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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>
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 */
Daniel Walkerc277e632007-10-18 03:06:08 -070059
Linus Torvalds1da177e2005-04-16 15:20:36 -070060NORET_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)
Daniel Walkerc277e632007-10-18 03:06:08 -070066 unsigned long caller = (unsigned long) __builtin_return_address(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067#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)
Daniel Walkerc277e632007-10-18 03:06:08 -0700131 disabled_wait(caller);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132#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 */
Daniel Walkerc277e632007-10-18 03:06:08 -0700157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158const char *print_tainted(void)
159{
160 static char buf[20];
161 if (tainted) {
Pavel Emelianovbcdcd8e2007-07-17 04:03:42 -0700162 snprintf(buf, sizeof(buf), "Tainted: %c%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' : ' ',
Daniel Walkerc277e632007-10-18 03:06:08 -0700167 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
Theodore Ts'o34f5a392007-02-10 01:45:24 -0800168 tainted & TAINT_BAD_PAGE ? 'B' : ' ',
Pavel Emelianovbcdcd8e2007-07-17 04:03:42 -0700169 tainted & TAINT_USER ? 'U' : ' ',
170 tainted & TAINT_DIE ? 'D' : ' ');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 }
172 else
173 snprintf(buf, sizeof(buf), "Not tainted");
174 return(buf);
175}
176
177void add_taint(unsigned flag)
178{
Ingo Molnar068c4572006-09-06 00:03:44 -0700179 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 tainted |= flag;
181}
182EXPORT_SYMBOL(add_taint);
Andrew Mortondd287792006-03-23 03:00:57 -0800183
184static int __init pause_on_oops_setup(char *str)
185{
186 pause_on_oops = simple_strtoul(str, NULL, 0);
187 return 1;
188}
189__setup("pause_on_oops=", pause_on_oops_setup);
190
191static void spin_msec(int msecs)
192{
193 int i;
194
195 for (i = 0; i < msecs; i++) {
196 touch_nmi_watchdog();
197 mdelay(1);
198 }
199}
200
201/*
202 * It just happens that oops_enter() and oops_exit() are identically
203 * implemented...
204 */
205static void do_oops_enter_exit(void)
206{
207 unsigned long flags;
208 static int spin_counter;
209
210 if (!pause_on_oops)
211 return;
212
213 spin_lock_irqsave(&pause_on_oops_lock, flags);
214 if (pause_on_oops_flag == 0) {
215 /* This CPU may now print the oops message */
216 pause_on_oops_flag = 1;
217 } else {
218 /* We need to stall this CPU */
219 if (!spin_counter) {
220 /* This CPU gets to do the counting */
221 spin_counter = pause_on_oops;
222 do {
223 spin_unlock(&pause_on_oops_lock);
224 spin_msec(MSEC_PER_SEC);
225 spin_lock(&pause_on_oops_lock);
226 } while (--spin_counter);
227 pause_on_oops_flag = 0;
228 } else {
229 /* This CPU waits for a different one */
230 while (spin_counter) {
231 spin_unlock(&pause_on_oops_lock);
232 spin_msec(1);
233 spin_lock(&pause_on_oops_lock);
234 }
235 }
236 }
237 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
238}
239
240/*
241 * Return true if the calling CPU is allowed to print oops-related info. This
242 * is a bit racy..
243 */
244int oops_may_print(void)
245{
246 return pause_on_oops_flag == 0;
247}
248
249/*
250 * Called when the architecture enters its oops handler, before it prints
251 * anything. If this is the first CPU to oops, and it's oopsing the first time
252 * then let it proceed.
253 *
254 * This is all enabled by the pause_on_oops kernel boot option. We do all this
255 * to ensure that oopses don't scroll off the screen. It has the side-effect
256 * of preventing later-oopsing CPUs from mucking up the display, too.
257 *
258 * It turns out that the CPU which is allowed to print ends up pausing for the
259 * right duration, whereas all the other CPUs pause for twice as long: once in
260 * oops_enter(), once in oops_exit().
261 */
262void oops_enter(void)
263{
Arjan van de Ven2c16e9c2006-07-10 04:45:42 -0700264 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
Andrew Mortondd287792006-03-23 03:00:57 -0800265 do_oops_enter_exit();
266}
267
268/*
269 * Called when the architecture exits its oops handler, after printing
270 * everything.
271 */
272void oops_exit(void)
273{
274 do_oops_enter_exit();
275}
Arjan van de Ven3162f752006-09-26 10:52:39 +0200276
277#ifdef CONFIG_CC_STACKPROTECTOR
278/*
279 * Called when gcc's -fstack-protector feature is used, and
280 * gcc detects corruption of the on-stack canary value
281 */
282void __stack_chk_fail(void)
283{
284 panic("stack-protector: Kernel stack is corrupted");
285}
286EXPORT_SYMBOL(__stack_chk_fail);
287#endif