kernel-doc: handle varargs cleanly
[linux-2.6/zen-sources.git] / kernel / panic.c
blob4d5088355bfefba8956ff5c91cbc4b932d23eff6
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 static unsigned long tainted_mask;
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 long no_blink(long time)
39 return 0;
42 /* Returns how long it waited in ms */
43 long (*panic_blink)(long time);
44 EXPORT_SYMBOL(panic_blink);
46 /**
47 * panic - halt the system
48 * @fmt: The text string to print
50 * Display a message, then perform cleanups.
52 * This function never returns.
55 NORET_TYPE void panic(const char * fmt, ...)
57 long i;
58 static char buf[1024];
59 va_list args;
60 #if defined(CONFIG_S390)
61 unsigned long caller = (unsigned long) __builtin_return_address(0);
62 #endif
65 * It's possible to come here directly from a panic-assertion and not
66 * have preempt disabled. Some functions called from here want
67 * preempt to be disabled. No point enabling it later though...
69 preempt_disable();
71 bust_spinlocks(1);
72 va_start(args, fmt);
73 vsnprintf(buf, sizeof(buf), fmt, args);
74 va_end(args);
75 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
76 bust_spinlocks(0);
79 * If we have crashed and we have a crash kernel loaded let it handle
80 * everything else.
81 * Do we want to call this before we try to display a message?
83 crash_kexec(NULL);
85 #ifdef CONFIG_SMP
87 * Note smp_send_stop is the usual smp shutdown function, which
88 * unfortunately means it may not be hardened to work in a panic
89 * situation.
91 smp_send_stop();
92 #endif
94 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
96 if (!panic_blink)
97 panic_blink = no_blink;
99 if (panic_timeout > 0) {
101 * Delay timeout seconds before rebooting the machine.
102 * We can't use the "normal" timers since we just panicked..
104 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
105 for (i = 0; i < panic_timeout*1000; ) {
106 touch_nmi_watchdog();
107 i += panic_blink(i);
108 mdelay(1);
109 i++;
111 /* This will not be a clean reboot, with everything
112 * shutting down. But if there is a chance of
113 * rebooting the system it will be rebooted.
115 emergency_restart();
117 #ifdef __sparc__
119 extern int stop_a_enabled;
120 /* Make sure the user can actually press Stop-A (L1-A) */
121 stop_a_enabled = 1;
122 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
124 #endif
125 #if defined(CONFIG_S390)
126 disabled_wait(caller);
127 #endif
128 local_irq_enable();
129 for (i = 0;;) {
130 touch_softlockup_watchdog();
131 i += panic_blink(i);
132 mdelay(1);
133 i++;
137 EXPORT_SYMBOL(panic);
140 struct tnt {
141 u8 bit;
142 char true;
143 char false;
146 static const struct tnt tnts[] = {
147 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
148 { TAINT_FORCED_MODULE, 'F', ' ' },
149 { TAINT_UNSAFE_SMP, 'S', ' ' },
150 { TAINT_FORCED_RMMOD, 'R', ' ' },
151 { TAINT_MACHINE_CHECK, 'M', ' ' },
152 { TAINT_BAD_PAGE, 'B', ' ' },
153 { TAINT_USER, 'U', ' ' },
154 { TAINT_DIE, 'D', ' ' },
155 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
156 { TAINT_WARN, 'W', ' ' },
157 { TAINT_CRAP, 'C', ' ' },
161 * print_tainted - return a string to represent the kernel taint state.
163 * 'P' - Proprietary module has been loaded.
164 * 'F' - Module has been forcibly loaded.
165 * 'S' - SMP with CPUs not designed for SMP.
166 * 'R' - User forced a module unload.
167 * 'M' - System experienced a machine check exception.
168 * 'B' - System has hit bad_page.
169 * 'U' - Userspace-defined naughtiness.
170 * 'D' - Kernel has oopsed before
171 * 'A' - ACPI table overridden.
172 * 'W' - Taint on warning.
173 * 'C' - modules from drivers/staging are loaded.
175 * The string is overwritten by the next call to print_taint().
177 const char *print_tainted(void)
179 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
181 if (tainted_mask) {
182 char *s;
183 int i;
185 s = buf + sprintf(buf, "Tainted: ");
186 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
187 const struct tnt *t = &tnts[i];
188 *s++ = test_bit(t->bit, &tainted_mask) ?
189 t->true : t->false;
191 *s = 0;
192 } else
193 snprintf(buf, sizeof(buf), "Not tainted");
194 return(buf);
197 int test_taint(unsigned flag)
199 return test_bit(flag, &tainted_mask);
201 EXPORT_SYMBOL(test_taint);
203 unsigned long get_taint(void)
205 return tainted_mask;
208 void add_taint(unsigned flag)
210 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
211 set_bit(flag, &tainted_mask);
213 EXPORT_SYMBOL(add_taint);
215 static void spin_msec(int msecs)
217 int i;
219 for (i = 0; i < msecs; i++) {
220 touch_nmi_watchdog();
221 mdelay(1);
226 * It just happens that oops_enter() and oops_exit() are identically
227 * implemented...
229 static void do_oops_enter_exit(void)
231 unsigned long flags;
232 static int spin_counter;
234 if (!pause_on_oops)
235 return;
237 spin_lock_irqsave(&pause_on_oops_lock, flags);
238 if (pause_on_oops_flag == 0) {
239 /* This CPU may now print the oops message */
240 pause_on_oops_flag = 1;
241 } else {
242 /* We need to stall this CPU */
243 if (!spin_counter) {
244 /* This CPU gets to do the counting */
245 spin_counter = pause_on_oops;
246 do {
247 spin_unlock(&pause_on_oops_lock);
248 spin_msec(MSEC_PER_SEC);
249 spin_lock(&pause_on_oops_lock);
250 } while (--spin_counter);
251 pause_on_oops_flag = 0;
252 } else {
253 /* This CPU waits for a different one */
254 while (spin_counter) {
255 spin_unlock(&pause_on_oops_lock);
256 spin_msec(1);
257 spin_lock(&pause_on_oops_lock);
261 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
265 * Return true if the calling CPU is allowed to print oops-related info. This
266 * is a bit racy..
268 int oops_may_print(void)
270 return pause_on_oops_flag == 0;
274 * Called when the architecture enters its oops handler, before it prints
275 * anything. If this is the first CPU to oops, and it's oopsing the first time
276 * then let it proceed.
278 * This is all enabled by the pause_on_oops kernel boot option. We do all this
279 * to ensure that oopses don't scroll off the screen. It has the side-effect
280 * of preventing later-oopsing CPUs from mucking up the display, too.
282 * It turns out that the CPU which is allowed to print ends up pausing for the
283 * right duration, whereas all the other CPUs pause for twice as long: once in
284 * oops_enter(), once in oops_exit().
286 void oops_enter(void)
288 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
289 do_oops_enter_exit();
293 * 64-bit random ID for oopses:
295 static u64 oops_id;
297 static int init_oops_id(void)
299 if (!oops_id)
300 get_random_bytes(&oops_id, sizeof(oops_id));
302 return 0;
304 late_initcall(init_oops_id);
306 static void print_oops_end_marker(void)
308 init_oops_id();
309 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
310 (unsigned long long)oops_id);
314 * Called when the architecture exits its oops handler, after printing
315 * everything.
317 void oops_exit(void)
319 do_oops_enter_exit();
320 print_oops_end_marker();
323 #ifdef WANT_WARN_ON_SLOWPATH
324 void warn_on_slowpath(const char *file, int line)
326 char function[KSYM_SYMBOL_LEN];
327 unsigned long caller = (unsigned long) __builtin_return_address(0);
328 sprint_symbol(function, caller);
330 printk(KERN_WARNING "------------[ cut here ]------------\n");
331 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
332 line, function);
333 print_modules();
334 dump_stack();
335 print_oops_end_marker();
336 add_taint(TAINT_WARN);
338 EXPORT_SYMBOL(warn_on_slowpath);
341 void warn_slowpath(const char *file, int line, const char *fmt, ...)
343 va_list args;
344 char function[KSYM_SYMBOL_LEN];
345 unsigned long caller = (unsigned long)__builtin_return_address(0);
346 sprint_symbol(function, caller);
348 printk(KERN_WARNING "------------[ cut here ]------------\n");
349 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
350 line, function);
351 va_start(args, fmt);
352 vprintk(fmt, args);
353 va_end(args);
355 print_modules();
356 dump_stack();
357 print_oops_end_marker();
358 add_taint(TAINT_WARN);
360 EXPORT_SYMBOL(warn_slowpath);
361 #endif
363 #ifdef CONFIG_CC_STACKPROTECTOR
365 * Called when gcc's -fstack-protector feature is used, and
366 * gcc detects corruption of the on-stack canary value
368 void __stack_chk_fail(void)
370 panic("stack-protector: Kernel stack is corrupted");
372 EXPORT_SYMBOL(__stack_chk_fail);
373 #endif
375 core_param(panic, panic_timeout, int, 0644);
376 core_param(pause_on_oops, pause_on_oops, int, 0644);