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CommitLineData
1da177e4
LT
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 */
c95dbf27
IM
11#include <linux/debug_locks.h>
12#include <linux/interrupt.h>
456b565c 13#include <linux/kmsg_dump.h>
c95dbf27
IM
14#include <linux/kallsyms.h>
15#include <linux/notifier.h>
1da177e4 16#include <linux/module.h>
c95dbf27 17#include <linux/random.h>
de7edd31 18#include <linux/ftrace.h>
1da177e4 19#include <linux/reboot.h>
c95dbf27
IM
20#include <linux/delay.h>
21#include <linux/kexec.h>
22#include <linux/sched.h>
1da177e4 23#include <linux/sysrq.h>
c95dbf27 24#include <linux/init.h>
1da177e4
LT
25#include <linux/nmi.h>
26
c7ff0d9c
TS
27#define PANIC_TIMER_STEP 100
28#define PANIC_BLINK_SPD 18
29
2a01bb38 30int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
25ddbb18 31static unsigned long tainted_mask;
dd287796
AM
32static int pause_on_oops;
33static int pause_on_oops_flag;
34static DEFINE_SPINLOCK(pause_on_oops_lock);
1da177e4 35
5800dc3c 36int panic_timeout = CONFIG_PANIC_TIMEOUT;
81e88fdc 37EXPORT_SYMBOL_GPL(panic_timeout);
1da177e4 38
e041c683 39ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4
LT
40
41EXPORT_SYMBOL(panic_notifier_list);
42
c7ff0d9c 43static long no_blink(int state)
8aeee85a 44{
c7ff0d9c 45 return 0;
8aeee85a
AB
46}
47
c7ff0d9c
TS
48/* Returns how long it waited in ms */
49long (*panic_blink)(int state);
50EXPORT_SYMBOL(panic_blink);
51
93e13a36
MH
52/*
53 * Stop ourself in panic -- architecture code may override this
54 */
55void __weak panic_smp_self_stop(void)
56{
57 while (1)
58 cpu_relax();
59}
60
1da177e4
LT
61/**
62 * panic - halt the system
63 * @fmt: The text string to print
64 *
65 * Display a message, then perform cleanups.
66 *
67 * This function never returns.
68 */
9402c95f 69void panic(const char *fmt, ...)
1da177e4 70{
93e13a36 71 static DEFINE_SPINLOCK(panic_lock);
1da177e4
LT
72 static char buf[1024];
73 va_list args;
c7ff0d9c
TS
74 long i, i_next = 0;
75 int state = 0;
1da177e4 76
190320c3
VM
77 /*
78 * Disable local interrupts. This will prevent panic_smp_self_stop
79 * from deadlocking the first cpu that invokes the panic, since
80 * there is nothing to prevent an interrupt handler (that runs
81 * after the panic_lock is acquired) from invoking panic again.
82 */
83 local_irq_disable();
84
dc009d92 85 /*
c95dbf27
IM
86 * It's possible to come here directly from a panic-assertion and
87 * not have preempt disabled. Some functions called from here want
dc009d92 88 * preempt to be disabled. No point enabling it later though...
93e13a36
MH
89 *
90 * Only one CPU is allowed to execute the panic code from here. For
91 * multiple parallel invocations of panic, all other CPUs either
92 * stop themself or will wait until they are stopped by the 1st CPU
93 * with smp_send_stop().
dc009d92 94 */
93e13a36
MH
95 if (!spin_trylock(&panic_lock))
96 panic_smp_self_stop();
dc009d92 97
5b530fc1 98 console_verbose();
1da177e4
LT
99 bust_spinlocks(1);
100 va_start(args, fmt);
101 vsnprintf(buf, sizeof(buf), fmt, args);
102 va_end(args);
d7c0847f 103 pr_emerg("Kernel panic - not syncing: %s\n", buf);
5cb27301 104#ifdef CONFIG_DEBUG_BUGVERBOSE
6e6f0a1f
AK
105 /*
106 * Avoid nested stack-dumping if a panic occurs during oops processing
107 */
026ee1f6 108 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
6e6f0a1f 109 dump_stack();
5cb27301 110#endif
1da177e4 111
dc009d92
EB
112 /*
113 * If we have crashed and we have a crash kernel loaded let it handle
114 * everything else.
115 * Do we want to call this before we try to display a message?
116 */
6e274d14 117 crash_kexec(NULL);
dc009d92 118
dc009d92
EB
119 /*
120 * Note smp_send_stop is the usual smp shutdown function, which
121 * unfortunately means it may not be hardened to work in a panic
122 * situation.
123 */
1da177e4 124 smp_send_stop();
1da177e4 125
6723734c
KC
126 /*
127 * Run any panic handlers, including those that might need to
128 * add information to the kmsg dump output.
129 */
e041c683 130 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4 131
6723734c
KC
132 kmsg_dump(KMSG_DUMP_PANIC);
133
d014e889
AK
134 bust_spinlocks(0);
135
c7ff0d9c
TS
136 if (!panic_blink)
137 panic_blink = no_blink;
138
dc009d92 139 if (panic_timeout > 0) {
1da177e4 140 /*
c95dbf27
IM
141 * Delay timeout seconds before rebooting the machine.
142 * We can't use the "normal" timers since we just panicked.
143 */
d7c0847f 144 pr_emerg("Rebooting in %d seconds..", panic_timeout);
c95dbf27 145
c7ff0d9c 146 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
1da177e4 147 touch_nmi_watchdog();
c7ff0d9c
TS
148 if (i >= i_next) {
149 i += panic_blink(state ^= 1);
150 i_next = i + 3600 / PANIC_BLINK_SPD;
151 }
152 mdelay(PANIC_TIMER_STEP);
1da177e4 153 }
4302fbc8
HD
154 }
155 if (panic_timeout != 0) {
c95dbf27
IM
156 /*
157 * This will not be a clean reboot, with everything
158 * shutting down. But if there is a chance of
159 * rebooting the system it will be rebooted.
1da177e4 160 */
2f048ea8 161 emergency_restart();
1da177e4
LT
162 }
163#ifdef __sparc__
164 {
165 extern int stop_a_enabled;
a271c241 166 /* Make sure the user can actually press Stop-A (L1-A) */
1da177e4 167 stop_a_enabled = 1;
d7c0847f 168 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4
LT
169 }
170#endif
347a8dc3 171#if defined(CONFIG_S390)
c95dbf27
IM
172 {
173 unsigned long caller;
174
175 caller = (unsigned long)__builtin_return_address(0);
176 disabled_wait(caller);
177 }
1da177e4 178#endif
d7c0847f 179 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
1da177e4 180 local_irq_enable();
c7ff0d9c 181 for (i = 0; ; i += PANIC_TIMER_STEP) {
c22db941 182 touch_softlockup_watchdog();
c7ff0d9c
TS
183 if (i >= i_next) {
184 i += panic_blink(state ^= 1);
185 i_next = i + 3600 / PANIC_BLINK_SPD;
186 }
187 mdelay(PANIC_TIMER_STEP);
1da177e4
LT
188 }
189}
190
191EXPORT_SYMBOL(panic);
192
c277e63f 193
25ddbb18 194struct tnt {
c95dbf27
IM
195 u8 bit;
196 char true;
197 char false;
25ddbb18
AK
198};
199
200static const struct tnt tnts[] = {
c95dbf27
IM
201 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
202 { TAINT_FORCED_MODULE, 'F', ' ' },
8c90487c 203 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
c95dbf27
IM
204 { TAINT_FORCED_RMMOD, 'R', ' ' },
205 { TAINT_MACHINE_CHECK, 'M', ' ' },
206 { TAINT_BAD_PAGE, 'B', ' ' },
207 { TAINT_USER, 'U', ' ' },
208 { TAINT_DIE, 'D', ' ' },
209 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
210 { TAINT_WARN, 'W', ' ' },
211 { TAINT_CRAP, 'C', ' ' },
92946bc7 212 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
2449b8ba 213 { TAINT_OOT_MODULE, 'O', ' ' },
57673c2b 214 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
25ddbb18
AK
215};
216
1da177e4
LT
217/**
218 * print_tainted - return a string to represent the kernel taint state.
219 *
220 * 'P' - Proprietary module has been loaded.
221 * 'F' - Module has been forcibly loaded.
222 * 'S' - SMP with CPUs not designed for SMP.
223 * 'R' - User forced a module unload.
9aa5e993 224 * 'M' - System experienced a machine check exception.
1da177e4 225 * 'B' - System has hit bad_page.
34f5a398 226 * 'U' - Userspace-defined naughtiness.
a8005992 227 * 'D' - Kernel has oopsed before
95b570c9
NH
228 * 'A' - ACPI table overridden.
229 * 'W' - Taint on warning.
061b1bd3 230 * 'C' - modules from drivers/staging are loaded.
92946bc7 231 * 'I' - Working around severe firmware bug.
2449b8ba 232 * 'O' - Out-of-tree module has been loaded.
57673c2b 233 * 'E' - Unsigned module has been loaded.
1da177e4 234 *
fe002a41 235 * The string is overwritten by the next call to print_tainted().
1da177e4 236 */
1da177e4
LT
237const char *print_tainted(void)
238{
01284764 239 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
25ddbb18
AK
240
241 if (tainted_mask) {
242 char *s;
243 int i;
244
245 s = buf + sprintf(buf, "Tainted: ");
246 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
247 const struct tnt *t = &tnts[i];
248 *s++ = test_bit(t->bit, &tainted_mask) ?
249 t->true : t->false;
250 }
251 *s = 0;
252 } else
1da177e4 253 snprintf(buf, sizeof(buf), "Not tainted");
c95dbf27
IM
254
255 return buf;
1da177e4
LT
256}
257
25ddbb18 258int test_taint(unsigned flag)
1da177e4 259{
25ddbb18
AK
260 return test_bit(flag, &tainted_mask);
261}
262EXPORT_SYMBOL(test_taint);
263
264unsigned long get_taint(void)
265{
266 return tainted_mask;
1da177e4 267}
dd287796 268
373d4d09
RR
269/**
270 * add_taint: add a taint flag if not already set.
271 * @flag: one of the TAINT_* constants.
272 * @lockdep_ok: whether lock debugging is still OK.
273 *
274 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
275 * some notewortht-but-not-corrupting cases, it can be set to true.
276 */
277void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
dd287796 278{
373d4d09 279 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
d7c0847f 280 pr_warn("Disabling lock debugging due to kernel taint\n");
9eeba613 281
25ddbb18 282 set_bit(flag, &tainted_mask);
dd287796 283}
1da177e4 284EXPORT_SYMBOL(add_taint);
dd287796
AM
285
286static void spin_msec(int msecs)
287{
288 int i;
289
290 for (i = 0; i < msecs; i++) {
291 touch_nmi_watchdog();
292 mdelay(1);
293 }
294}
295
296/*
297 * It just happens that oops_enter() and oops_exit() are identically
298 * implemented...
299 */
300static void do_oops_enter_exit(void)
301{
302 unsigned long flags;
303 static int spin_counter;
304
305 if (!pause_on_oops)
306 return;
307
308 spin_lock_irqsave(&pause_on_oops_lock, flags);
309 if (pause_on_oops_flag == 0) {
310 /* This CPU may now print the oops message */
311 pause_on_oops_flag = 1;
312 } else {
313 /* We need to stall this CPU */
314 if (!spin_counter) {
315 /* This CPU gets to do the counting */
316 spin_counter = pause_on_oops;
317 do {
318 spin_unlock(&pause_on_oops_lock);
319 spin_msec(MSEC_PER_SEC);
320 spin_lock(&pause_on_oops_lock);
321 } while (--spin_counter);
322 pause_on_oops_flag = 0;
323 } else {
324 /* This CPU waits for a different one */
325 while (spin_counter) {
326 spin_unlock(&pause_on_oops_lock);
327 spin_msec(1);
328 spin_lock(&pause_on_oops_lock);
329 }
330 }
331 }
332 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
333}
334
335/*
c95dbf27
IM
336 * Return true if the calling CPU is allowed to print oops-related info.
337 * This is a bit racy..
dd287796
AM
338 */
339int oops_may_print(void)
340{
341 return pause_on_oops_flag == 0;
342}
343
344/*
345 * Called when the architecture enters its oops handler, before it prints
c95dbf27
IM
346 * anything. If this is the first CPU to oops, and it's oopsing the first
347 * time then let it proceed.
dd287796 348 *
c95dbf27
IM
349 * This is all enabled by the pause_on_oops kernel boot option. We do all
350 * this to ensure that oopses don't scroll off the screen. It has the
351 * side-effect of preventing later-oopsing CPUs from mucking up the display,
352 * too.
dd287796 353 *
c95dbf27
IM
354 * It turns out that the CPU which is allowed to print ends up pausing for
355 * the right duration, whereas all the other CPUs pause for twice as long:
356 * once in oops_enter(), once in oops_exit().
dd287796
AM
357 */
358void oops_enter(void)
359{
bdff7870 360 tracing_off();
c95dbf27
IM
361 /* can't trust the integrity of the kernel anymore: */
362 debug_locks_off();
dd287796
AM
363 do_oops_enter_exit();
364}
365
2c3b20e9
AV
366/*
367 * 64-bit random ID for oopses:
368 */
369static u64 oops_id;
370
371static int init_oops_id(void)
372{
373 if (!oops_id)
374 get_random_bytes(&oops_id, sizeof(oops_id));
d6624f99
AV
375 else
376 oops_id++;
2c3b20e9
AV
377
378 return 0;
379}
380late_initcall(init_oops_id);
381
863a6049 382void print_oops_end_marker(void)
71c33911
AV
383{
384 init_oops_id();
d7c0847f 385 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
71c33911
AV
386}
387
dd287796
AM
388/*
389 * Called when the architecture exits its oops handler, after printing
390 * everything.
391 */
392void oops_exit(void)
393{
394 do_oops_enter_exit();
71c33911 395 print_oops_end_marker();
456b565c 396 kmsg_dump(KMSG_DUMP_OOPS);
dd287796 397}
3162f751 398
79b4cc5e 399#ifdef WANT_WARN_ON_SLOWPATH
0f6f49a8
LT
400struct slowpath_args {
401 const char *fmt;
a8f18b90 402 va_list args;
0f6f49a8 403};
bd89bb29 404
b2be0527
BH
405static void warn_slowpath_common(const char *file, int line, void *caller,
406 unsigned taint, struct slowpath_args *args)
0f6f49a8 407{
de7edd31
SRRH
408 disable_trace_on_warning();
409
dcb6b452
AT
410 pr_warn("------------[ cut here ]------------\n");
411 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
412 raw_smp_processor_id(), current->pid, file, line, caller);
74853dba 413
0f6f49a8
LT
414 if (args)
415 vprintk(args->fmt, args->args);
a8f18b90
AV
416
417 print_modules();
418 dump_stack();
419 print_oops_end_marker();
373d4d09
RR
420 /* Just a warning, don't kill lockdep. */
421 add_taint(taint, LOCKDEP_STILL_OK);
a8f18b90 422}
0f6f49a8
LT
423
424void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
425{
426 struct slowpath_args args;
427
428 args.fmt = fmt;
429 va_start(args.args, fmt);
b2be0527
BH
430 warn_slowpath_common(file, line, __builtin_return_address(0),
431 TAINT_WARN, &args);
0f6f49a8
LT
432 va_end(args.args);
433}
57adc4d2
AK
434EXPORT_SYMBOL(warn_slowpath_fmt);
435
b2be0527
BH
436void warn_slowpath_fmt_taint(const char *file, int line,
437 unsigned taint, const char *fmt, ...)
438{
439 struct slowpath_args args;
440
441 args.fmt = fmt;
442 va_start(args.args, fmt);
443 warn_slowpath_common(file, line, __builtin_return_address(0),
444 taint, &args);
445 va_end(args.args);
446}
447EXPORT_SYMBOL(warn_slowpath_fmt_taint);
448
57adc4d2
AK
449void warn_slowpath_null(const char *file, int line)
450{
b2be0527
BH
451 warn_slowpath_common(file, line, __builtin_return_address(0),
452 TAINT_WARN, NULL);
57adc4d2
AK
453}
454EXPORT_SYMBOL(warn_slowpath_null);
79b4cc5e
AV
455#endif
456
3162f751 457#ifdef CONFIG_CC_STACKPROTECTOR
54371a43 458
3162f751
AV
459/*
460 * Called when gcc's -fstack-protector feature is used, and
461 * gcc detects corruption of the on-stack canary value
462 */
a7330c99 463__visible void __stack_chk_fail(void)
3162f751 464{
517a92c4
IM
465 panic("stack-protector: Kernel stack is corrupted in: %p\n",
466 __builtin_return_address(0));
3162f751
AV
467}
468EXPORT_SYMBOL(__stack_chk_fail);
54371a43 469
3162f751 470#endif
f44dd164
RR
471
472core_param(panic, panic_timeout, int, 0644);
473core_param(pause_on_oops, pause_on_oops, int, 0644);
d404ab0a
OH
474
475static int __init oops_setup(char *s)
476{
477 if (!s)
478 return -EINVAL;
479 if (!strcmp(s, "panic"))
480 panic_on_oops = 1;
481 return 0;
482}
483early_param("oops", oops_setup);