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1/*
2 * linux/kernel/panic.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * This function is used through-out the kernel (including mm and fs)
9 * to indicate a major problem.
10 */
11#include <linux/debug_locks.h>
12#include <linux/interrupt.h>
13#include <linux/kmsg_dump.h>
14#include <linux/kallsyms.h>
15#include <linux/notifier.h>
16#include <linux/module.h>
17#include <linux/random.h>
18#include <linux/ftrace.h>
19#include <linux/reboot.h>
20#include <linux/delay.h>
21#include <linux/kexec.h>
22#include <linux/sched.h>
23#include <linux/sysrq.h>
24#include <linux/init.h>
25#include <linux/nmi.h>
26#include <linux/console.h>
27#include <linux/bug.h>
28
29#define PANIC_TIMER_STEP 100
30#define PANIC_BLINK_SPD 18
31
32int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
33static unsigned long tainted_mask;
34static int pause_on_oops;
35static int pause_on_oops_flag;
36static DEFINE_SPINLOCK(pause_on_oops_lock);
37bool crash_kexec_post_notifiers;
38int panic_on_warn __read_mostly;
39
40int panic_timeout = CONFIG_PANIC_TIMEOUT;
41EXPORT_SYMBOL_GPL(panic_timeout);
42
43ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
44
45EXPORT_SYMBOL(panic_notifier_list);
46
47static long no_blink(int state)
48{
49 return 0;
50}
51
52/* Returns how long it waited in ms */
53long (*panic_blink)(int state);
54EXPORT_SYMBOL(panic_blink);
55
56/*
57 * Stop ourself in panic -- architecture code may override this
58 */
59void __weak panic_smp_self_stop(void)
60{
61 while (1)
62 cpu_relax();
63}
64
65/*
66 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
67 * may override this to prepare for crash dumping, e.g. save regs info.
68 */
69void __weak nmi_panic_self_stop(struct pt_regs *regs)
70{
71 panic_smp_self_stop();
72}
73
74/*
75 * Stop other CPUs in panic. Architecture dependent code may override this
76 * with more suitable version. For example, if the architecture supports
77 * crash dump, it should save registers of each stopped CPU and disable
78 * per-CPU features such as virtualization extensions.
79 */
80void __weak crash_smp_send_stop(void)
81{
82 static int cpus_stopped;
83
84 /*
85 * This function can be called twice in panic path, but obviously
86 * we execute this only once.
87 */
88 if (cpus_stopped)
89 return;
90
91 /*
92 * Note smp_send_stop is the usual smp shutdown function, which
93 * unfortunately means it may not be hardened to work in a panic
94 * situation.
95 */
96 smp_send_stop();
97 cpus_stopped = 1;
98}
99
100atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
101
102/*
103 * A variant of panic() called from NMI context. We return if we've already
104 * panicked on this CPU. If another CPU already panicked, loop in
105 * nmi_panic_self_stop() which can provide architecture dependent code such
106 * as saving register state for crash dump.
107 */
108void nmi_panic(struct pt_regs *regs, const char *msg)
109{
110 int old_cpu, cpu;
111
112 cpu = raw_smp_processor_id();
113 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
114
115 if (old_cpu == PANIC_CPU_INVALID)
116 panic("%s", msg);
117 else if (old_cpu != cpu)
118 nmi_panic_self_stop(regs);
119}
120EXPORT_SYMBOL(nmi_panic);
121
122/**
123 * panic - halt the system
124 * @fmt: The text string to print
125 *
126 * Display a message, then perform cleanups.
127 *
128 * This function never returns.
129 */
130void panic(const char *fmt, ...)
131{
132 static char buf[1024];
133 va_list args;
134 long i, i_next = 0;
135 int state = 0;
136 int old_cpu, this_cpu;
137 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
138
139 /*
140 * Disable local interrupts. This will prevent panic_smp_self_stop
141 * from deadlocking the first cpu that invokes the panic, since
142 * there is nothing to prevent an interrupt handler (that runs
143 * after setting panic_cpu) from invoking panic() again.
144 */
145 local_irq_disable();
146
147 /*
148 * It's possible to come here directly from a panic-assertion and
149 * not have preempt disabled. Some functions called from here want
150 * preempt to be disabled. No point enabling it later though...
151 *
152 * Only one CPU is allowed to execute the panic code from here. For
153 * multiple parallel invocations of panic, all other CPUs either
154 * stop themself or will wait until they are stopped by the 1st CPU
155 * with smp_send_stop().
156 *
157 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
158 * comes here, so go ahead.
159 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
160 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
161 */
162 this_cpu = raw_smp_processor_id();
163 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
164
165 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
166 panic_smp_self_stop();
167
168 console_verbose();
169 bust_spinlocks(1);
170 va_start(args, fmt);
171 vsnprintf(buf, sizeof(buf), fmt, args);
172 va_end(args);
173 pr_emerg("Kernel panic - not syncing: %s\n", buf);
174#ifdef CONFIG_DEBUG_BUGVERBOSE
175 /*
176 * Avoid nested stack-dumping if a panic occurs during oops processing
177 */
178 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
179 dump_stack();
180#endif
181
182 /*
183 * If we have crashed and we have a crash kernel loaded let it handle
184 * everything else.
185 * If we want to run this after calling panic_notifiers, pass
186 * the "crash_kexec_post_notifiers" option to the kernel.
187 *
188 * Bypass the panic_cpu check and call __crash_kexec directly.
189 */
190 if (!_crash_kexec_post_notifiers) {
191 printk_nmi_flush_on_panic();
192 __crash_kexec(NULL);
193
194 /*
195 * Note smp_send_stop is the usual smp shutdown function, which
196 * unfortunately means it may not be hardened to work in a
197 * panic situation.
198 */
199 smp_send_stop();
200 } else {
201 /*
202 * If we want to do crash dump after notifier calls and
203 * kmsg_dump, we will need architecture dependent extra
204 * works in addition to stopping other CPUs.
205 */
206 crash_smp_send_stop();
207 }
208
209 /*
210 * Run any panic handlers, including those that might need to
211 * add information to the kmsg dump output.
212 */
213 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
214
215 /* Call flush even twice. It tries harder with a single online CPU */
216 printk_nmi_flush_on_panic();
217 kmsg_dump(KMSG_DUMP_PANIC);
218
219 /*
220 * If you doubt kdump always works fine in any situation,
221 * "crash_kexec_post_notifiers" offers you a chance to run
222 * panic_notifiers and dumping kmsg before kdump.
223 * Note: since some panic_notifiers can make crashed kernel
224 * more unstable, it can increase risks of the kdump failure too.
225 *
226 * Bypass the panic_cpu check and call __crash_kexec directly.
227 */
228 if (_crash_kexec_post_notifiers)
229 __crash_kexec(NULL);
230
231 bust_spinlocks(0);
232
233 /*
234 * We may have ended up stopping the CPU holding the lock (in
235 * smp_send_stop()) while still having some valuable data in the console
236 * buffer. Try to acquire the lock then release it regardless of the
237 * result. The release will also print the buffers out. Locks debug
238 * should be disabled to avoid reporting bad unlock balance when
239 * panic() is not being callled from OOPS.
240 */
241 debug_locks_off();
242 console_flush_on_panic();
243
244 if (!panic_blink)
245 panic_blink = no_blink;
246
247 if (panic_timeout > 0) {
248 /*
249 * Delay timeout seconds before rebooting the machine.
250 * We can't use the "normal" timers since we just panicked.
251 */
252 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
253
254 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
255 touch_nmi_watchdog();
256 if (i >= i_next) {
257 i += panic_blink(state ^= 1);
258 i_next = i + 3600 / PANIC_BLINK_SPD;
259 }
260 mdelay(PANIC_TIMER_STEP);
261 }
262 }
263 if (panic_timeout != 0) {
264 /*
265 * This will not be a clean reboot, with everything
266 * shutting down. But if there is a chance of
267 * rebooting the system it will be rebooted.
268 */
269 emergency_restart();
270 }
271#ifdef __sparc__
272 {
273 extern int stop_a_enabled;
274 /* Make sure the user can actually press Stop-A (L1-A) */
275 stop_a_enabled = 1;
276 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
277 }
278#endif
279#if defined(CONFIG_S390)
280 {
281 unsigned long caller;
282
283 caller = (unsigned long)__builtin_return_address(0);
284 disabled_wait(caller);
285 }
286#endif
287 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
288 local_irq_enable();
289 for (i = 0; ; i += PANIC_TIMER_STEP) {
290 touch_softlockup_watchdog();
291 if (i >= i_next) {
292 i += panic_blink(state ^= 1);
293 i_next = i + 3600 / PANIC_BLINK_SPD;
294 }
295 mdelay(PANIC_TIMER_STEP);
296 }
297}
298
299EXPORT_SYMBOL(panic);
300
301/*
302 * TAINT_FORCED_RMMOD could be a per-module flag but the module
303 * is being removed anyway.
304 */
305const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
306 { 'P', 'G', true }, /* TAINT_PROPRIETARY_MODULE */
307 { 'F', ' ', true }, /* TAINT_FORCED_MODULE */
308 { 'S', ' ', false }, /* TAINT_CPU_OUT_OF_SPEC */
309 { 'R', ' ', false }, /* TAINT_FORCED_RMMOD */
310 { 'M', ' ', false }, /* TAINT_MACHINE_CHECK */
311 { 'B', ' ', false }, /* TAINT_BAD_PAGE */
312 { 'U', ' ', false }, /* TAINT_USER */
313 { 'D', ' ', false }, /* TAINT_DIE */
314 { 'A', ' ', false }, /* TAINT_OVERRIDDEN_ACPI_TABLE */
315 { 'W', ' ', false }, /* TAINT_WARN */
316 { 'C', ' ', true }, /* TAINT_CRAP */
317 { 'I', ' ', false }, /* TAINT_FIRMWARE_WORKAROUND */
318 { 'O', ' ', true }, /* TAINT_OOT_MODULE */
319 { 'E', ' ', true }, /* TAINT_UNSIGNED_MODULE */
320 { 'L', ' ', false }, /* TAINT_SOFTLOCKUP */
321 { 'K', ' ', true }, /* TAINT_LIVEPATCH */
322};
323
324/**
325 * print_tainted - return a string to represent the kernel taint state.
326 *
327 * 'P' - Proprietary module has been loaded.
328 * 'F' - Module has been forcibly loaded.
329 * 'S' - SMP with CPUs not designed for SMP.
330 * 'R' - User forced a module unload.
331 * 'M' - System experienced a machine check exception.
332 * 'B' - System has hit bad_page.
333 * 'U' - Userspace-defined naughtiness.
334 * 'D' - Kernel has oopsed before
335 * 'A' - ACPI table overridden.
336 * 'W' - Taint on warning.
337 * 'C' - modules from drivers/staging are loaded.
338 * 'I' - Working around severe firmware bug.
339 * 'O' - Out-of-tree module has been loaded.
340 * 'E' - Unsigned module has been loaded.
341 * 'L' - A soft lockup has previously occurred.
342 * 'K' - Kernel has been live patched.
343 *
344 * The string is overwritten by the next call to print_tainted().
345 */
346const char *print_tainted(void)
347{
348 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
349
350 if (tainted_mask) {
351 char *s;
352 int i;
353
354 s = buf + sprintf(buf, "Tainted: ");
355 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
356 const struct taint_flag *t = &taint_flags[i];
357 *s++ = test_bit(i, &tainted_mask) ?
358 t->c_true : t->c_false;
359 }
360 *s = 0;
361 } else
362 snprintf(buf, sizeof(buf), "Not tainted");
363
364 return buf;
365}
366
367int test_taint(unsigned flag)
368{
369 return test_bit(flag, &tainted_mask);
370}
371EXPORT_SYMBOL(test_taint);
372
373unsigned long get_taint(void)
374{
375 return tainted_mask;
376}
377
378/**
379 * add_taint: add a taint flag if not already set.
380 * @flag: one of the TAINT_* constants.
381 * @lockdep_ok: whether lock debugging is still OK.
382 *
383 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
384 * some notewortht-but-not-corrupting cases, it can be set to true.
385 */
386void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
387{
388 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
389 pr_warn("Disabling lock debugging due to kernel taint\n");
390
391 set_bit(flag, &tainted_mask);
392}
393EXPORT_SYMBOL(add_taint);
394
395static void spin_msec(int msecs)
396{
397 int i;
398
399 for (i = 0; i < msecs; i++) {
400 touch_nmi_watchdog();
401 mdelay(1);
402 }
403}
404
405/*
406 * It just happens that oops_enter() and oops_exit() are identically
407 * implemented...
408 */
409static void do_oops_enter_exit(void)
410{
411 unsigned long flags;
412 static int spin_counter;
413
414 if (!pause_on_oops)
415 return;
416
417 spin_lock_irqsave(&pause_on_oops_lock, flags);
418 if (pause_on_oops_flag == 0) {
419 /* This CPU may now print the oops message */
420 pause_on_oops_flag = 1;
421 } else {
422 /* We need to stall this CPU */
423 if (!spin_counter) {
424 /* This CPU gets to do the counting */
425 spin_counter = pause_on_oops;
426 do {
427 spin_unlock(&pause_on_oops_lock);
428 spin_msec(MSEC_PER_SEC);
429 spin_lock(&pause_on_oops_lock);
430 } while (--spin_counter);
431 pause_on_oops_flag = 0;
432 } else {
433 /* This CPU waits for a different one */
434 while (spin_counter) {
435 spin_unlock(&pause_on_oops_lock);
436 spin_msec(1);
437 spin_lock(&pause_on_oops_lock);
438 }
439 }
440 }
441 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
442}
443
444/*
445 * Return true if the calling CPU is allowed to print oops-related info.
446 * This is a bit racy..
447 */
448int oops_may_print(void)
449{
450 return pause_on_oops_flag == 0;
451}
452
453/*
454 * Called when the architecture enters its oops handler, before it prints
455 * anything. If this is the first CPU to oops, and it's oopsing the first
456 * time then let it proceed.
457 *
458 * This is all enabled by the pause_on_oops kernel boot option. We do all
459 * this to ensure that oopses don't scroll off the screen. It has the
460 * side-effect of preventing later-oopsing CPUs from mucking up the display,
461 * too.
462 *
463 * It turns out that the CPU which is allowed to print ends up pausing for
464 * the right duration, whereas all the other CPUs pause for twice as long:
465 * once in oops_enter(), once in oops_exit().
466 */
467void oops_enter(void)
468{
469 tracing_off();
470 /* can't trust the integrity of the kernel anymore: */
471 debug_locks_off();
472 do_oops_enter_exit();
473}
474
475/*
476 * 64-bit random ID for oopses:
477 */
478static u64 oops_id;
479
480static int init_oops_id(void)
481{
482 if (!oops_id)
483 get_random_bytes(&oops_id, sizeof(oops_id));
484 else
485 oops_id++;
486
487 return 0;
488}
489late_initcall(init_oops_id);
490
491void print_oops_end_marker(void)
492{
493 init_oops_id();
494 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
495}
496
497/*
498 * Called when the architecture exits its oops handler, after printing
499 * everything.
500 */
501void oops_exit(void)
502{
503 do_oops_enter_exit();
504 print_oops_end_marker();
505 kmsg_dump(KMSG_DUMP_OOPS);
506}
507
508struct warn_args {
509 const char *fmt;
510 va_list args;
511};
512
513void __warn(const char *file, int line, void *caller, unsigned taint,
514 struct pt_regs *regs, struct warn_args *args)
515{
516 disable_trace_on_warning();
517
518 pr_warn("------------[ cut here ]------------\n");
519
520 if (file)
521 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
522 raw_smp_processor_id(), current->pid, file, line,
523 caller);
524 else
525 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
526 raw_smp_processor_id(), current->pid, caller);
527
528 if (args)
529 vprintk(args->fmt, args->args);
530
531 if (panic_on_warn) {
532 /*
533 * This thread may hit another WARN() in the panic path.
534 * Resetting this prevents additional WARN() from panicking the
535 * system on this thread. Other threads are blocked by the
536 * panic_mutex in panic().
537 */
538 panic_on_warn = 0;
539 panic("panic_on_warn set ...\n");
540 }
541
542 print_modules();
543
544 if (regs)
545 show_regs(regs);
546 else
547 dump_stack();
548
549 print_oops_end_marker();
550
551 /* Just a warning, don't kill lockdep. */
552 add_taint(taint, LOCKDEP_STILL_OK);
553}
554
555#ifdef WANT_WARN_ON_SLOWPATH
556void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
557{
558 struct warn_args args;
559
560 args.fmt = fmt;
561 va_start(args.args, fmt);
562 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
563 &args);
564 va_end(args.args);
565}
566EXPORT_SYMBOL(warn_slowpath_fmt);
567
568void warn_slowpath_fmt_taint(const char *file, int line,
569 unsigned taint, const char *fmt, ...)
570{
571 struct warn_args args;
572
573 args.fmt = fmt;
574 va_start(args.args, fmt);
575 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
576 va_end(args.args);
577}
578EXPORT_SYMBOL(warn_slowpath_fmt_taint);
579
580void warn_slowpath_null(const char *file, int line)
581{
582 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
583}
584EXPORT_SYMBOL(warn_slowpath_null);
585#endif
586
587#ifdef CONFIG_CC_STACKPROTECTOR
588
589/*
590 * Called when gcc's -fstack-protector feature is used, and
591 * gcc detects corruption of the on-stack canary value
592 */
593__visible void __stack_chk_fail(void)
594{
595 panic("stack-protector: Kernel stack is corrupted in: %p\n",
596 __builtin_return_address(0));
597}
598EXPORT_SYMBOL(__stack_chk_fail);
599
600#endif
601
602core_param(panic, panic_timeout, int, 0644);
603core_param(pause_on_oops, pause_on_oops, int, 0644);
604core_param(panic_on_warn, panic_on_warn, int, 0644);
605core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
606
607static int __init oops_setup(char *s)
608{
609 if (!s)
610 return -EINVAL;
611 if (!strcmp(s, "panic"))
612 panic_on_oops = 1;
613 return 0;
614}
615early_param("oops", oops_setup);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/panic.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * This function is used through-out the kernel (including mm and fs)
10 * to indicate a major problem.
11 */
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>
35
36#define PANIC_TIMER_STEP 100
37#define PANIC_BLINK_SPD 18
38
39#ifdef CONFIG_SMP
40/*
41 * Should we dump all CPUs backtraces in an oops event?
42 * Defaults to 0, can be changed via sysctl.
43 */
44unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
45#endif /* CONFIG_SMP */
46
47int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
48static unsigned long tainted_mask =
49 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
50static int pause_on_oops;
51static int pause_on_oops_flag;
52static DEFINE_SPINLOCK(pause_on_oops_lock);
53bool crash_kexec_post_notifiers;
54int panic_on_warn __read_mostly;
55unsigned long panic_on_taint;
56bool panic_on_taint_nousertaint = false;
57
58int panic_timeout = CONFIG_PANIC_TIMEOUT;
59EXPORT_SYMBOL_GPL(panic_timeout);
60
61#define PANIC_PRINT_TASK_INFO 0x00000001
62#define PANIC_PRINT_MEM_INFO 0x00000002
63#define PANIC_PRINT_TIMER_INFO 0x00000004
64#define PANIC_PRINT_LOCK_INFO 0x00000008
65#define PANIC_PRINT_FTRACE_INFO 0x00000010
66#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
67unsigned long panic_print;
68
69ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
70
71EXPORT_SYMBOL(panic_notifier_list);
72
73static long no_blink(int state)
74{
75 return 0;
76}
77
78/* Returns how long it waited in ms */
79long (*panic_blink)(int state);
80EXPORT_SYMBOL(panic_blink);
81
82/*
83 * Stop ourself in panic -- architecture code may override this
84 */
85void __weak panic_smp_self_stop(void)
86{
87 while (1)
88 cpu_relax();
89}
90
91/*
92 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
93 * may override this to prepare for crash dumping, e.g. save regs info.
94 */
95void __weak nmi_panic_self_stop(struct pt_regs *regs)
96{
97 panic_smp_self_stop();
98}
99
100/*
101 * Stop other CPUs in panic. Architecture dependent code may override this
102 * with more suitable version. For example, if the architecture supports
103 * crash dump, it should save registers of each stopped CPU and disable
104 * per-CPU features such as virtualization extensions.
105 */
106void __weak crash_smp_send_stop(void)
107{
108 static int cpus_stopped;
109
110 /*
111 * This function can be called twice in panic path, but obviously
112 * we execute this only once.
113 */
114 if (cpus_stopped)
115 return;
116
117 /*
118 * Note smp_send_stop is the usual smp shutdown function, which
119 * unfortunately means it may not be hardened to work in a panic
120 * situation.
121 */
122 smp_send_stop();
123 cpus_stopped = 1;
124}
125
126atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
127
128/*
129 * A variant of panic() called from NMI context. We return if we've already
130 * panicked on this CPU. If another CPU already panicked, loop in
131 * nmi_panic_self_stop() which can provide architecture dependent code such
132 * as saving register state for crash dump.
133 */
134void nmi_panic(struct pt_regs *regs, const char *msg)
135{
136 int old_cpu, cpu;
137
138 cpu = raw_smp_processor_id();
139 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
140
141 if (old_cpu == PANIC_CPU_INVALID)
142 panic("%s", msg);
143 else if (old_cpu != cpu)
144 nmi_panic_self_stop(regs);
145}
146EXPORT_SYMBOL(nmi_panic);
147
148static void panic_print_sys_info(void)
149{
150 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
151 console_flush_on_panic(CONSOLE_REPLAY_ALL);
152
153 if (panic_print & PANIC_PRINT_TASK_INFO)
154 show_state();
155
156 if (panic_print & PANIC_PRINT_MEM_INFO)
157 show_mem(0, NULL);
158
159 if (panic_print & PANIC_PRINT_TIMER_INFO)
160 sysrq_timer_list_show();
161
162 if (panic_print & PANIC_PRINT_LOCK_INFO)
163 debug_show_all_locks();
164
165 if (panic_print & PANIC_PRINT_FTRACE_INFO)
166 ftrace_dump(DUMP_ALL);
167}
168
169/**
170 * panic - halt the system
171 * @fmt: The text string to print
172 *
173 * Display a message, then perform cleanups.
174 *
175 * This function never returns.
176 */
177void panic(const char *fmt, ...)
178{
179 static char buf[1024];
180 va_list args;
181 long i, i_next = 0, len;
182 int state = 0;
183 int old_cpu, this_cpu;
184 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
185
186 /*
187 * Disable local interrupts. This will prevent panic_smp_self_stop
188 * from deadlocking the first cpu that invokes the panic, since
189 * there is nothing to prevent an interrupt handler (that runs
190 * after setting panic_cpu) from invoking panic() again.
191 */
192 local_irq_disable();
193 preempt_disable_notrace();
194
195 /*
196 * It's possible to come here directly from a panic-assertion and
197 * not have preempt disabled. Some functions called from here want
198 * preempt to be disabled. No point enabling it later though...
199 *
200 * Only one CPU is allowed to execute the panic code from here. For
201 * multiple parallel invocations of panic, all other CPUs either
202 * stop themself or will wait until they are stopped by the 1st CPU
203 * with smp_send_stop().
204 *
205 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
206 * comes here, so go ahead.
207 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
208 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
209 */
210 this_cpu = raw_smp_processor_id();
211 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
212
213 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
214 panic_smp_self_stop();
215
216 console_verbose();
217 bust_spinlocks(1);
218 va_start(args, fmt);
219 len = vscnprintf(buf, sizeof(buf), fmt, args);
220 va_end(args);
221
222 if (len && buf[len - 1] == '\n')
223 buf[len - 1] = '\0';
224
225 pr_emerg("Kernel panic - not syncing: %s\n", buf);
226#ifdef CONFIG_DEBUG_BUGVERBOSE
227 /*
228 * Avoid nested stack-dumping if a panic occurs during oops processing
229 */
230 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
231 dump_stack();
232#endif
233
234 /*
235 * If kgdb is enabled, give it a chance to run before we stop all
236 * the other CPUs or else we won't be able to debug processes left
237 * running on them.
238 */
239 kgdb_panic(buf);
240
241 /*
242 * If we have crashed and we have a crash kernel loaded let it handle
243 * everything else.
244 * If we want to run this after calling panic_notifiers, pass
245 * the "crash_kexec_post_notifiers" option to the kernel.
246 *
247 * Bypass the panic_cpu check and call __crash_kexec directly.
248 */
249 if (!_crash_kexec_post_notifiers) {
250 printk_safe_flush_on_panic();
251 __crash_kexec(NULL);
252
253 /*
254 * Note smp_send_stop is the usual smp shutdown function, which
255 * unfortunately means it may not be hardened to work in a
256 * panic situation.
257 */
258 smp_send_stop();
259 } else {
260 /*
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.
264 */
265 crash_smp_send_stop();
266 }
267
268 /*
269 * Run any panic handlers, including those that might need to
270 * add information to the kmsg dump output.
271 */
272 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
273
274 /* Call flush even twice. It tries harder with a single online CPU */
275 printk_safe_flush_on_panic();
276 kmsg_dump(KMSG_DUMP_PANIC);
277
278 /*
279 * If you doubt kdump always works fine in any situation,
280 * "crash_kexec_post_notifiers" offers you a chance to run
281 * panic_notifiers and dumping kmsg before kdump.
282 * Note: since some panic_notifiers can make crashed kernel
283 * more unstable, it can increase risks of the kdump failure too.
284 *
285 * Bypass the panic_cpu check and call __crash_kexec directly.
286 */
287 if (_crash_kexec_post_notifiers)
288 __crash_kexec(NULL);
289
290#ifdef CONFIG_VT
291 unblank_screen();
292#endif
293 console_unblank();
294
295 /*
296 * We may have ended up stopping the CPU holding the lock (in
297 * smp_send_stop()) while still having some valuable data in the console
298 * buffer. Try to acquire the lock then release it regardless of the
299 * result. The release will also print the buffers out. Locks debug
300 * should be disabled to avoid reporting bad unlock balance when
301 * panic() is not being callled from OOPS.
302 */
303 debug_locks_off();
304 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
305
306 panic_print_sys_info();
307
308 if (!panic_blink)
309 panic_blink = no_blink;
310
311 if (panic_timeout > 0) {
312 /*
313 * Delay timeout seconds before rebooting the machine.
314 * We can't use the "normal" timers since we just panicked.
315 */
316 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
317
318 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
319 touch_nmi_watchdog();
320 if (i >= i_next) {
321 i += panic_blink(state ^= 1);
322 i_next = i + 3600 / PANIC_BLINK_SPD;
323 }
324 mdelay(PANIC_TIMER_STEP);
325 }
326 }
327 if (panic_timeout != 0) {
328 /*
329 * This will not be a clean reboot, with everything
330 * shutting down. But if there is a chance of
331 * rebooting the system it will be rebooted.
332 */
333 if (panic_reboot_mode != REBOOT_UNDEFINED)
334 reboot_mode = panic_reboot_mode;
335 emergency_restart();
336 }
337#ifdef __sparc__
338 {
339 extern int stop_a_enabled;
340 /* Make sure the user can actually press Stop-A (L1-A) */
341 stop_a_enabled = 1;
342 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
343 "twice on console to return to the boot prom\n");
344 }
345#endif
346#if defined(CONFIG_S390)
347 disabled_wait();
348#endif
349 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
350
351 /* Do not scroll important messages printed above */
352 suppress_printk = 1;
353 local_irq_enable();
354 for (i = 0; ; i += PANIC_TIMER_STEP) {
355 touch_softlockup_watchdog();
356 if (i >= i_next) {
357 i += panic_blink(state ^= 1);
358 i_next = i + 3600 / PANIC_BLINK_SPD;
359 }
360 mdelay(PANIC_TIMER_STEP);
361 }
362}
363
364EXPORT_SYMBOL(panic);
365
366/*
367 * TAINT_FORCED_RMMOD could be a per-module flag but the module
368 * is being removed anyway.
369 */
370const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
371 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
372 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
373 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
374 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
375 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
376 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
377 [ TAINT_USER ] = { 'U', ' ', false },
378 [ TAINT_DIE ] = { 'D', ' ', false },
379 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
380 [ TAINT_WARN ] = { 'W', ' ', false },
381 [ TAINT_CRAP ] = { 'C', ' ', true },
382 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
383 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
384 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
385 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
386 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
387 [ TAINT_AUX ] = { 'X', ' ', true },
388 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
389};
390
391/**
392 * print_tainted - return a string to represent the kernel taint state.
393 *
394 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
395 *
396 * The string is overwritten by the next call to print_tainted(),
397 * but is always NULL terminated.
398 */
399const char *print_tainted(void)
400{
401 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
402
403 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
404
405 if (tainted_mask) {
406 char *s;
407 int i;
408
409 s = buf + sprintf(buf, "Tainted: ");
410 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
411 const struct taint_flag *t = &taint_flags[i];
412 *s++ = test_bit(i, &tainted_mask) ?
413 t->c_true : t->c_false;
414 }
415 *s = 0;
416 } else
417 snprintf(buf, sizeof(buf), "Not tainted");
418
419 return buf;
420}
421
422int test_taint(unsigned flag)
423{
424 return test_bit(flag, &tainted_mask);
425}
426EXPORT_SYMBOL(test_taint);
427
428unsigned long get_taint(void)
429{
430 return tainted_mask;
431}
432
433/**
434 * add_taint: add a taint flag if not already set.
435 * @flag: one of the TAINT_* constants.
436 * @lockdep_ok: whether lock debugging is still OK.
437 *
438 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
439 * some notewortht-but-not-corrupting cases, it can be set to true.
440 */
441void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
442{
443 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
444 pr_warn("Disabling lock debugging due to kernel taint\n");
445
446 set_bit(flag, &tainted_mask);
447
448 if (tainted_mask & panic_on_taint) {
449 panic_on_taint = 0;
450 panic("panic_on_taint set ...");
451 }
452}
453EXPORT_SYMBOL(add_taint);
454
455static void spin_msec(int msecs)
456{
457 int i;
458
459 for (i = 0; i < msecs; i++) {
460 touch_nmi_watchdog();
461 mdelay(1);
462 }
463}
464
465/*
466 * It just happens that oops_enter() and oops_exit() are identically
467 * implemented...
468 */
469static void do_oops_enter_exit(void)
470{
471 unsigned long flags;
472 static int spin_counter;
473
474 if (!pause_on_oops)
475 return;
476
477 spin_lock_irqsave(&pause_on_oops_lock, flags);
478 if (pause_on_oops_flag == 0) {
479 /* This CPU may now print the oops message */
480 pause_on_oops_flag = 1;
481 } else {
482 /* We need to stall this CPU */
483 if (!spin_counter) {
484 /* This CPU gets to do the counting */
485 spin_counter = pause_on_oops;
486 do {
487 spin_unlock(&pause_on_oops_lock);
488 spin_msec(MSEC_PER_SEC);
489 spin_lock(&pause_on_oops_lock);
490 } while (--spin_counter);
491 pause_on_oops_flag = 0;
492 } else {
493 /* This CPU waits for a different one */
494 while (spin_counter) {
495 spin_unlock(&pause_on_oops_lock);
496 spin_msec(1);
497 spin_lock(&pause_on_oops_lock);
498 }
499 }
500 }
501 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
502}
503
504/*
505 * Return true if the calling CPU is allowed to print oops-related info.
506 * This is a bit racy..
507 */
508bool oops_may_print(void)
509{
510 return pause_on_oops_flag == 0;
511}
512
513/*
514 * Called when the architecture enters its oops handler, before it prints
515 * anything. If this is the first CPU to oops, and it's oopsing the first
516 * time then let it proceed.
517 *
518 * This is all enabled by the pause_on_oops kernel boot option. We do all
519 * this to ensure that oopses don't scroll off the screen. It has the
520 * side-effect of preventing later-oopsing CPUs from mucking up the display,
521 * too.
522 *
523 * It turns out that the CPU which is allowed to print ends up pausing for
524 * the right duration, whereas all the other CPUs pause for twice as long:
525 * once in oops_enter(), once in oops_exit().
526 */
527void oops_enter(void)
528{
529 tracing_off();
530 /* can't trust the integrity of the kernel anymore: */
531 debug_locks_off();
532 do_oops_enter_exit();
533
534 if (sysctl_oops_all_cpu_backtrace)
535 trigger_all_cpu_backtrace();
536}
537
538/*
539 * 64-bit random ID for oopses:
540 */
541static u64 oops_id;
542
543static int init_oops_id(void)
544{
545 if (!oops_id)
546 get_random_bytes(&oops_id, sizeof(oops_id));
547 else
548 oops_id++;
549
550 return 0;
551}
552late_initcall(init_oops_id);
553
554static void print_oops_end_marker(void)
555{
556 init_oops_id();
557 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
558}
559
560/*
561 * Called when the architecture exits its oops handler, after printing
562 * everything.
563 */
564void oops_exit(void)
565{
566 do_oops_enter_exit();
567 print_oops_end_marker();
568 kmsg_dump(KMSG_DUMP_OOPS);
569}
570
571struct warn_args {
572 const char *fmt;
573 va_list args;
574};
575
576void __warn(const char *file, int line, void *caller, unsigned taint,
577 struct pt_regs *regs, struct warn_args *args)
578{
579 disable_trace_on_warning();
580
581 if (file)
582 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
583 raw_smp_processor_id(), current->pid, file, line,
584 caller);
585 else
586 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
587 raw_smp_processor_id(), current->pid, caller);
588
589 if (args)
590 vprintk(args->fmt, args->args);
591
592 if (panic_on_warn) {
593 /*
594 * This thread may hit another WARN() in the panic path.
595 * Resetting this prevents additional WARN() from panicking the
596 * system on this thread. Other threads are blocked by the
597 * panic_mutex in panic().
598 */
599 panic_on_warn = 0;
600 panic("panic_on_warn set ...\n");
601 }
602
603 print_modules();
604
605 if (regs)
606 show_regs(regs);
607 else
608 dump_stack();
609
610 print_irqtrace_events(current);
611
612 print_oops_end_marker();
613
614 /* Just a warning, don't kill lockdep. */
615 add_taint(taint, LOCKDEP_STILL_OK);
616}
617
618#ifndef __WARN_FLAGS
619void warn_slowpath_fmt(const char *file, int line, unsigned taint,
620 const char *fmt, ...)
621{
622 struct warn_args args;
623
624 pr_warn(CUT_HERE);
625
626 if (!fmt) {
627 __warn(file, line, __builtin_return_address(0), taint,
628 NULL, NULL);
629 return;
630 }
631
632 args.fmt = fmt;
633 va_start(args.args, fmt);
634 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
635 va_end(args.args);
636}
637EXPORT_SYMBOL(warn_slowpath_fmt);
638#else
639void __warn_printk(const char *fmt, ...)
640{
641 va_list args;
642
643 pr_warn(CUT_HERE);
644
645 va_start(args, fmt);
646 vprintk(fmt, args);
647 va_end(args);
648}
649EXPORT_SYMBOL(__warn_printk);
650#endif
651
652#ifdef CONFIG_BUG
653
654/* Support resetting WARN*_ONCE state */
655
656static int clear_warn_once_set(void *data, u64 val)
657{
658 generic_bug_clear_once();
659 memset(__start_once, 0, __end_once - __start_once);
660 return 0;
661}
662
663DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
664 "%lld\n");
665
666static __init int register_warn_debugfs(void)
667{
668 /* Don't care about failure */
669 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
670 &clear_warn_once_fops);
671 return 0;
672}
673
674device_initcall(register_warn_debugfs);
675#endif
676
677#ifdef CONFIG_STACKPROTECTOR
678
679/*
680 * Called when gcc's -fstack-protector feature is used, and
681 * gcc detects corruption of the on-stack canary value
682 */
683__visible noinstr void __stack_chk_fail(void)
684{
685 instrumentation_begin();
686 panic("stack-protector: Kernel stack is corrupted in: %pB",
687 __builtin_return_address(0));
688 instrumentation_end();
689}
690EXPORT_SYMBOL(__stack_chk_fail);
691
692#endif
693
694core_param(panic, panic_timeout, int, 0644);
695core_param(panic_print, panic_print, ulong, 0644);
696core_param(pause_on_oops, pause_on_oops, int, 0644);
697core_param(panic_on_warn, panic_on_warn, int, 0644);
698core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
699
700static int __init oops_setup(char *s)
701{
702 if (!s)
703 return -EINVAL;
704 if (!strcmp(s, "panic"))
705 panic_on_oops = 1;
706 return 0;
707}
708early_param("oops", oops_setup);
709
710static int __init panic_on_taint_setup(char *s)
711{
712 char *taint_str;
713
714 if (!s)
715 return -EINVAL;
716
717 taint_str = strsep(&s, ",");
718 if (kstrtoul(taint_str, 16, &panic_on_taint))
719 return -EINVAL;
720
721 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
722 panic_on_taint &= TAINT_FLAGS_MAX;
723
724 if (!panic_on_taint)
725 return -EINVAL;
726
727 if (s && !strcmp(s, "nousertaint"))
728 panic_on_taint_nousertaint = true;
729
730 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
731 panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
732
733 return 0;
734}
735early_param("panic_on_taint", panic_on_taint_setup);