powerpc: Allow 256kB pages with SHMEM
[linux-2.6.git] / kernel / panic.c
blob3fd8c5bf8b394dd94fee9ce22fa8c20135c76c4f
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/debug_locks.h>
12 #include <linux/interrupt.h>
13 #include <linux/kallsyms.h>
14 #include <linux/notifier.h>
15 #include <linux/module.h>
16 #include <linux/random.h>
17 #include <linux/reboot.h>
18 #include <linux/delay.h>
19 #include <linux/kexec.h>
20 #include <linux/sched.h>
21 #include <linux/sysrq.h>
22 #include <linux/init.h>
23 #include <linux/nmi.h>
24 #include <linux/dmi.h>
26 int panic_on_oops;
27 static unsigned long tainted_mask;
28 static int pause_on_oops;
29 static int pause_on_oops_flag;
30 static DEFINE_SPINLOCK(pause_on_oops_lock);
32 int panic_timeout;
34 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
36 EXPORT_SYMBOL(panic_notifier_list);
38 static long no_blink(long time)
40 return 0;
43 /* Returns how long it waited in ms */
44 long (*panic_blink)(long time);
45 EXPORT_SYMBOL(panic_blink);
47 /**
48 * panic - halt the system
49 * @fmt: The text string to print
51 * Display a message, then perform cleanups.
53 * This function never returns.
55 NORET_TYPE void panic(const char * fmt, ...)
57 static char buf[1024];
58 va_list args;
59 long i;
62 * It's possible to come here directly from a panic-assertion and
63 * not have preempt disabled. Some functions called from here want
64 * preempt to be disabled. No point enabling it later though...
66 preempt_disable();
68 bust_spinlocks(1);
69 va_start(args, fmt);
70 vsnprintf(buf, sizeof(buf), fmt, args);
71 va_end(args);
72 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
73 #ifdef CONFIG_DEBUG_BUGVERBOSE
74 dump_stack();
75 #endif
78 * If we have crashed and we have a crash kernel loaded let it handle
79 * everything else.
80 * Do we want to call this before we try to display a message?
82 crash_kexec(NULL);
85 * Note smp_send_stop is the usual smp shutdown function, which
86 * unfortunately means it may not be hardened to work in a panic
87 * situation.
89 smp_send_stop();
91 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
93 if (!panic_blink)
94 panic_blink = no_blink;
96 if (panic_timeout > 0) {
98 * Delay timeout seconds before rebooting the machine.
99 * We can't use the "normal" timers since we just panicked.
101 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
103 for (i = 0; i < panic_timeout*1000; ) {
104 touch_nmi_watchdog();
105 i += panic_blink(i);
106 mdelay(1);
107 i++;
110 * This will not be a clean reboot, with everything
111 * shutting down. But if there is a chance of
112 * rebooting the system it will be rebooted.
114 emergency_restart();
116 #ifdef __sparc__
118 extern int stop_a_enabled;
119 /* Make sure the user can actually press Stop-A (L1-A) */
120 stop_a_enabled = 1;
121 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
123 #endif
124 #if defined(CONFIG_S390)
126 unsigned long caller;
128 caller = (unsigned long)__builtin_return_address(0);
129 disabled_wait(caller);
131 #endif
132 local_irq_enable();
133 for (i = 0; ; ) {
134 touch_softlockup_watchdog();
135 i += panic_blink(i);
136 mdelay(1);
137 i++;
139 bust_spinlocks(0);
142 EXPORT_SYMBOL(panic);
145 struct tnt {
146 u8 bit;
147 char true;
148 char false;
151 static const struct tnt tnts[] = {
152 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
153 { TAINT_FORCED_MODULE, 'F', ' ' },
154 { TAINT_UNSAFE_SMP, 'S', ' ' },
155 { TAINT_FORCED_RMMOD, 'R', ' ' },
156 { TAINT_MACHINE_CHECK, 'M', ' ' },
157 { TAINT_BAD_PAGE, 'B', ' ' },
158 { TAINT_USER, 'U', ' ' },
159 { TAINT_DIE, 'D', ' ' },
160 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
161 { TAINT_WARN, 'W', ' ' },
162 { TAINT_CRAP, 'C', ' ' },
166 * print_tainted - return a string to represent the kernel taint state.
168 * 'P' - Proprietary module has been loaded.
169 * 'F' - Module has been forcibly loaded.
170 * 'S' - SMP with CPUs not designed for SMP.
171 * 'R' - User forced a module unload.
172 * 'M' - System experienced a machine check exception.
173 * 'B' - System has hit bad_page.
174 * 'U' - Userspace-defined naughtiness.
175 * 'D' - Kernel has oopsed before
176 * 'A' - ACPI table overridden.
177 * 'W' - Taint on warning.
178 * 'C' - modules from drivers/staging are loaded.
180 * The string is overwritten by the next call to print_taint().
182 const char *print_tainted(void)
184 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
186 if (tainted_mask) {
187 char *s;
188 int i;
190 s = buf + sprintf(buf, "Tainted: ");
191 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
192 const struct tnt *t = &tnts[i];
193 *s++ = test_bit(t->bit, &tainted_mask) ?
194 t->true : t->false;
196 *s = 0;
197 } else
198 snprintf(buf, sizeof(buf), "Not tainted");
200 return buf;
203 int test_taint(unsigned flag)
205 return test_bit(flag, &tainted_mask);
207 EXPORT_SYMBOL(test_taint);
209 unsigned long get_taint(void)
211 return tainted_mask;
214 void add_taint(unsigned flag)
216 /* can't trust the integrity of the kernel anymore: */
217 debug_locks = 0;
218 set_bit(flag, &tainted_mask);
220 EXPORT_SYMBOL(add_taint);
222 static void spin_msec(int msecs)
224 int i;
226 for (i = 0; i < msecs; i++) {
227 touch_nmi_watchdog();
228 mdelay(1);
233 * It just happens that oops_enter() and oops_exit() are identically
234 * implemented...
236 static void do_oops_enter_exit(void)
238 unsigned long flags;
239 static int spin_counter;
241 if (!pause_on_oops)
242 return;
244 spin_lock_irqsave(&pause_on_oops_lock, flags);
245 if (pause_on_oops_flag == 0) {
246 /* This CPU may now print the oops message */
247 pause_on_oops_flag = 1;
248 } else {
249 /* We need to stall this CPU */
250 if (!spin_counter) {
251 /* This CPU gets to do the counting */
252 spin_counter = pause_on_oops;
253 do {
254 spin_unlock(&pause_on_oops_lock);
255 spin_msec(MSEC_PER_SEC);
256 spin_lock(&pause_on_oops_lock);
257 } while (--spin_counter);
258 pause_on_oops_flag = 0;
259 } else {
260 /* This CPU waits for a different one */
261 while (spin_counter) {
262 spin_unlock(&pause_on_oops_lock);
263 spin_msec(1);
264 spin_lock(&pause_on_oops_lock);
268 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
272 * Return true if the calling CPU is allowed to print oops-related info.
273 * This is a bit racy..
275 int oops_may_print(void)
277 return pause_on_oops_flag == 0;
281 * Called when the architecture enters its oops handler, before it prints
282 * anything. If this is the first CPU to oops, and it's oopsing the first
283 * time then let it proceed.
285 * This is all enabled by the pause_on_oops kernel boot option. We do all
286 * this to ensure that oopses don't scroll off the screen. It has the
287 * side-effect of preventing later-oopsing CPUs from mucking up the display,
288 * too.
290 * It turns out that the CPU which is allowed to print ends up pausing for
291 * the right duration, whereas all the other CPUs pause for twice as long:
292 * once in oops_enter(), once in oops_exit().
294 void oops_enter(void)
296 /* can't trust the integrity of the kernel anymore: */
297 debug_locks_off();
298 do_oops_enter_exit();
302 * 64-bit random ID for oopses:
304 static u64 oops_id;
306 static int init_oops_id(void)
308 if (!oops_id)
309 get_random_bytes(&oops_id, sizeof(oops_id));
310 else
311 oops_id++;
313 return 0;
315 late_initcall(init_oops_id);
317 static void print_oops_end_marker(void)
319 init_oops_id();
320 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
321 (unsigned long long)oops_id);
325 * Called when the architecture exits its oops handler, after printing
326 * everything.
328 void oops_exit(void)
330 do_oops_enter_exit();
331 print_oops_end_marker();
334 #ifdef WANT_WARN_ON_SLOWPATH
335 void warn_slowpath(const char *file, int line, const char *fmt, ...)
337 va_list args;
338 char function[KSYM_SYMBOL_LEN];
339 unsigned long caller = (unsigned long)__builtin_return_address(0);
340 const char *board;
342 sprint_symbol(function, caller);
344 printk(KERN_WARNING "------------[ cut here ]------------\n");
345 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
346 line, function);
347 board = dmi_get_system_info(DMI_PRODUCT_NAME);
348 if (board)
349 printk(KERN_WARNING "Hardware name: %s\n", board);
351 if (fmt) {
352 va_start(args, fmt);
353 vprintk(fmt, args);
354 va_end(args);
357 print_modules();
358 dump_stack();
359 print_oops_end_marker();
360 add_taint(TAINT_WARN);
362 EXPORT_SYMBOL(warn_slowpath);
363 #endif
365 #ifdef CONFIG_CC_STACKPROTECTOR
368 * Called when gcc's -fstack-protector feature is used, and
369 * gcc detects corruption of the on-stack canary value
371 void __stack_chk_fail(void)
373 panic("stack-protector: Kernel stack is corrupted in: %p\n",
374 __builtin_return_address(0));
376 EXPORT_SYMBOL(__stack_chk_fail);
378 #endif
380 core_param(panic, panic_timeout, int, 0644);
381 core_param(pause_on_oops, pause_on_oops, int, 0644);