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/kmsg_dump.h>
16 #include <linux/kallsyms.h>
17 #include <linux/notifier.h>
18 #include <linux/vt_kern.h>
19 #include <linux/module.h>
20 #include <linux/random.h>
21 #include <linux/ftrace.h>
22 #include <linux/reboot.h>
23 #include <linux/delay.h>
24 #include <linux/kexec.h>
25 #include <linux/sched.h>
26 #include <linux/sysrq.h>
27 #include <linux/init.h>
28 #include <linux/nmi.h>
29 #include <linux/console.h>
30 #include <linux/bug.h>
31 #include <linux/ratelimit.h>
32 #include <linux/debugfs.h>
33 #include <asm/sections.h>
35 #define PANIC_TIMER_STEP 100
36 #define PANIC_BLINK_SPD 18
38 int panic_on_oops
= CONFIG_PANIC_ON_OOPS_VALUE
;
39 static unsigned long tainted_mask
=
40 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT
) ? (1 << TAINT_RANDSTRUCT
) : 0;
41 static int pause_on_oops
;
42 static int pause_on_oops_flag
;
43 static DEFINE_SPINLOCK(pause_on_oops_lock
);
44 bool crash_kexec_post_notifiers
;
45 int panic_on_warn __read_mostly
;
47 int panic_timeout
= CONFIG_PANIC_TIMEOUT
;
48 EXPORT_SYMBOL_GPL(panic_timeout
);
50 #define PANIC_PRINT_TASK_INFO 0x00000001
51 #define PANIC_PRINT_MEM_INFO 0x00000002
52 #define PANIC_PRINT_TIMER_INFO 0x00000004
53 #define PANIC_PRINT_LOCK_INFO 0x00000008
54 #define PANIC_PRINT_FTRACE_INFO 0x00000010
55 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
56 unsigned long panic_print
;
58 ATOMIC_NOTIFIER_HEAD(panic_notifier_list
);
60 EXPORT_SYMBOL(panic_notifier_list
);
62 static long no_blink(int state
)
67 /* Returns how long it waited in ms */
68 long (*panic_blink
)(int state
);
69 EXPORT_SYMBOL(panic_blink
);
72 * Stop ourself in panic -- architecture code may override this
74 void __weak
panic_smp_self_stop(void)
81 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
82 * may override this to prepare for crash dumping, e.g. save regs info.
84 void __weak
nmi_panic_self_stop(struct pt_regs
*regs
)
86 panic_smp_self_stop();
90 * Stop other CPUs in panic. Architecture dependent code may override this
91 * with more suitable version. For example, if the architecture supports
92 * crash dump, it should save registers of each stopped CPU and disable
93 * per-CPU features such as virtualization extensions.
95 void __weak
crash_smp_send_stop(void)
97 static int cpus_stopped
;
100 * This function can be called twice in panic path, but obviously
101 * we execute this only once.
107 * Note smp_send_stop is the usual smp shutdown function, which
108 * unfortunately means it may not be hardened to work in a panic
115 atomic_t panic_cpu
= ATOMIC_INIT(PANIC_CPU_INVALID
);
118 * A variant of panic() called from NMI context. We return if we've already
119 * panicked on this CPU. If another CPU already panicked, loop in
120 * nmi_panic_self_stop() which can provide architecture dependent code such
121 * as saving register state for crash dump.
123 void nmi_panic(struct pt_regs
*regs
, const char *msg
)
127 cpu
= raw_smp_processor_id();
128 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, cpu
);
130 if (old_cpu
== PANIC_CPU_INVALID
)
132 else if (old_cpu
!= cpu
)
133 nmi_panic_self_stop(regs
);
135 EXPORT_SYMBOL(nmi_panic
);
137 static void panic_print_sys_info(void)
139 if (panic_print
& PANIC_PRINT_ALL_PRINTK_MSG
)
140 console_flush_on_panic(CONSOLE_REPLAY_ALL
);
142 if (panic_print
& PANIC_PRINT_TASK_INFO
)
145 if (panic_print
& PANIC_PRINT_MEM_INFO
)
148 if (panic_print
& PANIC_PRINT_TIMER_INFO
)
149 sysrq_timer_list_show();
151 if (panic_print
& PANIC_PRINT_LOCK_INFO
)
152 debug_show_all_locks();
154 if (panic_print
& PANIC_PRINT_FTRACE_INFO
)
155 ftrace_dump(DUMP_ALL
);
159 * panic - halt the system
160 * @fmt: The text string to print
162 * Display a message, then perform cleanups.
164 * This function never returns.
166 void panic(const char *fmt
, ...)
168 static char buf
[1024];
170 long i
, i_next
= 0, len
;
172 int old_cpu
, this_cpu
;
173 bool _crash_kexec_post_notifiers
= crash_kexec_post_notifiers
;
176 * Disable local interrupts. This will prevent panic_smp_self_stop
177 * from deadlocking the first cpu that invokes the panic, since
178 * there is nothing to prevent an interrupt handler (that runs
179 * after setting panic_cpu) from invoking panic() again.
182 preempt_disable_notrace();
185 * It's possible to come here directly from a panic-assertion and
186 * not have preempt disabled. Some functions called from here want
187 * preempt to be disabled. No point enabling it later though...
189 * Only one CPU is allowed to execute the panic code from here. For
190 * multiple parallel invocations of panic, all other CPUs either
191 * stop themself or will wait until they are stopped by the 1st CPU
192 * with smp_send_stop().
194 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
195 * comes here, so go ahead.
196 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
197 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
199 this_cpu
= raw_smp_processor_id();
200 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, this_cpu
);
202 if (old_cpu
!= PANIC_CPU_INVALID
&& old_cpu
!= this_cpu
)
203 panic_smp_self_stop();
208 len
= vscnprintf(buf
, sizeof(buf
), fmt
, args
);
211 if (len
&& buf
[len
- 1] == '\n')
214 pr_emerg("Kernel panic - not syncing: %s\n", buf
);
215 #ifdef CONFIG_DEBUG_BUGVERBOSE
217 * Avoid nested stack-dumping if a panic occurs during oops processing
219 if (!test_taint(TAINT_DIE
) && oops_in_progress
<= 1)
224 * If we have crashed and we have a crash kernel loaded let it handle
226 * If we want to run this after calling panic_notifiers, pass
227 * the "crash_kexec_post_notifiers" option to the kernel.
229 * Bypass the panic_cpu check and call __crash_kexec directly.
231 if (!_crash_kexec_post_notifiers
) {
232 printk_safe_flush_on_panic();
236 * Note smp_send_stop is the usual smp shutdown function, which
237 * unfortunately means it may not be hardened to work in a
243 * If we want to do crash dump after notifier calls and
244 * kmsg_dump, we will need architecture dependent extra
245 * works in addition to stopping other CPUs.
247 crash_smp_send_stop();
251 * Run any panic handlers, including those that might need to
252 * add information to the kmsg dump output.
254 atomic_notifier_call_chain(&panic_notifier_list
, 0, buf
);
256 /* Call flush even twice. It tries harder with a single online CPU */
257 printk_safe_flush_on_panic();
258 kmsg_dump(KMSG_DUMP_PANIC
);
261 * If you doubt kdump always works fine in any situation,
262 * "crash_kexec_post_notifiers" offers you a chance to run
263 * panic_notifiers and dumping kmsg before kdump.
264 * Note: since some panic_notifiers can make crashed kernel
265 * more unstable, it can increase risks of the kdump failure too.
267 * Bypass the panic_cpu check and call __crash_kexec directly.
269 if (_crash_kexec_post_notifiers
)
278 * We may have ended up stopping the CPU holding the lock (in
279 * smp_send_stop()) while still having some valuable data in the console
280 * buffer. Try to acquire the lock then release it regardless of the
281 * result. The release will also print the buffers out. Locks debug
282 * should be disabled to avoid reporting bad unlock balance when
283 * panic() is not being callled from OOPS.
286 console_flush_on_panic(CONSOLE_FLUSH_PENDING
);
288 panic_print_sys_info();
291 panic_blink
= no_blink
;
293 if (panic_timeout
> 0) {
295 * Delay timeout seconds before rebooting the machine.
296 * We can't use the "normal" timers since we just panicked.
298 pr_emerg("Rebooting in %d seconds..\n", panic_timeout
);
300 for (i
= 0; i
< panic_timeout
* 1000; i
+= PANIC_TIMER_STEP
) {
301 touch_nmi_watchdog();
303 i
+= panic_blink(state
^= 1);
304 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
306 mdelay(PANIC_TIMER_STEP
);
309 if (panic_timeout
!= 0) {
311 * This will not be a clean reboot, with everything
312 * shutting down. But if there is a chance of
313 * rebooting the system it will be rebooted.
315 if (panic_reboot_mode
!= REBOOT_UNDEFINED
)
316 reboot_mode
= panic_reboot_mode
;
321 extern int stop_a_enabled
;
322 /* Make sure the user can actually press Stop-A (L1-A) */
324 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
325 "twice on console to return to the boot prom\n");
328 #if defined(CONFIG_S390)
331 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf
);
333 /* Do not scroll important messages printed above */
336 for (i
= 0; ; i
+= PANIC_TIMER_STEP
) {
337 touch_softlockup_watchdog();
339 i
+= panic_blink(state
^= 1);
340 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
342 mdelay(PANIC_TIMER_STEP
);
346 EXPORT_SYMBOL(panic
);
349 * TAINT_FORCED_RMMOD could be a per-module flag but the module
350 * is being removed anyway.
352 const struct taint_flag taint_flags
[TAINT_FLAGS_COUNT
] = {
353 [ TAINT_PROPRIETARY_MODULE
] = { 'P', 'G', true },
354 [ TAINT_FORCED_MODULE
] = { 'F', ' ', true },
355 [ TAINT_CPU_OUT_OF_SPEC
] = { 'S', ' ', false },
356 [ TAINT_FORCED_RMMOD
] = { 'R', ' ', false },
357 [ TAINT_MACHINE_CHECK
] = { 'M', ' ', false },
358 [ TAINT_BAD_PAGE
] = { 'B', ' ', false },
359 [ TAINT_USER
] = { 'U', ' ', false },
360 [ TAINT_DIE
] = { 'D', ' ', false },
361 [ TAINT_OVERRIDDEN_ACPI_TABLE
] = { 'A', ' ', false },
362 [ TAINT_WARN
] = { 'W', ' ', false },
363 [ TAINT_CRAP
] = { 'C', ' ', true },
364 [ TAINT_FIRMWARE_WORKAROUND
] = { 'I', ' ', false },
365 [ TAINT_OOT_MODULE
] = { 'O', ' ', true },
366 [ TAINT_UNSIGNED_MODULE
] = { 'E', ' ', true },
367 [ TAINT_SOFTLOCKUP
] = { 'L', ' ', false },
368 [ TAINT_LIVEPATCH
] = { 'K', ' ', true },
369 [ TAINT_AUX
] = { 'X', ' ', true },
370 [ TAINT_RANDSTRUCT
] = { 'T', ' ', true },
374 * print_tainted - return a string to represent the kernel taint state.
376 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
378 * The string is overwritten by the next call to print_tainted(),
379 * but is always NULL terminated.
381 const char *print_tainted(void)
383 static char buf
[TAINT_FLAGS_COUNT
+ sizeof("Tainted: ")];
385 BUILD_BUG_ON(ARRAY_SIZE(taint_flags
) != TAINT_FLAGS_COUNT
);
391 s
= buf
+ sprintf(buf
, "Tainted: ");
392 for (i
= 0; i
< TAINT_FLAGS_COUNT
; i
++) {
393 const struct taint_flag
*t
= &taint_flags
[i
];
394 *s
++ = test_bit(i
, &tainted_mask
) ?
395 t
->c_true
: t
->c_false
;
399 snprintf(buf
, sizeof(buf
), "Not tainted");
404 int test_taint(unsigned flag
)
406 return test_bit(flag
, &tainted_mask
);
408 EXPORT_SYMBOL(test_taint
);
410 unsigned long get_taint(void)
416 * add_taint: add a taint flag if not already set.
417 * @flag: one of the TAINT_* constants.
418 * @lockdep_ok: whether lock debugging is still OK.
420 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
421 * some notewortht-but-not-corrupting cases, it can be set to true.
423 void add_taint(unsigned flag
, enum lockdep_ok lockdep_ok
)
425 if (lockdep_ok
== LOCKDEP_NOW_UNRELIABLE
&& __debug_locks_off())
426 pr_warn("Disabling lock debugging due to kernel taint\n");
428 set_bit(flag
, &tainted_mask
);
430 EXPORT_SYMBOL(add_taint
);
432 static void spin_msec(int msecs
)
436 for (i
= 0; i
< msecs
; i
++) {
437 touch_nmi_watchdog();
443 * It just happens that oops_enter() and oops_exit() are identically
446 static void do_oops_enter_exit(void)
449 static int spin_counter
;
454 spin_lock_irqsave(&pause_on_oops_lock
, flags
);
455 if (pause_on_oops_flag
== 0) {
456 /* This CPU may now print the oops message */
457 pause_on_oops_flag
= 1;
459 /* We need to stall this CPU */
461 /* This CPU gets to do the counting */
462 spin_counter
= pause_on_oops
;
464 spin_unlock(&pause_on_oops_lock
);
465 spin_msec(MSEC_PER_SEC
);
466 spin_lock(&pause_on_oops_lock
);
467 } while (--spin_counter
);
468 pause_on_oops_flag
= 0;
470 /* This CPU waits for a different one */
471 while (spin_counter
) {
472 spin_unlock(&pause_on_oops_lock
);
474 spin_lock(&pause_on_oops_lock
);
478 spin_unlock_irqrestore(&pause_on_oops_lock
, flags
);
482 * Return true if the calling CPU is allowed to print oops-related info.
483 * This is a bit racy..
485 int oops_may_print(void)
487 return pause_on_oops_flag
== 0;
491 * Called when the architecture enters its oops handler, before it prints
492 * anything. If this is the first CPU to oops, and it's oopsing the first
493 * time then let it proceed.
495 * This is all enabled by the pause_on_oops kernel boot option. We do all
496 * this to ensure that oopses don't scroll off the screen. It has the
497 * side-effect of preventing later-oopsing CPUs from mucking up the display,
500 * It turns out that the CPU which is allowed to print ends up pausing for
501 * the right duration, whereas all the other CPUs pause for twice as long:
502 * once in oops_enter(), once in oops_exit().
504 void oops_enter(void)
507 /* can't trust the integrity of the kernel anymore: */
509 do_oops_enter_exit();
513 * 64-bit random ID for oopses:
517 static int init_oops_id(void)
520 get_random_bytes(&oops_id
, sizeof(oops_id
));
526 late_initcall(init_oops_id
);
528 void print_oops_end_marker(void)
531 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id
);
535 * Called when the architecture exits its oops handler, after printing
540 do_oops_enter_exit();
541 print_oops_end_marker();
542 kmsg_dump(KMSG_DUMP_OOPS
);
550 void __warn(const char *file
, int line
, void *caller
, unsigned taint
,
551 struct pt_regs
*regs
, struct warn_args
*args
)
553 disable_trace_on_warning();
559 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
560 raw_smp_processor_id(), current
->pid
, file
, line
,
563 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
564 raw_smp_processor_id(), current
->pid
, caller
);
567 vprintk(args
->fmt
, args
->args
);
571 * This thread may hit another WARN() in the panic path.
572 * Resetting this prevents additional WARN() from panicking the
573 * system on this thread. Other threads are blocked by the
574 * panic_mutex in panic().
577 panic("panic_on_warn set ...\n");
587 print_irqtrace_events(current
);
589 print_oops_end_marker();
591 /* Just a warning, don't kill lockdep. */
592 add_taint(taint
, LOCKDEP_STILL_OK
);
595 #ifdef WANT_WARN_ON_SLOWPATH
596 void warn_slowpath_fmt(const char *file
, int line
, const char *fmt
, ...)
598 struct warn_args args
;
601 va_start(args
.args
, fmt
);
602 __warn(file
, line
, __builtin_return_address(0), TAINT_WARN
, NULL
,
606 EXPORT_SYMBOL(warn_slowpath_fmt
);
608 void warn_slowpath_fmt_taint(const char *file
, int line
,
609 unsigned taint
, const char *fmt
, ...)
611 struct warn_args args
;
614 va_start(args
.args
, fmt
);
615 __warn(file
, line
, __builtin_return_address(0), taint
, NULL
, &args
);
618 EXPORT_SYMBOL(warn_slowpath_fmt_taint
);
620 void warn_slowpath_null(const char *file
, int line
)
623 __warn(file
, line
, __builtin_return_address(0), TAINT_WARN
, NULL
, NULL
);
625 EXPORT_SYMBOL(warn_slowpath_null
);
627 void __warn_printk(const char *fmt
, ...)
637 EXPORT_SYMBOL(__warn_printk
);
642 /* Support resetting WARN*_ONCE state */
644 static int clear_warn_once_set(void *data
, u64 val
)
646 generic_bug_clear_once();
647 memset(__start_once
, 0, __end_once
- __start_once
);
651 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops
, NULL
, clear_warn_once_set
,
654 static __init
int register_warn_debugfs(void)
656 /* Don't care about failure */
657 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL
, NULL
,
658 &clear_warn_once_fops
);
662 device_initcall(register_warn_debugfs
);
665 #ifdef CONFIG_STACKPROTECTOR
668 * Called when gcc's -fstack-protector feature is used, and
669 * gcc detects corruption of the on-stack canary value
671 __visible
void __stack_chk_fail(void)
673 panic("stack-protector: Kernel stack is corrupted in: %pB",
674 __builtin_return_address(0));
676 EXPORT_SYMBOL(__stack_chk_fail
);
680 #ifdef CONFIG_ARCH_HAS_REFCOUNT
681 void refcount_error_report(struct pt_regs
*regs
, const char *err
)
683 WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
684 err
, (void *)instruction_pointer(regs
),
685 current
->comm
, task_pid_nr(current
),
686 from_kuid_munged(&init_user_ns
, current_uid()),
687 from_kuid_munged(&init_user_ns
, current_euid()));
691 core_param(panic
, panic_timeout
, int, 0644);
692 core_param(panic_print
, panic_print
, ulong
, 0644);
693 core_param(pause_on_oops
, pause_on_oops
, int, 0644);
694 core_param(panic_on_warn
, panic_on_warn
, int, 0644);
695 core_param(crash_kexec_post_notifiers
, crash_kexec_post_notifiers
, bool, 0644);
697 static int __init
oops_setup(char *s
)
701 if (!strcmp(s
, "panic"))
705 early_param("oops", oops_setup
);