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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 | |
37 | int panic_timeout = CONFIG_PANIC_TIMEOUT; |
38 | EXPORT_SYMBOL_GPL(panic_timeout); |
39 | |
40 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
41 | |
42 | EXPORT_SYMBOL(panic_notifier_list); |
43 | |
44 | static long no_blink(int state) |
45 | { |
46 | return 0; |
47 | } |
48 | |
49 | /* Returns how long it waited in ms */ |
50 | long (*panic_blink)(int state); |
51 | EXPORT_SYMBOL(panic_blink); |
52 | |
53 | /* |
54 | * Stop ourself in panic -- architecture code may override this |
55 | */ |
56 | void __weak panic_smp_self_stop(void) |
57 | { |
58 | while (1) |
59 | cpu_relax(); |
60 | } |
61 | |
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 | */ |
70 | void panic(const char *fmt, ...) |
71 | { |
72 | static DEFINE_SPINLOCK(panic_lock); |
73 | static char buf[1024]; |
74 | va_list args; |
75 | long i, i_next = 0; |
76 | int state = 0; |
77 | |
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 | |
86 | /* |
87 | * It's possible to come here directly from a panic-assertion and |
88 | * not have preempt disabled. Some functions called from here want |
89 | * preempt to be disabled. No point enabling it later though... |
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(). |
95 | */ |
96 | if (!spin_trylock(&panic_lock)) |
97 | panic_smp_self_stop(); |
98 | |
99 | console_verbose(); |
100 | bust_spinlocks(1); |
101 | va_start(args, fmt); |
102 | vsnprintf(buf, sizeof(buf), fmt, args); |
103 | va_end(args); |
104 | pr_emerg("Kernel panic - not syncing: %s\n", buf); |
105 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
106 | /* |
107 | * Avoid nested stack-dumping if a panic occurs during oops processing |
108 | */ |
109 | if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
110 | dump_stack(); |
111 | #endif |
112 | |
113 | /* |
114 | * If we have crashed and we have a crash kernel loaded let it handle |
115 | * everything else. |
116 | * If we want to run this after calling panic_notifiers, pass |
117 | * the "crash_kexec_post_notifiers" option to the kernel. |
118 | */ |
119 | if (!crash_kexec_post_notifiers) |
120 | crash_kexec(NULL); |
121 | |
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 | */ |
127 | smp_send_stop(); |
128 | |
129 | /* |
130 | * Run any panic handlers, including those that might need to |
131 | * add information to the kmsg dump output. |
132 | */ |
133 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
134 | |
135 | kmsg_dump(KMSG_DUMP_PANIC); |
136 | |
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 | |
146 | bust_spinlocks(0); |
147 | |
148 | if (!panic_blink) |
149 | panic_blink = no_blink; |
150 | |
151 | if (panic_timeout > 0) { |
152 | /* |
153 | * Delay timeout seconds before rebooting the machine. |
154 | * We can't use the "normal" timers since we just panicked. |
155 | */ |
156 | pr_emerg("Rebooting in %d seconds..", panic_timeout); |
157 | |
158 | for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
159 | touch_nmi_watchdog(); |
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); |
165 | } |
166 | } |
167 | if (panic_timeout != 0) { |
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. |
172 | */ |
173 | emergency_restart(); |
174 | } |
175 | #ifdef __sparc__ |
176 | { |
177 | extern int stop_a_enabled; |
178 | /* Make sure the user can actually press Stop-A (L1-A) */ |
179 | stop_a_enabled = 1; |
180 | pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n"); |
181 | } |
182 | #endif |
183 | #if defined(CONFIG_S390) |
184 | { |
185 | unsigned long caller; |
186 | |
187 | caller = (unsigned long)__builtin_return_address(0); |
188 | disabled_wait(caller); |
189 | } |
190 | #endif |
191 | pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf); |
192 | local_irq_enable(); |
193 | for (i = 0; ; i += PANIC_TIMER_STEP) { |
194 | touch_softlockup_watchdog(); |
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); |
200 | } |
201 | } |
202 | |
203 | EXPORT_SYMBOL(panic); |
204 | |
205 | |
206 | struct tnt { |
207 | u8 bit; |
208 | char true; |
209 | char false; |
210 | }; |
211 | |
212 | static const struct tnt tnts[] = { |
213 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, |
214 | { TAINT_FORCED_MODULE, 'F', ' ' }, |
215 | { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' }, |
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', ' ' }, |
224 | { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, |
225 | { TAINT_OOT_MODULE, 'O', ' ' }, |
226 | { TAINT_UNSIGNED_MODULE, 'E', ' ' }, |
227 | }; |
228 | |
229 | /** |
230 | * print_tainted - return a string to represent the kernel taint state. |
231 | * |
232 | * 'P' - Proprietary module has been loaded. |
233 | * 'F' - Module has been forcibly loaded. |
234 | * 'S' - SMP with CPUs not designed for SMP. |
235 | * 'R' - User forced a module unload. |
236 | * 'M' - System experienced a machine check exception. |
237 | * 'B' - System has hit bad_page. |
238 | * 'U' - Userspace-defined naughtiness. |
239 | * 'D' - Kernel has oopsed before |
240 | * 'A' - ACPI table overridden. |
241 | * 'W' - Taint on warning. |
242 | * 'C' - modules from drivers/staging are loaded. |
243 | * 'I' - Working around severe firmware bug. |
244 | * 'O' - Out-of-tree module has been loaded. |
245 | * 'E' - Unsigned module has been loaded. |
246 | * |
247 | * The string is overwritten by the next call to print_tainted(). |
248 | */ |
249 | const char *print_tainted(void) |
250 | { |
251 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")]; |
252 | |
253 | if (tainted_mask) { |
254 | char *s; |
255 | int i; |
256 | |
257 | s = buf + sprintf(buf, "Tainted: "); |
258 | for (i = 0; i < ARRAY_SIZE(tnts); i++) { |
259 | const struct tnt *t = &tnts[i]; |
260 | *s++ = test_bit(t->bit, &tainted_mask) ? |
261 | t->true : t->false; |
262 | } |
263 | *s = 0; |
264 | } else |
265 | snprintf(buf, sizeof(buf), "Not tainted"); |
266 | |
267 | return buf; |
268 | } |
269 | |
270 | int test_taint(unsigned flag) |
271 | { |
272 | return test_bit(flag, &tainted_mask); |
273 | } |
274 | EXPORT_SYMBOL(test_taint); |
275 | |
276 | unsigned long get_taint(void) |
277 | { |
278 | return tainted_mask; |
279 | } |
280 | |
281 | /** |
282 | * add_taint: add a taint flag if not already set. |
283 | * @flag: one of the TAINT_* constants. |
284 | * @lockdep_ok: whether lock debugging is still OK. |
285 | * |
286 | * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for |
287 | * some notewortht-but-not-corrupting cases, it can be set to true. |
288 | */ |
289 | void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) |
290 | { |
291 | if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) |
292 | pr_warn("Disabling lock debugging due to kernel taint\n"); |
293 | |
294 | set_bit(flag, &tainted_mask); |
295 | } |
296 | EXPORT_SYMBOL(add_taint); |
297 | |
298 | static void spin_msec(int msecs) |
299 | { |
300 | int i; |
301 | |
302 | for (i = 0; i < msecs; i++) { |
303 | touch_nmi_watchdog(); |
304 | mdelay(1); |
305 | } |
306 | } |
307 | |
308 | /* |
309 | * It just happens that oops_enter() and oops_exit() are identically |
310 | * implemented... |
311 | */ |
312 | static void do_oops_enter_exit(void) |
313 | { |
314 | unsigned long flags; |
315 | static int spin_counter; |
316 | |
317 | if (!pause_on_oops) |
318 | return; |
319 | |
320 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
321 | if (pause_on_oops_flag == 0) { |
322 | /* This CPU may now print the oops message */ |
323 | pause_on_oops_flag = 1; |
324 | } else { |
325 | /* We need to stall this CPU */ |
326 | if (!spin_counter) { |
327 | /* This CPU gets to do the counting */ |
328 | spin_counter = pause_on_oops; |
329 | do { |
330 | spin_unlock(&pause_on_oops_lock); |
331 | spin_msec(MSEC_PER_SEC); |
332 | spin_lock(&pause_on_oops_lock); |
333 | } while (--spin_counter); |
334 | pause_on_oops_flag = 0; |
335 | } else { |
336 | /* This CPU waits for a different one */ |
337 | while (spin_counter) { |
338 | spin_unlock(&pause_on_oops_lock); |
339 | spin_msec(1); |
340 | spin_lock(&pause_on_oops_lock); |
341 | } |
342 | } |
343 | } |
344 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); |
345 | } |
346 | |
347 | /* |
348 | * Return true if the calling CPU is allowed to print oops-related info. |
349 | * This is a bit racy.. |
350 | */ |
351 | int oops_may_print(void) |
352 | { |
353 | return pause_on_oops_flag == 0; |
354 | } |
355 | |
356 | /* |
357 | * Called when the architecture enters its oops handler, before it prints |
358 | * anything. If this is the first CPU to oops, and it's oopsing the first |
359 | * time then let it proceed. |
360 | * |
361 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
362 | * this to ensure that oopses don't scroll off the screen. It has the |
363 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
364 | * too. |
365 | * |
366 | * It turns out that the CPU which is allowed to print ends up pausing for |
367 | * the right duration, whereas all the other CPUs pause for twice as long: |
368 | * once in oops_enter(), once in oops_exit(). |
369 | */ |
370 | void oops_enter(void) |
371 | { |
372 | tracing_off(); |
373 | /* can't trust the integrity of the kernel anymore: */ |
374 | debug_locks_off(); |
375 | do_oops_enter_exit(); |
376 | } |
377 | |
378 | /* |
379 | * 64-bit random ID for oopses: |
380 | */ |
381 | static u64 oops_id; |
382 | |
383 | static int init_oops_id(void) |
384 | { |
385 | if (!oops_id) |
386 | get_random_bytes(&oops_id, sizeof(oops_id)); |
387 | else |
388 | oops_id++; |
389 | |
390 | return 0; |
391 | } |
392 | late_initcall(init_oops_id); |
393 | |
394 | void print_oops_end_marker(void) |
395 | { |
396 | init_oops_id(); |
397 | pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id); |
398 | } |
399 | |
400 | /* |
401 | * Called when the architecture exits its oops handler, after printing |
402 | * everything. |
403 | */ |
404 | void oops_exit(void) |
405 | { |
406 | do_oops_enter_exit(); |
407 | print_oops_end_marker(); |
408 | kmsg_dump(KMSG_DUMP_OOPS); |
409 | } |
410 | |
411 | #ifdef WANT_WARN_ON_SLOWPATH |
412 | struct slowpath_args { |
413 | const char *fmt; |
414 | va_list args; |
415 | }; |
416 | |
417 | static void warn_slowpath_common(const char *file, int line, void *caller, |
418 | unsigned taint, struct slowpath_args *args) |
419 | { |
420 | disable_trace_on_warning(); |
421 | |
422 | pr_warn("------------[ cut here ]------------\n"); |
423 | pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", |
424 | raw_smp_processor_id(), current->pid, file, line, caller); |
425 | |
426 | if (args) |
427 | vprintk(args->fmt, args->args); |
428 | |
429 | print_modules(); |
430 | dump_stack(); |
431 | print_oops_end_marker(); |
432 | /* Just a warning, don't kill lockdep. */ |
433 | add_taint(taint, LOCKDEP_STILL_OK); |
434 | } |
435 | |
436 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) |
437 | { |
438 | struct slowpath_args args; |
439 | |
440 | args.fmt = fmt; |
441 | va_start(args.args, fmt); |
442 | warn_slowpath_common(file, line, __builtin_return_address(0), |
443 | TAINT_WARN, &args); |
444 | va_end(args.args); |
445 | } |
446 | EXPORT_SYMBOL(warn_slowpath_fmt); |
447 | |
448 | void warn_slowpath_fmt_taint(const char *file, int line, |
449 | unsigned taint, const char *fmt, ...) |
450 | { |
451 | struct slowpath_args args; |
452 | |
453 | args.fmt = fmt; |
454 | va_start(args.args, fmt); |
455 | warn_slowpath_common(file, line, __builtin_return_address(0), |
456 | taint, &args); |
457 | va_end(args.args); |
458 | } |
459 | EXPORT_SYMBOL(warn_slowpath_fmt_taint); |
460 | |
461 | void warn_slowpath_null(const char *file, int line) |
462 | { |
463 | warn_slowpath_common(file, line, __builtin_return_address(0), |
464 | TAINT_WARN, NULL); |
465 | } |
466 | EXPORT_SYMBOL(warn_slowpath_null); |
467 | #endif |
468 | |
469 | #ifdef CONFIG_CC_STACKPROTECTOR |
470 | |
471 | /* |
472 | * Called when gcc's -fstack-protector feature is used, and |
473 | * gcc detects corruption of the on-stack canary value |
474 | */ |
475 | __visible void __stack_chk_fail(void) |
476 | { |
477 | panic("stack-protector: Kernel stack is corrupted in: %p\n", |
478 | __builtin_return_address(0)); |
479 | } |
480 | EXPORT_SYMBOL(__stack_chk_fail); |
481 | |
482 | #endif |
483 | |
484 | core_param(panic, panic_timeout, int, 0644); |
485 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
486 | |
487 | static int __init setup_crash_kexec_post_notifiers(char *s) |
488 | { |
489 | crash_kexec_post_notifiers = true; |
490 | return 0; |
491 | } |
492 | early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers); |
493 | |
494 | static int __init oops_setup(char *s) |
495 | { |
496 | if (!s) |
497 | return -EINVAL; |
498 | if (!strcmp(s, "panic")) |
499 | panic_on_oops = 1; |
500 | return 0; |
501 | } |
502 | early_param("oops", oops_setup); |
503 |
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