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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Linus Torvalds1da177e2005-04-16 15:20:36 -070022int panic_on_oops;
23int tainted;
Andrew Mortondd287792006-03-23 03:00:57 -080024static int pause_on_oops;
25static int pause_on_oops_flag;
26static DEFINE_SPINLOCK(pause_on_oops_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Andrew Mortondd287792006-03-23 03:00:57 -080028int panic_timeout;
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Alan Sterne041c682006-03-27 01:16:30 -080030ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32EXPORT_SYMBOL(panic_notifier_list);
33
34static int __init panic_setup(char *str)
35{
36 panic_timeout = simple_strtoul(str, NULL, 0);
37 return 1;
38}
39__setup("panic=", panic_setup);
40
41static long no_blink(long time)
42{
43 return 0;
44}
45
46/* Returns how long it waited in ms */
47long (*panic_blink)(long time);
48EXPORT_SYMBOL(panic_blink);
49
50/**
51 * panic - halt the system
52 * @fmt: The text string to print
53 *
54 * Display a message, then perform cleanups.
55 *
56 * This function never returns.
57 */
58
59NORET_TYPE void panic(const char * fmt, ...)
60{
61 long i;
62 static char buf[1024];
63 va_list args;
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -080064#if defined(CONFIG_S390)
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 unsigned long caller = (unsigned long) __builtin_return_address(0);
66#endif
67
Eric W. Biedermandc009d92005-06-25 14:57:52 -070068 /*
69 * It's possible to come here directly from a panic-assertion and not
70 * have preempt disabled. Some functions called from here want
71 * preempt to be disabled. No point enabling it later though...
72 */
73 preempt_disable();
74
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 bust_spinlocks(1);
76 va_start(args, fmt);
77 vsnprintf(buf, sizeof(buf), fmt, args);
78 va_end(args);
79 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
80 bust_spinlocks(0);
81
Eric W. Biedermandc009d92005-06-25 14:57:52 -070082 /*
83 * If we have crashed and we have a crash kernel loaded let it handle
84 * everything else.
85 * Do we want to call this before we try to display a message?
86 */
Alexander Nyberg6e274d12005-06-25 14:58:26 -070087 crash_kexec(NULL);
Eric W. Biedermandc009d92005-06-25 14:57:52 -070088
Linus Torvalds1da177e2005-04-16 15:20:36 -070089#ifdef CONFIG_SMP
Eric W. Biedermandc009d92005-06-25 14:57:52 -070090 /*
91 * Note smp_send_stop is the usual smp shutdown function, which
92 * unfortunately means it may not be hardened to work in a panic
93 * situation.
94 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 smp_send_stop();
96#endif
97
Alan Sterne041c682006-03-27 01:16:30 -080098 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099
100 if (!panic_blink)
101 panic_blink = no_blink;
102
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700103 if (panic_timeout > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 /*
105 * Delay timeout seconds before rebooting the machine.
106 * We can't use the "normal" timers since we just panicked..
107 */
108 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
109 for (i = 0; i < panic_timeout*1000; ) {
110 touch_nmi_watchdog();
111 i += panic_blink(i);
112 mdelay(1);
113 i++;
114 }
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600115 /* This will not be a clean reboot, with everything
116 * shutting down. But if there is a chance of
117 * rebooting the system it will be rebooted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 */
Eric W. Biederman2f048ea2005-07-26 11:49:23 -0600119 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 }
121#ifdef __sparc__
122 {
123 extern int stop_a_enabled;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700124 /* Make sure the user can actually press Stop-A (L1-A) */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 stop_a_enabled = 1;
Tom 'spot' Callawaya271c242005-04-24 20:38:02 -0700126 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 }
128#endif
Martin Schwidefsky347a8dc2006-01-06 00:19:28 -0800129#if defined(CONFIG_S390)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 disabled_wait(caller);
131#endif
132 local_irq_enable();
133 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 }
139}
140
141EXPORT_SYMBOL(panic);
142
143/**
144 * print_tainted - return a string to represent the kernel taint state.
145 *
146 * 'P' - Proprietary module has been loaded.
147 * 'F' - Module has been forcibly loaded.
148 * 'S' - SMP with CPUs not designed for SMP.
149 * 'R' - User forced a module unload.
150 * 'M' - Machine had a machine check experience.
151 * 'B' - System has hit bad_page.
152 *
153 * The string is overwritten by the next call to print_taint().
154 */
155
156const char *print_tainted(void)
157{
158 static char buf[20];
159 if (tainted) {
160 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c",
161 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
162 tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
163 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
164 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
165 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
166 tainted & TAINT_BAD_PAGE ? 'B' : ' ');
167 }
168 else
169 snprintf(buf, sizeof(buf), "Not tainted");
170 return(buf);
171}
172
173void add_taint(unsigned flag)
174{
Arjan van de Ven2c16e9c2006-07-10 04:45:42 -0700175 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 tainted |= flag;
177}
178EXPORT_SYMBOL(add_taint);
Andrew Mortondd287792006-03-23 03:00:57 -0800179
180static int __init pause_on_oops_setup(char *str)
181{
182 pause_on_oops = simple_strtoul(str, NULL, 0);
183 return 1;
184}
185__setup("pause_on_oops=", pause_on_oops_setup);
186
187static void spin_msec(int msecs)
188{
189 int i;
190
191 for (i = 0; i < msecs; i++) {
192 touch_nmi_watchdog();
193 mdelay(1);
194 }
195}
196
197/*
198 * It just happens that oops_enter() and oops_exit() are identically
199 * implemented...
200 */
201static void do_oops_enter_exit(void)
202{
203 unsigned long flags;
204 static int spin_counter;
205
206 if (!pause_on_oops)
207 return;
208
209 spin_lock_irqsave(&pause_on_oops_lock, flags);
210 if (pause_on_oops_flag == 0) {
211 /* This CPU may now print the oops message */
212 pause_on_oops_flag = 1;
213 } else {
214 /* We need to stall this CPU */
215 if (!spin_counter) {
216 /* This CPU gets to do the counting */
217 spin_counter = pause_on_oops;
218 do {
219 spin_unlock(&pause_on_oops_lock);
220 spin_msec(MSEC_PER_SEC);
221 spin_lock(&pause_on_oops_lock);
222 } while (--spin_counter);
223 pause_on_oops_flag = 0;
224 } else {
225 /* This CPU waits for a different one */
226 while (spin_counter) {
227 spin_unlock(&pause_on_oops_lock);
228 spin_msec(1);
229 spin_lock(&pause_on_oops_lock);
230 }
231 }
232 }
233 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
234}
235
236/*
237 * Return true if the calling CPU is allowed to print oops-related info. This
238 * is a bit racy..
239 */
240int oops_may_print(void)
241{
242 return pause_on_oops_flag == 0;
243}
244
245/*
246 * Called when the architecture enters its oops handler, before it prints
247 * anything. If this is the first CPU to oops, and it's oopsing the first time
248 * then let it proceed.
249 *
250 * This is all enabled by the pause_on_oops kernel boot option. We do all this
251 * to ensure that oopses don't scroll off the screen. It has the side-effect
252 * of preventing later-oopsing CPUs from mucking up the display, too.
253 *
254 * It turns out that the CPU which is allowed to print ends up pausing for the
255 * right duration, whereas all the other CPUs pause for twice as long: once in
256 * oops_enter(), once in oops_exit().
257 */
258void oops_enter(void)
259{
Arjan van de Ven2c16e9c2006-07-10 04:45:42 -0700260 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
Andrew Mortondd287792006-03-23 03:00:57 -0800261 do_oops_enter_exit();
262}
263
264/*
265 * Called when the architecture exits its oops handler, after printing
266 * everything.
267 */
268void oops_exit(void)
269{
270 do_oops_enter_exit();
271}