projects/linux·blob v2.6.35-rc5 · refs

440 lines · 10.0 KiB

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
39/* Returns how long it waited in ms */
40long (*panic_blink)(long time);
41EXPORT_SYMBOL(panic_blink);
42
43static void panic_blink_one_second(void)
44{
45 static long i = 0, end;
46
47 if (panic_blink) {
48 end = i + MSEC_PER_SEC;
49
50 while (i < end) {
51 i += panic_blink(i);
52 mdelay(1);
53 i++;
54 }
55 } else {
56 /*
57 * When running under a hypervisor a small mdelay may get
58 * rounded up to the hypervisor timeslice. For example, with
59 * a 1ms in 10ms hypervisor timeslice we might inflate a
60 * mdelay(1) loop by 10x.
61 *
62 * If we have nothing to blink, spin on 1 second calls to
63 * mdelay to avoid this.
64 */
65 mdelay(MSEC_PER_SEC);
66 }
67}
68
69/**
70 * panic - halt the system
71 * @fmt: The text string to print
72 *
73 * Display a message, then perform cleanups.
74 *
75 * This function never returns.
76 */
77NORET_TYPE void panic(const char * fmt, ...)
78{
79 static char buf[1024];
80 va_list args;
81 long i;
82
83 /*
84 * It's possible to come here directly from a panic-assertion and
85 * not have preempt disabled. Some functions called from here want
86 * preempt to be disabled. No point enabling it later though...
87 */
88 preempt_disable();
89
90 console_verbose();
91 bust_spinlocks(1);
92 va_start(args, fmt);
93 vsnprintf(buf, sizeof(buf), fmt, args);
94 va_end(args);
95 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
96#ifdef CONFIG_DEBUG_BUGVERBOSE
97 dump_stack();
98#endif
99
100 /*
101 * If we have crashed and we have a crash kernel loaded let it handle
102 * everything else.
103 * Do we want to call this before we try to display a message?
104 */
105 crash_kexec(NULL);
106
107 kmsg_dump(KMSG_DUMP_PANIC);
108
109 /*
110 * Note smp_send_stop is the usual smp shutdown function, which
111 * unfortunately means it may not be hardened to work in a panic
112 * situation.
113 */
114 smp_send_stop();
115
116 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
117
118 bust_spinlocks(0);
119
120 if (panic_timeout > 0) {
121 /*
122 * Delay timeout seconds before rebooting the machine.
123 * We can't use the "normal" timers since we just panicked.
124 */
125 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
126
127 for (i = 0; i < panic_timeout; i++) {
128 touch_nmi_watchdog();
129 panic_blink_one_second();
130 }
131 /*
132 * This will not be a clean reboot, with everything
133 * shutting down. But if there is a chance of
134 * rebooting the system it will be rebooted.
135 */
136 emergency_restart();
137 }
138#ifdef __sparc__
139 {
140 extern int stop_a_enabled;
141 /* Make sure the user can actually press Stop-A (L1-A) */
142 stop_a_enabled = 1;
143 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
144 }
145#endif
146#if defined(CONFIG_S390)
147 {
148 unsigned long caller;
149
150 caller = (unsigned long)__builtin_return_address(0);
151 disabled_wait(caller);
152 }
153#endif
154 local_irq_enable();
155 while (1) {
156 touch_softlockup_watchdog();
157 panic_blink_one_second();
158 }
159}
160
161EXPORT_SYMBOL(panic);
162
163
164struct tnt {
165 u8 bit;
166 char true;
167 char false;
168};
169
170static const struct tnt tnts[] = {
171 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
172 { TAINT_FORCED_MODULE, 'F', ' ' },
173 { TAINT_UNSAFE_SMP, 'S', ' ' },
174 { TAINT_FORCED_RMMOD, 'R', ' ' },
175 { TAINT_MACHINE_CHECK, 'M', ' ' },
176 { TAINT_BAD_PAGE, 'B', ' ' },
177 { TAINT_USER, 'U', ' ' },
178 { TAINT_DIE, 'D', ' ' },
179 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
180 { TAINT_WARN, 'W', ' ' },
181 { TAINT_CRAP, 'C', ' ' },
182 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
183};
184
185/**
186 * print_tainted - return a string to represent the kernel taint state.
187 *
188 * 'P' - Proprietary module has been loaded.
189 * 'F' - Module has been forcibly loaded.
190 * 'S' - SMP with CPUs not designed for SMP.
191 * 'R' - User forced a module unload.
192 * 'M' - System experienced a machine check exception.
193 * 'B' - System has hit bad_page.
194 * 'U' - Userspace-defined naughtiness.
195 * 'D' - Kernel has oopsed before
196 * 'A' - ACPI table overridden.
197 * 'W' - Taint on warning.
198 * 'C' - modules from drivers/staging are loaded.
199 * 'I' - Working around severe firmware bug.
200 *
201 * The string is overwritten by the next call to print_tainted().
202 */
203const char *print_tainted(void)
204{
205 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
206
207 if (tainted_mask) {
208 char *s;
209 int i;
210
211 s = buf + sprintf(buf, "Tainted: ");
212 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
213 const struct tnt *t = &tnts[i];
214 *s++ = test_bit(t->bit, &tainted_mask) ?
215 t->true : t->false;
216 }
217 *s = 0;
218 } else
219 snprintf(buf, sizeof(buf), "Not tainted");
220
221 return buf;
222}
223
224int test_taint(unsigned flag)
225{
226 return test_bit(flag, &tainted_mask);
227}
228EXPORT_SYMBOL(test_taint);
229
230unsigned long get_taint(void)
231{
232 return tainted_mask;
233}
234
235void add_taint(unsigned flag)
236{
237 /*
238 * Can't trust the integrity of the kernel anymore.
239 * We don't call directly debug_locks_off() because the issue
240 * is not necessarily serious enough to set oops_in_progress to 1
241 * Also we want to keep up lockdep for staging development and
242 * post-warning case.
243 */
244 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
245 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
246
247 set_bit(flag, &tainted_mask);
248}
249EXPORT_SYMBOL(add_taint);
250
251static void spin_msec(int msecs)
252{
253 int i;
254
255 for (i = 0; i < msecs; i++) {
256 touch_nmi_watchdog();
257 mdelay(1);
258 }
259}
260
261/*
262 * It just happens that oops_enter() and oops_exit() are identically
263 * implemented...
264 */
265static void do_oops_enter_exit(void)
266{
267 unsigned long flags;
268 static int spin_counter;
269
270 if (!pause_on_oops)
271 return;
272
273 spin_lock_irqsave(&pause_on_oops_lock, flags);
274 if (pause_on_oops_flag == 0) {
275 /* This CPU may now print the oops message */
276 pause_on_oops_flag = 1;
277 } else {
278 /* We need to stall this CPU */
279 if (!spin_counter) {
280 /* This CPU gets to do the counting */
281 spin_counter = pause_on_oops;
282 do {
283 spin_unlock(&pause_on_oops_lock);
284 spin_msec(MSEC_PER_SEC);
285 spin_lock(&pause_on_oops_lock);
286 } while (--spin_counter);
287 pause_on_oops_flag = 0;
288 } else {
289 /* This CPU waits for a different one */
290 while (spin_counter) {
291 spin_unlock(&pause_on_oops_lock);
292 spin_msec(1);
293 spin_lock(&pause_on_oops_lock);
294 }
295 }
296 }
297 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
298}
299
300/*
301 * Return true if the calling CPU is allowed to print oops-related info.
302 * This is a bit racy..
303 */
304int oops_may_print(void)
305{
306 return pause_on_oops_flag == 0;
307}
308
309/*
310 * Called when the architecture enters its oops handler, before it prints
311 * anything. If this is the first CPU to oops, and it's oopsing the first
312 * time then let it proceed.
313 *
314 * This is all enabled by the pause_on_oops kernel boot option. We do all
315 * this to ensure that oopses don't scroll off the screen. It has the
316 * side-effect of preventing later-oopsing CPUs from mucking up the display,
317 * too.
318 *
319 * It turns out that the CPU which is allowed to print ends up pausing for
320 * the right duration, whereas all the other CPUs pause for twice as long:
321 * once in oops_enter(), once in oops_exit().
322 */
323void oops_enter(void)
324{
325 tracing_off();
326 /* can't trust the integrity of the kernel anymore: */
327 debug_locks_off();
328 do_oops_enter_exit();
329}
330
331/*
332 * 64-bit random ID for oopses:
333 */
334static u64 oops_id;
335
336static int init_oops_id(void)
337{
338 if (!oops_id)
339 get_random_bytes(&oops_id, sizeof(oops_id));
340 else
341 oops_id++;
342
343 return 0;
344}
345late_initcall(init_oops_id);
346
347static void print_oops_end_marker(void)
348{
349 init_oops_id();
350 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
351 (unsigned long long)oops_id);
352}
353
354/*
355 * Called when the architecture exits its oops handler, after printing
356 * everything.
357 */
358void oops_exit(void)
359{
360 do_oops_enter_exit();
361 print_oops_end_marker();
362 kmsg_dump(KMSG_DUMP_OOPS);
363}
364
365#ifdef WANT_WARN_ON_SLOWPATH
366struct slowpath_args {
367 const char *fmt;
368 va_list args;
369};
370
371static void warn_slowpath_common(const char *file, int line, void *caller,
372 unsigned taint, struct slowpath_args *args)
373{
374 const char *board;
375
376 printk(KERN_WARNING "------------[ cut here ]------------\n");
377 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
378 board = dmi_get_system_info(DMI_PRODUCT_NAME);
379 if (board)
380 printk(KERN_WARNING "Hardware name: %s\n", board);
381
382 if (args)
383 vprintk(args->fmt, args->args);
384
385 print_modules();
386 dump_stack();
387 print_oops_end_marker();
388 add_taint(taint);
389}
390
391void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
392{
393 struct slowpath_args args;
394
395 args.fmt = fmt;
396 va_start(args.args, fmt);
397 warn_slowpath_common(file, line, __builtin_return_address(0),
398 TAINT_WARN, &args);
399 va_end(args.args);
400}
401EXPORT_SYMBOL(warn_slowpath_fmt);
402
403void warn_slowpath_fmt_taint(const char *file, int line,
404 unsigned taint, const char *fmt, ...)
405{
406 struct slowpath_args args;
407
408 args.fmt = fmt;
409 va_start(args.args, fmt);
410 warn_slowpath_common(file, line, __builtin_return_address(0),
411 taint, &args);
412 va_end(args.args);
413}
414EXPORT_SYMBOL(warn_slowpath_fmt_taint);
415
416void warn_slowpath_null(const char *file, int line)
417{
418 warn_slowpath_common(file, line, __builtin_return_address(0),
419 TAINT_WARN, NULL);
420}
421EXPORT_SYMBOL(warn_slowpath_null);
422#endif
423
424#ifdef CONFIG_CC_STACKPROTECTOR
425
426/*
427 * Called when gcc's -fstack-protector feature is used, and
428 * gcc detects corruption of the on-stack canary value
429 */
430void __stack_chk_fail(void)
431{
432 panic("stack-protector: Kernel stack is corrupted in: %p\n",
433 __builtin_return_address(0));
434}
435EXPORT_SYMBOL(__stack_chk_fail);
436
437#endif
438
439core_param(panic, panic_timeout, int, 0644);
440core_param(pause_on_oops, pause_on_oops, int, 0644);