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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
27#define PANIC_TIMER_STEP 100
28#define PANIC_BLINK_SPD 18
29
30int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
31static unsigned long tainted_mask;
32static int pause_on_oops;
33static int pause_on_oops_flag;
34static DEFINE_SPINLOCK(pause_on_oops_lock);
35
36int panic_timeout = CONFIG_PANIC_TIMEOUT;
37EXPORT_SYMBOL_GPL(panic_timeout);
38
39ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
40
41EXPORT_SYMBOL(panic_notifier_list);
42
43static long no_blink(int state)
44{
45 return 0;
46}
47
48/* Returns how long it waited in ms */
49long (*panic_blink)(int state);
50EXPORT_SYMBOL(panic_blink);
51
52/*
53 * Stop ourself in panic -- architecture code may override this
54 */
55void __weak panic_smp_self_stop(void)
56{
57 while (1)
58 cpu_relax();
59}
60
61/**
62 * panic - halt the system
63 * @fmt: The text string to print
64 *
65 * Display a message, then perform cleanups.
66 *
67 * This function never returns.
68 */
69void panic(const char *fmt, ...)
70{
71 static DEFINE_SPINLOCK(panic_lock);
72 static char buf[1024];
73 va_list args;
74 long i, i_next = 0;
75 int state = 0;
76
77 /*
78 * Disable local interrupts. This will prevent panic_smp_self_stop
79 * from deadlocking the first cpu that invokes the panic, since
80 * there is nothing to prevent an interrupt handler (that runs
81 * after the panic_lock is acquired) from invoking panic again.
82 */
83 local_irq_disable();
84
85 /*
86 * It's possible to come here directly from a panic-assertion and
87 * not have preempt disabled. Some functions called from here want
88 * preempt to be disabled. No point enabling it later though...
89 *
90 * Only one CPU is allowed to execute the panic code from here. For
91 * multiple parallel invocations of panic, all other CPUs either
92 * stop themself or will wait until they are stopped by the 1st CPU
93 * with smp_send_stop().
94 */
95 if (!spin_trylock(&panic_lock))
96 panic_smp_self_stop();
97
98 console_verbose();
99 bust_spinlocks(1);
100 va_start(args, fmt);
101 vsnprintf(buf, sizeof(buf), fmt, args);
102 va_end(args);
103 pr_emerg("Kernel panic - not syncing: %s\n", buf);
104#ifdef CONFIG_DEBUG_BUGVERBOSE
105 /*
106 * Avoid nested stack-dumping if a panic occurs during oops processing
107 */
108 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
109 dump_stack();
110#endif
111
112 /*
113 * If we have crashed and we have a crash kernel loaded let it handle
114 * everything else.
115 * Do we want to call this before we try to display a message?
116 */
117 crash_kexec(NULL);
118
119 /*
120 * Note smp_send_stop is the usual smp shutdown function, which
121 * unfortunately means it may not be hardened to work in a panic
122 * situation.
123 */
124 smp_send_stop();
125
126 /*
127 * Run any panic handlers, including those that might need to
128 * add information to the kmsg dump output.
129 */
130 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
131
132 kmsg_dump(KMSG_DUMP_PANIC);
133
134 bust_spinlocks(0);
135
136 if (!panic_blink)
137 panic_blink = no_blink;
138
139 if (panic_timeout > 0) {
140 /*
141 * Delay timeout seconds before rebooting the machine.
142 * We can't use the "normal" timers since we just panicked.
143 */
144 pr_emerg("Rebooting in %d seconds..", panic_timeout);
145
146 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
147 touch_nmi_watchdog();
148 if (i >= i_next) {
149 i += panic_blink(state ^= 1);
150 i_next = i + 3600 / PANIC_BLINK_SPD;
151 }
152 mdelay(PANIC_TIMER_STEP);
153 }
154 }
155 if (panic_timeout != 0) {
156 /*
157 * This will not be a clean reboot, with everything
158 * shutting down. But if there is a chance of
159 * rebooting the system it will be rebooted.
160 */
161 emergency_restart();
162 }
163#ifdef __sparc__
164 {
165 extern int stop_a_enabled;
166 /* Make sure the user can actually press Stop-A (L1-A) */
167 stop_a_enabled = 1;
168 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
169 }
170#endif
171#if defined(CONFIG_S390)
172 {
173 unsigned long caller;
174
175 caller = (unsigned long)__builtin_return_address(0);
176 disabled_wait(caller);
177 }
178#endif
179 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
180 local_irq_enable();
181 for (i = 0; ; i += PANIC_TIMER_STEP) {
182 touch_softlockup_watchdog();
183 if (i >= i_next) {
184 i += panic_blink(state ^= 1);
185 i_next = i + 3600 / PANIC_BLINK_SPD;
186 }
187 mdelay(PANIC_TIMER_STEP);
188 }
189}
190
191EXPORT_SYMBOL(panic);
192
193
194struct tnt {
195 u8 bit;
196 char true;
197 char false;
198};
199
200static const struct tnt tnts[] = {
201 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
202 { TAINT_FORCED_MODULE, 'F', ' ' },
203 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
204 { TAINT_FORCED_RMMOD, 'R', ' ' },
205 { TAINT_MACHINE_CHECK, 'M', ' ' },
206 { TAINT_BAD_PAGE, 'B', ' ' },
207 { TAINT_USER, 'U', ' ' },
208 { TAINT_DIE, 'D', ' ' },
209 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
210 { TAINT_WARN, 'W', ' ' },
211 { TAINT_CRAP, 'C', ' ' },
212 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
213 { TAINT_OOT_MODULE, 'O', ' ' },
214 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
215};
216
217/**
218 * print_tainted - return a string to represent the kernel taint state.
219 *
220 * 'P' - Proprietary module has been loaded.
221 * 'F' - Module has been forcibly loaded.
222 * 'S' - SMP with CPUs not designed for SMP.
223 * 'R' - User forced a module unload.
224 * 'M' - System experienced a machine check exception.
225 * 'B' - System has hit bad_page.
226 * 'U' - Userspace-defined naughtiness.
227 * 'D' - Kernel has oopsed before
228 * 'A' - ACPI table overridden.
229 * 'W' - Taint on warning.
230 * 'C' - modules from drivers/staging are loaded.
231 * 'I' - Working around severe firmware bug.
232 * 'O' - Out-of-tree module has been loaded.
233 * 'E' - Unsigned module has been loaded.
234 *
235 * The string is overwritten by the next call to print_tainted().
236 */
237const char *print_tainted(void)
238{
239 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
240
241 if (tainted_mask) {
242 char *s;
243 int i;
244
245 s = buf + sprintf(buf, "Tainted: ");
246 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
247 const struct tnt *t = &tnts[i];
248 *s++ = test_bit(t->bit, &tainted_mask) ?
249 t->true : t->false;
250 }
251 *s = 0;
252 } else
253 snprintf(buf, sizeof(buf), "Not tainted");
254
255 return buf;
256}
257
258int test_taint(unsigned flag)
259{
260 return test_bit(flag, &tainted_mask);
261}
262EXPORT_SYMBOL(test_taint);
263
264unsigned long get_taint(void)
265{
266 return tainted_mask;
267}
268
269/**
270 * add_taint: add a taint flag if not already set.
271 * @flag: one of the TAINT_* constants.
272 * @lockdep_ok: whether lock debugging is still OK.
273 *
274 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
275 * some notewortht-but-not-corrupting cases, it can be set to true.
276 */
277void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
278{
279 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
280 pr_warn("Disabling lock debugging due to kernel taint\n");
281
282 set_bit(flag, &tainted_mask);
283}
284EXPORT_SYMBOL(add_taint);
285
286static void spin_msec(int msecs)
287{
288 int i;
289
290 for (i = 0; i < msecs; i++) {
291 touch_nmi_watchdog();
292 mdelay(1);
293 }
294}
295
296/*
297 * It just happens that oops_enter() and oops_exit() are identically
298 * implemented...
299 */
300static void do_oops_enter_exit(void)
301{
302 unsigned long flags;
303 static int spin_counter;
304
305 if (!pause_on_oops)
306 return;
307
308 spin_lock_irqsave(&pause_on_oops_lock, flags);
309 if (pause_on_oops_flag == 0) {
310 /* This CPU may now print the oops message */
311 pause_on_oops_flag = 1;
312 } else {
313 /* We need to stall this CPU */
314 if (!spin_counter) {
315 /* This CPU gets to do the counting */
316 spin_counter = pause_on_oops;
317 do {
318 spin_unlock(&pause_on_oops_lock);
319 spin_msec(MSEC_PER_SEC);
320 spin_lock(&pause_on_oops_lock);
321 } while (--spin_counter);
322 pause_on_oops_flag = 0;
323 } else {
324 /* This CPU waits for a different one */
325 while (spin_counter) {
326 spin_unlock(&pause_on_oops_lock);
327 spin_msec(1);
328 spin_lock(&pause_on_oops_lock);
329 }
330 }
331 }
332 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
333}
334
335/*
336 * Return true if the calling CPU is allowed to print oops-related info.
337 * This is a bit racy..
338 */
339int oops_may_print(void)
340{
341 return pause_on_oops_flag == 0;
342}
343
344/*
345 * Called when the architecture enters its oops handler, before it prints
346 * anything. If this is the first CPU to oops, and it's oopsing the first
347 * time then let it proceed.
348 *
349 * This is all enabled by the pause_on_oops kernel boot option. We do all
350 * this to ensure that oopses don't scroll off the screen. It has the
351 * side-effect of preventing later-oopsing CPUs from mucking up the display,
352 * too.
353 *
354 * It turns out that the CPU which is allowed to print ends up pausing for
355 * the right duration, whereas all the other CPUs pause for twice as long:
356 * once in oops_enter(), once in oops_exit().
357 */
358void oops_enter(void)
359{
360 tracing_off();
361 /* can't trust the integrity of the kernel anymore: */
362 debug_locks_off();
363 do_oops_enter_exit();
364}
365
366/*
367 * 64-bit random ID for oopses:
368 */
369static u64 oops_id;
370
371static int init_oops_id(void)
372{
373 if (!oops_id)
374 get_random_bytes(&oops_id, sizeof(oops_id));
375 else
376 oops_id++;
377
378 return 0;
379}
380late_initcall(init_oops_id);
381
382void print_oops_end_marker(void)
383{
384 init_oops_id();
385 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
386}
387
388/*
389 * Called when the architecture exits its oops handler, after printing
390 * everything.
391 */
392void oops_exit(void)
393{
394 do_oops_enter_exit();
395 print_oops_end_marker();
396 kmsg_dump(KMSG_DUMP_OOPS);
397}
398
399#ifdef WANT_WARN_ON_SLOWPATH
400struct slowpath_args {
401 const char *fmt;
402 va_list args;
403};
404
405static void warn_slowpath_common(const char *file, int line, void *caller,
406 unsigned taint, struct slowpath_args *args)
407{
408 disable_trace_on_warning();
409
410 pr_warn("------------[ cut here ]------------\n");
411 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
412 raw_smp_processor_id(), current->pid, file, line, caller);
413
414 if (args)
415 vprintk(args->fmt, args->args);
416
417 print_modules();
418 dump_stack();
419 print_oops_end_marker();
420 /* Just a warning, don't kill lockdep. */
421 add_taint(taint, LOCKDEP_STILL_OK);
422}
423
424void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
425{
426 struct slowpath_args args;
427
428 args.fmt = fmt;
429 va_start(args.args, fmt);
430 warn_slowpath_common(file, line, __builtin_return_address(0),
431 TAINT_WARN, &args);
432 va_end(args.args);
433}
434EXPORT_SYMBOL(warn_slowpath_fmt);
435
436void warn_slowpath_fmt_taint(const char *file, int line,
437 unsigned taint, const char *fmt, ...)
438{
439 struct slowpath_args args;
440
441 args.fmt = fmt;
442 va_start(args.args, fmt);
443 warn_slowpath_common(file, line, __builtin_return_address(0),
444 taint, &args);
445 va_end(args.args);
446}
447EXPORT_SYMBOL(warn_slowpath_fmt_taint);
448
449void warn_slowpath_null(const char *file, int line)
450{
451 warn_slowpath_common(file, line, __builtin_return_address(0),
452 TAINT_WARN, NULL);
453}
454EXPORT_SYMBOL(warn_slowpath_null);
455#endif
456
457#ifdef CONFIG_CC_STACKPROTECTOR
458
459/*
460 * Called when gcc's -fstack-protector feature is used, and
461 * gcc detects corruption of the on-stack canary value
462 */
463__visible void __stack_chk_fail(void)
464{
465 panic("stack-protector: Kernel stack is corrupted in: %p\n",
466 __builtin_return_address(0));
467}
468EXPORT_SYMBOL(__stack_chk_fail);
469
470#endif
471
472core_param(panic, panic_timeout, int, 0644);
473core_param(pause_on_oops, pause_on_oops, int, 0644);
474
475static int __init oops_setup(char *s)
476{
477 if (!s)
478 return -EINVAL;
479 if (!strcmp(s, "panic"))
480 panic_on_oops = 1;
481 return 0;
482}
483early_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/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>
36
37#define PANIC_TIMER_STEP 100
38#define PANIC_BLINK_SPD 18
39
40#ifdef CONFIG_SMP
41/*
42 * Should we dump all CPUs backtraces in an oops event?
43 * Defaults to 0, can be changed via sysctl.
44 */
45unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
46#endif /* CONFIG_SMP */
47
48int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
49static unsigned long tainted_mask =
50 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
51static int pause_on_oops;
52static int pause_on_oops_flag;
53static DEFINE_SPINLOCK(pause_on_oops_lock);
54bool crash_kexec_post_notifiers;
55int panic_on_warn __read_mostly;
56unsigned long panic_on_taint;
57bool panic_on_taint_nousertaint = false;
58
59int panic_timeout = CONFIG_PANIC_TIMEOUT;
60EXPORT_SYMBOL_GPL(panic_timeout);
61
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
68unsigned long panic_print;
69
70ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
71
72EXPORT_SYMBOL(panic_notifier_list);
73
74static long no_blink(int state)
75{
76 return 0;
77}
78
79/* Returns how long it waited in ms */
80long (*panic_blink)(int state);
81EXPORT_SYMBOL(panic_blink);
82
83/*
84 * Stop ourself in panic -- architecture code may override this
85 */
86void __weak panic_smp_self_stop(void)
87{
88 while (1)
89 cpu_relax();
90}
91
92/*
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.
95 */
96void __weak nmi_panic_self_stop(struct pt_regs *regs)
97{
98 panic_smp_self_stop();
99}
100
101/*
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.
106 */
107void __weak crash_smp_send_stop(void)
108{
109 static int cpus_stopped;
110
111 /*
112 * This function can be called twice in panic path, but obviously
113 * we execute this only once.
114 */
115 if (cpus_stopped)
116 return;
117
118 /*
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
121 * situation.
122 */
123 smp_send_stop();
124 cpus_stopped = 1;
125}
126
127atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
128
129/*
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.
134 */
135void nmi_panic(struct pt_regs *regs, const char *msg)
136{
137 int old_cpu, cpu;
138
139 cpu = raw_smp_processor_id();
140 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
141
142 if (old_cpu == PANIC_CPU_INVALID)
143 panic("%s", msg);
144 else if (old_cpu != cpu)
145 nmi_panic_self_stop(regs);
146}
147EXPORT_SYMBOL(nmi_panic);
148
149static void panic_print_sys_info(void)
150{
151 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
152 console_flush_on_panic(CONSOLE_REPLAY_ALL);
153
154 if (panic_print & PANIC_PRINT_TASK_INFO)
155 show_state();
156
157 if (panic_print & PANIC_PRINT_MEM_INFO)
158 show_mem(0, NULL);
159
160 if (panic_print & PANIC_PRINT_TIMER_INFO)
161 sysrq_timer_list_show();
162
163 if (panic_print & PANIC_PRINT_LOCK_INFO)
164 debug_show_all_locks();
165
166 if (panic_print & PANIC_PRINT_FTRACE_INFO)
167 ftrace_dump(DUMP_ALL);
168}
169
170/**
171 * panic - halt the system
172 * @fmt: The text string to print
173 *
174 * Display a message, then perform cleanups.
175 *
176 * This function never returns.
177 */
178void panic(const char *fmt, ...)
179{
180 static char buf[1024];
181 va_list args;
182 long i, i_next = 0, len;
183 int state = 0;
184 int old_cpu, this_cpu;
185 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
186
187 /*
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.
192 */
193 local_irq_disable();
194 preempt_disable_notrace();
195
196 /*
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...
200 *
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().
205 *
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.
210 */
211 this_cpu = raw_smp_processor_id();
212 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
213
214 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
215 panic_smp_self_stop();
216
217 console_verbose();
218 bust_spinlocks(1);
219 va_start(args, fmt);
220 len = vscnprintf(buf, sizeof(buf), fmt, args);
221 va_end(args);
222
223 if (len && buf[len - 1] == '\n')
224 buf[len - 1] = '\0';
225
226 pr_emerg("Kernel panic - not syncing: %s\n", buf);
227#ifdef CONFIG_DEBUG_BUGVERBOSE
228 /*
229 * Avoid nested stack-dumping if a panic occurs during oops processing
230 */
231 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
232 dump_stack();
233#endif
234
235 /*
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
238 * running on them.
239 */
240 kgdb_panic(buf);
241
242 /*
243 * If we have crashed and we have a crash kernel loaded let it handle
244 * everything else.
245 * If we want to run this after calling panic_notifiers, pass
246 * the "crash_kexec_post_notifiers" option to the kernel.
247 *
248 * Bypass the panic_cpu check and call __crash_kexec directly.
249 */
250 if (!_crash_kexec_post_notifiers) {
251 printk_safe_flush_on_panic();
252 __crash_kexec(NULL);
253
254 /*
255 * Note smp_send_stop is the usual smp shutdown function, which
256 * unfortunately means it may not be hardened to work in a
257 * panic situation.
258 */
259 smp_send_stop();
260 } else {
261 /*
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.
265 */
266 crash_smp_send_stop();
267 }
268
269 /*
270 * Run any panic handlers, including those that might need to
271 * add information to the kmsg dump output.
272 */
273 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
274
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);
278
279 /*
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.
285 *
286 * Bypass the panic_cpu check and call __crash_kexec directly.
287 */
288 if (_crash_kexec_post_notifiers)
289 __crash_kexec(NULL);
290
291#ifdef CONFIG_VT
292 unblank_screen();
293#endif
294 console_unblank();
295
296 /*
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.
303 */
304 debug_locks_off();
305 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
306
307 panic_print_sys_info();
308
309 if (!panic_blink)
310 panic_blink = no_blink;
311
312 if (panic_timeout > 0) {
313 /*
314 * Delay timeout seconds before rebooting the machine.
315 * We can't use the "normal" timers since we just panicked.
316 */
317 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
318
319 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
320 touch_nmi_watchdog();
321 if (i >= i_next) {
322 i += panic_blink(state ^= 1);
323 i_next = i + 3600 / PANIC_BLINK_SPD;
324 }
325 mdelay(PANIC_TIMER_STEP);
326 }
327 }
328 if (panic_timeout != 0) {
329 /*
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.
333 */
334 if (panic_reboot_mode != REBOOT_UNDEFINED)
335 reboot_mode = panic_reboot_mode;
336 emergency_restart();
337 }
338#ifdef __sparc__
339 {
340 extern int stop_a_enabled;
341 /* Make sure the user can actually press Stop-A (L1-A) */
342 stop_a_enabled = 1;
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");
345 }
346#endif
347#if defined(CONFIG_S390)
348 disabled_wait();
349#endif
350 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
351
352 /* Do not scroll important messages printed above */
353 suppress_printk = 1;
354 local_irq_enable();
355 for (i = 0; ; i += PANIC_TIMER_STEP) {
356 touch_softlockup_watchdog();
357 if (i >= i_next) {
358 i += panic_blink(state ^= 1);
359 i_next = i + 3600 / PANIC_BLINK_SPD;
360 }
361 mdelay(PANIC_TIMER_STEP);
362 }
363}
364
365EXPORT_SYMBOL(panic);
366
367/*
368 * TAINT_FORCED_RMMOD could be a per-module flag but the module
369 * is being removed anyway.
370 */
371const 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 },
390};
391
392/**
393 * print_tainted - return a string to represent the kernel taint state.
394 *
395 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
396 *
397 * The string is overwritten by the next call to print_tainted(),
398 * but is always NULL terminated.
399 */
400const char *print_tainted(void)
401{
402 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
403
404 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
405
406 if (tainted_mask) {
407 char *s;
408 int i;
409
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;
415 }
416 *s = 0;
417 } else
418 snprintf(buf, sizeof(buf), "Not tainted");
419
420 return buf;
421}
422
423int test_taint(unsigned flag)
424{
425 return test_bit(flag, &tainted_mask);
426}
427EXPORT_SYMBOL(test_taint);
428
429unsigned long get_taint(void)
430{
431 return tainted_mask;
432}
433
434/**
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.
438 *
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.
441 */
442void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
443{
444 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
445 pr_warn("Disabling lock debugging due to kernel taint\n");
446
447 set_bit(flag, &tainted_mask);
448
449 if (tainted_mask & panic_on_taint) {
450 panic_on_taint = 0;
451 panic("panic_on_taint set ...");
452 }
453}
454EXPORT_SYMBOL(add_taint);
455
456static void spin_msec(int msecs)
457{
458 int i;
459
460 for (i = 0; i < msecs; i++) {
461 touch_nmi_watchdog();
462 mdelay(1);
463 }
464}
465
466/*
467 * It just happens that oops_enter() and oops_exit() are identically
468 * implemented...
469 */
470static void do_oops_enter_exit(void)
471{
472 unsigned long flags;
473 static int spin_counter;
474
475 if (!pause_on_oops)
476 return;
477
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;
482 } else {
483 /* We need to stall this CPU */
484 if (!spin_counter) {
485 /* This CPU gets to do the counting */
486 spin_counter = pause_on_oops;
487 do {
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;
493 } else {
494 /* This CPU waits for a different one */
495 while (spin_counter) {
496 spin_unlock(&pause_on_oops_lock);
497 spin_msec(1);
498 spin_lock(&pause_on_oops_lock);
499 }
500 }
501 }
502 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
503}
504
505/*
506 * Return true if the calling CPU is allowed to print oops-related info.
507 * This is a bit racy..
508 */
509bool oops_may_print(void)
510{
511 return pause_on_oops_flag == 0;
512}
513
514/*
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.
518 *
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,
522 * too.
523 *
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().
527 */
528void oops_enter(void)
529{
530 tracing_off();
531 /* can't trust the integrity of the kernel anymore: */
532 debug_locks_off();
533 do_oops_enter_exit();
534
535 if (sysctl_oops_all_cpu_backtrace)
536 trigger_all_cpu_backtrace();
537}
538
539/*
540 * 64-bit random ID for oopses:
541 */
542static u64 oops_id;
543
544static int init_oops_id(void)
545{
546 if (!oops_id)
547 get_random_bytes(&oops_id, sizeof(oops_id));
548 else
549 oops_id++;
550
551 return 0;
552}
553late_initcall(init_oops_id);
554
555static void print_oops_end_marker(void)
556{
557 init_oops_id();
558 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
559}
560
561/*
562 * Called when the architecture exits its oops handler, after printing
563 * everything.
564 */
565void oops_exit(void)
566{
567 do_oops_enter_exit();
568 print_oops_end_marker();
569 kmsg_dump(KMSG_DUMP_OOPS);
570}
571
572struct warn_args {
573 const char *fmt;
574 va_list args;
575};
576
577void __warn(const char *file, int line, void *caller, unsigned taint,
578 struct pt_regs *regs, struct warn_args *args)
579{
580 disable_trace_on_warning();
581
582 if (file)
583 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
584 raw_smp_processor_id(), current->pid, file, line,
585 caller);
586 else
587 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
588 raw_smp_processor_id(), current->pid, caller);
589
590 if (args)
591 vprintk(args->fmt, args->args);
592
593 print_modules();
594
595 if (regs)
596 show_regs(regs);
597
598 if (panic_on_warn) {
599 /*
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().
604 */
605 panic_on_warn = 0;
606 panic("panic_on_warn set ...\n");
607 }
608
609 if (!regs)
610 dump_stack();
611
612 print_irqtrace_events(current);
613
614 print_oops_end_marker();
615
616 /* Just a warning, don't kill lockdep. */
617 add_taint(taint, LOCKDEP_STILL_OK);
618}
619
620#ifndef __WARN_FLAGS
621void warn_slowpath_fmt(const char *file, int line, unsigned taint,
622 const char *fmt, ...)
623{
624 struct warn_args args;
625
626 pr_warn(CUT_HERE);
627
628 if (!fmt) {
629 __warn(file, line, __builtin_return_address(0), taint,
630 NULL, NULL);
631 return;
632 }
633
634 args.fmt = fmt;
635 va_start(args.args, fmt);
636 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
637 va_end(args.args);
638}
639EXPORT_SYMBOL(warn_slowpath_fmt);
640#else
641void __warn_printk(const char *fmt, ...)
642{
643 va_list args;
644
645 pr_warn(CUT_HERE);
646
647 va_start(args, fmt);
648 vprintk(fmt, args);
649 va_end(args);
650}
651EXPORT_SYMBOL(__warn_printk);
652#endif
653
654#ifdef CONFIG_BUG
655
656/* Support resetting WARN*_ONCE state */
657
658static int clear_warn_once_set(void *data, u64 val)
659{
660 generic_bug_clear_once();
661 memset(__start_once, 0, __end_once - __start_once);
662 return 0;
663}
664
665DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
666 "%lld\n");
667
668static __init int register_warn_debugfs(void)
669{
670 /* Don't care about failure */
671 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
672 &clear_warn_once_fops);
673 return 0;
674}
675
676device_initcall(register_warn_debugfs);
677#endif
678
679#ifdef CONFIG_STACKPROTECTOR
680
681/*
682 * Called when gcc's -fstack-protector feature is used, and
683 * gcc detects corruption of the on-stack canary value
684 */
685__visible noinstr void __stack_chk_fail(void)
686{
687 instrumentation_begin();
688 panic("stack-protector: Kernel stack is corrupted in: %pB",
689 __builtin_return_address(0));
690 instrumentation_end();
691}
692EXPORT_SYMBOL(__stack_chk_fail);
693
694#endif
695
696core_param(panic, panic_timeout, int, 0644);
697core_param(panic_print, panic_print, ulong, 0644);
698core_param(pause_on_oops, pause_on_oops, int, 0644);
699core_param(panic_on_warn, panic_on_warn, int, 0644);
700core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
701
702static int __init oops_setup(char *s)
703{
704 if (!s)
705 return -EINVAL;
706 if (!strcmp(s, "panic"))
707 panic_on_oops = 1;
708 return 0;
709}
710early_param("oops", oops_setup);
711
712static int __init panic_on_taint_setup(char *s)
713{
714 char *taint_str;
715
716 if (!s)
717 return -EINVAL;
718
719 taint_str = strsep(&s, ",");
720 if (kstrtoul(taint_str, 16, &panic_on_taint))
721 return -EINVAL;
722
723 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
724 panic_on_taint &= TAINT_FLAGS_MAX;
725
726 if (!panic_on_taint)
727 return -EINVAL;
728
729 if (s && !strcmp(s, "nousertaint"))
730 panic_on_taint_nousertaint = true;
731
732 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
733 panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
734
735 return 0;
736}
737early_param("panic_on_taint", panic_on_taint_setup);