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1da177e4 LT |
1 | /* |
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 | */ | |
1da177e4 LT |
11 | #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> | |
dc009d92 | 20 | #include <linux/kexec.h> |
1da177e4 | 21 | |
1da177e4 LT |
22 | int panic_on_oops; |
23 | int tainted; | |
dd287796 AM |
24 | static int pause_on_oops; |
25 | static int pause_on_oops_flag; | |
26 | static DEFINE_SPINLOCK(pause_on_oops_lock); | |
1da177e4 | 27 | |
dd287796 | 28 | int panic_timeout; |
1da177e4 | 29 | |
e041c683 | 30 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
1da177e4 LT |
31 | |
32 | EXPORT_SYMBOL(panic_notifier_list); | |
33 | ||
34 | static 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 | ||
41 | static long no_blink(long time) | |
42 | { | |
43 | return 0; | |
44 | } | |
45 | ||
46 | /* Returns how long it waited in ms */ | |
47 | long (*panic_blink)(long time); | |
48 | EXPORT_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 | ||
59 | NORET_TYPE void panic(const char * fmt, ...) | |
60 | { | |
61 | long i; | |
62 | static char buf[1024]; | |
63 | va_list args; | |
347a8dc3 | 64 | #if defined(CONFIG_S390) |
1da177e4 LT |
65 | unsigned long caller = (unsigned long) __builtin_return_address(0); |
66 | #endif | |
67 | ||
dc009d92 EB |
68 | /* |
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 | ||
1da177e4 LT |
75 | 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 | ||
dc009d92 EB |
82 | /* |
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 | */ | |
6e274d14 | 87 | crash_kexec(NULL); |
dc009d92 | 88 | |
1da177e4 | 89 | #ifdef CONFIG_SMP |
dc009d92 EB |
90 | /* |
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 | */ | |
1da177e4 LT |
95 | smp_send_stop(); |
96 | #endif | |
97 | ||
e041c683 | 98 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
1da177e4 LT |
99 | |
100 | if (!panic_blink) | |
101 | panic_blink = no_blink; | |
102 | ||
dc009d92 | 103 | if (panic_timeout > 0) { |
1da177e4 LT |
104 | /* |
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 | } | |
2f048ea8 EB |
115 | /* 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. | |
1da177e4 | 118 | */ |
2f048ea8 | 119 | emergency_restart(); |
1da177e4 LT |
120 | } |
121 | #ifdef __sparc__ | |
122 | { | |
123 | extern int stop_a_enabled; | |
a271c241 | 124 | /* Make sure the user can actually press Stop-A (L1-A) */ |
1da177e4 | 125 | stop_a_enabled = 1; |
a271c241 | 126 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); |
1da177e4 LT |
127 | } |
128 | #endif | |
347a8dc3 | 129 | #if defined(CONFIG_S390) |
1da177e4 LT |
130 | disabled_wait(caller); |
131 | #endif | |
132 | local_irq_enable(); | |
133 | for (i = 0;;) { | |
c22db941 | 134 | touch_softlockup_watchdog(); |
1da177e4 LT |
135 | i += panic_blink(i); |
136 | mdelay(1); | |
137 | i++; | |
138 | } | |
139 | } | |
140 | ||
141 | EXPORT_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 | ||
156 | const 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 | ||
173 | void add_taint(unsigned flag) | |
174 | { | |
175 | tainted |= flag; | |
176 | } | |
177 | EXPORT_SYMBOL(add_taint); | |
dd287796 AM |
178 | |
179 | static int __init pause_on_oops_setup(char *str) | |
180 | { | |
181 | pause_on_oops = simple_strtoul(str, NULL, 0); | |
182 | return 1; | |
183 | } | |
184 | __setup("pause_on_oops=", pause_on_oops_setup); | |
185 | ||
186 | static void spin_msec(int msecs) | |
187 | { | |
188 | int i; | |
189 | ||
190 | for (i = 0; i < msecs; i++) { | |
191 | touch_nmi_watchdog(); | |
192 | mdelay(1); | |
193 | } | |
194 | } | |
195 | ||
196 | /* | |
197 | * It just happens that oops_enter() and oops_exit() are identically | |
198 | * implemented... | |
199 | */ | |
200 | static void do_oops_enter_exit(void) | |
201 | { | |
202 | unsigned long flags; | |
203 | static int spin_counter; | |
204 | ||
205 | if (!pause_on_oops) | |
206 | return; | |
207 | ||
208 | spin_lock_irqsave(&pause_on_oops_lock, flags); | |
209 | if (pause_on_oops_flag == 0) { | |
210 | /* This CPU may now print the oops message */ | |
211 | pause_on_oops_flag = 1; | |
212 | } else { | |
213 | /* We need to stall this CPU */ | |
214 | if (!spin_counter) { | |
215 | /* This CPU gets to do the counting */ | |
216 | spin_counter = pause_on_oops; | |
217 | do { | |
218 | spin_unlock(&pause_on_oops_lock); | |
219 | spin_msec(MSEC_PER_SEC); | |
220 | spin_lock(&pause_on_oops_lock); | |
221 | } while (--spin_counter); | |
222 | pause_on_oops_flag = 0; | |
223 | } else { | |
224 | /* This CPU waits for a different one */ | |
225 | while (spin_counter) { | |
226 | spin_unlock(&pause_on_oops_lock); | |
227 | spin_msec(1); | |
228 | spin_lock(&pause_on_oops_lock); | |
229 | } | |
230 | } | |
231 | } | |
232 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); | |
233 | } | |
234 | ||
235 | /* | |
236 | * Return true if the calling CPU is allowed to print oops-related info. This | |
237 | * is a bit racy.. | |
238 | */ | |
239 | int oops_may_print(void) | |
240 | { | |
241 | return pause_on_oops_flag == 0; | |
242 | } | |
243 | ||
244 | /* | |
245 | * Called when the architecture enters its oops handler, before it prints | |
246 | * anything. If this is the first CPU to oops, and it's oopsing the first time | |
247 | * then let it proceed. | |
248 | * | |
249 | * This is all enabled by the pause_on_oops kernel boot option. We do all this | |
250 | * to ensure that oopses don't scroll off the screen. It has the side-effect | |
251 | * of preventing later-oopsing CPUs from mucking up the display, too. | |
252 | * | |
253 | * It turns out that the CPU which is allowed to print ends up pausing for the | |
254 | * right duration, whereas all the other CPUs pause for twice as long: once in | |
255 | * oops_enter(), once in oops_exit(). | |
256 | */ | |
257 | void oops_enter(void) | |
258 | { | |
259 | do_oops_enter_exit(); | |
260 | } | |
261 | ||
262 | /* | |
263 | * Called when the architecture exits its oops handler, after printing | |
264 | * everything. | |
265 | */ | |
266 | void oops_exit(void) | |
267 | { | |
268 | do_oops_enter_exit(); | |
269 | } |