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 <asm/sections.h>
37 #define PANIC_TIMER_STEP 100
38 #define PANIC_BLINK_SPD 18
42 * Should we dump all CPUs backtraces in an oops event?
43 * Defaults to 0, can be changed via sysctl.
45 unsigned int __read_mostly sysctl_oops_all_cpu_backtrace
;
46 #endif /* CONFIG_SMP */
48 int panic_on_oops
= CONFIG_PANIC_ON_OOPS_VALUE
;
49 static unsigned long tainted_mask
=
50 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT
) ? (1 << TAINT_RANDSTRUCT
) : 0;
51 static int pause_on_oops
;
52 static int pause_on_oops_flag
;
53 static DEFINE_SPINLOCK(pause_on_oops_lock
);
54 bool crash_kexec_post_notifiers
;
55 int panic_on_warn __read_mostly
;
56 unsigned long panic_on_taint
;
57 bool panic_on_taint_nousertaint
= false;
59 int panic_timeout
= CONFIG_PANIC_TIMEOUT
;
60 EXPORT_SYMBOL_GPL(panic_timeout
);
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
68 unsigned long panic_print
;
70 ATOMIC_NOTIFIER_HEAD(panic_notifier_list
);
72 EXPORT_SYMBOL(panic_notifier_list
);
74 static long no_blink(int state
)
79 /* Returns how long it waited in ms */
80 long (*panic_blink
)(int state
);
81 EXPORT_SYMBOL(panic_blink
);
84 * Stop ourself in panic -- architecture code may override this
86 void __weak
panic_smp_self_stop(void)
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.
96 void __weak
nmi_panic_self_stop(struct pt_regs
*regs
)
98 panic_smp_self_stop();
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.
107 void __weak
crash_smp_send_stop(void)
109 static int cpus_stopped
;
112 * This function can be called twice in panic path, but obviously
113 * we execute this only once.
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
127 atomic_t panic_cpu
= ATOMIC_INIT(PANIC_CPU_INVALID
);
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.
135 void nmi_panic(struct pt_regs
*regs
, const char *msg
)
139 cpu
= raw_smp_processor_id();
140 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, cpu
);
142 if (old_cpu
== PANIC_CPU_INVALID
)
144 else if (old_cpu
!= cpu
)
145 nmi_panic_self_stop(regs
);
147 EXPORT_SYMBOL(nmi_panic
);
149 static void panic_print_sys_info(void)
151 if (panic_print
& PANIC_PRINT_ALL_PRINTK_MSG
)
152 console_flush_on_panic(CONSOLE_REPLAY_ALL
);
154 if (panic_print
& PANIC_PRINT_TASK_INFO
)
157 if (panic_print
& PANIC_PRINT_MEM_INFO
)
160 if (panic_print
& PANIC_PRINT_TIMER_INFO
)
161 sysrq_timer_list_show();
163 if (panic_print
& PANIC_PRINT_LOCK_INFO
)
164 debug_show_all_locks();
166 if (panic_print
& PANIC_PRINT_FTRACE_INFO
)
167 ftrace_dump(DUMP_ALL
);
171 * panic - halt the system
172 * @fmt: The text string to print
174 * Display a message, then perform cleanups.
176 * This function never returns.
178 void panic(const char *fmt
, ...)
180 static char buf
[1024];
182 long i
, i_next
= 0, len
;
184 int old_cpu
, this_cpu
;
185 bool _crash_kexec_post_notifiers
= crash_kexec_post_notifiers
;
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.
194 preempt_disable_notrace();
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...
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().
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.
211 this_cpu
= raw_smp_processor_id();
212 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, this_cpu
);
214 if (old_cpu
!= PANIC_CPU_INVALID
&& old_cpu
!= this_cpu
)
215 panic_smp_self_stop();
220 len
= vscnprintf(buf
, sizeof(buf
), fmt
, args
);
223 if (len
&& buf
[len
- 1] == '\n')
226 pr_emerg("Kernel panic - not syncing: %s\n", buf
);
227 #ifdef CONFIG_DEBUG_BUGVERBOSE
229 * Avoid nested stack-dumping if a panic occurs during oops processing
231 if (!test_taint(TAINT_DIE
) && oops_in_progress
<= 1)
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
243 * If we have crashed and we have a crash kernel loaded let it handle
245 * If we want to run this after calling panic_notifiers, pass
246 * the "crash_kexec_post_notifiers" option to the kernel.
248 * Bypass the panic_cpu check and call __crash_kexec directly.
250 if (!_crash_kexec_post_notifiers
) {
251 printk_safe_flush_on_panic();
255 * Note smp_send_stop is the usual smp shutdown function, which
256 * unfortunately means it may not be hardened to work in a
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.
266 crash_smp_send_stop();
270 * Run any panic handlers, including those that might need to
271 * add information to the kmsg dump output.
273 atomic_notifier_call_chain(&panic_notifier_list
, 0, buf
);
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
);
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.
286 * Bypass the panic_cpu check and call __crash_kexec directly.
288 if (_crash_kexec_post_notifiers
)
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.
305 console_flush_on_panic(CONSOLE_FLUSH_PENDING
);
307 panic_print_sys_info();
310 panic_blink
= no_blink
;
312 if (panic_timeout
> 0) {
314 * Delay timeout seconds before rebooting the machine.
315 * We can't use the "normal" timers since we just panicked.
317 pr_emerg("Rebooting in %d seconds..\n", panic_timeout
);
319 for (i
= 0; i
< panic_timeout
* 1000; i
+= PANIC_TIMER_STEP
) {
320 touch_nmi_watchdog();
322 i
+= panic_blink(state
^= 1);
323 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
325 mdelay(PANIC_TIMER_STEP
);
328 if (panic_timeout
!= 0) {
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.
334 if (panic_reboot_mode
!= REBOOT_UNDEFINED
)
335 reboot_mode
= panic_reboot_mode
;
340 extern int stop_a_enabled
;
341 /* Make sure the user can actually press Stop-A (L1-A) */
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");
347 #if defined(CONFIG_S390)
350 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf
);
352 /* Do not scroll important messages printed above */
355 for (i
= 0; ; i
+= PANIC_TIMER_STEP
) {
356 touch_softlockup_watchdog();
358 i
+= panic_blink(state
^= 1);
359 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
361 mdelay(PANIC_TIMER_STEP
);
365 EXPORT_SYMBOL(panic
);
368 * TAINT_FORCED_RMMOD could be a per-module flag but the module
369 * is being removed anyway.
371 const 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 },
393 * print_tainted - return a string to represent the kernel taint state.
395 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
397 * The string is overwritten by the next call to print_tainted(),
398 * but is always NULL terminated.
400 const char *print_tainted(void)
402 static char buf
[TAINT_FLAGS_COUNT
+ sizeof("Tainted: ")];
404 BUILD_BUG_ON(ARRAY_SIZE(taint_flags
) != TAINT_FLAGS_COUNT
);
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
;
418 snprintf(buf
, sizeof(buf
), "Not tainted");
423 int test_taint(unsigned flag
)
425 return test_bit(flag
, &tainted_mask
);
427 EXPORT_SYMBOL(test_taint
);
429 unsigned long get_taint(void)
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.
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.
442 void add_taint(unsigned flag
, enum lockdep_ok lockdep_ok
)
444 if (lockdep_ok
== LOCKDEP_NOW_UNRELIABLE
&& __debug_locks_off())
445 pr_warn("Disabling lock debugging due to kernel taint\n");
447 set_bit(flag
, &tainted_mask
);
449 if (tainted_mask
& panic_on_taint
) {
451 panic("panic_on_taint set ...");
454 EXPORT_SYMBOL(add_taint
);
456 static void spin_msec(int msecs
)
460 for (i
= 0; i
< msecs
; i
++) {
461 touch_nmi_watchdog();
467 * It just happens that oops_enter() and oops_exit() are identically
470 static void do_oops_enter_exit(void)
473 static int spin_counter
;
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;
483 /* We need to stall this CPU */
485 /* This CPU gets to do the counting */
486 spin_counter
= pause_on_oops
;
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;
494 /* This CPU waits for a different one */
495 while (spin_counter
) {
496 spin_unlock(&pause_on_oops_lock
);
498 spin_lock(&pause_on_oops_lock
);
502 spin_unlock_irqrestore(&pause_on_oops_lock
, flags
);
506 * Return true if the calling CPU is allowed to print oops-related info.
507 * This is a bit racy..
509 bool oops_may_print(void)
511 return pause_on_oops_flag
== 0;
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.
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,
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().
528 void oops_enter(void)
531 /* can't trust the integrity of the kernel anymore: */
533 do_oops_enter_exit();
535 if (sysctl_oops_all_cpu_backtrace
)
536 trigger_all_cpu_backtrace();
540 * 64-bit random ID for oopses:
544 static int init_oops_id(void)
547 get_random_bytes(&oops_id
, sizeof(oops_id
));
553 late_initcall(init_oops_id
);
555 static void print_oops_end_marker(void)
558 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id
);
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();
583 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
584 raw_smp_processor_id(), current
->pid
, file
, line
,
587 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
588 raw_smp_processor_id(), current
->pid
, caller
);
591 vprintk(args
->fmt
, args
->args
);
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().
606 panic("panic_on_warn set ...\n");
612 print_irqtrace_events(current
);
614 print_oops_end_marker();
616 /* Just a warning, don't kill lockdep. */
617 add_taint(taint
, LOCKDEP_STILL_OK
);
621 void warn_slowpath_fmt(const char *file
, int line
, unsigned taint
,
622 const char *fmt
, ...)
624 struct warn_args args
;
629 __warn(file
, line
, __builtin_return_address(0), taint
,
635 va_start(args
.args
, fmt
);
636 __warn(file
, line
, __builtin_return_address(0), taint
, NULL
, &args
);
639 EXPORT_SYMBOL(warn_slowpath_fmt
);
641 void __warn_printk(const char *fmt
, ...)
651 EXPORT_SYMBOL(__warn_printk
);
656 /* Support resetting WARN*_ONCE state */
658 static int clear_warn_once_set(void *data
, u64 val
)
660 generic_bug_clear_once();
661 memset(__start_once
, 0, __end_once
- __start_once
);
665 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops
, NULL
, clear_warn_once_set
,
668 static __init
int register_warn_debugfs(void)
670 /* Don't care about failure */
671 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL
, NULL
,
672 &clear_warn_once_fops
);
676 device_initcall(register_warn_debugfs
);
679 #ifdef CONFIG_STACKPROTECTOR
682 * Called when gcc's -fstack-protector feature is used, and
683 * gcc detects corruption of the on-stack canary value
685 __visible noinstr
void __stack_chk_fail(void)
687 instrumentation_begin();
688 panic("stack-protector: Kernel stack is corrupted in: %pB",
689 __builtin_return_address(0));
690 instrumentation_end();
692 EXPORT_SYMBOL(__stack_chk_fail
);
696 core_param(panic
, panic_timeout
, int, 0644);
697 core_param(panic_print
, panic_print
, ulong
, 0644);
698 core_param(pause_on_oops
, pause_on_oops
, int, 0644);
699 core_param(panic_on_warn
, panic_on_warn
, int, 0644);
700 core_param(crash_kexec_post_notifiers
, crash_kexec_post_notifiers
, bool, 0644);
702 static int __init
oops_setup(char *s
)
706 if (!strcmp(s
, "panic"))
710 early_param("oops", oops_setup
);
712 static int __init
panic_on_taint_setup(char *s
)
719 taint_str
= strsep(&s
, ",");
720 if (kstrtoul(taint_str
, 16, &panic_on_taint
))
723 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
724 panic_on_taint
&= TAINT_FLAGS_MAX
;
729 if (s
&& !strcmp(s
, "nousertaint"))
730 panic_on_taint_nousertaint
= true;
732 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
733 panic_on_taint
, panic_on_taint_nousertaint
? "en" : "dis");
737 early_param("panic_on_taint", panic_on_taint_setup
);