blob: 623d1828259a9a4f1b9f7b6776bf0ea3b339c75d [file] [log] [blame]
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
Linus Torvalds1da177e2005-04-16 15:20:36 -070023int panic_on_oops;
24int tainted;
Andrew Mortondd287792006-03-23 03:00:57 -080025static int pause_on_oops;
26static int pause_on_oops_flag;
27static DEFINE_SPINLOCK(pause_on_oops_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Andrew Mortondd287792006-03-23 03:00:57 -080029int panic_timeout;
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Alan Sterne041c682006-03-27 01:16:30 -080031ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33EXPORT_SYMBOL(panic_notifier_list);
34
35static int __init panic_setup(char *str)
36{
37 panic_timeout = simple_strtoul(str, NULL, 0);
38 return 1;
39}
40__setup("panic=", panic_setup);
41
42static long no_blink(long time)
43{
44 return 0;
45}
46
47/* Returns how long it waited in ms */
48long (*panic_blink)(long time);
49EXPORT_SYMBOL(panic_blink);
50
51/**
52 * panic - halt the system
53 * @fmt: The text string to print
54 *
55 * Display a message, then perform cleanups.
56 *
57 * This function never returns.
58 */
59
60NORET_TYPE void panic(const char * fmt, ...)
61{
62 long i;
63 static char buf[1024];
64 va_list args;
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -080065#if defined(CONFIG_S390)
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 unsigned long caller = (unsigned long) __builtin_return_address(0);
67#endif
68
Eric W. Biedermandc009d92005-06-25 14:57:52 -070069 /*
70 * It's possible to come here directly from a panic-assertion and not
71 * have preempt disabled. Some functions called from here want
72 * preempt to be disabled. No point enabling it later though...
73 */
74 preempt_disable();
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 bust_spinlocks(1);
77 va_start(args, fmt);
78 vsnprintf(buf, sizeof(buf), fmt, args);
79 va_end(args);
80 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
81 bust_spinlocks(0);
82
Eric W. Biedermandc009d92005-06-25 14:57:52 -070083 /*
84 * If we have crashed and we have a crash kernel loaded let it handle
85 * everything else.
86 * Do we want to call this before we try to display a message?
87 */
Alexander Nyberg6e274d12005-06-25 14:58:26 -070088 crash_kexec(NULL);
Eric W. Biedermandc009d92005-06-25 14:57:52 -070089
Linus Torvalds1da177e2005-04-16 15:20:36 -070090#ifdef CONFIG_SMP
Eric W. Biedermandc009d92005-06-25 14:57:52 -070091 /*
92 * Note smp_send_stop is the usual smp shutdown function, which
93 * unfortunately means it may not be hardened to work in a panic
94 * situation.
95 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 smp_send_stop();
97#endif
98
Alan Sterne041c682006-03-27 01:16:30 -080099 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
101 if (!panic_blink)
102 panic_blink = no_blink;
103
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700104 if (panic_timeout > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 /*
106 * Delay timeout seconds before rebooting the machine.
107 * We can't use the "normal" timers since we just panicked..
108 */
109 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
110 for (i = 0; i < panic_timeout*1000; ) {
111 touch_nmi_watchdog();
112 i += panic_blink(i);
113 mdelay(1);
114 i++;
115 }
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600116 /* This will not be a clean reboot, with everything
117 * shutting down. But if there is a chance of
118 * rebooting the system it will be rebooted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 */
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600120 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 }
122#ifdef __sparc__
123 {
124 extern int stop_a_enabled;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700125 /* Make sure the user can actually press Stop-A (L1-A) */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 stop_a_enabled = 1;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700127 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 }
129#endif
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -0800130#if defined(CONFIG_S390)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 disabled_wait(caller);
132#endif
133 local_irq_enable();
134 for (i = 0;;) {
Jan Beulichc22db942006-02-10 01:51:11 -0800135 touch_softlockup_watchdog();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 i += panic_blink(i);
137 mdelay(1);
138 i++;
139 }
140}
141
142EXPORT_SYMBOL(panic);
143
144/**
145 * print_tainted - return a string to represent the kernel taint state.
146 *
147 * 'P' - Proprietary module has been loaded.
148 * 'F' - Module has been forcibly loaded.
149 * 'S' - SMP with CPUs not designed for SMP.
150 * 'R' - User forced a module unload.
151 * 'M' - Machine had a machine check experience.
152 * 'B' - System has hit bad_page.
Theodore Ts'o34f5a392007-02-10 01:45:24 -0800153 * 'U' - Userspace-defined naughtiness.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 *
155 * The string is overwritten by the next call to print_taint().
156 */
157
158const char *print_tainted(void)
159{
160 static char buf[20];
161 if (tainted) {
Theodore Ts'o34f5a392007-02-10 01:45:24 -0800162 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
164 tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
165 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
166 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
167 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
Theodore Ts'o34f5a392007-02-10 01:45:24 -0800168 tainted & TAINT_BAD_PAGE ? 'B' : ' ',
169 tainted & TAINT_USER ? 'U' : ' ');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 }
171 else
172 snprintf(buf, sizeof(buf), "Not tainted");
173 return(buf);
174}
175
176void add_taint(unsigned flag)
177{
Ingo Molnar068c4572006-09-06 00:03:44 -0700178 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 tainted |= flag;
180}
181EXPORT_SYMBOL(add_taint);
Andrew Mortondd287792006-03-23 03:00:57 -0800182
183static int __init pause_on_oops_setup(char *str)
184{
185 pause_on_oops = simple_strtoul(str, NULL, 0);
186 return 1;
187}
188__setup("pause_on_oops=", pause_on_oops_setup);
189
190static void spin_msec(int msecs)
191{
192 int i;
193
194 for (i = 0; i < msecs; i++) {
195 touch_nmi_watchdog();
196 mdelay(1);
197 }
198}
199
200/*
201 * It just happens that oops_enter() and oops_exit() are identically
202 * implemented...
203 */
204static void do_oops_enter_exit(void)
205{
206 unsigned long flags;
207 static int spin_counter;
208
209 if (!pause_on_oops)
210 return;
211
212 spin_lock_irqsave(&pause_on_oops_lock, flags);
213 if (pause_on_oops_flag == 0) {
214 /* This CPU may now print the oops message */
215 pause_on_oops_flag = 1;
216 } else {
217 /* We need to stall this CPU */
218 if (!spin_counter) {
219 /* This CPU gets to do the counting */
220 spin_counter = pause_on_oops;
221 do {
222 spin_unlock(&pause_on_oops_lock);
223 spin_msec(MSEC_PER_SEC);
224 spin_lock(&pause_on_oops_lock);
225 } while (--spin_counter);
226 pause_on_oops_flag = 0;
227 } else {
228 /* This CPU waits for a different one */
229 while (spin_counter) {
230 spin_unlock(&pause_on_oops_lock);
231 spin_msec(1);
232 spin_lock(&pause_on_oops_lock);
233 }
234 }
235 }
236 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
237}
238
239/*
240 * Return true if the calling CPU is allowed to print oops-related info. This
241 * is a bit racy..
242 */
243int oops_may_print(void)
244{
245 return pause_on_oops_flag == 0;
246}
247
248/*
249 * Called when the architecture enters its oops handler, before it prints
250 * anything. If this is the first CPU to oops, and it's oopsing the first time
251 * then let it proceed.
252 *
253 * This is all enabled by the pause_on_oops kernel boot option. We do all this
254 * to ensure that oopses don't scroll off the screen. It has the side-effect
255 * of preventing later-oopsing CPUs from mucking up the display, too.
256 *
257 * It turns out that the CPU which is allowed to print ends up pausing for the
258 * right duration, whereas all the other CPUs pause for twice as long: once in
259 * oops_enter(), once in oops_exit().
260 */
261void oops_enter(void)
262{
Arjan van de Ven2c16e9c2006-07-10 04:45:42 -0700263 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
Andrew Mortondd287792006-03-23 03:00:57 -0800264 do_oops_enter_exit();
265}
266
267/*
268 * Called when the architecture exits its oops handler, after printing
269 * everything.
270 */
271void oops_exit(void)
272{
273 do_oops_enter_exit();
274}
Arjan van de Ven3162f752006-09-26 10:52:39 +0200275
276#ifdef CONFIG_CC_STACKPROTECTOR
277/*
278 * Called when gcc's -fstack-protector feature is used, and
279 * gcc detects corruption of the on-stack canary value
280 */
281void __stack_chk_fail(void)
282{
283 panic("stack-protector: Kernel stack is corrupted");
284}
285EXPORT_SYMBOL(__stack_chk_fail);
286#endif