1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * linux/kernel/panic.c |
4 | * |
5 | * Copyright (C) 1991, 1992 Linus Torvalds |
6 | */ |
7 | |
8 | /* |
9 | * This function is used through-out the kernel (including mm and fs) |
10 | * to indicate a major problem. |
11 | */ |
12 | #include <linux/debug_locks.h> |
13 | #include <linux/sched/debug.h> |
14 | #include <linux/interrupt.h> |
15 | #include <linux/kgdb.h> |
16 | #include <linux/kmsg_dump.h> |
17 | #include <linux/kallsyms.h> |
18 | #include <linux/notifier.h> |
19 | #include <linux/vt_kern.h> |
20 | #include <linux/module.h> |
21 | #include <linux/random.h> |
22 | #include <linux/ftrace.h> |
23 | #include <linux/reboot.h> |
24 | #include <linux/delay.h> |
25 | #include <linux/kexec.h> |
26 | #include <linux/panic_notifier.h> |
27 | #include <linux/sched.h> |
28 | #include <linux/string_helpers.h> |
29 | #include <linux/sysrq.h> |
30 | #include <linux/init.h> |
31 | #include <linux/nmi.h> |
32 | #include <linux/console.h> |
33 | #include <linux/bug.h> |
34 | #include <linux/ratelimit.h> |
35 | #include <linux/debugfs.h> |
36 | #include <linux/sysfs.h> |
37 | #include <linux/context_tracking.h> |
38 | #include <trace/events/error_report.h> |
39 | #include <asm/sections.h> |
40 | |
41 | #define PANIC_TIMER_STEP 100 |
42 | #define PANIC_BLINK_SPD 18 |
43 | |
44 | #ifdef CONFIG_SMP |
45 | /* |
46 | * Should we dump all CPUs backtraces in an oops event? |
47 | * Defaults to 0, can be changed via sysctl. |
48 | */ |
49 | static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; |
50 | #else |
51 | #define sysctl_oops_all_cpu_backtrace 0 |
52 | #endif /* CONFIG_SMP */ |
53 | |
54 | int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; |
55 | static unsigned long tainted_mask = |
56 | IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0; |
57 | static int pause_on_oops; |
58 | static int pause_on_oops_flag; |
59 | static DEFINE_SPINLOCK(pause_on_oops_lock); |
60 | bool crash_kexec_post_notifiers; |
61 | int panic_on_warn __read_mostly; |
62 | unsigned long panic_on_taint; |
63 | bool panic_on_taint_nousertaint = false; |
64 | static unsigned int warn_limit __read_mostly; |
65 | |
66 | int panic_timeout = CONFIG_PANIC_TIMEOUT; |
67 | EXPORT_SYMBOL_GPL(panic_timeout); |
68 | |
69 | #define PANIC_PRINT_TASK_INFO 0x00000001 |
70 | #define PANIC_PRINT_MEM_INFO 0x00000002 |
71 | #define PANIC_PRINT_TIMER_INFO 0x00000004 |
72 | #define PANIC_PRINT_LOCK_INFO 0x00000008 |
73 | #define PANIC_PRINT_FTRACE_INFO 0x00000010 |
74 | #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 |
75 | #define PANIC_PRINT_ALL_CPU_BT 0x00000040 |
76 | unsigned long panic_print; |
77 | |
78 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
79 | |
80 | EXPORT_SYMBOL(panic_notifier_list); |
81 | |
82 | #ifdef CONFIG_SYSCTL |
83 | static struct ctl_table kern_panic_table[] = { |
84 | #ifdef CONFIG_SMP |
85 | { |
86 | .procname = "oops_all_cpu_backtrace" , |
87 | .data = &sysctl_oops_all_cpu_backtrace, |
88 | .maxlen = sizeof(int), |
89 | .mode = 0644, |
90 | .proc_handler = proc_dointvec_minmax, |
91 | .extra1 = SYSCTL_ZERO, |
92 | .extra2 = SYSCTL_ONE, |
93 | }, |
94 | #endif |
95 | { |
96 | .procname = "warn_limit" , |
97 | .data = &warn_limit, |
98 | .maxlen = sizeof(warn_limit), |
99 | .mode = 0644, |
100 | .proc_handler = proc_douintvec, |
101 | }, |
102 | { } |
103 | }; |
104 | |
105 | static __init int kernel_panic_sysctls_init(void) |
106 | { |
107 | register_sysctl_init("kernel" , kern_panic_table); |
108 | return 0; |
109 | } |
110 | late_initcall(kernel_panic_sysctls_init); |
111 | #endif |
112 | |
113 | static atomic_t warn_count = ATOMIC_INIT(0); |
114 | |
115 | #ifdef CONFIG_SYSFS |
116 | static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, |
117 | char *page) |
118 | { |
119 | return sysfs_emit(buf: page, fmt: "%d\n" , atomic_read(v: &warn_count)); |
120 | } |
121 | |
122 | static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); |
123 | |
124 | static __init int kernel_panic_sysfs_init(void) |
125 | { |
126 | sysfs_add_file_to_group(kobj: kernel_kobj, attr: &warn_count_attr.attr, NULL); |
127 | return 0; |
128 | } |
129 | late_initcall(kernel_panic_sysfs_init); |
130 | #endif |
131 | |
132 | static long no_blink(int state) |
133 | { |
134 | return 0; |
135 | } |
136 | |
137 | /* Returns how long it waited in ms */ |
138 | long (*panic_blink)(int state); |
139 | EXPORT_SYMBOL(panic_blink); |
140 | |
141 | /* |
142 | * Stop ourself in panic -- architecture code may override this |
143 | */ |
144 | void __weak __noreturn panic_smp_self_stop(void) |
145 | { |
146 | while (1) |
147 | cpu_relax(); |
148 | } |
149 | |
150 | /* |
151 | * Stop ourselves in NMI context if another CPU has already panicked. Arch code |
152 | * may override this to prepare for crash dumping, e.g. save regs info. |
153 | */ |
154 | void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs) |
155 | { |
156 | panic_smp_self_stop(); |
157 | } |
158 | |
159 | /* |
160 | * Stop other CPUs in panic. Architecture dependent code may override this |
161 | * with more suitable version. For example, if the architecture supports |
162 | * crash dump, it should save registers of each stopped CPU and disable |
163 | * per-CPU features such as virtualization extensions. |
164 | */ |
165 | void __weak crash_smp_send_stop(void) |
166 | { |
167 | static int cpus_stopped; |
168 | |
169 | /* |
170 | * This function can be called twice in panic path, but obviously |
171 | * we execute this only once. |
172 | */ |
173 | if (cpus_stopped) |
174 | return; |
175 | |
176 | /* |
177 | * Note smp_send_stop is the usual smp shutdown function, which |
178 | * unfortunately means it may not be hardened to work in a panic |
179 | * situation. |
180 | */ |
181 | smp_send_stop(); |
182 | cpus_stopped = 1; |
183 | } |
184 | |
185 | atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); |
186 | |
187 | /* |
188 | * A variant of panic() called from NMI context. We return if we've already |
189 | * panicked on this CPU. If another CPU already panicked, loop in |
190 | * nmi_panic_self_stop() which can provide architecture dependent code such |
191 | * as saving register state for crash dump. |
192 | */ |
193 | void nmi_panic(struct pt_regs *regs, const char *msg) |
194 | { |
195 | int old_cpu, this_cpu; |
196 | |
197 | old_cpu = PANIC_CPU_INVALID; |
198 | this_cpu = raw_smp_processor_id(); |
199 | |
200 | /* atomic_try_cmpxchg updates old_cpu on failure */ |
201 | if (atomic_try_cmpxchg(v: &panic_cpu, old: &old_cpu, new: this_cpu)) |
202 | panic(fmt: "%s" , msg); |
203 | else if (old_cpu != this_cpu) |
204 | nmi_panic_self_stop(regs); |
205 | } |
206 | EXPORT_SYMBOL(nmi_panic); |
207 | |
208 | static void panic_print_sys_info(bool console_flush) |
209 | { |
210 | if (console_flush) { |
211 | if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) |
212 | console_flush_on_panic(mode: CONSOLE_REPLAY_ALL); |
213 | return; |
214 | } |
215 | |
216 | if (panic_print & PANIC_PRINT_TASK_INFO) |
217 | show_state(); |
218 | |
219 | if (panic_print & PANIC_PRINT_MEM_INFO) |
220 | show_mem(); |
221 | |
222 | if (panic_print & PANIC_PRINT_TIMER_INFO) |
223 | sysrq_timer_list_show(); |
224 | |
225 | if (panic_print & PANIC_PRINT_LOCK_INFO) |
226 | debug_show_all_locks(); |
227 | |
228 | if (panic_print & PANIC_PRINT_FTRACE_INFO) |
229 | ftrace_dump(oops_dump_mode: DUMP_ALL); |
230 | } |
231 | |
232 | void check_panic_on_warn(const char *origin) |
233 | { |
234 | unsigned int limit; |
235 | |
236 | if (panic_on_warn) |
237 | panic(fmt: "%s: panic_on_warn set ...\n" , origin); |
238 | |
239 | limit = READ_ONCE(warn_limit); |
240 | if (atomic_inc_return(v: &warn_count) >= limit && limit) |
241 | panic(fmt: "%s: system warned too often (kernel.warn_limit is %d)" , |
242 | origin, limit); |
243 | } |
244 | |
245 | /* |
246 | * Helper that triggers the NMI backtrace (if set in panic_print) |
247 | * and then performs the secondary CPUs shutdown - we cannot have |
248 | * the NMI backtrace after the CPUs are off! |
249 | */ |
250 | static void panic_other_cpus_shutdown(bool crash_kexec) |
251 | { |
252 | if (panic_print & PANIC_PRINT_ALL_CPU_BT) |
253 | trigger_all_cpu_backtrace(); |
254 | |
255 | /* |
256 | * Note that smp_send_stop() is the usual SMP shutdown function, |
257 | * which unfortunately may not be hardened to work in a panic |
258 | * situation. If we want to do crash dump after notifier calls |
259 | * and kmsg_dump, we will need architecture dependent extra |
260 | * bits in addition to stopping other CPUs, hence we rely on |
261 | * crash_smp_send_stop() for that. |
262 | */ |
263 | if (!crash_kexec) |
264 | smp_send_stop(); |
265 | else |
266 | crash_smp_send_stop(); |
267 | } |
268 | |
269 | /** |
270 | * panic - halt the system |
271 | * @fmt: The text string to print |
272 | * |
273 | * Display a message, then perform cleanups. |
274 | * |
275 | * This function never returns. |
276 | */ |
277 | void panic(const char *fmt, ...) |
278 | { |
279 | static char buf[1024]; |
280 | va_list args; |
281 | long i, i_next = 0, len; |
282 | int state = 0; |
283 | int old_cpu, this_cpu; |
284 | bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; |
285 | |
286 | if (panic_on_warn) { |
287 | /* |
288 | * This thread may hit another WARN() in the panic path. |
289 | * Resetting this prevents additional WARN() from panicking the |
290 | * system on this thread. Other threads are blocked by the |
291 | * panic_mutex in panic(). |
292 | */ |
293 | panic_on_warn = 0; |
294 | } |
295 | |
296 | /* |
297 | * Disable local interrupts. This will prevent panic_smp_self_stop |
298 | * from deadlocking the first cpu that invokes the panic, since |
299 | * there is nothing to prevent an interrupt handler (that runs |
300 | * after setting panic_cpu) from invoking panic() again. |
301 | */ |
302 | local_irq_disable(); |
303 | preempt_disable_notrace(); |
304 | |
305 | /* |
306 | * It's possible to come here directly from a panic-assertion and |
307 | * not have preempt disabled. Some functions called from here want |
308 | * preempt to be disabled. No point enabling it later though... |
309 | * |
310 | * Only one CPU is allowed to execute the panic code from here. For |
311 | * multiple parallel invocations of panic, all other CPUs either |
312 | * stop themself or will wait until they are stopped by the 1st CPU |
313 | * with smp_send_stop(). |
314 | * |
315 | * cmpxchg success means this is the 1st CPU which comes here, |
316 | * so go ahead. |
317 | * `old_cpu == this_cpu' means we came from nmi_panic() which sets |
318 | * panic_cpu to this CPU. In this case, this is also the 1st CPU. |
319 | */ |
320 | old_cpu = PANIC_CPU_INVALID; |
321 | this_cpu = raw_smp_processor_id(); |
322 | |
323 | /* atomic_try_cmpxchg updates old_cpu on failure */ |
324 | if (atomic_try_cmpxchg(v: &panic_cpu, old: &old_cpu, new: this_cpu)) { |
325 | /* go ahead */ |
326 | } else if (old_cpu != this_cpu) |
327 | panic_smp_self_stop(); |
328 | |
329 | console_verbose(); |
330 | bust_spinlocks(yes: 1); |
331 | va_start(args, fmt); |
332 | len = vscnprintf(buf, size: sizeof(buf), fmt, args); |
333 | va_end(args); |
334 | |
335 | if (len && buf[len - 1] == '\n') |
336 | buf[len - 1] = '\0'; |
337 | |
338 | pr_emerg("Kernel panic - not syncing: %s\n" , buf); |
339 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
340 | /* |
341 | * Avoid nested stack-dumping if a panic occurs during oops processing |
342 | */ |
343 | if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
344 | dump_stack(); |
345 | #endif |
346 | |
347 | /* |
348 | * If kgdb is enabled, give it a chance to run before we stop all |
349 | * the other CPUs or else we won't be able to debug processes left |
350 | * running on them. |
351 | */ |
352 | kgdb_panic(msg: buf); |
353 | |
354 | /* |
355 | * If we have crashed and we have a crash kernel loaded let it handle |
356 | * everything else. |
357 | * If we want to run this after calling panic_notifiers, pass |
358 | * the "crash_kexec_post_notifiers" option to the kernel. |
359 | * |
360 | * Bypass the panic_cpu check and call __crash_kexec directly. |
361 | */ |
362 | if (!_crash_kexec_post_notifiers) |
363 | __crash_kexec(NULL); |
364 | |
365 | panic_other_cpus_shutdown(crash_kexec: _crash_kexec_post_notifiers); |
366 | |
367 | /* |
368 | * Run any panic handlers, including those that might need to |
369 | * add information to the kmsg dump output. |
370 | */ |
371 | atomic_notifier_call_chain(nh: &panic_notifier_list, val: 0, v: buf); |
372 | |
373 | panic_print_sys_info(console_flush: false); |
374 | |
375 | kmsg_dump(reason: KMSG_DUMP_PANIC); |
376 | |
377 | /* |
378 | * If you doubt kdump always works fine in any situation, |
379 | * "crash_kexec_post_notifiers" offers you a chance to run |
380 | * panic_notifiers and dumping kmsg before kdump. |
381 | * Note: since some panic_notifiers can make crashed kernel |
382 | * more unstable, it can increase risks of the kdump failure too. |
383 | * |
384 | * Bypass the panic_cpu check and call __crash_kexec directly. |
385 | */ |
386 | if (_crash_kexec_post_notifiers) |
387 | __crash_kexec(NULL); |
388 | |
389 | console_unblank(); |
390 | |
391 | /* |
392 | * We may have ended up stopping the CPU holding the lock (in |
393 | * smp_send_stop()) while still having some valuable data in the console |
394 | * buffer. Try to acquire the lock then release it regardless of the |
395 | * result. The release will also print the buffers out. Locks debug |
396 | * should be disabled to avoid reporting bad unlock balance when |
397 | * panic() is not being callled from OOPS. |
398 | */ |
399 | debug_locks_off(); |
400 | console_flush_on_panic(mode: CONSOLE_FLUSH_PENDING); |
401 | |
402 | panic_print_sys_info(console_flush: true); |
403 | |
404 | if (!panic_blink) |
405 | panic_blink = no_blink; |
406 | |
407 | if (panic_timeout > 0) { |
408 | /* |
409 | * Delay timeout seconds before rebooting the machine. |
410 | * We can't use the "normal" timers since we just panicked. |
411 | */ |
412 | pr_emerg("Rebooting in %d seconds..\n" , panic_timeout); |
413 | |
414 | for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
415 | touch_nmi_watchdog(); |
416 | if (i >= i_next) { |
417 | i += panic_blink(state ^= 1); |
418 | i_next = i + 3600 / PANIC_BLINK_SPD; |
419 | } |
420 | mdelay(PANIC_TIMER_STEP); |
421 | } |
422 | } |
423 | if (panic_timeout != 0) { |
424 | /* |
425 | * This will not be a clean reboot, with everything |
426 | * shutting down. But if there is a chance of |
427 | * rebooting the system it will be rebooted. |
428 | */ |
429 | if (panic_reboot_mode != REBOOT_UNDEFINED) |
430 | reboot_mode = panic_reboot_mode; |
431 | emergency_restart(); |
432 | } |
433 | #ifdef __sparc__ |
434 | { |
435 | extern int stop_a_enabled; |
436 | /* Make sure the user can actually press Stop-A (L1-A) */ |
437 | stop_a_enabled = 1; |
438 | pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" |
439 | "twice on console to return to the boot prom\n" ); |
440 | } |
441 | #endif |
442 | #if defined(CONFIG_S390) |
443 | disabled_wait(); |
444 | #endif |
445 | pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n" , buf); |
446 | |
447 | /* Do not scroll important messages printed above */ |
448 | suppress_printk = 1; |
449 | local_irq_enable(); |
450 | for (i = 0; ; i += PANIC_TIMER_STEP) { |
451 | touch_softlockup_watchdog(); |
452 | if (i >= i_next) { |
453 | i += panic_blink(state ^= 1); |
454 | i_next = i + 3600 / PANIC_BLINK_SPD; |
455 | } |
456 | mdelay(PANIC_TIMER_STEP); |
457 | } |
458 | } |
459 | |
460 | EXPORT_SYMBOL(panic); |
461 | |
462 | /* |
463 | * TAINT_FORCED_RMMOD could be a per-module flag but the module |
464 | * is being removed anyway. |
465 | */ |
466 | const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { |
467 | [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true }, |
468 | [ TAINT_FORCED_MODULE ] = { 'F', ' ', true }, |
469 | [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false }, |
470 | [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false }, |
471 | [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false }, |
472 | [ TAINT_BAD_PAGE ] = { 'B', ' ', false }, |
473 | [ TAINT_USER ] = { 'U', ' ', false }, |
474 | [ TAINT_DIE ] = { 'D', ' ', false }, |
475 | [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false }, |
476 | [ TAINT_WARN ] = { 'W', ' ', false }, |
477 | [ TAINT_CRAP ] = { 'C', ' ', true }, |
478 | [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false }, |
479 | [ TAINT_OOT_MODULE ] = { 'O', ' ', true }, |
480 | [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true }, |
481 | [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false }, |
482 | [ TAINT_LIVEPATCH ] = { 'K', ' ', true }, |
483 | [ TAINT_AUX ] = { 'X', ' ', true }, |
484 | [ TAINT_RANDSTRUCT ] = { 'T', ' ', true }, |
485 | [ TAINT_TEST ] = { 'N', ' ', true }, |
486 | }; |
487 | |
488 | /** |
489 | * print_tainted - return a string to represent the kernel taint state. |
490 | * |
491 | * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst |
492 | * |
493 | * The string is overwritten by the next call to print_tainted(), |
494 | * but is always NULL terminated. |
495 | */ |
496 | const char *print_tainted(void) |
497 | { |
498 | static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: " )]; |
499 | |
500 | BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); |
501 | |
502 | if (tainted_mask) { |
503 | char *s; |
504 | int i; |
505 | |
506 | s = buf + sprintf(buf, fmt: "Tainted: " ); |
507 | for (i = 0; i < TAINT_FLAGS_COUNT; i++) { |
508 | const struct taint_flag *t = &taint_flags[i]; |
509 | *s++ = test_bit(i, &tainted_mask) ? |
510 | t->c_true : t->c_false; |
511 | } |
512 | *s = 0; |
513 | } else |
514 | snprintf(buf, size: sizeof(buf), fmt: "Not tainted" ); |
515 | |
516 | return buf; |
517 | } |
518 | |
519 | int test_taint(unsigned flag) |
520 | { |
521 | return test_bit(flag, &tainted_mask); |
522 | } |
523 | EXPORT_SYMBOL(test_taint); |
524 | |
525 | unsigned long get_taint(void) |
526 | { |
527 | return tainted_mask; |
528 | } |
529 | |
530 | /** |
531 | * add_taint: add a taint flag if not already set. |
532 | * @flag: one of the TAINT_* constants. |
533 | * @lockdep_ok: whether lock debugging is still OK. |
534 | * |
535 | * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for |
536 | * some notewortht-but-not-corrupting cases, it can be set to true. |
537 | */ |
538 | void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) |
539 | { |
540 | if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) |
541 | pr_warn("Disabling lock debugging due to kernel taint\n" ); |
542 | |
543 | set_bit(nr: flag, addr: &tainted_mask); |
544 | |
545 | if (tainted_mask & panic_on_taint) { |
546 | panic_on_taint = 0; |
547 | panic("panic_on_taint set ..." ); |
548 | } |
549 | } |
550 | EXPORT_SYMBOL(add_taint); |
551 | |
552 | static void spin_msec(int msecs) |
553 | { |
554 | int i; |
555 | |
556 | for (i = 0; i < msecs; i++) { |
557 | touch_nmi_watchdog(); |
558 | mdelay(1); |
559 | } |
560 | } |
561 | |
562 | /* |
563 | * It just happens that oops_enter() and oops_exit() are identically |
564 | * implemented... |
565 | */ |
566 | static void do_oops_enter_exit(void) |
567 | { |
568 | unsigned long flags; |
569 | static int spin_counter; |
570 | |
571 | if (!pause_on_oops) |
572 | return; |
573 | |
574 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
575 | if (pause_on_oops_flag == 0) { |
576 | /* This CPU may now print the oops message */ |
577 | pause_on_oops_flag = 1; |
578 | } else { |
579 | /* We need to stall this CPU */ |
580 | if (!spin_counter) { |
581 | /* This CPU gets to do the counting */ |
582 | spin_counter = pause_on_oops; |
583 | do { |
584 | spin_unlock(lock: &pause_on_oops_lock); |
585 | spin_msec(MSEC_PER_SEC); |
586 | spin_lock(lock: &pause_on_oops_lock); |
587 | } while (--spin_counter); |
588 | pause_on_oops_flag = 0; |
589 | } else { |
590 | /* This CPU waits for a different one */ |
591 | while (spin_counter) { |
592 | spin_unlock(lock: &pause_on_oops_lock); |
593 | spin_msec(msecs: 1); |
594 | spin_lock(lock: &pause_on_oops_lock); |
595 | } |
596 | } |
597 | } |
598 | spin_unlock_irqrestore(lock: &pause_on_oops_lock, flags); |
599 | } |
600 | |
601 | /* |
602 | * Return true if the calling CPU is allowed to print oops-related info. |
603 | * This is a bit racy.. |
604 | */ |
605 | bool oops_may_print(void) |
606 | { |
607 | return pause_on_oops_flag == 0; |
608 | } |
609 | |
610 | /* |
611 | * Called when the architecture enters its oops handler, before it prints |
612 | * anything. If this is the first CPU to oops, and it's oopsing the first |
613 | * time then let it proceed. |
614 | * |
615 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
616 | * this to ensure that oopses don't scroll off the screen. It has the |
617 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
618 | * too. |
619 | * |
620 | * It turns out that the CPU which is allowed to print ends up pausing for |
621 | * the right duration, whereas all the other CPUs pause for twice as long: |
622 | * once in oops_enter(), once in oops_exit(). |
623 | */ |
624 | void oops_enter(void) |
625 | { |
626 | tracing_off(); |
627 | /* can't trust the integrity of the kernel anymore: */ |
628 | debug_locks_off(); |
629 | do_oops_enter_exit(); |
630 | |
631 | if (sysctl_oops_all_cpu_backtrace) |
632 | trigger_all_cpu_backtrace(); |
633 | } |
634 | |
635 | static void print_oops_end_marker(void) |
636 | { |
637 | pr_warn("---[ end trace %016llx ]---\n" , 0ULL); |
638 | } |
639 | |
640 | /* |
641 | * Called when the architecture exits its oops handler, after printing |
642 | * everything. |
643 | */ |
644 | void oops_exit(void) |
645 | { |
646 | do_oops_enter_exit(); |
647 | print_oops_end_marker(); |
648 | kmsg_dump(reason: KMSG_DUMP_OOPS); |
649 | } |
650 | |
651 | struct warn_args { |
652 | const char *fmt; |
653 | va_list args; |
654 | }; |
655 | |
656 | void __warn(const char *file, int line, void *caller, unsigned taint, |
657 | struct pt_regs *regs, struct warn_args *args) |
658 | { |
659 | disable_trace_on_warning(); |
660 | |
661 | if (file) |
662 | pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n" , |
663 | raw_smp_processor_id(), current->pid, file, line, |
664 | caller); |
665 | else |
666 | pr_warn("WARNING: CPU: %d PID: %d at %pS\n" , |
667 | raw_smp_processor_id(), current->pid, caller); |
668 | |
669 | if (args) |
670 | vprintk(fmt: args->fmt, args: args->args); |
671 | |
672 | print_modules(); |
673 | |
674 | if (regs) |
675 | show_regs(regs); |
676 | |
677 | check_panic_on_warn(origin: "kernel" ); |
678 | |
679 | if (!regs) |
680 | dump_stack(); |
681 | |
682 | print_irqtrace_events(current); |
683 | |
684 | print_oops_end_marker(); |
685 | trace_error_report_end(error_detector: ERROR_DETECTOR_WARN, id: (unsigned long)caller); |
686 | |
687 | /* Just a warning, don't kill lockdep. */ |
688 | add_taint(taint, LOCKDEP_STILL_OK); |
689 | } |
690 | |
691 | #ifdef CONFIG_BUG |
692 | #ifndef __WARN_FLAGS |
693 | void warn_slowpath_fmt(const char *file, int line, unsigned taint, |
694 | const char *fmt, ...) |
695 | { |
696 | bool rcu = warn_rcu_enter(); |
697 | struct warn_args args; |
698 | |
699 | pr_warn(CUT_HERE); |
700 | |
701 | if (!fmt) { |
702 | __warn(file, line, __builtin_return_address(0), taint, |
703 | NULL, NULL); |
704 | warn_rcu_exit(rcu); |
705 | return; |
706 | } |
707 | |
708 | args.fmt = fmt; |
709 | va_start(args.args, fmt); |
710 | __warn(file, line, __builtin_return_address(0), taint, NULL, &args); |
711 | va_end(args.args); |
712 | warn_rcu_exit(rcu); |
713 | } |
714 | EXPORT_SYMBOL(warn_slowpath_fmt); |
715 | #else |
716 | void __warn_printk(const char *fmt, ...) |
717 | { |
718 | bool rcu = warn_rcu_enter(); |
719 | va_list args; |
720 | |
721 | pr_warn(CUT_HERE); |
722 | |
723 | va_start(args, fmt); |
724 | vprintk(fmt, args); |
725 | va_end(args); |
726 | warn_rcu_exit(rcu); |
727 | } |
728 | EXPORT_SYMBOL(__warn_printk); |
729 | #endif |
730 | |
731 | /* Support resetting WARN*_ONCE state */ |
732 | |
733 | static int clear_warn_once_set(void *data, u64 val) |
734 | { |
735 | generic_bug_clear_once(); |
736 | memset(__start_once, 0, __end_once - __start_once); |
737 | return 0; |
738 | } |
739 | |
740 | DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, |
741 | "%lld\n" ); |
742 | |
743 | static __init int register_warn_debugfs(void) |
744 | { |
745 | /* Don't care about failure */ |
746 | debugfs_create_file_unsafe(name: "clear_warn_once" , mode: 0200, NULL, NULL, |
747 | fops: &clear_warn_once_fops); |
748 | return 0; |
749 | } |
750 | |
751 | device_initcall(register_warn_debugfs); |
752 | #endif |
753 | |
754 | #ifdef CONFIG_STACKPROTECTOR |
755 | |
756 | /* |
757 | * Called when gcc's -fstack-protector feature is used, and |
758 | * gcc detects corruption of the on-stack canary value |
759 | */ |
760 | __visible noinstr void __stack_chk_fail(void) |
761 | { |
762 | instrumentation_begin(); |
763 | panic("stack-protector: Kernel stack is corrupted in: %pB" , |
764 | __builtin_return_address(0)); |
765 | instrumentation_end(); |
766 | } |
767 | EXPORT_SYMBOL(__stack_chk_fail); |
768 | |
769 | #endif |
770 | |
771 | core_param(panic, panic_timeout, int, 0644); |
772 | core_param(panic_print, panic_print, ulong, 0644); |
773 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
774 | core_param(panic_on_warn, panic_on_warn, int, 0644); |
775 | core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); |
776 | |
777 | static int __init oops_setup(char *s) |
778 | { |
779 | if (!s) |
780 | return -EINVAL; |
781 | if (!strcmp(s, "panic" )) |
782 | panic_on_oops = 1; |
783 | return 0; |
784 | } |
785 | early_param("oops" , oops_setup); |
786 | |
787 | static int __init panic_on_taint_setup(char *s) |
788 | { |
789 | char *taint_str; |
790 | |
791 | if (!s) |
792 | return -EINVAL; |
793 | |
794 | taint_str = strsep(&s, "," ); |
795 | if (kstrtoul(s: taint_str, base: 16, res: &panic_on_taint)) |
796 | return -EINVAL; |
797 | |
798 | /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ |
799 | panic_on_taint &= TAINT_FLAGS_MAX; |
800 | |
801 | if (!panic_on_taint) |
802 | return -EINVAL; |
803 | |
804 | if (s && !strcmp(s, "nousertaint" )) |
805 | panic_on_taint_nousertaint = true; |
806 | |
807 | pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n" , |
808 | panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); |
809 | |
810 | return 0; |
811 | } |
812 | early_param("panic_on_taint" , panic_on_taint_setup); |
813 | |