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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 */
49static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
50#else
51#define sysctl_oops_all_cpu_backtrace 0
52#endif /* CONFIG_SMP */
53
54int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
55static unsigned long tainted_mask =
56 IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
57static int pause_on_oops;
58static int pause_on_oops_flag;
59static DEFINE_SPINLOCK(pause_on_oops_lock);
60bool crash_kexec_post_notifiers;
61int panic_on_warn __read_mostly;
62unsigned long panic_on_taint;
63bool panic_on_taint_nousertaint = false;
64static unsigned int warn_limit __read_mostly;
65
66int panic_timeout = CONFIG_PANIC_TIMEOUT;
67EXPORT_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
76unsigned long panic_print;
77
78ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
79
80EXPORT_SYMBOL(panic_notifier_list);
81
82#ifdef CONFIG_SYSCTL
83static 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
105static __init int kernel_panic_sysctls_init(void)
106{
107 register_sysctl_init("kernel", kern_panic_table);
108 return 0;
109}
110late_initcall(kernel_panic_sysctls_init);
111#endif
112
113static atomic_t warn_count = ATOMIC_INIT(0);
114
115#ifdef CONFIG_SYSFS
116static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
117 char *page)
118{
119 return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
120}
121
122static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
123
124static __init int kernel_panic_sysfs_init(void)
125{
126 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
127 return 0;
128}
129late_initcall(kernel_panic_sysfs_init);
130#endif
131
132static long no_blink(int state)
133{
134 return 0;
135}
136
137/* Returns how long it waited in ms */
138long (*panic_blink)(int state);
139EXPORT_SYMBOL(panic_blink);
140
141/*
142 * Stop ourself in panic -- architecture code may override this
143 */
144void __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 */
154void __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 */
165void __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
185atomic_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 */
193void 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(&panic_cpu, &old_cpu, this_cpu))
202 panic("%s", msg);
203 else if (old_cpu != this_cpu)
204 nmi_panic_self_stop(regs);
205}
206EXPORT_SYMBOL(nmi_panic);
207
208static 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(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(DUMP_ALL);
230}
231
232void check_panic_on_warn(const char *origin)
233{
234 unsigned int limit;
235
236 if (panic_on_warn)
237 panic("%s: panic_on_warn set ...\n", origin);
238
239 limit = READ_ONCE(warn_limit);
240 if (atomic_inc_return(&warn_count) >= limit && limit)
241 panic("%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 */
250static 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 */
277void 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(&panic_cpu, &old_cpu, this_cpu)) {
325 /* go ahead */
326 } else if (old_cpu != this_cpu)
327 panic_smp_self_stop();
328
329 console_verbose();
330 bust_spinlocks(1);
331 va_start(args, fmt);
332 len = vscnprintf(buf, 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(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_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(&panic_notifier_list, 0, buf);
372
373 panic_print_sys_info(false);
374
375 kmsg_dump(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(CONSOLE_FLUSH_PENDING);
401
402 panic_print_sys_info(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
460EXPORT_SYMBOL(panic);
461
462/*
463 * TAINT_FORCED_RMMOD could be a per-module flag but the module
464 * is being removed anyway.
465 */
466const 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 */
496const 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, "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, sizeof(buf), "Not tainted");
515
516 return buf;
517}
518
519int test_taint(unsigned flag)
520{
521 return test_bit(flag, &tainted_mask);
522}
523EXPORT_SYMBOL(test_taint);
524
525unsigned 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 */
538void 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(flag, &tainted_mask);
544
545 if (tainted_mask & panic_on_taint) {
546 panic_on_taint = 0;
547 panic("panic_on_taint set ...");
548 }
549}
550EXPORT_SYMBOL(add_taint);
551
552static 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 */
566static 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(&pause_on_oops_lock);
585 spin_msec(MSEC_PER_SEC);
586 spin_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(&pause_on_oops_lock);
593 spin_msec(1);
594 spin_lock(&pause_on_oops_lock);
595 }
596 }
597 }
598 spin_unlock_irqrestore(&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 */
605bool 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 */
624void 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
635static 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 */
644void oops_exit(void)
645{
646 do_oops_enter_exit();
647 print_oops_end_marker();
648 kmsg_dump(KMSG_DUMP_OOPS);
649}
650
651struct warn_args {
652 const char *fmt;
653 va_list args;
654};
655
656void __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(args->fmt, args->args);
671
672 print_modules();
673
674 if (regs)
675 show_regs(regs);
676
677 check_panic_on_warn("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_WARN, (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
693void 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}
714EXPORT_SYMBOL(warn_slowpath_fmt);
715#else
716void __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}
728EXPORT_SYMBOL(__warn_printk);
729#endif
730
731/* Support resetting WARN*_ONCE state */
732
733static 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
740DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
741 "%lld\n");
742
743static __init int register_warn_debugfs(void)
744{
745 /* Don't care about failure */
746 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
747 &clear_warn_once_fops);
748 return 0;
749}
750
751device_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}
767EXPORT_SYMBOL(__stack_chk_fail);
768
769#endif
770
771core_param(panic, panic_timeout, int, 0644);
772core_param(panic_print, panic_print, ulong, 0644);
773core_param(pause_on_oops, pause_on_oops, int, 0644);
774core_param(panic_on_warn, panic_on_warn, int, 0644);
775core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
776
777static 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}
785early_param("oops", oops_setup);
786
787static 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(taint_str, 16, &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}
812early_param("panic_on_taint", panic_on_taint_setup);
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 */
49static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
50#else
51#define sysctl_oops_all_cpu_backtrace 0
52#endif /* CONFIG_SMP */
53
54int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
55static unsigned long tainted_mask =
56 IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
57static int pause_on_oops;
58static int pause_on_oops_flag;
59static DEFINE_SPINLOCK(pause_on_oops_lock);
60bool crash_kexec_post_notifiers;
61int panic_on_warn __read_mostly;
62unsigned long panic_on_taint;
63bool panic_on_taint_nousertaint = false;
64static unsigned int warn_limit __read_mostly;
65
66int panic_timeout = CONFIG_PANIC_TIMEOUT;
67EXPORT_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#define PANIC_PRINT_BLOCKED_TASKS 0x00000080
77unsigned long panic_print;
78
79ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
80
81EXPORT_SYMBOL(panic_notifier_list);
82
83#ifdef CONFIG_SYSCTL
84static struct ctl_table kern_panic_table[] = {
85#ifdef CONFIG_SMP
86 {
87 .procname = "oops_all_cpu_backtrace",
88 .data = &sysctl_oops_all_cpu_backtrace,
89 .maxlen = sizeof(int),
90 .mode = 0644,
91 .proc_handler = proc_dointvec_minmax,
92 .extra1 = SYSCTL_ZERO,
93 .extra2 = SYSCTL_ONE,
94 },
95#endif
96 {
97 .procname = "warn_limit",
98 .data = &warn_limit,
99 .maxlen = sizeof(warn_limit),
100 .mode = 0644,
101 .proc_handler = proc_douintvec,
102 },
103 { }
104};
105
106static __init int kernel_panic_sysctls_init(void)
107{
108 register_sysctl_init("kernel", kern_panic_table);
109 return 0;
110}
111late_initcall(kernel_panic_sysctls_init);
112#endif
113
114static atomic_t warn_count = ATOMIC_INIT(0);
115
116#ifdef CONFIG_SYSFS
117static 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
123static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
124
125static __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}
130late_initcall(kernel_panic_sysfs_init);
131#endif
132
133static long no_blink(int state)
134{
135 return 0;
136}
137
138/* Returns how long it waited in ms */
139long (*panic_blink)(int state);
140EXPORT_SYMBOL(panic_blink);
141
142/*
143 * Stop ourself in panic -- architecture code may override this
144 */
145void __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 */
155void __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 */
166void __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
186atomic_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 */
194void 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}
207EXPORT_SYMBOL(nmi_panic);
208
209static 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
236void 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 */
254static 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 */
281void 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
472EXPORT_SYMBOL(panic);
473
474/*
475 * TAINT_FORCED_RMMOD could be a per-module flag but the module
476 * is being removed anyway.
477 */
478const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
479 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
480 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
481 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
482 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
483 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
484 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
485 [ TAINT_USER ] = { 'U', ' ', false },
486 [ TAINT_DIE ] = { 'D', ' ', false },
487 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
488 [ TAINT_WARN ] = { 'W', ' ', false },
489 [ TAINT_CRAP ] = { 'C', ' ', true },
490 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
491 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
492 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
493 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
494 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
495 [ TAINT_AUX ] = { 'X', ' ', true },
496 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
497 [ TAINT_TEST ] = { 'N', ' ', true },
498};
499
500/**
501 * print_tainted - return a string to represent the kernel taint state.
502 *
503 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
504 *
505 * The string is overwritten by the next call to print_tainted(),
506 * but is always NULL terminated.
507 */
508const char *print_tainted(void)
509{
510 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
511
512 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
513
514 if (tainted_mask) {
515 char *s;
516 int i;
517
518 s = buf + sprintf(buf, "Tainted: ");
519 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
520 const struct taint_flag *t = &taint_flags[i];
521 *s++ = test_bit(i, &tainted_mask) ?
522 t->c_true : t->c_false;
523 }
524 *s = 0;
525 } else
526 snprintf(buf, sizeof(buf), "Not tainted");
527
528 return buf;
529}
530
531int test_taint(unsigned flag)
532{
533 return test_bit(flag, &tainted_mask);
534}
535EXPORT_SYMBOL(test_taint);
536
537unsigned long get_taint(void)
538{
539 return tainted_mask;
540}
541
542/**
543 * add_taint: add a taint flag if not already set.
544 * @flag: one of the TAINT_* constants.
545 * @lockdep_ok: whether lock debugging is still OK.
546 *
547 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
548 * some notewortht-but-not-corrupting cases, it can be set to true.
549 */
550void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
551{
552 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
553 pr_warn("Disabling lock debugging due to kernel taint\n");
554
555 set_bit(flag, &tainted_mask);
556
557 if (tainted_mask & panic_on_taint) {
558 panic_on_taint = 0;
559 panic("panic_on_taint set ...");
560 }
561}
562EXPORT_SYMBOL(add_taint);
563
564static void spin_msec(int msecs)
565{
566 int i;
567
568 for (i = 0; i < msecs; i++) {
569 touch_nmi_watchdog();
570 mdelay(1);
571 }
572}
573
574/*
575 * It just happens that oops_enter() and oops_exit() are identically
576 * implemented...
577 */
578static void do_oops_enter_exit(void)
579{
580 unsigned long flags;
581 static int spin_counter;
582
583 if (!pause_on_oops)
584 return;
585
586 spin_lock_irqsave(&pause_on_oops_lock, flags);
587 if (pause_on_oops_flag == 0) {
588 /* This CPU may now print the oops message */
589 pause_on_oops_flag = 1;
590 } else {
591 /* We need to stall this CPU */
592 if (!spin_counter) {
593 /* This CPU gets to do the counting */
594 spin_counter = pause_on_oops;
595 do {
596 spin_unlock(&pause_on_oops_lock);
597 spin_msec(MSEC_PER_SEC);
598 spin_lock(&pause_on_oops_lock);
599 } while (--spin_counter);
600 pause_on_oops_flag = 0;
601 } else {
602 /* This CPU waits for a different one */
603 while (spin_counter) {
604 spin_unlock(&pause_on_oops_lock);
605 spin_msec(1);
606 spin_lock(&pause_on_oops_lock);
607 }
608 }
609 }
610 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
611}
612
613/*
614 * Return true if the calling CPU is allowed to print oops-related info.
615 * This is a bit racy..
616 */
617bool oops_may_print(void)
618{
619 return pause_on_oops_flag == 0;
620}
621
622/*
623 * Called when the architecture enters its oops handler, before it prints
624 * anything. If this is the first CPU to oops, and it's oopsing the first
625 * time then let it proceed.
626 *
627 * This is all enabled by the pause_on_oops kernel boot option. We do all
628 * this to ensure that oopses don't scroll off the screen. It has the
629 * side-effect of preventing later-oopsing CPUs from mucking up the display,
630 * too.
631 *
632 * It turns out that the CPU which is allowed to print ends up pausing for
633 * the right duration, whereas all the other CPUs pause for twice as long:
634 * once in oops_enter(), once in oops_exit().
635 */
636void oops_enter(void)
637{
638 tracing_off();
639 /* can't trust the integrity of the kernel anymore: */
640 debug_locks_off();
641 do_oops_enter_exit();
642
643 if (sysctl_oops_all_cpu_backtrace)
644 trigger_all_cpu_backtrace();
645}
646
647static void print_oops_end_marker(void)
648{
649 pr_warn("---[ end trace %016llx ]---\n", 0ULL);
650}
651
652/*
653 * Called when the architecture exits its oops handler, after printing
654 * everything.
655 */
656void oops_exit(void)
657{
658 do_oops_enter_exit();
659 print_oops_end_marker();
660 kmsg_dump(KMSG_DUMP_OOPS);
661}
662
663struct warn_args {
664 const char *fmt;
665 va_list args;
666};
667
668void __warn(const char *file, int line, void *caller, unsigned taint,
669 struct pt_regs *regs, struct warn_args *args)
670{
671 disable_trace_on_warning();
672
673 if (file)
674 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
675 raw_smp_processor_id(), current->pid, file, line,
676 caller);
677 else
678 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
679 raw_smp_processor_id(), current->pid, caller);
680
681#pragma GCC diagnostic push
682#ifndef __clang__
683#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
684#endif
685 if (args)
686 vprintk(args->fmt, args->args);
687#pragma GCC diagnostic pop
688
689 print_modules();
690
691 if (regs)
692 show_regs(regs);
693
694 check_panic_on_warn("kernel");
695
696 if (!regs)
697 dump_stack();
698
699 print_irqtrace_events(current);
700
701 print_oops_end_marker();
702 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);
703
704 /* Just a warning, don't kill lockdep. */
705 add_taint(taint, LOCKDEP_STILL_OK);
706}
707
708#ifdef CONFIG_BUG
709#ifndef __WARN_FLAGS
710void warn_slowpath_fmt(const char *file, int line, unsigned taint,
711 const char *fmt, ...)
712{
713 bool rcu = warn_rcu_enter();
714 struct warn_args args;
715
716 pr_warn(CUT_HERE);
717
718 if (!fmt) {
719 __warn(file, line, __builtin_return_address(0), taint,
720 NULL, NULL);
721 warn_rcu_exit(rcu);
722 return;
723 }
724
725 args.fmt = fmt;
726 va_start(args.args, fmt);
727 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
728 va_end(args.args);
729 warn_rcu_exit(rcu);
730}
731EXPORT_SYMBOL(warn_slowpath_fmt);
732#else
733void __warn_printk(const char *fmt, ...)
734{
735 bool rcu = warn_rcu_enter();
736 va_list args;
737
738 pr_warn(CUT_HERE);
739
740 va_start(args, fmt);
741 vprintk(fmt, args);
742 va_end(args);
743 warn_rcu_exit(rcu);
744}
745EXPORT_SYMBOL(__warn_printk);
746#endif
747
748/* Support resetting WARN*_ONCE state */
749
750static int clear_warn_once_set(void *data, u64 val)
751{
752 generic_bug_clear_once();
753 memset(__start_once, 0, __end_once - __start_once);
754 return 0;
755}
756
757DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
758 "%lld\n");
759
760static __init int register_warn_debugfs(void)
761{
762 /* Don't care about failure */
763 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
764 &clear_warn_once_fops);
765 return 0;
766}
767
768device_initcall(register_warn_debugfs);
769#endif
770
771#ifdef CONFIG_STACKPROTECTOR
772
773/*
774 * Called when gcc's -fstack-protector feature is used, and
775 * gcc detects corruption of the on-stack canary value
776 */
777__visible noinstr void __stack_chk_fail(void)
778{
779 instrumentation_begin();
780 panic("stack-protector: Kernel stack is corrupted in: %pB",
781 __builtin_return_address(0));
782 instrumentation_end();
783}
784EXPORT_SYMBOL(__stack_chk_fail);
785
786#endif
787
788core_param(panic, panic_timeout, int, 0644);
789core_param(panic_print, panic_print, ulong, 0644);
790core_param(pause_on_oops, pause_on_oops, int, 0644);
791core_param(panic_on_warn, panic_on_warn, int, 0644);
792core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
793
794static int __init oops_setup(char *s)
795{
796 if (!s)
797 return -EINVAL;
798 if (!strcmp(s, "panic"))
799 panic_on_oops = 1;
800 return 0;
801}
802early_param("oops", oops_setup);
803
804static int __init panic_on_taint_setup(char *s)
805{
806 char *taint_str;
807
808 if (!s)
809 return -EINVAL;
810
811 taint_str = strsep(&s, ",");
812 if (kstrtoul(taint_str, 16, &panic_on_taint))
813 return -EINVAL;
814
815 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
816 panic_on_taint &= TAINT_FLAGS_MAX;
817
818 if (!panic_on_taint)
819 return -EINVAL;
820
821 if (s && !strcmp(s, "nousertaint"))
822 panic_on_taint_nousertaint = true;
823
824 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n",
825 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint));
826
827 return 0;
828}
829early_param("panic_on_taint", panic_on_taint_setup);