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