4 * Copyright (C) 1991, 1992 Linus Torvalds
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>
24 int panic_on_unrecovered_nmi;
26 static int pause_on_oops;
27 static int pause_on_oops_flag;
28 static DEFINE_SPINLOCK(pause_on_oops_lock);
32 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
34 EXPORT_SYMBOL(panic_notifier_list);
36 static int __init panic_setup(char *str)
38 panic_timeout = simple_strtoul(str, NULL, 0);
41 __setup("panic=", panic_setup);
43 static long no_blink(long time)
48 /* Returns how long it waited in ms */
49 long (*panic_blink)(long time);
50 EXPORT_SYMBOL(panic_blink);
53 * panic - halt the system
54 * @fmt: The text string to print
56 * Display a message, then perform cleanups.
58 * This function never returns.
61 NORET_TYPE void panic(const char * fmt, ...)
64 static char buf[1024];
66 #if defined(CONFIG_S390)
67 unsigned long caller = (unsigned long) __builtin_return_address(0);
71 * It's possible to come here directly from a panic-assertion and not
72 * have preempt disabled. Some functions called from here want
73 * preempt to be disabled. No point enabling it later though...
79 vsnprintf(buf, sizeof(buf), fmt, args);
81 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
85 * If we have crashed and we have a crash kernel loaded let it handle
87 * Do we want to call this before we try to display a message?
93 * Note smp_send_stop is the usual smp shutdown function, which
94 * unfortunately means it may not be hardened to work in a panic
100 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
103 panic_blink = no_blink;
105 if (panic_timeout > 0) {
107 * Delay timeout seconds before rebooting the machine.
108 * We can't use the "normal" timers since we just panicked..
110 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
111 for (i = 0; i < panic_timeout*1000; ) {
112 touch_nmi_watchdog();
117 /* This will not be a clean reboot, with everything
118 * shutting down. But if there is a chance of
119 * rebooting the system it will be rebooted.
125 extern int stop_a_enabled;
126 /* Make sure the user can actually press Stop-A (L1-A) */
128 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
131 #if defined(CONFIG_S390)
132 disabled_wait(caller);
136 touch_softlockup_watchdog();
143 EXPORT_SYMBOL(panic);
146 * print_tainted - return a string to represent the kernel taint state.
148 * 'P' - Proprietary module has been loaded.
149 * 'F' - Module has been forcibly loaded.
150 * 'S' - SMP with CPUs not designed for SMP.
151 * 'R' - User forced a module unload.
152 * 'M' - Machine had a machine check experience.
153 * 'B' - System has hit bad_page.
155 * The string is overwritten by the next call to print_taint().
158 const char *print_tainted(void)
162 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c",
163 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
164 tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
165 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
166 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
167 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
168 tainted & TAINT_BAD_PAGE ? 'B' : ' ');
171 snprintf(buf, sizeof(buf), "Not tainted");
175 void add_taint(unsigned flag)
177 debug_locks = 0; /* can't trust the integrity of the kernel anymore */
180 EXPORT_SYMBOL(add_taint);
182 static int __init pause_on_oops_setup(char *str)
184 pause_on_oops = simple_strtoul(str, NULL, 0);
187 __setup("pause_on_oops=", pause_on_oops_setup);
189 static void spin_msec(int msecs)
193 for (i = 0; i < msecs; i++) {
194 touch_nmi_watchdog();
200 * It just happens that oops_enter() and oops_exit() are identically
203 static void do_oops_enter_exit(void)
206 static int spin_counter;
211 spin_lock_irqsave(&pause_on_oops_lock, flags);
212 if (pause_on_oops_flag == 0) {
213 /* This CPU may now print the oops message */
214 pause_on_oops_flag = 1;
216 /* We need to stall this CPU */
218 /* This CPU gets to do the counting */
219 spin_counter = pause_on_oops;
221 spin_unlock(&pause_on_oops_lock);
222 spin_msec(MSEC_PER_SEC);
223 spin_lock(&pause_on_oops_lock);
224 } while (--spin_counter);
225 pause_on_oops_flag = 0;
227 /* This CPU waits for a different one */
228 while (spin_counter) {
229 spin_unlock(&pause_on_oops_lock);
231 spin_lock(&pause_on_oops_lock);
235 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
239 * Return true if the calling CPU is allowed to print oops-related info. This
242 int oops_may_print(void)
244 return pause_on_oops_flag == 0;
248 * Called when the architecture enters its oops handler, before it prints
249 * anything. If this is the first CPU to oops, and it's oopsing the first time
250 * then let it proceed.
252 * This is all enabled by the pause_on_oops kernel boot option. We do all this
253 * to ensure that oopses don't scroll off the screen. It has the side-effect
254 * of preventing later-oopsing CPUs from mucking up the display, too.
256 * It turns out that the CPU which is allowed to print ends up pausing for the
257 * right duration, whereas all the other CPUs pause for twice as long: once in
258 * oops_enter(), once in oops_exit().
260 void oops_enter(void)
262 debug_locks_off(); /* can't trust the integrity of the kernel anymore */
263 do_oops_enter_exit();
267 * Called when the architecture exits its oops handler, after printing
272 do_oops_enter_exit();
275 #ifdef CONFIG_CC_STACKPROTECTOR
277 * Called when gcc's -fstack-protector feature is used, and
278 * gcc detects corruption of the on-stack canary value
280 void __stack_chk_fail(void)
282 panic("stack-protector: Kernel stack is corrupted");
284 EXPORT_SYMBOL(__stack_chk_fail);