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