Linux 2.6.26-rc1
[cris-mirror.git] / kernel / panic.c
blob425567f45b9f776148f1767b2f4af2d357a0c2fd
1 /*
2 * linux/kernel/panic.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
8 * This function is used through-out the kernel (including mm and fs)
9 * to indicate a major problem.
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>
20 #include <linux/kexec.h>
21 #include <linux/debug_locks.h>
22 #include <linux/random.h>
23 #include <linux/kallsyms.h>
25 int panic_on_oops;
26 int tainted;
27 static int pause_on_oops;
28 static int pause_on_oops_flag;
29 static DEFINE_SPINLOCK(pause_on_oops_lock);
31 int panic_timeout;
33 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
35 EXPORT_SYMBOL(panic_notifier_list);
37 static int __init panic_setup(char *str)
39 panic_timeout = simple_strtoul(str, NULL, 0);
40 return 1;
42 __setup("panic=", panic_setup);
44 static long no_blink(long time)
46 return 0;
49 /* Returns how long it waited in ms */
50 long (*panic_blink)(long time);
51 EXPORT_SYMBOL(panic_blink);
53 /**
54 * panic - halt the system
55 * @fmt: The text string to print
57 * Display a message, then perform cleanups.
59 * This function never returns.
62 NORET_TYPE void panic(const char * fmt, ...)
64 long i;
65 static char buf[1024];
66 va_list args;
67 #if defined(CONFIG_S390)
68 unsigned long caller = (unsigned long) __builtin_return_address(0);
69 #endif
72 * It's possible to come here directly from a panic-assertion and not
73 * have preempt disabled. Some functions called from here want
74 * preempt to be disabled. No point enabling it later though...
76 preempt_disable();
78 bust_spinlocks(1);
79 va_start(args, fmt);
80 vsnprintf(buf, sizeof(buf), fmt, args);
81 va_end(args);
82 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
83 bust_spinlocks(0);
86 * If we have crashed and we have a crash kernel loaded let it handle
87 * everything else.
88 * Do we want to call this before we try to display a message?
90 crash_kexec(NULL);
92 #ifdef CONFIG_SMP
94 * Note smp_send_stop is the usual smp shutdown function, which
95 * unfortunately means it may not be hardened to work in a panic
96 * situation.
98 smp_send_stop();
99 #endif
101 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
103 if (!panic_blink)
104 panic_blink = no_blink;
106 if (panic_timeout > 0) {
108 * Delay timeout seconds before rebooting the machine.
109 * We can't use the "normal" timers since we just panicked..
111 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
112 for (i = 0; i < panic_timeout*1000; ) {
113 touch_nmi_watchdog();
114 i += panic_blink(i);
115 mdelay(1);
116 i++;
118 /* This will not be a clean reboot, with everything
119 * shutting down. But if there is a chance of
120 * rebooting the system it will be rebooted.
122 emergency_restart();
124 #ifdef __sparc__
126 extern int stop_a_enabled;
127 /* Make sure the user can actually press Stop-A (L1-A) */
128 stop_a_enabled = 1;
129 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
131 #endif
132 #if defined(CONFIG_S390)
133 disabled_wait(caller);
134 #endif
135 local_irq_enable();
136 for (i = 0;;) {
137 touch_softlockup_watchdog();
138 i += panic_blink(i);
139 mdelay(1);
140 i++;
144 EXPORT_SYMBOL(panic);
147 * print_tainted - return a string to represent the kernel taint state.
149 * 'P' - Proprietary module has been loaded.
150 * 'F' - Module has been forcibly loaded.
151 * 'S' - SMP with CPUs not designed for SMP.
152 * 'R' - User forced a module unload.
153 * 'M' - System experienced a machine check exception.
154 * 'B' - System has hit bad_page.
155 * 'U' - Userspace-defined naughtiness.
156 * 'A' - ACPI table overridden.
157 * 'W' - Taint on warning.
159 * The string is overwritten by the next call to print_taint().
162 const char *print_tainted(void)
164 static char buf[20];
165 if (tainted) {
166 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c%c%c",
167 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
168 tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
169 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
170 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
171 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
172 tainted & TAINT_BAD_PAGE ? 'B' : ' ',
173 tainted & TAINT_USER ? 'U' : ' ',
174 tainted & TAINT_DIE ? 'D' : ' ',
175 tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' ',
176 tainted & TAINT_WARN ? 'W' : ' ');
178 else
179 snprintf(buf, sizeof(buf), "Not tainted");
180 return(buf);
183 void add_taint(unsigned flag)
185 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
186 tainted |= flag;
188 EXPORT_SYMBOL(add_taint);
190 static int __init pause_on_oops_setup(char *str)
192 pause_on_oops = simple_strtoul(str, NULL, 0);
193 return 1;
195 __setup("pause_on_oops=", pause_on_oops_setup);
197 static void spin_msec(int msecs)
199 int i;
201 for (i = 0; i < msecs; i++) {
202 touch_nmi_watchdog();
203 mdelay(1);
208 * It just happens that oops_enter() and oops_exit() are identically
209 * implemented...
211 static void do_oops_enter_exit(void)
213 unsigned long flags;
214 static int spin_counter;
216 if (!pause_on_oops)
217 return;
219 spin_lock_irqsave(&pause_on_oops_lock, flags);
220 if (pause_on_oops_flag == 0) {
221 /* This CPU may now print the oops message */
222 pause_on_oops_flag = 1;
223 } else {
224 /* We need to stall this CPU */
225 if (!spin_counter) {
226 /* This CPU gets to do the counting */
227 spin_counter = pause_on_oops;
228 do {
229 spin_unlock(&pause_on_oops_lock);
230 spin_msec(MSEC_PER_SEC);
231 spin_lock(&pause_on_oops_lock);
232 } while (--spin_counter);
233 pause_on_oops_flag = 0;
234 } else {
235 /* This CPU waits for a different one */
236 while (spin_counter) {
237 spin_unlock(&pause_on_oops_lock);
238 spin_msec(1);
239 spin_lock(&pause_on_oops_lock);
243 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
247 * Return true if the calling CPU is allowed to print oops-related info. This
248 * is a bit racy..
250 int oops_may_print(void)
252 return pause_on_oops_flag == 0;
256 * Called when the architecture enters its oops handler, before it prints
257 * anything. If this is the first CPU to oops, and it's oopsing the first time
258 * then let it proceed.
260 * This is all enabled by the pause_on_oops kernel boot option. We do all this
261 * to ensure that oopses don't scroll off the screen. It has the side-effect
262 * of preventing later-oopsing CPUs from mucking up the display, too.
264 * It turns out that the CPU which is allowed to print ends up pausing for the
265 * right duration, whereas all the other CPUs pause for twice as long: once in
266 * oops_enter(), once in oops_exit().
268 void oops_enter(void)
270 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
271 do_oops_enter_exit();
275 * 64-bit random ID for oopses:
277 static u64 oops_id;
279 static int init_oops_id(void)
281 if (!oops_id)
282 get_random_bytes(&oops_id, sizeof(oops_id));
284 return 0;
286 late_initcall(init_oops_id);
288 static void print_oops_end_marker(void)
290 init_oops_id();
291 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
292 (unsigned long long)oops_id);
296 * Called when the architecture exits its oops handler, after printing
297 * everything.
299 void oops_exit(void)
301 do_oops_enter_exit();
302 print_oops_end_marker();
305 #ifdef WANT_WARN_ON_SLOWPATH
306 void warn_on_slowpath(const char *file, int line)
308 char function[KSYM_SYMBOL_LEN];
309 unsigned long caller = (unsigned long) __builtin_return_address(0);
310 sprint_symbol(function, caller);
312 printk(KERN_WARNING "------------[ cut here ]------------\n");
313 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
314 line, function);
315 print_modules();
316 dump_stack();
317 print_oops_end_marker();
318 add_taint(TAINT_WARN);
320 EXPORT_SYMBOL(warn_on_slowpath);
321 #endif
323 #ifdef CONFIG_CC_STACKPROTECTOR
325 * Called when gcc's -fstack-protector feature is used, and
326 * gcc detects corruption of the on-stack canary value
328 void __stack_chk_fail(void)
330 panic("stack-protector: Kernel stack is corrupted");
332 EXPORT_SYMBOL(__stack_chk_fail);
333 #endif