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 */
11 #include <linux/config.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/delay.h>
15 #include <linux/reboot.h>
16 #include <linux/notifier.h>
17 #include <linux/init.h>
18 #include <linux/sysrq.h>
19 #include <linux/interrupt.h>
20 #include <linux/nmi.h>
21 #include <linux/kexec.h>
22
23 int panic_on_oops;
24 int tainted;
25 static int pause_on_oops;
26 static int pause_on_oops_flag;
27 static DEFINE_SPINLOCK(pause_on_oops_lock);
28
29 int panic_timeout;
30
31 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
32
33 EXPORT_SYMBOL(panic_notifier_list);
34
35 static 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
42 static long no_blink(long time)
43 {
44 return 0;
45 }
46
47 /* Returns how long it waited in ms */
48 long (*panic_blink)(long time);
49 EXPORT_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
60 NORET_TYPE void panic(const char * fmt, ...)
61 {
62 long i;
63 static char buf[1024];
64 va_list args;
65 #if defined(CONFIG_S390)
66 unsigned long caller = (unsigned long) __builtin_return_address(0);
67 #endif
68
69 /*
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
76 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
83 /*
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 */
88 crash_kexec(NULL);
89
90 #ifdef CONFIG_SMP
91 /*
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 */
96 smp_send_stop();
97 #endif
98
99 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
100
101 if (!panic_blink)
102 panic_blink = no_blink;
103
104 if (panic_timeout > 0) {
105 /*
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 }
116 /* 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.
119 */
120 emergency_restart();
121 }
122 #ifdef __sparc__
123 {
124 extern int stop_a_enabled;
125 /* Make sure the user can actually press Stop-A (L1-A) */
126 stop_a_enabled = 1;
127 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
128 }
129 #endif
130 #if defined(CONFIG_S390)
131 disabled_wait(caller);
132 #endif
133 local_irq_enable();
134 for (i = 0;;) {
135 touch_softlockup_watchdog();
136 i += panic_blink(i);
137 mdelay(1);
138 i++;
139 }
140 }
141
142 EXPORT_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.
153 *
154 * The string is overwritten by the next call to print_taint().
155 */
156
157 const char *print_tainted(void)
158 {
159 static char buf[20];
160 if (tainted) {
161 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c",
162 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
163 tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
164 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
165 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
166 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
167 tainted & TAINT_BAD_PAGE ? 'B' : ' ');
168 }
169 else
170 snprintf(buf, sizeof(buf), "Not tainted");
171 return(buf);
172 }
173
174 void add_taint(unsigned flag)
175 {
176 tainted |= flag;
177 }
178 EXPORT_SYMBOL(add_taint);
179
180 static 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
187 static 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 */
201 static 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 */
240 int 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 */
258 void oops_enter(void)
259 {
260 do_oops_enter_exit();
261 }
262
263 /*
264 * Called when the architecture exits its oops handler, after printing
265 * everything.
266 */
267 void oops_exit(void)
268 {
269 do_oops_enter_exit();
270 }
271
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