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
) {
254 * Note smp_send_stop is the usual smp shutdown function, which
255 * unfortunately means it may not be hardened to work in a
261 * If we want to do crash dump after notifier calls and
262 * kmsg_dump, we will need architecture dependent extra
263 * works in addition to stopping other CPUs.
265 crash_smp_send_stop();
269 * Run any panic handlers, including those that might need to
270 * add information to the kmsg dump output.
272 atomic_notifier_call_chain(&panic_notifier_list
, 0, buf
);
274 kmsg_dump(KMSG_DUMP_PANIC
);
277 * If you doubt kdump always works fine in any situation,
278 * "crash_kexec_post_notifiers" offers you a chance to run
279 * panic_notifiers and dumping kmsg before kdump.
280 * Note: since some panic_notifiers can make crashed kernel
281 * more unstable, it can increase risks of the kdump failure too.
283 * Bypass the panic_cpu check and call __crash_kexec directly.
285 if (_crash_kexec_post_notifiers
)
294 * We may have ended up stopping the CPU holding the lock (in
295 * smp_send_stop()) while still having some valuable data in the console
296 * buffer. Try to acquire the lock then release it regardless of the
297 * result. The release will also print the buffers out. Locks debug
298 * should be disabled to avoid reporting bad unlock balance when
299 * panic() is not being callled from OOPS.
302 console_flush_on_panic(CONSOLE_FLUSH_PENDING
);
304 panic_print_sys_info();
307 panic_blink
= no_blink
;
309 if (panic_timeout
> 0) {
311 * Delay timeout seconds before rebooting the machine.
312 * We can't use the "normal" timers since we just panicked.
314 pr_emerg("Rebooting in %d seconds..\n", panic_timeout
);
316 for (i
= 0; i
< panic_timeout
* 1000; i
+= PANIC_TIMER_STEP
) {
317 touch_nmi_watchdog();
319 i
+= panic_blink(state
^= 1);
320 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
322 mdelay(PANIC_TIMER_STEP
);
325 if (panic_timeout
!= 0) {
327 * This will not be a clean reboot, with everything
328 * shutting down. But if there is a chance of
329 * rebooting the system it will be rebooted.
331 if (panic_reboot_mode
!= REBOOT_UNDEFINED
)
332 reboot_mode
= panic_reboot_mode
;
337 extern int stop_a_enabled
;
338 /* Make sure the user can actually press Stop-A (L1-A) */
340 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
341 "twice on console to return to the boot prom\n");
344 #if defined(CONFIG_S390)
347 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf
);
349 /* Do not scroll important messages printed above */
352 for (i
= 0; ; i
+= PANIC_TIMER_STEP
) {
353 touch_softlockup_watchdog();
355 i
+= panic_blink(state
^= 1);
356 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
358 mdelay(PANIC_TIMER_STEP
);
362 EXPORT_SYMBOL(panic
);
365 * TAINT_FORCED_RMMOD could be a per-module flag but the module
366 * is being removed anyway.
368 const struct taint_flag taint_flags
[TAINT_FLAGS_COUNT
] = {
369 [ TAINT_PROPRIETARY_MODULE
] = { 'P', 'G', true },
370 [ TAINT_FORCED_MODULE
] = { 'F', ' ', true },
371 [ TAINT_CPU_OUT_OF_SPEC
] = { 'S', ' ', false },
372 [ TAINT_FORCED_RMMOD
] = { 'R', ' ', false },
373 [ TAINT_MACHINE_CHECK
] = { 'M', ' ', false },
374 [ TAINT_BAD_PAGE
] = { 'B', ' ', false },
375 [ TAINT_USER
] = { 'U', ' ', false },
376 [ TAINT_DIE
] = { 'D', ' ', false },
377 [ TAINT_OVERRIDDEN_ACPI_TABLE
] = { 'A', ' ', false },
378 [ TAINT_WARN
] = { 'W', ' ', false },
379 [ TAINT_CRAP
] = { 'C', ' ', true },
380 [ TAINT_FIRMWARE_WORKAROUND
] = { 'I', ' ', false },
381 [ TAINT_OOT_MODULE
] = { 'O', ' ', true },
382 [ TAINT_UNSIGNED_MODULE
] = { 'E', ' ', true },
383 [ TAINT_SOFTLOCKUP
] = { 'L', ' ', false },
384 [ TAINT_LIVEPATCH
] = { 'K', ' ', true },
385 [ TAINT_AUX
] = { 'X', ' ', true },
386 [ TAINT_RANDSTRUCT
] = { 'T', ' ', true },
390 * print_tainted - return a string to represent the kernel taint state.
392 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
394 * The string is overwritten by the next call to print_tainted(),
395 * but is always NULL terminated.
397 const char *print_tainted(void)
399 static char buf
[TAINT_FLAGS_COUNT
+ sizeof("Tainted: ")];
401 BUILD_BUG_ON(ARRAY_SIZE(taint_flags
) != TAINT_FLAGS_COUNT
);
407 s
= buf
+ sprintf(buf
, "Tainted: ");
408 for (i
= 0; i
< TAINT_FLAGS_COUNT
; i
++) {
409 const struct taint_flag
*t
= &taint_flags
[i
];
410 *s
++ = test_bit(i
, &tainted_mask
) ?
411 t
->c_true
: t
->c_false
;
415 snprintf(buf
, sizeof(buf
), "Not tainted");
420 int test_taint(unsigned flag
)
422 return test_bit(flag
, &tainted_mask
);
424 EXPORT_SYMBOL(test_taint
);
426 unsigned long get_taint(void)
432 * add_taint: add a taint flag if not already set.
433 * @flag: one of the TAINT_* constants.
434 * @lockdep_ok: whether lock debugging is still OK.
436 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
437 * some notewortht-but-not-corrupting cases, it can be set to true.
439 void add_taint(unsigned flag
, enum lockdep_ok lockdep_ok
)
441 if (lockdep_ok
== LOCKDEP_NOW_UNRELIABLE
&& __debug_locks_off())
442 pr_warn("Disabling lock debugging due to kernel taint\n");
444 set_bit(flag
, &tainted_mask
);
446 if (tainted_mask
& panic_on_taint
) {
448 panic("panic_on_taint set ...");
451 EXPORT_SYMBOL(add_taint
);
453 static void spin_msec(int msecs
)
457 for (i
= 0; i
< msecs
; i
++) {
458 touch_nmi_watchdog();
464 * It just happens that oops_enter() and oops_exit() are identically
467 static void do_oops_enter_exit(void)
470 static int spin_counter
;
475 spin_lock_irqsave(&pause_on_oops_lock
, flags
);
476 if (pause_on_oops_flag
== 0) {
477 /* This CPU may now print the oops message */
478 pause_on_oops_flag
= 1;
480 /* We need to stall this CPU */
482 /* This CPU gets to do the counting */
483 spin_counter
= pause_on_oops
;
485 spin_unlock(&pause_on_oops_lock
);
486 spin_msec(MSEC_PER_SEC
);
487 spin_lock(&pause_on_oops_lock
);
488 } while (--spin_counter
);
489 pause_on_oops_flag
= 0;
491 /* This CPU waits for a different one */
492 while (spin_counter
) {
493 spin_unlock(&pause_on_oops_lock
);
495 spin_lock(&pause_on_oops_lock
);
499 spin_unlock_irqrestore(&pause_on_oops_lock
, flags
);
503 * Return true if the calling CPU is allowed to print oops-related info.
504 * This is a bit racy..
506 bool oops_may_print(void)
508 return pause_on_oops_flag
== 0;
512 * Called when the architecture enters its oops handler, before it prints
513 * anything. If this is the first CPU to oops, and it's oopsing the first
514 * time then let it proceed.
516 * This is all enabled by the pause_on_oops kernel boot option. We do all
517 * this to ensure that oopses don't scroll off the screen. It has the
518 * side-effect of preventing later-oopsing CPUs from mucking up the display,
521 * It turns out that the CPU which is allowed to print ends up pausing for
522 * the right duration, whereas all the other CPUs pause for twice as long:
523 * once in oops_enter(), once in oops_exit().
525 void oops_enter(void)
528 /* can't trust the integrity of the kernel anymore: */
530 do_oops_enter_exit();
532 if (sysctl_oops_all_cpu_backtrace
)
533 trigger_all_cpu_backtrace();
537 * 64-bit random ID for oopses:
541 static int init_oops_id(void)
544 get_random_bytes(&oops_id
, sizeof(oops_id
));
550 late_initcall(init_oops_id
);
552 static void print_oops_end_marker(void)
555 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id
);
559 * Called when the architecture exits its oops handler, after printing
564 do_oops_enter_exit();
565 print_oops_end_marker();
566 kmsg_dump(KMSG_DUMP_OOPS
);
574 void __warn(const char *file
, int line
, void *caller
, unsigned taint
,
575 struct pt_regs
*regs
, struct warn_args
*args
)
577 disable_trace_on_warning();
580 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
581 raw_smp_processor_id(), current
->pid
, file
, line
,
584 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
585 raw_smp_processor_id(), current
->pid
, caller
);
588 vprintk(args
->fmt
, args
->args
);
597 * This thread may hit another WARN() in the panic path.
598 * Resetting this prevents additional WARN() from panicking the
599 * system on this thread. Other threads are blocked by the
600 * panic_mutex in panic().
603 panic("panic_on_warn set ...\n");
609 print_irqtrace_events(current
);
611 print_oops_end_marker();
613 /* Just a warning, don't kill lockdep. */
614 add_taint(taint
, LOCKDEP_STILL_OK
);
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
);