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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);
f06e5153 35static bool crash_kexec_post_notifiers;
1da177e4 36
5800dc3c 37int panic_timeout = CONFIG_PANIC_TIMEOUT;
81e88fdc 38EXPORT_SYMBOL_GPL(panic_timeout);
1da177e4 39
e041c683 40ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4
LT
41
42EXPORT_SYMBOL(panic_notifier_list);
43
c7ff0d9c 44static long no_blink(int state)
8aeee85a 45{
c7ff0d9c 46 return 0;
8aeee85a
AB
47}
48
c7ff0d9c
TS
49/* Returns how long it waited in ms */
50long (*panic_blink)(int state);
51EXPORT_SYMBOL(panic_blink);
52
93e13a36
MH
53/*
54 * Stop ourself in panic -- architecture code may override this
55 */
56void __weak panic_smp_self_stop(void)
57{
58 while (1)
59 cpu_relax();
60}
61
1da177e4
LT
62/**
63 * panic - halt the system
64 * @fmt: The text string to print
65 *
66 * Display a message, then perform cleanups.
67 *
68 * This function never returns.
69 */
9402c95f 70void panic(const char *fmt, ...)
1da177e4 71{
93e13a36 72 static DEFINE_SPINLOCK(panic_lock);
1da177e4
LT
73 static char buf[1024];
74 va_list args;
c7ff0d9c
TS
75 long i, i_next = 0;
76 int state = 0;
1da177e4 77
190320c3
VM
78 /*
79 * Disable local interrupts. This will prevent panic_smp_self_stop
80 * from deadlocking the first cpu that invokes the panic, since
81 * there is nothing to prevent an interrupt handler (that runs
82 * after the panic_lock is acquired) from invoking panic again.
83 */
84 local_irq_disable();
85
dc009d92 86 /*
c95dbf27
IM
87 * It's possible to come here directly from a panic-assertion and
88 * not have preempt disabled. Some functions called from here want
dc009d92 89 * preempt to be disabled. No point enabling it later though...
93e13a36
MH
90 *
91 * Only one CPU is allowed to execute the panic code from here. For
92 * multiple parallel invocations of panic, all other CPUs either
93 * stop themself or will wait until they are stopped by the 1st CPU
94 * with smp_send_stop().
dc009d92 95 */
93e13a36
MH
96 if (!spin_trylock(&panic_lock))
97 panic_smp_self_stop();
dc009d92 98
5b530fc1 99 console_verbose();
1da177e4
LT
100 bust_spinlocks(1);
101 va_start(args, fmt);
102 vsnprintf(buf, sizeof(buf), fmt, args);
103 va_end(args);
d7c0847f 104 pr_emerg("Kernel panic - not syncing: %s\n", buf);
5cb27301 105#ifdef CONFIG_DEBUG_BUGVERBOSE
6e6f0a1f
AK
106 /*
107 * Avoid nested stack-dumping if a panic occurs during oops processing
108 */
026ee1f6 109 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
6e6f0a1f 110 dump_stack();
5cb27301 111#endif
1da177e4 112
dc009d92
EB
113 /*
114 * If we have crashed and we have a crash kernel loaded let it handle
115 * everything else.
f06e5153
MH
116 * If we want to run this after calling panic_notifiers, pass
117 * the "crash_kexec_post_notifiers" option to the kernel.
dc009d92 118 */
f06e5153
MH
119 if (!crash_kexec_post_notifiers)
120 crash_kexec(NULL);
dc009d92 121
dc009d92
EB
122 /*
123 * Note smp_send_stop is the usual smp shutdown function, which
124 * unfortunately means it may not be hardened to work in a panic
125 * situation.
126 */
1da177e4 127 smp_send_stop();
1da177e4 128
6723734c
KC
129 /*
130 * Run any panic handlers, including those that might need to
131 * add information to the kmsg dump output.
132 */
e041c683 133 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4 134
6723734c
KC
135 kmsg_dump(KMSG_DUMP_PANIC);
136
f06e5153
MH
137 /*
138 * If you doubt kdump always works fine in any situation,
139 * "crash_kexec_post_notifiers" offers you a chance to run
140 * panic_notifiers and dumping kmsg before kdump.
141 * Note: since some panic_notifiers can make crashed kernel
142 * more unstable, it can increase risks of the kdump failure too.
143 */
144 crash_kexec(NULL);
145
d014e889
AK
146 bust_spinlocks(0);
147
c7ff0d9c
TS
148 if (!panic_blink)
149 panic_blink = no_blink;
150
dc009d92 151 if (panic_timeout > 0) {
1da177e4 152 /*
c95dbf27
IM
153 * Delay timeout seconds before rebooting the machine.
154 * We can't use the "normal" timers since we just panicked.
155 */
d7c0847f 156 pr_emerg("Rebooting in %d seconds..", panic_timeout);
c95dbf27 157
c7ff0d9c 158 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
1da177e4 159 touch_nmi_watchdog();
c7ff0d9c
TS
160 if (i >= i_next) {
161 i += panic_blink(state ^= 1);
162 i_next = i + 3600 / PANIC_BLINK_SPD;
163 }
164 mdelay(PANIC_TIMER_STEP);
1da177e4 165 }
4302fbc8
HD
166 }
167 if (panic_timeout != 0) {
c95dbf27
IM
168 /*
169 * This will not be a clean reboot, with everything
170 * shutting down. But if there is a chance of
171 * rebooting the system it will be rebooted.
1da177e4 172 */
2f048ea8 173 emergency_restart();
1da177e4
LT
174 }
175#ifdef __sparc__
176 {
177 extern int stop_a_enabled;
a271c241 178 /* Make sure the user can actually press Stop-A (L1-A) */
1da177e4 179 stop_a_enabled = 1;
d7c0847f 180 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4
LT
181 }
182#endif
347a8dc3 183#if defined(CONFIG_S390)
c95dbf27
IM
184 {
185 unsigned long caller;
186
187 caller = (unsigned long)__builtin_return_address(0);
188 disabled_wait(caller);
189 }
1da177e4 190#endif
d7c0847f 191 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
1da177e4 192 local_irq_enable();
c7ff0d9c 193 for (i = 0; ; i += PANIC_TIMER_STEP) {
c22db941 194 touch_softlockup_watchdog();
c7ff0d9c
TS
195 if (i >= i_next) {
196 i += panic_blink(state ^= 1);
197 i_next = i + 3600 / PANIC_BLINK_SPD;
198 }
199 mdelay(PANIC_TIMER_STEP);
1da177e4
LT
200 }
201}
202
203EXPORT_SYMBOL(panic);
204
c277e63f 205
25ddbb18 206struct tnt {
c95dbf27
IM
207 u8 bit;
208 char true;
209 char false;
25ddbb18
AK
210};
211
212static const struct tnt tnts[] = {
c95dbf27
IM
213 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
214 { TAINT_FORCED_MODULE, 'F', ' ' },
8c90487c 215 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
c95dbf27
IM
216 { TAINT_FORCED_RMMOD, 'R', ' ' },
217 { TAINT_MACHINE_CHECK, 'M', ' ' },
218 { TAINT_BAD_PAGE, 'B', ' ' },
219 { TAINT_USER, 'U', ' ' },
220 { TAINT_DIE, 'D', ' ' },
221 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
222 { TAINT_WARN, 'W', ' ' },
223 { TAINT_CRAP, 'C', ' ' },
92946bc7 224 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
2449b8ba 225 { TAINT_OOT_MODULE, 'O', ' ' },
57673c2b 226 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
69361eef 227 { TAINT_SOFTLOCKUP, 'L', ' ' },
25ddbb18
AK
228};
229
1da177e4
LT
230/**
231 * print_tainted - return a string to represent the kernel taint state.
232 *
233 * 'P' - Proprietary module has been loaded.
234 * 'F' - Module has been forcibly loaded.
235 * 'S' - SMP with CPUs not designed for SMP.
236 * 'R' - User forced a module unload.
9aa5e993 237 * 'M' - System experienced a machine check exception.
1da177e4 238 * 'B' - System has hit bad_page.
34f5a398 239 * 'U' - Userspace-defined naughtiness.
a8005992 240 * 'D' - Kernel has oopsed before
95b570c9
NH
241 * 'A' - ACPI table overridden.
242 * 'W' - Taint on warning.
061b1bd3 243 * 'C' - modules from drivers/staging are loaded.
92946bc7 244 * 'I' - Working around severe firmware bug.
2449b8ba 245 * 'O' - Out-of-tree module has been loaded.
57673c2b 246 * 'E' - Unsigned module has been loaded.
bc53a3f4 247 * 'L' - A soft lockup has previously occurred.
1da177e4 248 *
fe002a41 249 * The string is overwritten by the next call to print_tainted().
1da177e4 250 */
1da177e4
LT
251const char *print_tainted(void)
252{
01284764 253 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
25ddbb18
AK
254
255 if (tainted_mask) {
256 char *s;
257 int i;
258
259 s = buf + sprintf(buf, "Tainted: ");
260 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
261 const struct tnt *t = &tnts[i];
262 *s++ = test_bit(t->bit, &tainted_mask) ?
263 t->true : t->false;
264 }
265 *s = 0;
266 } else
1da177e4 267 snprintf(buf, sizeof(buf), "Not tainted");
c95dbf27
IM
268
269 return buf;
1da177e4
LT
270}
271
25ddbb18 272int test_taint(unsigned flag)
1da177e4 273{
25ddbb18
AK
274 return test_bit(flag, &tainted_mask);
275}
276EXPORT_SYMBOL(test_taint);
277
278unsigned long get_taint(void)
279{
280 return tainted_mask;
1da177e4 281}
dd287796 282
373d4d09
RR
283/**
284 * add_taint: add a taint flag if not already set.
285 * @flag: one of the TAINT_* constants.
286 * @lockdep_ok: whether lock debugging is still OK.
287 *
288 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
289 * some notewortht-but-not-corrupting cases, it can be set to true.
290 */
291void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
dd287796 292{
373d4d09 293 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
d7c0847f 294 pr_warn("Disabling lock debugging due to kernel taint\n");
9eeba613 295
25ddbb18 296 set_bit(flag, &tainted_mask);
dd287796 297}
1da177e4 298EXPORT_SYMBOL(add_taint);
dd287796
AM
299
300static void spin_msec(int msecs)
301{
302 int i;
303
304 for (i = 0; i < msecs; i++) {
305 touch_nmi_watchdog();
306 mdelay(1);
307 }
308}
309
310/*
311 * It just happens that oops_enter() and oops_exit() are identically
312 * implemented...
313 */
314static void do_oops_enter_exit(void)
315{
316 unsigned long flags;
317 static int spin_counter;
318
319 if (!pause_on_oops)
320 return;
321
322 spin_lock_irqsave(&pause_on_oops_lock, flags);
323 if (pause_on_oops_flag == 0) {
324 /* This CPU may now print the oops message */
325 pause_on_oops_flag = 1;
326 } else {
327 /* We need to stall this CPU */
328 if (!spin_counter) {
329 /* This CPU gets to do the counting */
330 spin_counter = pause_on_oops;
331 do {
332 spin_unlock(&pause_on_oops_lock);
333 spin_msec(MSEC_PER_SEC);
334 spin_lock(&pause_on_oops_lock);
335 } while (--spin_counter);
336 pause_on_oops_flag = 0;
337 } else {
338 /* This CPU waits for a different one */
339 while (spin_counter) {
340 spin_unlock(&pause_on_oops_lock);
341 spin_msec(1);
342 spin_lock(&pause_on_oops_lock);
343 }
344 }
345 }
346 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
347}
348
349/*
c95dbf27
IM
350 * Return true if the calling CPU is allowed to print oops-related info.
351 * This is a bit racy..
dd287796
AM
352 */
353int oops_may_print(void)
354{
355 return pause_on_oops_flag == 0;
356}
357
358/*
359 * Called when the architecture enters its oops handler, before it prints
c95dbf27
IM
360 * anything. If this is the first CPU to oops, and it's oopsing the first
361 * time then let it proceed.
dd287796 362 *
c95dbf27
IM
363 * This is all enabled by the pause_on_oops kernel boot option. We do all
364 * this to ensure that oopses don't scroll off the screen. It has the
365 * side-effect of preventing later-oopsing CPUs from mucking up the display,
366 * too.
dd287796 367 *
c95dbf27
IM
368 * It turns out that the CPU which is allowed to print ends up pausing for
369 * the right duration, whereas all the other CPUs pause for twice as long:
370 * once in oops_enter(), once in oops_exit().
dd287796
AM
371 */
372void oops_enter(void)
373{
bdff7870 374 tracing_off();
c95dbf27
IM
375 /* can't trust the integrity of the kernel anymore: */
376 debug_locks_off();
dd287796
AM
377 do_oops_enter_exit();
378}
379
2c3b20e9
AV
380/*
381 * 64-bit random ID for oopses:
382 */
383static u64 oops_id;
384
385static int init_oops_id(void)
386{
387 if (!oops_id)
388 get_random_bytes(&oops_id, sizeof(oops_id));
d6624f99
AV
389 else
390 oops_id++;
2c3b20e9
AV
391
392 return 0;
393}
394late_initcall(init_oops_id);
395
863a6049 396void print_oops_end_marker(void)
71c33911
AV
397{
398 init_oops_id();
d7c0847f 399 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
71c33911
AV
400}
401
dd287796
AM
402/*
403 * Called when the architecture exits its oops handler, after printing
404 * everything.
405 */
406void oops_exit(void)
407{
408 do_oops_enter_exit();
71c33911 409 print_oops_end_marker();
456b565c 410 kmsg_dump(KMSG_DUMP_OOPS);
dd287796 411}
3162f751 412
79b4cc5e 413#ifdef WANT_WARN_ON_SLOWPATH
0f6f49a8
LT
414struct slowpath_args {
415 const char *fmt;
a8f18b90 416 va_list args;
0f6f49a8 417};
bd89bb29 418
b2be0527
BH
419static void warn_slowpath_common(const char *file, int line, void *caller,
420 unsigned taint, struct slowpath_args *args)
0f6f49a8 421{
de7edd31
SRRH
422 disable_trace_on_warning();
423
dcb6b452
AT
424 pr_warn("------------[ cut here ]------------\n");
425 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
426 raw_smp_processor_id(), current->pid, file, line, caller);
74853dba 427
0f6f49a8
LT
428 if (args)
429 vprintk(args->fmt, args->args);
a8f18b90
AV
430
431 print_modules();
432 dump_stack();
433 print_oops_end_marker();
373d4d09
RR
434 /* Just a warning, don't kill lockdep. */
435 add_taint(taint, LOCKDEP_STILL_OK);
a8f18b90 436}
0f6f49a8
LT
437
438void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
439{
440 struct slowpath_args args;
441
442 args.fmt = fmt;
443 va_start(args.args, fmt);
b2be0527
BH
444 warn_slowpath_common(file, line, __builtin_return_address(0),
445 TAINT_WARN, &args);
0f6f49a8
LT
446 va_end(args.args);
447}
57adc4d2
AK
448EXPORT_SYMBOL(warn_slowpath_fmt);
449
b2be0527
BH
450void warn_slowpath_fmt_taint(const char *file, int line,
451 unsigned taint, const char *fmt, ...)
452{
453 struct slowpath_args args;
454
455 args.fmt = fmt;
456 va_start(args.args, fmt);
457 warn_slowpath_common(file, line, __builtin_return_address(0),
458 taint, &args);
459 va_end(args.args);
460}
461EXPORT_SYMBOL(warn_slowpath_fmt_taint);
462
57adc4d2
AK
463void warn_slowpath_null(const char *file, int line)
464{
b2be0527
BH
465 warn_slowpath_common(file, line, __builtin_return_address(0),
466 TAINT_WARN, NULL);
57adc4d2
AK
467}
468EXPORT_SYMBOL(warn_slowpath_null);
79b4cc5e
AV
469#endif
470
3162f751 471#ifdef CONFIG_CC_STACKPROTECTOR
54371a43 472
3162f751
AV
473/*
474 * Called when gcc's -fstack-protector feature is used, and
475 * gcc detects corruption of the on-stack canary value
476 */
a7330c99 477__visible void __stack_chk_fail(void)
3162f751 478{
517a92c4
IM
479 panic("stack-protector: Kernel stack is corrupted in: %p\n",
480 __builtin_return_address(0));
3162f751
AV
481}
482EXPORT_SYMBOL(__stack_chk_fail);
54371a43 483
3162f751 484#endif
f44dd164
RR
485
486core_param(panic, panic_timeout, int, 0644);
487core_param(pause_on_oops, pause_on_oops, int, 0644);
d404ab0a 488
f06e5153
MH
489static int __init setup_crash_kexec_post_notifiers(char *s)
490{
491 crash_kexec_post_notifiers = true;
492 return 0;
493}
494early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
495
d404ab0a
OH
496static int __init oops_setup(char *s)
497{
498 if (!s)
499 return -EINVAL;
500 if (!strcmp(s, "panic"))
501 panic_on_oops = 1;
502 return 0;
503}
504early_param("oops", oops_setup);