projects/linux·blob v4.4-rc1 · refs

530 lines · 12.9 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/ftrace.h>
19#include <linux/reboot.h>
20#include <linux/delay.h>
21#include <linux/kexec.h>
22#include <linux/sched.h>
23#include <linux/sysrq.h>
24#include <linux/init.h>
25#include <linux/nmi.h>
26#include <linux/console.h>
27
28#define PANIC_TIMER_STEP 100
29#define PANIC_BLINK_SPD 18
30
31int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
32static unsigned long tainted_mask;
33static int pause_on_oops;
34static int pause_on_oops_flag;
35static DEFINE_SPINLOCK(pause_on_oops_lock);
36bool crash_kexec_post_notifiers;
37int panic_on_warn __read_mostly;
38
39int panic_timeout = CONFIG_PANIC_TIMEOUT;
40EXPORT_SYMBOL_GPL(panic_timeout);
41
42ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
43
44EXPORT_SYMBOL(panic_notifier_list);
45
46static long no_blink(int state)
47{
48 return 0;
49}
50
51/* Returns how long it waited in ms */
52long (*panic_blink)(int state);
53EXPORT_SYMBOL(panic_blink);
54
55/*
56 * Stop ourself in panic -- architecture code may override this
57 */
58void __weak panic_smp_self_stop(void)
59{
60 while (1)
61 cpu_relax();
62}
63
64/**
65 * panic - halt the system
66 * @fmt: The text string to print
67 *
68 * Display a message, then perform cleanups.
69 *
70 * This function never returns.
71 */
72void panic(const char *fmt, ...)
73{
74 static DEFINE_SPINLOCK(panic_lock);
75 static char buf[1024];
76 va_list args;
77 long i, i_next = 0;
78 int state = 0;
79
80 /*
81 * Disable local interrupts. This will prevent panic_smp_self_stop
82 * from deadlocking the first cpu that invokes the panic, since
83 * there is nothing to prevent an interrupt handler (that runs
84 * after the panic_lock is acquired) from invoking panic again.
85 */
86 local_irq_disable();
87
88 /*
89 * It's possible to come here directly from a panic-assertion and
90 * not have preempt disabled. Some functions called from here want
91 * preempt to be disabled. No point enabling it later though...
92 *
93 * Only one CPU is allowed to execute the panic code from here. For
94 * multiple parallel invocations of panic, all other CPUs either
95 * stop themself or will wait until they are stopped by the 1st CPU
96 * with smp_send_stop().
97 */
98 if (!spin_trylock(&panic_lock))
99 panic_smp_self_stop();
100
101 console_verbose();
102 bust_spinlocks(1);
103 va_start(args, fmt);
104 vsnprintf(buf, sizeof(buf), fmt, args);
105 va_end(args);
106 pr_emerg("Kernel panic - not syncing: %s\n", buf);
107#ifdef CONFIG_DEBUG_BUGVERBOSE
108 /*
109 * Avoid nested stack-dumping if a panic occurs during oops processing
110 */
111 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
112 dump_stack();
113#endif
114
115 /*
116 * If we have crashed and we have a crash kernel loaded let it handle
117 * everything else.
118 * If we want to run this after calling panic_notifiers, pass
119 * the "crash_kexec_post_notifiers" option to the kernel.
120 */
121 if (!crash_kexec_post_notifiers)
122 crash_kexec(NULL);
123
124 /*
125 * Note smp_send_stop is the usual smp shutdown function, which
126 * unfortunately means it may not be hardened to work in a panic
127 * situation.
128 */
129 smp_send_stop();
130
131 /*
132 * Run any panic handlers, including those that might need to
133 * add information to the kmsg dump output.
134 */
135 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
136
137 kmsg_dump(KMSG_DUMP_PANIC);
138
139 /*
140 * If you doubt kdump always works fine in any situation,
141 * "crash_kexec_post_notifiers" offers you a chance to run
142 * panic_notifiers and dumping kmsg before kdump.
143 * Note: since some panic_notifiers can make crashed kernel
144 * more unstable, it can increase risks of the kdump failure too.
145 */
146 if (crash_kexec_post_notifiers)
147 crash_kexec(NULL);
148
149 bust_spinlocks(0);
150
151 /*
152 * We may have ended up stopping the CPU holding the lock (in
153 * smp_send_stop()) while still having some valuable data in the console
154 * buffer. Try to acquire the lock then release it regardless of the
155 * result. The release will also print the buffers out.
156 */
157 console_trylock();
158 console_unlock();
159
160 if (!panic_blink)
161 panic_blink = no_blink;
162
163 if (panic_timeout > 0) {
164 /*
165 * Delay timeout seconds before rebooting the machine.
166 * We can't use the "normal" timers since we just panicked.
167 */
168 pr_emerg("Rebooting in %d seconds..", panic_timeout);
169
170 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
171 touch_nmi_watchdog();
172 if (i >= i_next) {
173 i += panic_blink(state ^= 1);
174 i_next = i + 3600 / PANIC_BLINK_SPD;
175 }
176 mdelay(PANIC_TIMER_STEP);
177 }
178 }
179 if (panic_timeout != 0) {
180 /*
181 * This will not be a clean reboot, with everything
182 * shutting down. But if there is a chance of
183 * rebooting the system it will be rebooted.
184 */
185 emergency_restart();
186 }
187#ifdef __sparc__
188 {
189 extern int stop_a_enabled;
190 /* Make sure the user can actually press Stop-A (L1-A) */
191 stop_a_enabled = 1;
192 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
193 }
194#endif
195#if defined(CONFIG_S390)
196 {
197 unsigned long caller;
198
199 caller = (unsigned long)__builtin_return_address(0);
200 disabled_wait(caller);
201 }
202#endif
203 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
204 local_irq_enable();
205 for (i = 0; ; i += PANIC_TIMER_STEP) {
206 touch_softlockup_watchdog();
207 if (i >= i_next) {
208 i += panic_blink(state ^= 1);
209 i_next = i + 3600 / PANIC_BLINK_SPD;
210 }
211 mdelay(PANIC_TIMER_STEP);
212 }
213}
214
215EXPORT_SYMBOL(panic);
216
217
218struct tnt {
219 u8 bit;
220 char true;
221 char false;
222};
223
224static const struct tnt tnts[] = {
225 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
226 { TAINT_FORCED_MODULE, 'F', ' ' },
227 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
228 { TAINT_FORCED_RMMOD, 'R', ' ' },
229 { TAINT_MACHINE_CHECK, 'M', ' ' },
230 { TAINT_BAD_PAGE, 'B', ' ' },
231 { TAINT_USER, 'U', ' ' },
232 { TAINT_DIE, 'D', ' ' },
233 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
234 { TAINT_WARN, 'W', ' ' },
235 { TAINT_CRAP, 'C', ' ' },
236 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
237 { TAINT_OOT_MODULE, 'O', ' ' },
238 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
239 { TAINT_SOFTLOCKUP, 'L', ' ' },
240 { TAINT_LIVEPATCH, 'K', ' ' },
241};
242
243/**
244 * print_tainted - return a string to represent the kernel taint state.
245 *
246 * 'P' - Proprietary module has been loaded.
247 * 'F' - Module has been forcibly loaded.
248 * 'S' - SMP with CPUs not designed for SMP.
249 * 'R' - User forced a module unload.
250 * 'M' - System experienced a machine check exception.
251 * 'B' - System has hit bad_page.
252 * 'U' - Userspace-defined naughtiness.
253 * 'D' - Kernel has oopsed before
254 * 'A' - ACPI table overridden.
255 * 'W' - Taint on warning.
256 * 'C' - modules from drivers/staging are loaded.
257 * 'I' - Working around severe firmware bug.
258 * 'O' - Out-of-tree module has been loaded.
259 * 'E' - Unsigned module has been loaded.
260 * 'L' - A soft lockup has previously occurred.
261 * 'K' - Kernel has been live patched.
262 *
263 * The string is overwritten by the next call to print_tainted().
264 */
265const char *print_tainted(void)
266{
267 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
268
269 if (tainted_mask) {
270 char *s;
271 int i;
272
273 s = buf + sprintf(buf, "Tainted: ");
274 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
275 const struct tnt *t = &tnts[i];
276 *s++ = test_bit(t->bit, &tainted_mask) ?
277 t->true : t->false;
278 }
279 *s = 0;
280 } else
281 snprintf(buf, sizeof(buf), "Not tainted");
282
283 return buf;
284}
285
286int test_taint(unsigned flag)
287{
288 return test_bit(flag, &tainted_mask);
289}
290EXPORT_SYMBOL(test_taint);
291
292unsigned long get_taint(void)
293{
294 return tainted_mask;
295}
296
297/**
298 * add_taint: add a taint flag if not already set.
299 * @flag: one of the TAINT_* constants.
300 * @lockdep_ok: whether lock debugging is still OK.
301 *
302 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
303 * some notewortht-but-not-corrupting cases, it can be set to true.
304 */
305void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
306{
307 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
308 pr_warn("Disabling lock debugging due to kernel taint\n");
309
310 set_bit(flag, &tainted_mask);
311}
312EXPORT_SYMBOL(add_taint);
313
314static void spin_msec(int msecs)
315{
316 int i;
317
318 for (i = 0; i < msecs; i++) {
319 touch_nmi_watchdog();
320 mdelay(1);
321 }
322}
323
324/*
325 * It just happens that oops_enter() and oops_exit() are identically
326 * implemented...
327 */
328static void do_oops_enter_exit(void)
329{
330 unsigned long flags;
331 static int spin_counter;
332
333 if (!pause_on_oops)
334 return;
335
336 spin_lock_irqsave(&pause_on_oops_lock, flags);
337 if (pause_on_oops_flag == 0) {
338 /* This CPU may now print the oops message */
339 pause_on_oops_flag = 1;
340 } else {
341 /* We need to stall this CPU */
342 if (!spin_counter) {
343 /* This CPU gets to do the counting */
344 spin_counter = pause_on_oops;
345 do {
346 spin_unlock(&pause_on_oops_lock);
347 spin_msec(MSEC_PER_SEC);
348 spin_lock(&pause_on_oops_lock);
349 } while (--spin_counter);
350 pause_on_oops_flag = 0;
351 } else {
352 /* This CPU waits for a different one */
353 while (spin_counter) {
354 spin_unlock(&pause_on_oops_lock);
355 spin_msec(1);
356 spin_lock(&pause_on_oops_lock);
357 }
358 }
359 }
360 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
361}
362
363/*
364 * Return true if the calling CPU is allowed to print oops-related info.
365 * This is a bit racy..
366 */
367int oops_may_print(void)
368{
369 return pause_on_oops_flag == 0;
370}
371
372/*
373 * Called when the architecture enters its oops handler, before it prints
374 * anything. If this is the first CPU to oops, and it's oopsing the first
375 * time then let it proceed.
376 *
377 * This is all enabled by the pause_on_oops kernel boot option. We do all
378 * this to ensure that oopses don't scroll off the screen. It has the
379 * side-effect of preventing later-oopsing CPUs from mucking up the display,
380 * too.
381 *
382 * It turns out that the CPU which is allowed to print ends up pausing for
383 * the right duration, whereas all the other CPUs pause for twice as long:
384 * once in oops_enter(), once in oops_exit().
385 */
386void oops_enter(void)
387{
388 tracing_off();
389 /* can't trust the integrity of the kernel anymore: */
390 debug_locks_off();
391 do_oops_enter_exit();
392}
393
394/*
395 * 64-bit random ID for oopses:
396 */
397static u64 oops_id;
398
399static int init_oops_id(void)
400{
401 if (!oops_id)
402 get_random_bytes(&oops_id, sizeof(oops_id));
403 else
404 oops_id++;
405
406 return 0;
407}
408late_initcall(init_oops_id);
409
410void print_oops_end_marker(void)
411{
412 init_oops_id();
413 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
414}
415
416/*
417 * Called when the architecture exits its oops handler, after printing
418 * everything.
419 */
420void oops_exit(void)
421{
422 do_oops_enter_exit();
423 print_oops_end_marker();
424 kmsg_dump(KMSG_DUMP_OOPS);
425}
426
427#ifdef WANT_WARN_ON_SLOWPATH
428struct slowpath_args {
429 const char *fmt;
430 va_list args;
431};
432
433static void warn_slowpath_common(const char *file, int line, void *caller,
434 unsigned taint, struct slowpath_args *args)
435{
436 disable_trace_on_warning();
437
438 pr_warn("------------[ cut here ]------------\n");
439 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
440 raw_smp_processor_id(), current->pid, file, line, caller);
441
442 if (args)
443 vprintk(args->fmt, args->args);
444
445 if (panic_on_warn) {
446 /*
447 * This thread may hit another WARN() in the panic path.
448 * Resetting this prevents additional WARN() from panicking the
449 * system on this thread. Other threads are blocked by the
450 * panic_mutex in panic().
451 */
452 panic_on_warn = 0;
453 panic("panic_on_warn set ...\n");
454 }
455
456 print_modules();
457 dump_stack();
458 print_oops_end_marker();
459 /* Just a warning, don't kill lockdep. */
460 add_taint(taint, LOCKDEP_STILL_OK);
461}
462
463void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
464{
465 struct slowpath_args args;
466
467 args.fmt = fmt;
468 va_start(args.args, fmt);
469 warn_slowpath_common(file, line, __builtin_return_address(0),
470 TAINT_WARN, &args);
471 va_end(args.args);
472}
473EXPORT_SYMBOL(warn_slowpath_fmt);
474
475void warn_slowpath_fmt_taint(const char *file, int line,
476 unsigned taint, const char *fmt, ...)
477{
478 struct slowpath_args args;
479
480 args.fmt = fmt;
481 va_start(args.args, fmt);
482 warn_slowpath_common(file, line, __builtin_return_address(0),
483 taint, &args);
484 va_end(args.args);
485}
486EXPORT_SYMBOL(warn_slowpath_fmt_taint);
487
488void warn_slowpath_null(const char *file, int line)
489{
490 warn_slowpath_common(file, line, __builtin_return_address(0),
491 TAINT_WARN, NULL);
492}
493EXPORT_SYMBOL(warn_slowpath_null);
494#endif
495
496#ifdef CONFIG_CC_STACKPROTECTOR
497
498/*
499 * Called when gcc's -fstack-protector feature is used, and
500 * gcc detects corruption of the on-stack canary value
501 */
502__visible void __stack_chk_fail(void)
503{
504 panic("stack-protector: Kernel stack is corrupted in: %p\n",
505 __builtin_return_address(0));
506}
507EXPORT_SYMBOL(__stack_chk_fail);
508
509#endif
510
511core_param(panic, panic_timeout, int, 0644);
512core_param(pause_on_oops, pause_on_oops, int, 0644);
513core_param(panic_on_warn, panic_on_warn, int, 0644);
514
515static int __init setup_crash_kexec_post_notifiers(char *s)
516{
517 crash_kexec_post_notifiers = true;
518 return 0;
519}
520early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
521
522static int __init oops_setup(char *s)
523{
524 if (!s)
525 return -EINVAL;
526 if (!strcmp(s, "panic"))
527 panic_on_oops = 1;
528 return 0;
529}
530early_param("oops", oops_setup);