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