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/sched.h>
27 #include <linux/sysrq.h>
28 #include <linux/init.h>
29 #include <linux/nmi.h>
30 #include <linux/console.h>
31 #include <linux/bug.h>
32 #include <linux/ratelimit.h>
33 #include <linux/debugfs.h>
34 #include <asm/sections.h>
36 #define PANIC_TIMER_STEP 100
37 #define PANIC_BLINK_SPD 18
39 int panic_on_oops
= CONFIG_PANIC_ON_OOPS_VALUE
;
40 static unsigned long tainted_mask
=
41 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT
) ? (1 << TAINT_RANDSTRUCT
) : 0;
42 static int pause_on_oops
;
43 static int pause_on_oops_flag
;
44 static DEFINE_SPINLOCK(pause_on_oops_lock
);
45 bool crash_kexec_post_notifiers
;
46 int panic_on_warn __read_mostly
;
48 int panic_timeout
= CONFIG_PANIC_TIMEOUT
;
49 EXPORT_SYMBOL_GPL(panic_timeout
);
51 #define PANIC_PRINT_TASK_INFO 0x00000001
52 #define PANIC_PRINT_MEM_INFO 0x00000002
53 #define PANIC_PRINT_TIMER_INFO 0x00000004
54 #define PANIC_PRINT_LOCK_INFO 0x00000008
55 #define PANIC_PRINT_FTRACE_INFO 0x00000010
56 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
57 unsigned long panic_print
;
59 ATOMIC_NOTIFIER_HEAD(panic_notifier_list
);
61 EXPORT_SYMBOL(panic_notifier_list
);
63 static long no_blink(int state
)
68 /* Returns how long it waited in ms */
69 long (*panic_blink
)(int state
);
70 EXPORT_SYMBOL(panic_blink
);
73 * Stop ourself in panic -- architecture code may override this
75 void __weak
panic_smp_self_stop(void)
82 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
83 * may override this to prepare for crash dumping, e.g. save regs info.
85 void __weak
nmi_panic_self_stop(struct pt_regs
*regs
)
87 panic_smp_self_stop();
91 * Stop other CPUs in panic. Architecture dependent code may override this
92 * with more suitable version. For example, if the architecture supports
93 * crash dump, it should save registers of each stopped CPU and disable
94 * per-CPU features such as virtualization extensions.
96 void __weak
crash_smp_send_stop(void)
98 static int cpus_stopped
;
101 * This function can be called twice in panic path, but obviously
102 * we execute this only once.
108 * Note smp_send_stop is the usual smp shutdown function, which
109 * unfortunately means it may not be hardened to work in a panic
116 atomic_t panic_cpu
= ATOMIC_INIT(PANIC_CPU_INVALID
);
119 * A variant of panic() called from NMI context. We return if we've already
120 * panicked on this CPU. If another CPU already panicked, loop in
121 * nmi_panic_self_stop() which can provide architecture dependent code such
122 * as saving register state for crash dump.
124 void nmi_panic(struct pt_regs
*regs
, const char *msg
)
128 cpu
= raw_smp_processor_id();
129 old_cpu
= atomic_cmpxchg(&panic_cpu
, PANIC_CPU_INVALID
, cpu
);
131 if (old_cpu
== PANIC_CPU_INVALID
)
133 else if (old_cpu
!= cpu
)
134 nmi_panic_self_stop(regs
);
136 EXPORT_SYMBOL(nmi_panic
);
138 static void panic_print_sys_info(void)
140 if (panic_print
& PANIC_PRINT_ALL_PRINTK_MSG
)
141 console_flush_on_panic(CONSOLE_REPLAY_ALL
);
143 if (panic_print
& PANIC_PRINT_TASK_INFO
)
146 if (panic_print
& PANIC_PRINT_MEM_INFO
)
149 if (panic_print
& PANIC_PRINT_TIMER_INFO
)
150 sysrq_timer_list_show();
152 if (panic_print
& PANIC_PRINT_LOCK_INFO
)
153 debug_show_all_locks();
155 if (panic_print
& PANIC_PRINT_FTRACE_INFO
)
156 ftrace_dump(DUMP_ALL
);
160 * panic - halt the system
161 * @fmt: The text string to print
163 * Display a message, then perform cleanups.
165 * This function never returns.
167 void panic(const char *fmt
, ...)
169 static char buf
[1024];
171 long i
, i_next
= 0, len
;
173 int old_cpu
, this_cpu
;
174 bool _crash_kexec_post_notifiers
= crash_kexec_post_notifiers
;
177 * Disable local interrupts. This will prevent panic_smp_self_stop
178 * from deadlocking the first cpu that invokes the panic, since
179 * there is nothing to prevent an interrupt handler (that runs
180 * after setting panic_cpu) from invoking panic() again.
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 kgdb is enabled, give it a chance to run before we stop all
225 * the other CPUs or else we won't be able to debug processes left
231 * If we have crashed and we have a crash kernel loaded let it handle
233 * If we want to run this after calling panic_notifiers, pass
234 * the "crash_kexec_post_notifiers" option to the kernel.
236 * Bypass the panic_cpu check and call __crash_kexec directly.
238 if (!_crash_kexec_post_notifiers
) {
239 printk_safe_flush_on_panic();
243 * Note smp_send_stop is the usual smp shutdown function, which
244 * unfortunately means it may not be hardened to work in a
250 * If we want to do crash dump after notifier calls and
251 * kmsg_dump, we will need architecture dependent extra
252 * works in addition to stopping other CPUs.
254 crash_smp_send_stop();
258 * Run any panic handlers, including those that might need to
259 * add information to the kmsg dump output.
261 atomic_notifier_call_chain(&panic_notifier_list
, 0, buf
);
263 /* Call flush even twice. It tries harder with a single online CPU */
264 printk_safe_flush_on_panic();
265 kmsg_dump(KMSG_DUMP_PANIC
);
268 * If you doubt kdump always works fine in any situation,
269 * "crash_kexec_post_notifiers" offers you a chance to run
270 * panic_notifiers and dumping kmsg before kdump.
271 * Note: since some panic_notifiers can make crashed kernel
272 * more unstable, it can increase risks of the kdump failure too.
274 * Bypass the panic_cpu check and call __crash_kexec directly.
276 if (_crash_kexec_post_notifiers
)
285 * We may have ended up stopping the CPU holding the lock (in
286 * smp_send_stop()) while still having some valuable data in the console
287 * buffer. Try to acquire the lock then release it regardless of the
288 * result. The release will also print the buffers out. Locks debug
289 * should be disabled to avoid reporting bad unlock balance when
290 * panic() is not being callled from OOPS.
293 console_flush_on_panic(CONSOLE_FLUSH_PENDING
);
295 panic_print_sys_info();
298 panic_blink
= no_blink
;
300 if (panic_timeout
> 0) {
302 * Delay timeout seconds before rebooting the machine.
303 * We can't use the "normal" timers since we just panicked.
305 pr_emerg("Rebooting in %d seconds..\n", panic_timeout
);
307 for (i
= 0; i
< panic_timeout
* 1000; i
+= PANIC_TIMER_STEP
) {
308 touch_nmi_watchdog();
310 i
+= panic_blink(state
^= 1);
311 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
313 mdelay(PANIC_TIMER_STEP
);
316 if (panic_timeout
!= 0) {
318 * This will not be a clean reboot, with everything
319 * shutting down. But if there is a chance of
320 * rebooting the system it will be rebooted.
322 if (panic_reboot_mode
!= REBOOT_UNDEFINED
)
323 reboot_mode
= panic_reboot_mode
;
328 extern int stop_a_enabled
;
329 /* Make sure the user can actually press Stop-A (L1-A) */
331 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
332 "twice on console to return to the boot prom\n");
335 #if defined(CONFIG_S390)
338 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf
);
340 /* Do not scroll important messages printed above */
343 for (i
= 0; ; i
+= PANIC_TIMER_STEP
) {
344 touch_softlockup_watchdog();
346 i
+= panic_blink(state
^= 1);
347 i_next
= i
+ 3600 / PANIC_BLINK_SPD
;
349 mdelay(PANIC_TIMER_STEP
);
353 EXPORT_SYMBOL(panic
);
356 * TAINT_FORCED_RMMOD could be a per-module flag but the module
357 * is being removed anyway.
359 const struct taint_flag taint_flags
[TAINT_FLAGS_COUNT
] = {
360 [ TAINT_PROPRIETARY_MODULE
] = { 'P', 'G', true },
361 [ TAINT_FORCED_MODULE
] = { 'F', ' ', true },
362 [ TAINT_CPU_OUT_OF_SPEC
] = { 'S', ' ', false },
363 [ TAINT_FORCED_RMMOD
] = { 'R', ' ', false },
364 [ TAINT_MACHINE_CHECK
] = { 'M', ' ', false },
365 [ TAINT_BAD_PAGE
] = { 'B', ' ', false },
366 [ TAINT_USER
] = { 'U', ' ', false },
367 [ TAINT_DIE
] = { 'D', ' ', false },
368 [ TAINT_OVERRIDDEN_ACPI_TABLE
] = { 'A', ' ', false },
369 [ TAINT_WARN
] = { 'W', ' ', false },
370 [ TAINT_CRAP
] = { 'C', ' ', true },
371 [ TAINT_FIRMWARE_WORKAROUND
] = { 'I', ' ', false },
372 [ TAINT_OOT_MODULE
] = { 'O', ' ', true },
373 [ TAINT_UNSIGNED_MODULE
] = { 'E', ' ', true },
374 [ TAINT_SOFTLOCKUP
] = { 'L', ' ', false },
375 [ TAINT_LIVEPATCH
] = { 'K', ' ', true },
376 [ TAINT_AUX
] = { 'X', ' ', true },
377 [ TAINT_RANDSTRUCT
] = { 'T', ' ', true },
381 * print_tainted - return a string to represent the kernel taint state.
383 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
385 * The string is overwritten by the next call to print_tainted(),
386 * but is always NULL terminated.
388 const char *print_tainted(void)
390 static char buf
[TAINT_FLAGS_COUNT
+ sizeof("Tainted: ")];
392 BUILD_BUG_ON(ARRAY_SIZE(taint_flags
) != TAINT_FLAGS_COUNT
);
398 s
= buf
+ sprintf(buf
, "Tainted: ");
399 for (i
= 0; i
< TAINT_FLAGS_COUNT
; i
++) {
400 const struct taint_flag
*t
= &taint_flags
[i
];
401 *s
++ = test_bit(i
, &tainted_mask
) ?
402 t
->c_true
: t
->c_false
;
406 snprintf(buf
, sizeof(buf
), "Not tainted");
411 int test_taint(unsigned flag
)
413 return test_bit(flag
, &tainted_mask
);
415 EXPORT_SYMBOL(test_taint
);
417 unsigned long get_taint(void)
423 * add_taint: add a taint flag if not already set.
424 * @flag: one of the TAINT_* constants.
425 * @lockdep_ok: whether lock debugging is still OK.
427 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
428 * some notewortht-but-not-corrupting cases, it can be set to true.
430 void add_taint(unsigned flag
, enum lockdep_ok lockdep_ok
)
432 if (lockdep_ok
== LOCKDEP_NOW_UNRELIABLE
&& __debug_locks_off())
433 pr_warn("Disabling lock debugging due to kernel taint\n");
435 set_bit(flag
, &tainted_mask
);
437 EXPORT_SYMBOL(add_taint
);
439 static void spin_msec(int msecs
)
443 for (i
= 0; i
< msecs
; i
++) {
444 touch_nmi_watchdog();
450 * It just happens that oops_enter() and oops_exit() are identically
453 static void do_oops_enter_exit(void)
456 static int spin_counter
;
461 spin_lock_irqsave(&pause_on_oops_lock
, flags
);
462 if (pause_on_oops_flag
== 0) {
463 /* This CPU may now print the oops message */
464 pause_on_oops_flag
= 1;
466 /* We need to stall this CPU */
468 /* This CPU gets to do the counting */
469 spin_counter
= pause_on_oops
;
471 spin_unlock(&pause_on_oops_lock
);
472 spin_msec(MSEC_PER_SEC
);
473 spin_lock(&pause_on_oops_lock
);
474 } while (--spin_counter
);
475 pause_on_oops_flag
= 0;
477 /* This CPU waits for a different one */
478 while (spin_counter
) {
479 spin_unlock(&pause_on_oops_lock
);
481 spin_lock(&pause_on_oops_lock
);
485 spin_unlock_irqrestore(&pause_on_oops_lock
, flags
);
489 * Return true if the calling CPU is allowed to print oops-related info.
490 * This is a bit racy..
492 int oops_may_print(void)
494 return pause_on_oops_flag
== 0;
498 * Called when the architecture enters its oops handler, before it prints
499 * anything. If this is the first CPU to oops, and it's oopsing the first
500 * time then let it proceed.
502 * This is all enabled by the pause_on_oops kernel boot option. We do all
503 * this to ensure that oopses don't scroll off the screen. It has the
504 * side-effect of preventing later-oopsing CPUs from mucking up the display,
507 * It turns out that the CPU which is allowed to print ends up pausing for
508 * the right duration, whereas all the other CPUs pause for twice as long:
509 * once in oops_enter(), once in oops_exit().
511 void oops_enter(void)
514 /* can't trust the integrity of the kernel anymore: */
516 do_oops_enter_exit();
520 * 64-bit random ID for oopses:
524 static int init_oops_id(void)
527 get_random_bytes(&oops_id
, sizeof(oops_id
));
533 late_initcall(init_oops_id
);
535 void print_oops_end_marker(void)
538 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id
);
542 * Called when the architecture exits its oops handler, after printing
547 do_oops_enter_exit();
548 print_oops_end_marker();
549 kmsg_dump(KMSG_DUMP_OOPS
);
557 void __warn(const char *file
, int line
, void *caller
, unsigned taint
,
558 struct pt_regs
*regs
, struct warn_args
*args
)
560 disable_trace_on_warning();
563 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
564 raw_smp_processor_id(), current
->pid
, file
, line
,
567 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
568 raw_smp_processor_id(), current
->pid
, caller
);
571 vprintk(args
->fmt
, args
->args
);
575 * This thread may hit another WARN() in the panic path.
576 * Resetting this prevents additional WARN() from panicking the
577 * system on this thread. Other threads are blocked by the
578 * panic_mutex in panic().
581 panic("panic_on_warn set ...\n");
591 print_irqtrace_events(current
);
593 print_oops_end_marker();
595 /* Just a warning, don't kill lockdep. */
596 add_taint(taint
, LOCKDEP_STILL_OK
);
600 void warn_slowpath_fmt(const char *file
, int line
, unsigned taint
,
601 const char *fmt
, ...)
603 struct warn_args args
;
608 __warn(file
, line
, __builtin_return_address(0), taint
,
614 va_start(args
.args
, fmt
);
615 __warn(file
, line
, __builtin_return_address(0), taint
, NULL
, &args
);
618 EXPORT_SYMBOL(warn_slowpath_fmt
);
620 void __warn_printk(const char *fmt
, ...)
630 EXPORT_SYMBOL(__warn_printk
);
635 /* Support resetting WARN*_ONCE state */
637 static int clear_warn_once_set(void *data
, u64 val
)
639 generic_bug_clear_once();
640 memset(__start_once
, 0, __end_once
- __start_once
);
644 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops
, NULL
, clear_warn_once_set
,
647 static __init
int register_warn_debugfs(void)
649 /* Don't care about failure */
650 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL
, NULL
,
651 &clear_warn_once_fops
);
655 device_initcall(register_warn_debugfs
);
658 #ifdef CONFIG_STACKPROTECTOR
661 * Called when gcc's -fstack-protector feature is used, and
662 * gcc detects corruption of the on-stack canary value
664 __visible
void __stack_chk_fail(void)
666 panic("stack-protector: Kernel stack is corrupted in: %pB",
667 __builtin_return_address(0));
669 EXPORT_SYMBOL(__stack_chk_fail
);
673 #ifdef CONFIG_ARCH_HAS_REFCOUNT
674 void refcount_error_report(struct pt_regs
*regs
, const char *err
)
676 WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
677 err
, (void *)instruction_pointer(regs
),
678 current
->comm
, task_pid_nr(current
),
679 from_kuid_munged(&init_user_ns
, current_uid()),
680 from_kuid_munged(&init_user_ns
, current_euid()));
684 core_param(panic
, panic_timeout
, int, 0644);
685 core_param(panic_print
, panic_print
, ulong
, 0644);
686 core_param(pause_on_oops
, pause_on_oops
, int, 0644);
687 core_param(panic_on_warn
, panic_on_warn
, int, 0644);
688 core_param(crash_kexec_post_notifiers
, crash_kexec_post_notifiers
, bool, 0644);
690 static int __init
oops_setup(char *s
)
694 if (!strcmp(s
, "panic"))
698 early_param("oops", oops_setup
);