1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * This function is used through-out the kernel (including mm and fs)
10 * to indicate a major problem.
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 <trace/events/error_report.h>
36 #include <asm/sections.h>
38 #define PANIC_TIMER_STEP 100
39 #define PANIC_BLINK_SPD 18
43 * Should we dump all CPUs backtraces in an oops event?
44 * Defaults to 0, can be changed via sysctl.
46 unsigned int __read_mostly sysctl_oops_all_cpu_backtrace
;
47 #endif /* CONFIG_SMP */
49 int panic_on_oops
= CONFIG_PANIC_ON_OOPS_VALUE
;
50 static unsigned long tainted_mask
=
51 IS_ENABLED(CONFIG_RANDSTRUCT
) ? (1 << TAINT_RANDSTRUCT
) : 0;
52 static int pause_on_oops
;
53 static int pause_on_oops_flag
;
54 static DEFINE_SPINLOCK(pause_on_oops_lock
);
55 bool crash_kexec_post_notifiers
;
56 int panic_on_warn __read_mostly
;
57 unsigned long panic_on_taint
;
58 bool panic_on_taint_nousertaint
= false;
60 int panic_timeout
= CONFIG_PANIC_TIMEOUT
;
61 EXPORT_SYMBOL_GPL(panic_timeout
);
63 #define PANIC_PRINT_TASK_INFO 0x00000001
64 #define PANIC_PRINT_MEM_INFO 0x00000002
65 #define PANIC_PRINT_TIMER_INFO 0x00000004
66 #define PANIC_PRINT_LOCK_INFO 0x00000008
67 #define PANIC_PRINT_FTRACE_INFO 0x00000010
68 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
69 #define PANIC_PRINT_ALL_CPU_BT 0x00000040
70 unsigned long panic_print
;
72 ATOMIC_NOTIFIER_HEAD(panic_notifier_list
);
74 EXPORT_SYMBOL(panic_notifier_list
);
76 static long no_blink(int state
)
81 /* Returns how long it waited in ms */
82 long (*panic_blink
)(int state
);
83 EXPORT_SYMBOL(panic_blink
);
86 * Stop ourself in panic -- architecture code may override this
88 void __weak
panic_smp_self_stop(void)
95 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
96 * may override this to prepare for crash dumping, e.g. save regs info.
98 void __weak
nmi_panic_self_stop(struct pt_regs
*regs
)
100 panic_smp_self_stop();
104 * Stop other CPUs in panic. Architecture dependent code may override this
105 * with more suitable version. For example, if the architecture supports
106 * crash dump, it should save registers of each stopped CPU and disable
107 * per-CPU features such as virtualization extensions.
109 void __weak
crash_smp_send_stop(void)
111 static int cpus_stopped
;
114 * This function can be called twice in panic path, but obviously
115 * we execute this only once.
121 * Note smp_send_stop is the usual smp shutdown function, which
122 * unfortunately means it may not be hardened to work in a panic
129 atomic_t panic_cpu
= ATOMIC_INIT(PANIC_CPU_INVALID
);
132 * A variant of panic() called from NMI context. We return if we've already
133 * panicked on this CPU. If another CPU already panicked, loop in
134 * nmi_panic_self_stop() which can provide architecture dependent code such
135 * as saving register state for crash dump.
137 void nmi_panic(struct pt_regs
*regs
, const char *msg
)
141 cpu
= raw_smp_processor_id();
142 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, cpu
);
144 if (old_cpu
== PANIC_CPU_INVALID
)
146 else if (old_cpu
!= cpu
)
147 nmi_panic_self_stop(regs
);
149 EXPORT_SYMBOL(nmi_panic
);
151 static void panic_print_sys_info(bool console_flush
)
154 if (panic_print
& PANIC_PRINT_ALL_PRINTK_MSG
)
155 console_flush_on_panic(CONSOLE_REPLAY_ALL
);
159 if (panic_print
& PANIC_PRINT_ALL_CPU_BT
)
160 trigger_all_cpu_backtrace();
162 if (panic_print
& PANIC_PRINT_TASK_INFO
)
165 if (panic_print
& PANIC_PRINT_MEM_INFO
)
168 if (panic_print
& PANIC_PRINT_TIMER_INFO
)
169 sysrq_timer_list_show();
171 if (panic_print
& PANIC_PRINT_LOCK_INFO
)
172 debug_show_all_locks();
174 if (panic_print
& PANIC_PRINT_FTRACE_INFO
)
175 ftrace_dump(DUMP_ALL
);
179 * panic - halt the system
180 * @fmt: The text string to print
182 * Display a message, then perform cleanups.
184 * This function never returns.
186 void panic(const char *fmt
, ...)
188 static char buf
[1024];
190 long i
, i_next
= 0, len
;
192 int old_cpu
, this_cpu
;
193 bool _crash_kexec_post_notifiers
= crash_kexec_post_notifiers
;
197 * This thread may hit another WARN() in the panic path.
198 * Resetting this prevents additional WARN() from panicking the
199 * system on this thread. Other threads are blocked by the
200 * panic_mutex in panic().
206 * Disable local interrupts. This will prevent panic_smp_self_stop
207 * from deadlocking the first cpu that invokes the panic, since
208 * there is nothing to prevent an interrupt handler (that runs
209 * after setting panic_cpu) from invoking panic() again.
212 preempt_disable_notrace();
215 * It's possible to come here directly from a panic-assertion and
216 * not have preempt disabled. Some functions called from here want
217 * preempt to be disabled. No point enabling it later though...
219 * Only one CPU is allowed to execute the panic code from here. For
220 * multiple parallel invocations of panic, all other CPUs either
221 * stop themself or will wait until they are stopped by the 1st CPU
222 * with smp_send_stop().
224 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
225 * comes here, so go ahead.
226 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
227 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
229 this_cpu
= raw_smp_processor_id();
230 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, this_cpu
);
232 if (old_cpu
!= PANIC_CPU_INVALID
&& old_cpu
!= this_cpu
)
233 panic_smp_self_stop();
238 len
= vscnprintf(buf
, sizeof(buf
), fmt
, args
);
241 if (len
&& buf
[len
- 1] == '\n')
244 pr_emerg("Kernel panic - not syncing: %s\n", buf
);
245 #ifdef CONFIG_DEBUG_BUGVERBOSE
247 * Avoid nested stack-dumping if a panic occurs during oops processing
249 if (!test_taint(TAINT_DIE
) && oops_in_progress
<= 1)
254 * If kgdb is enabled, give it a chance to run before we stop all
255 * the other CPUs or else we won't be able to debug processes left
261 * If we have crashed and we have a crash kernel loaded let it handle
263 * If we want to run this after calling panic_notifiers, pass
264 * the "crash_kexec_post_notifiers" option to the kernel.
266 * Bypass the panic_cpu check and call __crash_kexec directly.
268 if (!_crash_kexec_post_notifiers
) {
272 * Note smp_send_stop is the usual smp shutdown function, which
273 * unfortunately means it may not be hardened to work in a
279 * If we want to do crash dump after notifier calls and
280 * kmsg_dump, we will need architecture dependent extra
281 * works in addition to stopping other CPUs.
283 crash_smp_send_stop();
287 * Run any panic handlers, including those that might need to
288 * add information to the kmsg dump output.
290 atomic_notifier_call_chain(&panic_notifier_list
, 0, buf
);
292 panic_print_sys_info(false);
294 kmsg_dump(KMSG_DUMP_PANIC
);
297 * If you doubt kdump always works fine in any situation,
298 * "crash_kexec_post_notifiers" offers you a chance to run
299 * panic_notifiers and dumping kmsg before kdump.
300 * Note: since some panic_notifiers can make crashed kernel
301 * more unstable, it can increase risks of the kdump failure too.
303 * Bypass the panic_cpu check and call __crash_kexec directly.
305 if (_crash_kexec_post_notifiers
)
314 * We may have ended up stopping the CPU holding the lock (in
315 * smp_send_stop()) while still having some valuable data in the console
316 * buffer. Try to acquire the lock then release it regardless of the
317 * result. The release will also print the buffers out. Locks debug
318 * should be disabled to avoid reporting bad unlock balance when
319 * panic() is not being callled from OOPS.
322 console_flush_on_panic(CONSOLE_FLUSH_PENDING
);
324 panic_print_sys_info(true);
327 panic_blink
= no_blink
;
329 if (panic_timeout
> 0) {
331 * Delay timeout seconds before rebooting the machine.
332 * We can't use the "normal" timers since we just panicked.
334 pr_emerg("Rebooting in %d seconds..\n", panic_timeout
);
336 for (i
= 0; i
< panic_timeout
* 1000; i
+= PANIC_TIMER_STEP
) {
337 touch_nmi_watchdog();
339 i
+= panic_blink(state
^= 1);
340 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
342 mdelay(PANIC_TIMER_STEP
);
345 if (panic_timeout
!= 0) {
347 * This will not be a clean reboot, with everything
348 * shutting down. But if there is a chance of
349 * rebooting the system it will be rebooted.
351 if (panic_reboot_mode
!= REBOOT_UNDEFINED
)
352 reboot_mode
= panic_reboot_mode
;
357 extern int stop_a_enabled
;
358 /* Make sure the user can actually press Stop-A (L1-A) */
360 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
361 "twice on console to return to the boot prom\n");
364 #if defined(CONFIG_S390)
367 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf
);
369 /* Do not scroll important messages printed above */
372 for (i
= 0; ; i
+= PANIC_TIMER_STEP
) {
373 touch_softlockup_watchdog();
375 i
+= panic_blink(state
^= 1);
376 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
378 mdelay(PANIC_TIMER_STEP
);
382 EXPORT_SYMBOL(panic
);
385 * TAINT_FORCED_RMMOD could be a per-module flag but the module
386 * is being removed anyway.
388 const struct taint_flag taint_flags
[TAINT_FLAGS_COUNT
] = {
389 [ TAINT_PROPRIETARY_MODULE
] = { 'P', 'G', true },
390 [ TAINT_FORCED_MODULE
] = { 'F', ' ', true },
391 [ TAINT_CPU_OUT_OF_SPEC
] = { 'S', ' ', false },
392 [ TAINT_FORCED_RMMOD
] = { 'R', ' ', false },
393 [ TAINT_MACHINE_CHECK
] = { 'M', ' ', false },
394 [ TAINT_BAD_PAGE
] = { 'B', ' ', false },
395 [ TAINT_USER
] = { 'U', ' ', false },
396 [ TAINT_DIE
] = { 'D', ' ', false },
397 [ TAINT_OVERRIDDEN_ACPI_TABLE
] = { 'A', ' ', false },
398 [ TAINT_WARN
] = { 'W', ' ', false },
399 [ TAINT_CRAP
] = { 'C', ' ', true },
400 [ TAINT_FIRMWARE_WORKAROUND
] = { 'I', ' ', false },
401 [ TAINT_OOT_MODULE
] = { 'O', ' ', true },
402 [ TAINT_UNSIGNED_MODULE
] = { 'E', ' ', true },
403 [ TAINT_SOFTLOCKUP
] = { 'L', ' ', false },
404 [ TAINT_LIVEPATCH
] = { 'K', ' ', true },
405 [ TAINT_AUX
] = { 'X', ' ', true },
406 [ TAINT_RANDSTRUCT
] = { 'T', ' ', true },
410 * print_tainted - return a string to represent the kernel taint state.
412 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
414 * The string is overwritten by the next call to print_tainted(),
415 * but is always NULL terminated.
417 const char *print_tainted(void)
419 static char buf
[TAINT_FLAGS_COUNT
+ sizeof("Tainted: ")];
421 BUILD_BUG_ON(ARRAY_SIZE(taint_flags
) != TAINT_FLAGS_COUNT
);
427 s
= buf
+ sprintf(buf
, "Tainted: ");
428 for (i
= 0; i
< TAINT_FLAGS_COUNT
; i
++) {
429 const struct taint_flag
*t
= &taint_flags
[i
];
430 *s
++ = test_bit(i
, &tainted_mask
) ?
431 t
->c_true
: t
->c_false
;
435 snprintf(buf
, sizeof(buf
), "Not tainted");
440 int test_taint(unsigned flag
)
442 return test_bit(flag
, &tainted_mask
);
444 EXPORT_SYMBOL(test_taint
);
446 unsigned long get_taint(void)
452 * add_taint: add a taint flag if not already set.
453 * @flag: one of the TAINT_* constants.
454 * @lockdep_ok: whether lock debugging is still OK.
456 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
457 * some notewortht-but-not-corrupting cases, it can be set to true.
459 void add_taint(unsigned flag
, enum lockdep_ok lockdep_ok
)
461 if (lockdep_ok
== LOCKDEP_NOW_UNRELIABLE
&& __debug_locks_off())
462 pr_warn("Disabling lock debugging due to kernel taint\n");
464 set_bit(flag
, &tainted_mask
);
466 if (tainted_mask
& panic_on_taint
) {
468 panic("panic_on_taint set ...");
471 EXPORT_SYMBOL(add_taint
);
473 static void spin_msec(int msecs
)
477 for (i
= 0; i
< msecs
; i
++) {
478 touch_nmi_watchdog();
484 * It just happens that oops_enter() and oops_exit() are identically
487 static void do_oops_enter_exit(void)
490 static int spin_counter
;
495 spin_lock_irqsave(&pause_on_oops_lock
, flags
);
496 if (pause_on_oops_flag
== 0) {
497 /* This CPU may now print the oops message */
498 pause_on_oops_flag
= 1;
500 /* We need to stall this CPU */
502 /* This CPU gets to do the counting */
503 spin_counter
= pause_on_oops
;
505 spin_unlock(&pause_on_oops_lock
);
506 spin_msec(MSEC_PER_SEC
);
507 spin_lock(&pause_on_oops_lock
);
508 } while (--spin_counter
);
509 pause_on_oops_flag
= 0;
511 /* This CPU waits for a different one */
512 while (spin_counter
) {
513 spin_unlock(&pause_on_oops_lock
);
515 spin_lock(&pause_on_oops_lock
);
519 spin_unlock_irqrestore(&pause_on_oops_lock
, flags
);
523 * Return true if the calling CPU is allowed to print oops-related info.
524 * This is a bit racy..
526 bool oops_may_print(void)
528 return pause_on_oops_flag
== 0;
532 * Called when the architecture enters its oops handler, before it prints
533 * anything. If this is the first CPU to oops, and it's oopsing the first
534 * time then let it proceed.
536 * This is all enabled by the pause_on_oops kernel boot option. We do all
537 * this to ensure that oopses don't scroll off the screen. It has the
538 * side-effect of preventing later-oopsing CPUs from mucking up the display,
541 * It turns out that the CPU which is allowed to print ends up pausing for
542 * the right duration, whereas all the other CPUs pause for twice as long:
543 * once in oops_enter(), once in oops_exit().
545 void oops_enter(void)
548 /* can't trust the integrity of the kernel anymore: */
550 do_oops_enter_exit();
552 if (sysctl_oops_all_cpu_backtrace
)
553 trigger_all_cpu_backtrace();
556 static void print_oops_end_marker(void)
558 pr_warn("---[ end trace %016llx ]---\n", 0ULL);
562 * Called when the architecture exits its oops handler, after printing
567 do_oops_enter_exit();
568 print_oops_end_marker();
569 kmsg_dump(KMSG_DUMP_OOPS
);
577 void __warn(const char *file
, int line
, void *caller
, unsigned taint
,
578 struct pt_regs
*regs
, struct warn_args
*args
)
580 disable_trace_on_warning();
582 printk_prefer_direct_enter();
585 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
586 raw_smp_processor_id(), current
->pid
, file
, line
,
589 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
590 raw_smp_processor_id(), current
->pid
, caller
);
593 vprintk(args
->fmt
, args
->args
);
601 panic("panic_on_warn set ...\n");
606 print_irqtrace_events(current
);
608 print_oops_end_marker();
609 trace_error_report_end(ERROR_DETECTOR_WARN
, (unsigned long)caller
);
611 /* Just a warning, don't kill lockdep. */
612 add_taint(taint
, LOCKDEP_STILL_OK
);
614 printk_prefer_direct_exit();
618 void warn_slowpath_fmt(const char *file
, int line
, unsigned taint
,
619 const char *fmt
, ...)
621 struct warn_args args
;
626 __warn(file
, line
, __builtin_return_address(0), taint
,
632 va_start(args
.args
, fmt
);
633 __warn(file
, line
, __builtin_return_address(0), taint
, NULL
, &args
);
636 EXPORT_SYMBOL(warn_slowpath_fmt
);
638 void __warn_printk(const char *fmt
, ...)
648 EXPORT_SYMBOL(__warn_printk
);
653 /* Support resetting WARN*_ONCE state */
655 static int clear_warn_once_set(void *data
, u64 val
)
657 generic_bug_clear_once();
658 memset(__start_once
, 0, __end_once
- __start_once
);
662 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops
, NULL
, clear_warn_once_set
,
665 static __init
int register_warn_debugfs(void)
667 /* Don't care about failure */
668 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL
, NULL
,
669 &clear_warn_once_fops
);
673 device_initcall(register_warn_debugfs
);
676 #ifdef CONFIG_STACKPROTECTOR
679 * Called when gcc's -fstack-protector feature is used, and
680 * gcc detects corruption of the on-stack canary value
682 __visible noinstr
void __stack_chk_fail(void)
684 instrumentation_begin();
685 panic("stack-protector: Kernel stack is corrupted in: %pB",
686 __builtin_return_address(0));
687 instrumentation_end();
689 EXPORT_SYMBOL(__stack_chk_fail
);
693 core_param(panic
, panic_timeout
, int, 0644);
694 core_param(panic_print
, panic_print
, ulong
, 0644);
695 core_param(pause_on_oops
, pause_on_oops
, int, 0644);
696 core_param(panic_on_warn
, panic_on_warn
, int, 0644);
697 core_param(crash_kexec_post_notifiers
, crash_kexec_post_notifiers
, bool, 0644);
699 static int __init
oops_setup(char *s
)
703 if (!strcmp(s
, "panic"))
707 early_param("oops", oops_setup
);
709 static int __init
panic_on_taint_setup(char *s
)
716 taint_str
= strsep(&s
, ",");
717 if (kstrtoul(taint_str
, 16, &panic_on_taint
))
720 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
721 panic_on_taint
&= TAINT_FLAGS_MAX
;
726 if (s
&& !strcmp(s
, "nousertaint"))
727 panic_on_taint_nousertaint
= true;
729 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
730 panic_on_taint
, panic_on_taint_nousertaint
? "en" : "dis");
734 early_param("panic_on_taint", panic_on_taint_setup
);