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