panic_blink(i);
139 mdelay(1);
140 i++;
141 }
142}
143
144EXPORT_SYMBOL(panic);
145
Daniel Walkerc277e632007-10-18 03:06:08 -0700146
Andi Kleen25ddbb12008-10-15 22:01:41 -0700147struct tnt {
148 u8 bit;
149 char true;
150 char false;
151};
152
153static const struct tnt tnts[] = {
154 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
155 { TAINT_FORCED_MODULE, 'F', ' ' },
156 { TAINT_UNSAFE_SMP, 'S', ' ' },
157 { TAINT_FORCED_RMMOD, 'R', ' ' },
158 { TAINT_MACHINE_CHECK, 'M', ' ' },
159 { TAINT_BAD_PAGE, 'B', ' ' },
160 { TAINT_USER, 'U', ' ' },
161 { TAINT_DIE, 'D', ' ' },
162 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
163 { TAINT_WARN, 'W', ' ' },
Linus Torvalds26e9a392008-10-17 09:50:12 -0700164 { TAINT_CRAP, 'C', ' ' },
Andi Kleen25ddbb12008-10-15 22:01:41 -0700165};
166
Randy Dunlap6d5cd6e2008-10-15 22:02:00 -0700167/**
168 * print_tainted - return a string to represent the kernel taint state.
169 *
170 * 'P' - Proprietary module has been loaded.
171 * 'F' - Module has been forcibly loaded.
172 * 'S' - SMP with CPUs not designed for SMP.
173 * 'R' - User forced a module unload.
174 * 'M' - System experienced a machine check exception.
175 * 'B' - System has hit bad_page.
176 * 'U' - Userspace-defined naughtiness.
177 * 'A' - ACPI table overridden.
178 * 'W' - Taint on warning.
Greg Kroah-Hartman061b1bd2008-09-24 14:46:44 -0700179 * 'C' - modules from drivers/staging are loaded.
Randy Dunlap6d5cd6e2008-10-15 22:02:00 -0700180 *
181 * The string is overwritten by the next call to print_taint().
182 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183const char *print_tainted(void)
184{
Andi Kleen25ddbb12008-10-15 22:01:41 -0700185 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
186
187 if (tainted_mask) {
188 char *s;
189 int i;
190
191 s = buf + sprintf(buf, "Tainted: ");
192 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
193 const struct tnt *t = &tnts[i];
194 *s++ = test_bit(t->bit, &tainted_mask) ?
195 t->true : t->false;
196 }
197 *s = 0;
198 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 snprintf(buf, sizeof(buf), "Not tainted");
200 return(buf);
201}
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{
Ingo Molnar068c4572006-09-06 00:03:44 -0700216 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
Andi Kleen25ddbb12008-10-15 22:01:41 -0700217 set_bit(flag, &tainted_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218}
219EXPORT_SYMBOL(add_taint);
Andrew Mortondd287792006-03-23 03:00:57 -0800220
221static int __init pause_on_oops_setup(char *str)
222{
223 pause_on_oops = simple_strtoul(str, NULL, 0);
224 return 1;
225}
226__setup("pause_on_oops=", pause_on_oops_setup);
227
228static void spin_msec(int msecs)
229{
230 int i;
231
232 for (i = 0; i < msecs; i++) {
233 touch_nmi_watchdog();
234 mdelay(1);
235 }
236}
237
238/*
239 * It just happens that oops_enter() and oops_exit() are identically
240 * implemented...
241 */
242static void do_oops_enter_exit(void)
243{
244 unsigned long flags;
245 static int spin_counter;
246
247 if (!pause_on_oops)
248 return;
249
250 spin_lock_irqsave(&pause_on_oops_lock, flags);
251 if (pause_on_oops_flag == 0) {
252 /* This CPU may now print the oops message */
253 pause_on_oops_flag = 1;
254 } else {
255 /* We need to stall this CPU */
256 if (!spin_counter) {
257 /* This CPU gets to do the counting */
258 spin_counter = pause_on_oops;
259 do {
260 spin_unlock(&pause_on_oops_lock);
261 spin_msec(MSEC_PER_SEC);
262 spin_lock(&pause_on_oops_lock);
263 } while (--spin_counter);
264 pause_on_oops_flag = 0;
265 } else {
266 /* This CPU waits for a different one */
267 while (spin_counter) {
268 spin_unlock(&pause_on_oops_lock);
269 spin_msec(1);
270 spin_lock(&pause_on_oops_lock);
271 }
272 }
273 }
274 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
275}
276
277/*
278 * Return true if the calling CPU is allowed to print oops-related info. This
279 * is a bit racy..
280 */
281int oops_may_print(void)
282{
283 return pause_on_oops_flag == 0;
284}
285
286/*
287 * Called when the architecture enters its oops handler, before it prints
288 * anything. If this is the first CPU to oops, and it's oopsing the first time
289 * then let it proceed.
290 *
291 * This is all enabled by the pause_on_oops kernel boot option. We do all this
292 * to ensure that oopses don't scroll off the screen. It has the side-effect
293 * of preventing later-oopsing CPUs from mucking up the display, too.
294 *
295 * It turns out that the CPU which is allowed to print ends up pausing for the
296 * right duration, whereas all the other CPUs pause for twice as long: once in
297 * oops_enter(), once in oops_exit().
298 */
299void oops_enter(void)
300{
Arjan van de Ven2c16e9c2006-07-10 04:45:42 -0700301 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
Andrew Mortondd287792006-03-23 03:00:57 -0800302 do_oops_enter_exit();
303}
304
305/*
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +0100306 * 64-bit random ID for oopses:
307 */
308static u64 oops_id;
309
310static int init_oops_id(void)
311{
312 if (!oops_id)
313 get_random_bytes(&oops_id, sizeof(oops_id));
314
315 return 0;
316}
317late_initcall(init_oops_id);
318
Arjan van de Ven71c33912008-01-30 13:32:50 +0100319static void print_oops_end_marker(void)
320{
321 init_oops_id();
322 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
323 (unsigned long long)oops_id);
324}
325
Arjan van de Ven2c3b20e92007-12-20 15:01:17 +0100326/*
Andrew Mortondd287792006-03-23 03:00:57 -0800327 * Called when the architecture exits its oops handler, after printing
328 * everything.
329 */
330void oops_exit(void)
331{
332 do_oops_enter_exit();
Arjan van de Ven71c33912008-01-30 13:32:50 +0100333 print_oops_end_marker();
Andrew Mortondd287792006-03-23 03:00:57 -0800334}
Arjan van de Ven3162f752006-09-26 10:52:39 +0200335
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100336#ifdef WANT_WARN_ON_SLOWPATH
337void warn_on_slowpath(const char *file, int line)
338{
339 char function[KSYM_SYMBOL_LEN];
340 unsigned long caller = (unsigned long) __builtin_return_address(0);
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100341 sprint_symbol(function, caller);
Arjan van de Ven71c33912008-01-30 13:32:50 +0100342
343 printk(KERN_WARNING "------------[ cut here ]------------\n");
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100344 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
345 line, function);
Arjan van de Ven71c33912008-01-30 13:32:50 +0100346 print_modules();
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100347 dump_stack();
Arjan van de Ven71c33912008-01-30 13:32:50 +0100348 print_oops_end_marker();
Nur Hussein95b570c2008-04-29 00:58:39 -0700349 add_taint(TAINT_WARN);
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100350}
351EXPORT_SYMBOL(warn_on_slowpath);
Arjan van de Vena8f18b92008-07-25 01:45:53 -0700352
353
354void warn_slowpath(const char *file, int line, const char *fmt, ...)
355{
356 va_list args;
357 char function[KSYM_SYMBOL_LEN];
358 unsigned long caller = (unsigned long)__builtin_return_address(0);
359 sprint_symbol(function, caller);
360
361 printk(KERN_WARNING "------------[ cut here ]------------\n");
362 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
363 line, function);
364 va_start(args, fmt);
365 vprintk(fmt, args);
366 va_end(args);
367
368 print_modules();
369 dump_stack();
370 print_oops_end_marker();
371 add_taint(TAINT_WARN);
372}
373EXPORT_SYMBOL(warn_slowpath);
Arjan van de Ven79b4cc52008-01-30 13:32:50 +0100374#endif
375
Arjan van de Ven3162f752006-09-26 10:52:39 +0200376#ifdef CONFIG_CC_STACKPROTECTOR
377/*
378 * Called when gcc's -fstack-protector feature is used, and
379 * gcc detects corruption of the on-stack canary value
380 */
381void __stack_chk_fail(void)
382{
383 panic("stack-protector: Kernel stack is corrupted");
384}
385EXPORT_SYMBOL(__stack_chk_fail);
386#endif