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 <linux/seq_buf.h> |
39 | #include <trace/events/error_report.h> |
40 | #include <asm/sections.h> |
41 | |
42 | #define PANIC_TIMER_STEP 100 |
43 | #define PANIC_BLINK_SPD 18 |
44 | |
45 | #ifdef CONFIG_SMP |
46 | /* |
47 | * Should we dump all CPUs backtraces in an oops event? |
48 | * Defaults to 0, can be changed via sysctl. |
49 | */ |
50 | static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; |
51 | #else |
52 | #define sysctl_oops_all_cpu_backtrace 0 |
53 | #endif /* CONFIG_SMP */ |
54 | |
55 | int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; |
56 | static unsigned long tainted_mask = |
57 | IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0; |
58 | static int pause_on_oops; |
59 | static int pause_on_oops_flag; |
60 | static DEFINE_SPINLOCK(pause_on_oops_lock); |
61 | bool crash_kexec_post_notifiers; |
62 | int panic_on_warn __read_mostly; |
63 | unsigned long panic_on_taint; |
64 | bool panic_on_taint_nousertaint = false; |
65 | static unsigned int warn_limit __read_mostly; |
66 | |
67 | bool panic_triggering_all_cpu_backtrace; |
68 | |
69 | int panic_timeout = CONFIG_PANIC_TIMEOUT; |
70 | EXPORT_SYMBOL_GPL(panic_timeout); |
71 | |
72 | #define PANIC_PRINT_TASK_INFO 0x00000001 |
73 | #define PANIC_PRINT_MEM_INFO 0x00000002 |
74 | #define PANIC_PRINT_TIMER_INFO 0x00000004 |
75 | #define PANIC_PRINT_LOCK_INFO 0x00000008 |
76 | #define PANIC_PRINT_FTRACE_INFO 0x00000010 |
77 | #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 |
78 | #define PANIC_PRINT_ALL_CPU_BT 0x00000040 |
79 | #define PANIC_PRINT_BLOCKED_TASKS 0x00000080 |
80 | unsigned long panic_print; |
81 | |
82 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
83 | |
84 | EXPORT_SYMBOL(panic_notifier_list); |
85 | |
86 | #ifdef CONFIG_SYSCTL |
87 | static const struct ctl_table kern_panic_table[] = { |
88 | #ifdef CONFIG_SMP |
89 | { |
90 | .procname = "oops_all_cpu_backtrace", |
91 | .data = &sysctl_oops_all_cpu_backtrace, |
92 | .maxlen = sizeof(int), |
93 | .mode = 0644, |
94 | .proc_handler = proc_dointvec_minmax, |
95 | .extra1 = SYSCTL_ZERO, |
96 | .extra2 = SYSCTL_ONE, |
97 | }, |
98 | #endif |
99 | { |
100 | .procname = "panic", |
101 | .data = &panic_timeout, |
102 | .maxlen = sizeof(int), |
103 | .mode = 0644, |
104 | .proc_handler = proc_dointvec, |
105 | }, |
106 | { |
107 | .procname = "panic_on_oops", |
108 | .data = &panic_on_oops, |
109 | .maxlen = sizeof(int), |
110 | .mode = 0644, |
111 | .proc_handler = proc_dointvec, |
112 | }, |
113 | { |
114 | .procname = "panic_print", |
115 | .data = &panic_print, |
116 | .maxlen = sizeof(unsigned long), |
117 | .mode = 0644, |
118 | .proc_handler = proc_doulongvec_minmax, |
119 | }, |
120 | { |
121 | .procname = "panic_on_warn", |
122 | .data = &panic_on_warn, |
123 | .maxlen = sizeof(int), |
124 | .mode = 0644, |
125 | .proc_handler = proc_dointvec_minmax, |
126 | .extra1 = SYSCTL_ZERO, |
127 | .extra2 = SYSCTL_ONE, |
128 | }, |
129 | { |
130 | .procname = "warn_limit", |
131 | .data = &warn_limit, |
132 | .maxlen = sizeof(warn_limit), |
133 | .mode = 0644, |
134 | .proc_handler = proc_douintvec, |
135 | }, |
136 | }; |
137 | |
138 | static __init int kernel_panic_sysctls_init(void) |
139 | { |
140 | register_sysctl_init("kernel", kern_panic_table); |
141 | return 0; |
142 | } |
143 | late_initcall(kernel_panic_sysctls_init); |
144 | #endif |
145 | |
146 | static atomic_t warn_count = ATOMIC_INIT(0); |
147 | |
148 | #ifdef CONFIG_SYSFS |
149 | static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, |
150 | char *page) |
151 | { |
152 | return sysfs_emit(buf: page, fmt: "%d\n", atomic_read(v: &warn_count)); |
153 | } |
154 | |
155 | static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); |
156 | |
157 | static __init int kernel_panic_sysfs_init(void) |
158 | { |
159 | sysfs_add_file_to_group(kobj: kernel_kobj, attr: &warn_count_attr.attr, NULL); |
160 | return 0; |
161 | } |
162 | late_initcall(kernel_panic_sysfs_init); |
163 | #endif |
164 | |
165 | static long no_blink(int state) |
166 | { |
167 | return 0; |
168 | } |
169 | |
170 | /* Returns how long it waited in ms */ |
171 | long (*panic_blink)(int state); |
172 | EXPORT_SYMBOL(panic_blink); |
173 | |
174 | /* |
175 | * Stop ourself in panic -- architecture code may override this |
176 | */ |
177 | void __weak __noreturn panic_smp_self_stop(void) |
178 | { |
179 | while (1) |
180 | cpu_relax(); |
181 | } |
182 | |
183 | /* |
184 | * Stop ourselves in NMI context if another CPU has already panicked. Arch code |
185 | * may override this to prepare for crash dumping, e.g. save regs info. |
186 | */ |
187 | void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs) |
188 | { |
189 | panic_smp_self_stop(); |
190 | } |
191 | |
192 | /* |
193 | * Stop other CPUs in panic. Architecture dependent code may override this |
194 | * with more suitable version. For example, if the architecture supports |
195 | * crash dump, it should save registers of each stopped CPU and disable |
196 | * per-CPU features such as virtualization extensions. |
197 | */ |
198 | void __weak crash_smp_send_stop(void) |
199 | { |
200 | static int cpus_stopped; |
201 | |
202 | /* |
203 | * This function can be called twice in panic path, but obviously |
204 | * we execute this only once. |
205 | */ |
206 | if (cpus_stopped) |
207 | return; |
208 | |
209 | /* |
210 | * Note smp_send_stop is the usual smp shutdown function, which |
211 | * unfortunately means it may not be hardened to work in a panic |
212 | * situation. |
213 | */ |
214 | smp_send_stop(); |
215 | cpus_stopped = 1; |
216 | } |
217 | |
218 | atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); |
219 | |
220 | /* |
221 | * A variant of panic() called from NMI context. We return if we've already |
222 | * panicked on this CPU. If another CPU already panicked, loop in |
223 | * nmi_panic_self_stop() which can provide architecture dependent code such |
224 | * as saving register state for crash dump. |
225 | */ |
226 | void nmi_panic(struct pt_regs *regs, const char *msg) |
227 | { |
228 | int old_cpu, this_cpu; |
229 | |
230 | old_cpu = PANIC_CPU_INVALID; |
231 | this_cpu = raw_smp_processor_id(); |
232 | |
233 | /* atomic_try_cmpxchg updates old_cpu on failure */ |
234 | if (atomic_try_cmpxchg(v: &panic_cpu, old: &old_cpu, new: this_cpu)) |
235 | panic(fmt: "%s", msg); |
236 | else if (old_cpu != this_cpu) |
237 | nmi_panic_self_stop(regs); |
238 | } |
239 | EXPORT_SYMBOL(nmi_panic); |
240 | |
241 | static void panic_print_sys_info(bool console_flush) |
242 | { |
243 | if (console_flush) { |
244 | if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) |
245 | console_flush_on_panic(mode: CONSOLE_REPLAY_ALL); |
246 | return; |
247 | } |
248 | |
249 | if (panic_print & PANIC_PRINT_TASK_INFO) |
250 | show_state(); |
251 | |
252 | if (panic_print & PANIC_PRINT_MEM_INFO) |
253 | show_mem(); |
254 | |
255 | if (panic_print & PANIC_PRINT_TIMER_INFO) |
256 | sysrq_timer_list_show(); |
257 | |
258 | if (panic_print & PANIC_PRINT_LOCK_INFO) |
259 | debug_show_all_locks(); |
260 | |
261 | if (panic_print & PANIC_PRINT_FTRACE_INFO) |
262 | ftrace_dump(oops_dump_mode: DUMP_ALL); |
263 | |
264 | if (panic_print & PANIC_PRINT_BLOCKED_TASKS) |
265 | show_state_filter(TASK_UNINTERRUPTIBLE); |
266 | } |
267 | |
268 | void check_panic_on_warn(const char *origin) |
269 | { |
270 | unsigned int limit; |
271 | |
272 | if (panic_on_warn) |
273 | panic(fmt: "%s: panic_on_warn set ...\n", origin); |
274 | |
275 | limit = READ_ONCE(warn_limit); |
276 | if (atomic_inc_return(v: &warn_count) >= limit && limit) |
277 | panic(fmt: "%s: system warned too often (kernel.warn_limit is %d)", |
278 | origin, limit); |
279 | } |
280 | |
281 | /* |
282 | * Helper that triggers the NMI backtrace (if set in panic_print) |
283 | * and then performs the secondary CPUs shutdown - we cannot have |
284 | * the NMI backtrace after the CPUs are off! |
285 | */ |
286 | static void panic_other_cpus_shutdown(bool crash_kexec) |
287 | { |
288 | if (panic_print & PANIC_PRINT_ALL_CPU_BT) { |
289 | /* Temporary allow non-panic CPUs to write their backtraces. */ |
290 | panic_triggering_all_cpu_backtrace = true; |
291 | trigger_all_cpu_backtrace(); |
292 | panic_triggering_all_cpu_backtrace = false; |
293 | } |
294 | |
295 | /* |
296 | * Note that smp_send_stop() is the usual SMP shutdown function, |
297 | * which unfortunately may not be hardened to work in a panic |
298 | * situation. If we want to do crash dump after notifier calls |
299 | * and kmsg_dump, we will need architecture dependent extra |
300 | * bits in addition to stopping other CPUs, hence we rely on |
301 | * crash_smp_send_stop() for that. |
302 | */ |
303 | if (!crash_kexec) |
304 | smp_send_stop(); |
305 | else |
306 | crash_smp_send_stop(); |
307 | } |
308 | |
309 | /** |
310 | * panic - halt the system |
311 | * @fmt: The text string to print |
312 | * |
313 | * Display a message, then perform cleanups. This function never returns. |
314 | */ |
315 | void panic(const char *fmt, ...) |
316 | { |
317 | static char buf[1024]; |
318 | va_list args; |
319 | long i, i_next = 0, len; |
320 | int state = 0; |
321 | int old_cpu, this_cpu; |
322 | bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; |
323 | |
324 | if (panic_on_warn) { |
325 | /* |
326 | * This thread may hit another WARN() in the panic path. |
327 | * Resetting this prevents additional WARN() from panicking the |
328 | * system on this thread. Other threads are blocked by the |
329 | * panic_mutex in panic(). |
330 | */ |
331 | panic_on_warn = 0; |
332 | } |
333 | |
334 | /* |
335 | * Disable local interrupts. This will prevent panic_smp_self_stop |
336 | * from deadlocking the first cpu that invokes the panic, since |
337 | * there is nothing to prevent an interrupt handler (that runs |
338 | * after setting panic_cpu) from invoking panic() again. |
339 | */ |
340 | local_irq_disable(); |
341 | preempt_disable_notrace(); |
342 | |
343 | /* |
344 | * It's possible to come here directly from a panic-assertion and |
345 | * not have preempt disabled. Some functions called from here want |
346 | * preempt to be disabled. No point enabling it later though... |
347 | * |
348 | * Only one CPU is allowed to execute the panic code from here. For |
349 | * multiple parallel invocations of panic, all other CPUs either |
350 | * stop themself or will wait until they are stopped by the 1st CPU |
351 | * with smp_send_stop(). |
352 | * |
353 | * cmpxchg success means this is the 1st CPU which comes here, |
354 | * so go ahead. |
355 | * `old_cpu == this_cpu' means we came from nmi_panic() which sets |
356 | * panic_cpu to this CPU. In this case, this is also the 1st CPU. |
357 | */ |
358 | old_cpu = PANIC_CPU_INVALID; |
359 | this_cpu = raw_smp_processor_id(); |
360 | |
361 | /* atomic_try_cmpxchg updates old_cpu on failure */ |
362 | if (atomic_try_cmpxchg(v: &panic_cpu, old: &old_cpu, new: this_cpu)) { |
363 | /* go ahead */ |
364 | } else if (old_cpu != this_cpu) |
365 | panic_smp_self_stop(); |
366 | |
367 | console_verbose(); |
368 | bust_spinlocks(yes: 1); |
369 | va_start(args, fmt); |
370 | len = vscnprintf(buf, size: sizeof(buf), fmt, args); |
371 | va_end(args); |
372 | |
373 | if (len && buf[len - 1] == '\n') |
374 | buf[len - 1] = '\0'; |
375 | |
376 | pr_emerg("Kernel panic - not syncing: %s\n", buf); |
377 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
378 | /* |
379 | * Avoid nested stack-dumping if a panic occurs during oops processing |
380 | */ |
381 | if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
382 | dump_stack(); |
383 | #endif |
384 | |
385 | /* |
386 | * If kgdb is enabled, give it a chance to run before we stop all |
387 | * the other CPUs or else we won't be able to debug processes left |
388 | * running on them. |
389 | */ |
390 | kgdb_panic(msg: buf); |
391 | |
392 | /* |
393 | * If we have crashed and we have a crash kernel loaded let it handle |
394 | * everything else. |
395 | * If we want to run this after calling panic_notifiers, pass |
396 | * the "crash_kexec_post_notifiers" option to the kernel. |
397 | * |
398 | * Bypass the panic_cpu check and call __crash_kexec directly. |
399 | */ |
400 | if (!_crash_kexec_post_notifiers) |
401 | __crash_kexec(NULL); |
402 | |
403 | panic_other_cpus_shutdown(crash_kexec: _crash_kexec_post_notifiers); |
404 | |
405 | printk_legacy_allow_panic_sync(); |
406 | |
407 | /* |
408 | * Run any panic handlers, including those that might need to |
409 | * add information to the kmsg dump output. |
410 | */ |
411 | atomic_notifier_call_chain(nh: &panic_notifier_list, val: 0, v: buf); |
412 | |
413 | panic_print_sys_info(console_flush: false); |
414 | |
415 | kmsg_dump_desc(reason: KMSG_DUMP_PANIC, desc: buf); |
416 | |
417 | /* |
418 | * If you doubt kdump always works fine in any situation, |
419 | * "crash_kexec_post_notifiers" offers you a chance to run |
420 | * panic_notifiers and dumping kmsg before kdump. |
421 | * Note: since some panic_notifiers can make crashed kernel |
422 | * more unstable, it can increase risks of the kdump failure too. |
423 | * |
424 | * Bypass the panic_cpu check and call __crash_kexec directly. |
425 | */ |
426 | if (_crash_kexec_post_notifiers) |
427 | __crash_kexec(NULL); |
428 | |
429 | console_unblank(); |
430 | |
431 | /* |
432 | * We may have ended up stopping the CPU holding the lock (in |
433 | * smp_send_stop()) while still having some valuable data in the console |
434 | * buffer. Try to acquire the lock then release it regardless of the |
435 | * result. The release will also print the buffers out. Locks debug |
436 | * should be disabled to avoid reporting bad unlock balance when |
437 | * panic() is not being callled from OOPS. |
438 | */ |
439 | debug_locks_off(); |
440 | console_flush_on_panic(mode: CONSOLE_FLUSH_PENDING); |
441 | |
442 | panic_print_sys_info(console_flush: true); |
443 | |
444 | if (!panic_blink) |
445 | panic_blink = no_blink; |
446 | |
447 | if (panic_timeout > 0) { |
448 | /* |
449 | * Delay timeout seconds before rebooting the machine. |
450 | * We can't use the "normal" timers since we just panicked. |
451 | */ |
452 | pr_emerg("Rebooting in %d seconds..\n", panic_timeout); |
453 | |
454 | for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
455 | touch_nmi_watchdog(); |
456 | if (i >= i_next) { |
457 | i += panic_blink(state ^= 1); |
458 | i_next = i + 3600 / PANIC_BLINK_SPD; |
459 | } |
460 | mdelay(PANIC_TIMER_STEP); |
461 | } |
462 | } |
463 | if (panic_timeout != 0) { |
464 | /* |
465 | * This will not be a clean reboot, with everything |
466 | * shutting down. But if there is a chance of |
467 | * rebooting the system it will be rebooted. |
468 | */ |
469 | if (panic_reboot_mode != REBOOT_UNDEFINED) |
470 | reboot_mode = panic_reboot_mode; |
471 | emergency_restart(); |
472 | } |
473 | #ifdef __sparc__ |
474 | { |
475 | extern int stop_a_enabled; |
476 | /* Make sure the user can actually press Stop-A (L1-A) */ |
477 | stop_a_enabled = 1; |
478 | pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" |
479 | "twice on console to return to the boot prom\n"); |
480 | } |
481 | #endif |
482 | #if defined(CONFIG_S390) |
483 | disabled_wait(); |
484 | #endif |
485 | pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); |
486 | |
487 | /* Do not scroll important messages printed above */ |
488 | suppress_printk = 1; |
489 | |
490 | /* |
491 | * The final messages may not have been printed if in a context that |
492 | * defers printing (such as NMI) and irq_work is not available. |
493 | * Explicitly flush the kernel log buffer one last time. |
494 | */ |
495 | console_flush_on_panic(mode: CONSOLE_FLUSH_PENDING); |
496 | nbcon_atomic_flush_unsafe(); |
497 | |
498 | local_irq_enable(); |
499 | for (i = 0; ; i += PANIC_TIMER_STEP) { |
500 | touch_softlockup_watchdog(); |
501 | if (i >= i_next) { |
502 | i += panic_blink(state ^= 1); |
503 | i_next = i + 3600 / PANIC_BLINK_SPD; |
504 | } |
505 | mdelay(PANIC_TIMER_STEP); |
506 | } |
507 | } |
508 | |
509 | EXPORT_SYMBOL(panic); |
510 | |
511 | #define TAINT_FLAG(taint, _c_true, _c_false, _module) \ |
512 | [ TAINT_##taint ] = { \ |
513 | .c_true = _c_true, .c_false = _c_false, \ |
514 | .module = _module, \ |
515 | .desc = #taint, \ |
516 | } |
517 | |
518 | /* |
519 | * TAINT_FORCED_RMMOD could be a per-module flag but the module |
520 | * is being removed anyway. |
521 | */ |
522 | const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { |
523 | TAINT_FLAG(PROPRIETARY_MODULE, 'P', 'G', true), |
524 | TAINT_FLAG(FORCED_MODULE, 'F', ' ', true), |
525 | TAINT_FLAG(CPU_OUT_OF_SPEC, 'S', ' ', false), |
526 | TAINT_FLAG(FORCED_RMMOD, 'R', ' ', false), |
527 | TAINT_FLAG(MACHINE_CHECK, 'M', ' ', false), |
528 | TAINT_FLAG(BAD_PAGE, 'B', ' ', false), |
529 | TAINT_FLAG(USER, 'U', ' ', false), |
530 | TAINT_FLAG(DIE, 'D', ' ', false), |
531 | TAINT_FLAG(OVERRIDDEN_ACPI_TABLE, 'A', ' ', false), |
532 | TAINT_FLAG(WARN, 'W', ' ', false), |
533 | TAINT_FLAG(CRAP, 'C', ' ', true), |
534 | TAINT_FLAG(FIRMWARE_WORKAROUND, 'I', ' ', false), |
535 | TAINT_FLAG(OOT_MODULE, 'O', ' ', true), |
536 | TAINT_FLAG(UNSIGNED_MODULE, 'E', ' ', true), |
537 | TAINT_FLAG(SOFTLOCKUP, 'L', ' ', false), |
538 | TAINT_FLAG(LIVEPATCH, 'K', ' ', true), |
539 | TAINT_FLAG(AUX, 'X', ' ', true), |
540 | TAINT_FLAG(RANDSTRUCT, 'T', ' ', true), |
541 | TAINT_FLAG(TEST, 'N', ' ', true), |
542 | TAINT_FLAG(FWCTL, 'J', ' ', true), |
543 | }; |
544 | |
545 | #undef TAINT_FLAG |
546 | |
547 | static void print_tainted_seq(struct seq_buf *s, bool verbose) |
548 | { |
549 | const char *sep = ""; |
550 | int i; |
551 | |
552 | if (!tainted_mask) { |
553 | seq_buf_puts(s, str: "Not tainted"); |
554 | return; |
555 | } |
556 | |
557 | seq_buf_printf(s, fmt: "Tainted: "); |
558 | for (i = 0; i < TAINT_FLAGS_COUNT; i++) { |
559 | const struct taint_flag *t = &taint_flags[i]; |
560 | bool is_set = test_bit(i, &tainted_mask); |
561 | char c = is_set ? t->c_true : t->c_false; |
562 | |
563 | if (verbose) { |
564 | if (is_set) { |
565 | seq_buf_printf(s, fmt: "%s[%c]=%s", sep, c, t->desc); |
566 | sep = ", "; |
567 | } |
568 | } else { |
569 | seq_buf_putc(s, c); |
570 | } |
571 | } |
572 | } |
573 | |
574 | static const char *_print_tainted(bool verbose) |
575 | { |
576 | /* FIXME: what should the size be? */ |
577 | static char buf[sizeof(taint_flags)]; |
578 | struct seq_buf s; |
579 | |
580 | BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); |
581 | |
582 | seq_buf_init(s: &s, buf, size: sizeof(buf)); |
583 | |
584 | print_tainted_seq(s: &s, verbose); |
585 | |
586 | return seq_buf_str(s: &s); |
587 | } |
588 | |
589 | /** |
590 | * print_tainted - return a string to represent the kernel taint state. |
591 | * |
592 | * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst |
593 | * |
594 | * The string is overwritten by the next call to print_tainted(), |
595 | * but is always NULL terminated. |
596 | */ |
597 | const char *print_tainted(void) |
598 | { |
599 | return _print_tainted(verbose: false); |
600 | } |
601 | |
602 | /** |
603 | * print_tainted_verbose - A more verbose version of print_tainted() |
604 | */ |
605 | const char *print_tainted_verbose(void) |
606 | { |
607 | return _print_tainted(verbose: true); |
608 | } |
609 | |
610 | int test_taint(unsigned flag) |
611 | { |
612 | return test_bit(flag, &tainted_mask); |
613 | } |
614 | EXPORT_SYMBOL(test_taint); |
615 | |
616 | unsigned long get_taint(void) |
617 | { |
618 | return tainted_mask; |
619 | } |
620 | |
621 | /** |
622 | * add_taint: add a taint flag if not already set. |
623 | * @flag: one of the TAINT_* constants. |
624 | * @lockdep_ok: whether lock debugging is still OK. |
625 | * |
626 | * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for |
627 | * some notewortht-but-not-corrupting cases, it can be set to true. |
628 | */ |
629 | void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) |
630 | { |
631 | if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) |
632 | pr_warn("Disabling lock debugging due to kernel taint\n"); |
633 | |
634 | set_bit(nr: flag, addr: &tainted_mask); |
635 | |
636 | if (tainted_mask & panic_on_taint) { |
637 | panic_on_taint = 0; |
638 | panic("panic_on_taint set ..."); |
639 | } |
640 | } |
641 | EXPORT_SYMBOL(add_taint); |
642 | |
643 | static void spin_msec(int msecs) |
644 | { |
645 | int i; |
646 | |
647 | for (i = 0; i < msecs; i++) { |
648 | touch_nmi_watchdog(); |
649 | mdelay(1); |
650 | } |
651 | } |
652 | |
653 | /* |
654 | * It just happens that oops_enter() and oops_exit() are identically |
655 | * implemented... |
656 | */ |
657 | static void do_oops_enter_exit(void) |
658 | { |
659 | unsigned long flags; |
660 | static int spin_counter; |
661 | |
662 | if (!pause_on_oops) |
663 | return; |
664 | |
665 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
666 | if (pause_on_oops_flag == 0) { |
667 | /* This CPU may now print the oops message */ |
668 | pause_on_oops_flag = 1; |
669 | } else { |
670 | /* We need to stall this CPU */ |
671 | if (!spin_counter) { |
672 | /* This CPU gets to do the counting */ |
673 | spin_counter = pause_on_oops; |
674 | do { |
675 | spin_unlock(lock: &pause_on_oops_lock); |
676 | spin_msec(MSEC_PER_SEC); |
677 | spin_lock(lock: &pause_on_oops_lock); |
678 | } while (--spin_counter); |
679 | pause_on_oops_flag = 0; |
680 | } else { |
681 | /* This CPU waits for a different one */ |
682 | while (spin_counter) { |
683 | spin_unlock(lock: &pause_on_oops_lock); |
684 | spin_msec(msecs: 1); |
685 | spin_lock(lock: &pause_on_oops_lock); |
686 | } |
687 | } |
688 | } |
689 | spin_unlock_irqrestore(lock: &pause_on_oops_lock, flags); |
690 | } |
691 | |
692 | /* |
693 | * Return true if the calling CPU is allowed to print oops-related info. |
694 | * This is a bit racy.. |
695 | */ |
696 | bool oops_may_print(void) |
697 | { |
698 | return pause_on_oops_flag == 0; |
699 | } |
700 | |
701 | /* |
702 | * Called when the architecture enters its oops handler, before it prints |
703 | * anything. If this is the first CPU to oops, and it's oopsing the first |
704 | * time then let it proceed. |
705 | * |
706 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
707 | * this to ensure that oopses don't scroll off the screen. It has the |
708 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
709 | * too. |
710 | * |
711 | * It turns out that the CPU which is allowed to print ends up pausing for |
712 | * the right duration, whereas all the other CPUs pause for twice as long: |
713 | * once in oops_enter(), once in oops_exit(). |
714 | */ |
715 | void oops_enter(void) |
716 | { |
717 | nbcon_cpu_emergency_enter(); |
718 | tracing_off(); |
719 | /* can't trust the integrity of the kernel anymore: */ |
720 | debug_locks_off(); |
721 | do_oops_enter_exit(); |
722 | |
723 | if (sysctl_oops_all_cpu_backtrace) |
724 | trigger_all_cpu_backtrace(); |
725 | } |
726 | |
727 | static void print_oops_end_marker(void) |
728 | { |
729 | pr_warn("---[ end trace %016llx ]---\n", 0ULL); |
730 | } |
731 | |
732 | /* |
733 | * Called when the architecture exits its oops handler, after printing |
734 | * everything. |
735 | */ |
736 | void oops_exit(void) |
737 | { |
738 | do_oops_enter_exit(); |
739 | print_oops_end_marker(); |
740 | nbcon_cpu_emergency_exit(); |
741 | kmsg_dump(reason: KMSG_DUMP_OOPS); |
742 | } |
743 | |
744 | struct warn_args { |
745 | const char *fmt; |
746 | va_list args; |
747 | }; |
748 | |
749 | void __warn(const char *file, int line, void *caller, unsigned taint, |
750 | struct pt_regs *regs, struct warn_args *args) |
751 | { |
752 | nbcon_cpu_emergency_enter(); |
753 | |
754 | disable_trace_on_warning(); |
755 | |
756 | if (file) |
757 | pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", |
758 | raw_smp_processor_id(), current->pid, file, line, |
759 | caller); |
760 | else |
761 | pr_warn("WARNING: CPU: %d PID: %d at %pS\n", |
762 | raw_smp_processor_id(), current->pid, caller); |
763 | |
764 | #pragma GCC diagnostic push |
765 | #ifndef __clang__ |
766 | #pragma GCC diagnostic ignored "-Wsuggest-attribute=format" |
767 | #endif |
768 | if (args) |
769 | vprintk(fmt: args->fmt, args: args->args); |
770 | #pragma GCC diagnostic pop |
771 | |
772 | print_modules(); |
773 | |
774 | if (regs) |
775 | show_regs(regs); |
776 | |
777 | check_panic_on_warn(origin: "kernel"); |
778 | |
779 | if (!regs) |
780 | dump_stack(); |
781 | |
782 | print_irqtrace_events(current); |
783 | |
784 | print_oops_end_marker(); |
785 | trace_error_report_end(error_detector: ERROR_DETECTOR_WARN, id: (unsigned long)caller); |
786 | |
787 | /* Just a warning, don't kill lockdep. */ |
788 | add_taint(taint, LOCKDEP_STILL_OK); |
789 | |
790 | nbcon_cpu_emergency_exit(); |
791 | } |
792 | |
793 | #ifdef CONFIG_BUG |
794 | #ifndef __WARN_FLAGS |
795 | void warn_slowpath_fmt(const char *file, int line, unsigned taint, |
796 | const char *fmt, ...) |
797 | { |
798 | bool rcu = warn_rcu_enter(); |
799 | struct warn_args args; |
800 | |
801 | pr_warn(CUT_HERE); |
802 | |
803 | if (!fmt) { |
804 | __warn(file, line, __builtin_return_address(0), taint, |
805 | NULL, NULL); |
806 | warn_rcu_exit(rcu); |
807 | return; |
808 | } |
809 | |
810 | args.fmt = fmt; |
811 | va_start(args.args, fmt); |
812 | __warn(file, line, __builtin_return_address(0), taint, NULL, &args); |
813 | va_end(args.args); |
814 | warn_rcu_exit(rcu); |
815 | } |
816 | EXPORT_SYMBOL(warn_slowpath_fmt); |
817 | #else |
818 | void __warn_printk(const char *fmt, ...) |
819 | { |
820 | bool rcu = warn_rcu_enter(); |
821 | va_list args; |
822 | |
823 | pr_warn(CUT_HERE); |
824 | |
825 | va_start(args, fmt); |
826 | vprintk(fmt, args); |
827 | va_end(args); |
828 | warn_rcu_exit(rcu); |
829 | } |
830 | EXPORT_SYMBOL(__warn_printk); |
831 | #endif |
832 | |
833 | /* Support resetting WARN*_ONCE state */ |
834 | |
835 | static int clear_warn_once_set(void *data, u64 val) |
836 | { |
837 | generic_bug_clear_once(); |
838 | memset(__start_once, 0, __end_once - __start_once); |
839 | return 0; |
840 | } |
841 | |
842 | DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, |
843 | "%lld\n"); |
844 | |
845 | static __init int register_warn_debugfs(void) |
846 | { |
847 | /* Don't care about failure */ |
848 | debugfs_create_file_unsafe(name: "clear_warn_once", mode: 0200, NULL, NULL, |
849 | fops: &clear_warn_once_fops); |
850 | return 0; |
851 | } |
852 | |
853 | device_initcall(register_warn_debugfs); |
854 | #endif |
855 | |
856 | #ifdef CONFIG_STACKPROTECTOR |
857 | |
858 | /* |
859 | * Called when gcc's -fstack-protector feature is used, and |
860 | * gcc detects corruption of the on-stack canary value |
861 | */ |
862 | __visible noinstr void __stack_chk_fail(void) |
863 | { |
864 | unsigned long flags; |
865 | |
866 | instrumentation_begin(); |
867 | flags = user_access_save(); |
868 | |
869 | panic("stack-protector: Kernel stack is corrupted in: %pB", |
870 | __builtin_return_address(0)); |
871 | |
872 | user_access_restore(flags); |
873 | instrumentation_end(); |
874 | } |
875 | EXPORT_SYMBOL(__stack_chk_fail); |
876 | |
877 | #endif |
878 | |
879 | core_param(panic, panic_timeout, int, 0644); |
880 | core_param(panic_print, panic_print, ulong, 0644); |
881 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
882 | core_param(panic_on_warn, panic_on_warn, int, 0644); |
883 | core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); |
884 | |
885 | static int __init oops_setup(char *s) |
886 | { |
887 | if (!s) |
888 | return -EINVAL; |
889 | if (!strcmp(s, "panic")) |
890 | panic_on_oops = 1; |
891 | return 0; |
892 | } |
893 | early_param("oops", oops_setup); |
894 | |
895 | static int __init panic_on_taint_setup(char *s) |
896 | { |
897 | char *taint_str; |
898 | |
899 | if (!s) |
900 | return -EINVAL; |
901 | |
902 | taint_str = strsep(&s, ","); |
903 | if (kstrtoul(s: taint_str, base: 16, res: &panic_on_taint)) |
904 | return -EINVAL; |
905 | |
906 | /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ |
907 | panic_on_taint &= TAINT_FLAGS_MAX; |
908 | |
909 | if (!panic_on_taint) |
910 | return -EINVAL; |
911 | |
912 | if (s && !strcmp(s, "nousertaint")) |
913 | panic_on_taint_nousertaint = true; |
914 | |
915 | pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", |
916 | panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); |
917 | |
918 | return 0; |
919 | } |
920 | early_param("panic_on_taint", panic_on_taint_setup); |
921 |
Definitions
- sysctl_oops_all_cpu_backtrace
- panic_on_oops
- tainted_mask
- pause_on_oops
- pause_on_oops_flag
- pause_on_oops_lock
- crash_kexec_post_notifiers
- panic_on_warn
- panic_on_taint
- panic_on_taint_nousertaint
- warn_limit
- panic_triggering_all_cpu_backtrace
- panic_timeout
- panic_print
- panic_notifier_list
- kern_panic_table
- kernel_panic_sysctls_init
- warn_count
- warn_count_show
- warn_count_attr
- kernel_panic_sysfs_init
- no_blink
- panic_blink
- panic_smp_self_stop
- nmi_panic_self_stop
- crash_smp_send_stop
- panic_cpu
- nmi_panic
- panic_print_sys_info
- check_panic_on_warn
- panic_other_cpus_shutdown
- panic
- taint_flags
- print_tainted_seq
- _print_tainted
- print_tainted
- print_tainted_verbose
- test_taint
- get_taint
- add_taint
- spin_msec
- do_oops_enter_exit
- oops_may_print
- oops_enter
- print_oops_end_marker
- oops_exit
- warn_args
- __warn
- __warn_printk
- clear_warn_once_set
- clear_warn_once_fops
- register_warn_debugfs
- __stack_chk_fail
- oops_setup
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