projects/linux·blob v2.6.33 · refs

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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/debug_locks.h>
12#include <linux/interrupt.h>
13#include <linux/kmsg_dump.h>
14#include <linux/kallsyms.h>
15#include <linux/notifier.h>
16#include <linux/module.h>
17#include <linux/random.h>
18#include <linux/reboot.h>
19#include <linux/delay.h>
20#include <linux/kexec.h>
21#include <linux/sched.h>
22#include <linux/sysrq.h>
23#include <linux/init.h>
24#include <linux/nmi.h>
25#include <linux/dmi.h>
26
27int panic_on_oops;
28static unsigned long tainted_mask;
29static int pause_on_oops;
30static int pause_on_oops_flag;
31static DEFINE_SPINLOCK(pause_on_oops_lock);
32
33int panic_timeout;
34
35ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
36
37EXPORT_SYMBOL(panic_notifier_list);
38
39static long no_blink(long time)
40{
41 return 0;
42}
43
44/* Returns how long it waited in ms */
45long (*panic_blink)(long time);
46EXPORT_SYMBOL(panic_blink);
47
48/**
49 * panic - halt the system
50 * @fmt: The text string to print
51 *
52 * Display a message, then perform cleanups.
53 *
54 * This function never returns.
55 */
56NORET_TYPE void panic(const char * fmt, ...)
57{
58 static char buf[1024];
59 va_list args;
60 long i;
61
62 /*
63 * It's possible to come here directly from a panic-assertion and
64 * not have preempt disabled. Some functions called from here want
65 * preempt to be disabled. No point enabling it later though...
66 */
67 preempt_disable();
68
69 bust_spinlocks(1);
70 va_start(args, fmt);
71 vsnprintf(buf, sizeof(buf), fmt, args);
72 va_end(args);
73 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
74#ifdef CONFIG_DEBUG_BUGVERBOSE
75 dump_stack();
76#endif
77
78 /*
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?
82 */
83 crash_kexec(NULL);
84
85 kmsg_dump(KMSG_DUMP_PANIC);
86
87 /*
88 * Note smp_send_stop is the usual smp shutdown function, which
89 * unfortunately means it may not be hardened to work in a panic
90 * situation.
91 */
92 smp_send_stop();
93
94 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
95
96 bust_spinlocks(0);
97
98 if (!panic_blink)
99 panic_blink = no_blink;
100
101 if (panic_timeout > 0) {
102 /*
103 * Delay timeout seconds before rebooting the machine.
104 * We can't use the "normal" timers since we just panicked.
105 */
106 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
107
108 for (i = 0; i < panic_timeout*1000; ) {
109 touch_nmi_watchdog();
110 i += panic_blink(i);
111 mdelay(1);
112 i++;
113 }
114 /*
115 * This will not be a clean reboot, with everything
116 * shutting down. But if there is a chance of
117 * rebooting the system it will be rebooted.
118 */
119 emergency_restart();
120 }
121#ifdef __sparc__
122 {
123 extern int stop_a_enabled;
124 /* Make sure the user can actually press Stop-A (L1-A) */
125 stop_a_enabled = 1;
126 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
127 }
128#endif
129#if defined(CONFIG_S390)
130 {
131 unsigned long caller;
132
133 caller = (unsigned long)__builtin_return_address(0);
134 disabled_wait(caller);
135 }
136#endif
137 local_irq_enable();
138 for (i = 0; ; ) {
139 touch_softlockup_watchdog();
140 i += panic_blink(i);
141 mdelay(1);
142 i++;
143 }
144}
145
146EXPORT_SYMBOL(panic);
147
148
149struct tnt {
150 u8 bit;
151 char true;
152 char false;
153};
154
155static const struct tnt tnts[] = {
156 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
157 { TAINT_FORCED_MODULE, 'F', ' ' },
158 { TAINT_UNSAFE_SMP, 'S', ' ' },
159 { TAINT_FORCED_RMMOD, 'R', ' ' },
160 { TAINT_MACHINE_CHECK, 'M', ' ' },
161 { TAINT_BAD_PAGE, 'B', ' ' },
162 { TAINT_USER, 'U', ' ' },
163 { TAINT_DIE, 'D', ' ' },
164 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
165 { TAINT_WARN, 'W', ' ' },
166 { TAINT_CRAP, 'C', ' ' },
167};
168
169/**
170 * print_tainted - return a string to represent the kernel taint state.
171 *
172 * 'P' - Proprietary module has been loaded.
173 * 'F' - Module has been forcibly loaded.
174 * 'S' - SMP with CPUs not designed for SMP.
175 * 'R' - User forced a module unload.
176 * 'M' - System experienced a machine check exception.
177 * 'B' - System has hit bad_page.
178 * 'U' - Userspace-defined naughtiness.
179 * 'D' - Kernel has oopsed before
180 * 'A' - ACPI table overridden.
181 * 'W' - Taint on warning.
182 * 'C' - modules from drivers/staging are loaded.
183 *
184 * The string is overwritten by the next call to print_tainted().
185 */
186const char *print_tainted(void)
187{
188 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
189
190 if (tainted_mask) {
191 char *s;
192 int i;
193
194 s = buf + sprintf(buf, "Tainted: ");
195 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
196 const struct tnt *t = &tnts[i];
197 *s++ = test_bit(t->bit, &tainted_mask) ?
198 t->true : t->false;
199 }
200 *s = 0;
201 } else
202 snprintf(buf, sizeof(buf), "Not tainted");
203
204 return buf;
205}
206
207int test_taint(unsigned flag)
208{
209 return test_bit(flag, &tainted_mask);
210}
211EXPORT_SYMBOL(test_taint);
212
213unsigned long get_taint(void)
214{
215 return tainted_mask;
216}
217
218void add_taint(unsigned flag)
219{
220 /*
221 * Can't trust the integrity of the kernel anymore.
222 * We don't call directly debug_locks_off() because the issue
223 * is not necessarily serious enough to set oops_in_progress to 1
224 * Also we want to keep up lockdep for staging development and
225 * post-warning case.
226 */
227 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
228 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
229
230 set_bit(flag, &tainted_mask);
231}
232EXPORT_SYMBOL(add_taint);
233
234static void spin_msec(int msecs)
235{
236 int i;
237
238 for (i = 0; i < msecs; i++) {
239 touch_nmi_watchdog();
240 mdelay(1);
241 }
242}
243
244/*
245 * It just happens that oops_enter() and oops_exit() are identically
246 * implemented...
247 */
248static void do_oops_enter_exit(void)
249{
250 unsigned long flags;
251 static int spin_counter;
252
253 if (!pause_on_oops)
254 return;
255
256 spin_lock_irqsave(&pause_on_oops_lock, flags);
257 if (pause_on_oops_flag == 0) {
258 /* This CPU may now print the oops message */
259 pause_on_oops_flag = 1;
260 } else {
261 /* We need to stall this CPU */
262 if (!spin_counter) {
263 /* This CPU gets to do the counting */
264 spin_counter = pause_on_oops;
265 do {
266 spin_unlock(&pause_on_oops_lock);
267 spin_msec(MSEC_PER_SEC);
268 spin_lock(&pause_on_oops_lock);
269 } while (--spin_counter);
270 pause_on_oops_flag = 0;
271 } else {
272 /* This CPU waits for a different one */
273 while (spin_counter) {
274 spin_unlock(&pause_on_oops_lock);
275 spin_msec(1);
276 spin_lock(&pause_on_oops_lock);
277 }
278 }
279 }
280 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
281}
282
283/*
284 * Return true if the calling CPU is allowed to print oops-related info.
285 * This is a bit racy..
286 */
287int oops_may_print(void)
288{
289 return pause_on_oops_flag == 0;
290}
291
292/*
293 * Called when the architecture enters its oops handler, before it prints
294 * anything. If this is the first CPU to oops, and it's oopsing the first
295 * time then let it proceed.
296 *
297 * This is all enabled by the pause_on_oops kernel boot option. We do all
298 * this to ensure that oopses don't scroll off the screen. It has the
299 * side-effect of preventing later-oopsing CPUs from mucking up the display,
300 * too.
301 *
302 * It turns out that the CPU which is allowed to print ends up pausing for
303 * the right duration, whereas all the other CPUs pause for twice as long:
304 * once in oops_enter(), once in oops_exit().
305 */
306void oops_enter(void)
307{
308 tracing_off();
309 /* can't trust the integrity of the kernel anymore: */
310 debug_locks_off();
311 do_oops_enter_exit();
312}
313
314/*
315 * 64-bit random ID for oopses:
316 */
317static u64 oops_id;
318
319static int init_oops_id(void)
320{
321 if (!oops_id)
322 get_random_bytes(&oops_id, sizeof(oops_id));
323 else
324 oops_id++;
325
326 return 0;
327}
328late_initcall(init_oops_id);
329
330static void print_oops_end_marker(void)
331{
332 init_oops_id();
333 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
334 (unsigned long long)oops_id);
335}
336
337/*
338 * Called when the architecture exits its oops handler, after printing
339 * everything.
340 */
341void oops_exit(void)
342{
343 do_oops_enter_exit();
344 print_oops_end_marker();
345 kmsg_dump(KMSG_DUMP_OOPS);
346}
347
348#ifdef WANT_WARN_ON_SLOWPATH
349struct slowpath_args {
350 const char *fmt;
351 va_list args;
352};
353
354static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
355{
356 const char *board;
357
358 printk(KERN_WARNING "------------[ cut here ]------------\n");
359 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
360 board = dmi_get_system_info(DMI_PRODUCT_NAME);
361 if (board)
362 printk(KERN_WARNING "Hardware name: %s\n", board);
363
364 if (args)
365 vprintk(args->fmt, args->args);
366
367 print_modules();
368 dump_stack();
369 print_oops_end_marker();
370 add_taint(TAINT_WARN);
371}
372
373void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
374{
375 struct slowpath_args args;
376
377 args.fmt = fmt;
378 va_start(args.args, fmt);
379 warn_slowpath_common(file, line, __builtin_return_address(0), &args);
380 va_end(args.args);
381}
382EXPORT_SYMBOL(warn_slowpath_fmt);
383
384void warn_slowpath_null(const char *file, int line)
385{
386 warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
387}
388EXPORT_SYMBOL(warn_slowpath_null);
389#endif
390
391#ifdef CONFIG_CC_STACKPROTECTOR
392
393/*
394 * Called when gcc's -fstack-protector feature is used, and
395 * gcc detects corruption of the on-stack canary value
396 */
397void __stack_chk_fail(void)
398{
399 panic("stack-protector: Kernel stack is corrupted in: %p\n",
400 __builtin_return_address(0));
401}
402EXPORT_SYMBOL(__stack_chk_fail);
403
404#endif
405
406core_param(panic, panic_timeout, int, 0644);
407core_param(pause_on_oops, pause_on_oops, int, 0644);