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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/string_helpers.h>
29#include <linux/sysrq.h>
30#include <linux/init.h>
31#include <linux/nmi.h>
32#include <linux/console.h>
33#include <linux/bug.h>
34#include <linux/ratelimit.h>
35#include <linux/debugfs.h>
36#include <linux/sysfs.h>
37#include <linux/context_tracking.h>
38#include <linux/seq_buf.h>
39#include <trace/events/error_report.h>
40#include <asm/sections.h>
41
42#define PANIC_TIMER_STEP 100
43#define PANIC_BLINK_SPD 18
44
45#ifdef CONFIG_SMP
46/*
47 * Should we dump all CPUs backtraces in an oops event?
48 * Defaults to 0, can be changed via sysctl.
49 */
50static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
51#else
52#define sysctl_oops_all_cpu_backtrace 0
53#endif /* CONFIG_SMP */
54
55int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
56static unsigned long tainted_mask =
57 IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
58static int pause_on_oops;
59static int pause_on_oops_flag;
60static DEFINE_SPINLOCK(pause_on_oops_lock);
61bool crash_kexec_post_notifiers;
62int panic_on_warn __read_mostly;
63unsigned long panic_on_taint;
64bool panic_on_taint_nousertaint = false;
65static unsigned int warn_limit __read_mostly;
66
67bool panic_triggering_all_cpu_backtrace;
68
69int panic_timeout = CONFIG_PANIC_TIMEOUT;
70EXPORT_SYMBOL_GPL(panic_timeout);
71
72#define PANIC_PRINT_TASK_INFO 0x00000001
73#define PANIC_PRINT_MEM_INFO 0x00000002
74#define PANIC_PRINT_TIMER_INFO 0x00000004
75#define PANIC_PRINT_LOCK_INFO 0x00000008
76#define PANIC_PRINT_FTRACE_INFO 0x00000010
77#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
78#define PANIC_PRINT_ALL_CPU_BT 0x00000040
79#define PANIC_PRINT_BLOCKED_TASKS 0x00000080
80unsigned long panic_print;
81
82ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
83
84EXPORT_SYMBOL(panic_notifier_list);
85
86#ifdef CONFIG_SYSCTL
87static struct ctl_table kern_panic_table[] = {
88#ifdef CONFIG_SMP
89 {
90 .procname = "oops_all_cpu_backtrace",
91 .data = &sysctl_oops_all_cpu_backtrace,
92 .maxlen = sizeof(int),
93 .mode = 0644,
94 .proc_handler = proc_dointvec_minmax,
95 .extra1 = SYSCTL_ZERO,
96 .extra2 = SYSCTL_ONE,
97 },
98#endif
99 {
100 .procname = "warn_limit",
101 .data = &warn_limit,
102 .maxlen = sizeof(warn_limit),
103 .mode = 0644,
104 .proc_handler = proc_douintvec,
105 },
106};
107
108static __init int kernel_panic_sysctls_init(void)
109{
110 register_sysctl_init("kernel", kern_panic_table);
111 return 0;
112}
113late_initcall(kernel_panic_sysctls_init);
114#endif
115
116static atomic_t warn_count = ATOMIC_INIT(0);
117
118#ifdef CONFIG_SYSFS
119static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
120 char *page)
121{
122 return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
123}
124
125static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
126
127static __init int kernel_panic_sysfs_init(void)
128{
129 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
130 return 0;
131}
132late_initcall(kernel_panic_sysfs_init);
133#endif
134
135static long no_blink(int state)
136{
137 return 0;
138}
139
140/* Returns how long it waited in ms */
141long (*panic_blink)(int state);
142EXPORT_SYMBOL(panic_blink);
143
144/*
145 * Stop ourself in panic -- architecture code may override this
146 */
147void __weak __noreturn panic_smp_self_stop(void)
148{
149 while (1)
150 cpu_relax();
151}
152
153/*
154 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
155 * may override this to prepare for crash dumping, e.g. save regs info.
156 */
157void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs)
158{
159 panic_smp_self_stop();
160}
161
162/*
163 * Stop other CPUs in panic. Architecture dependent code may override this
164 * with more suitable version. For example, if the architecture supports
165 * crash dump, it should save registers of each stopped CPU and disable
166 * per-CPU features such as virtualization extensions.
167 */
168void __weak crash_smp_send_stop(void)
169{
170 static int cpus_stopped;
171
172 /*
173 * This function can be called twice in panic path, but obviously
174 * we execute this only once.
175 */
176 if (cpus_stopped)
177 return;
178
179 /*
180 * Note smp_send_stop is the usual smp shutdown function, which
181 * unfortunately means it may not be hardened to work in a panic
182 * situation.
183 */
184 smp_send_stop();
185 cpus_stopped = 1;
186}
187
188atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
189
190/*
191 * A variant of panic() called from NMI context. We return if we've already
192 * panicked on this CPU. If another CPU already panicked, loop in
193 * nmi_panic_self_stop() which can provide architecture dependent code such
194 * as saving register state for crash dump.
195 */
196void nmi_panic(struct pt_regs *regs, const char *msg)
197{
198 int old_cpu, this_cpu;
199
200 old_cpu = PANIC_CPU_INVALID;
201 this_cpu = raw_smp_processor_id();
202
203 /* atomic_try_cmpxchg updates old_cpu on failure */
204 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
205 panic("%s", msg);
206 else if (old_cpu != this_cpu)
207 nmi_panic_self_stop(regs);
208}
209EXPORT_SYMBOL(nmi_panic);
210
211static void panic_print_sys_info(bool console_flush)
212{
213 if (console_flush) {
214 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
215 console_flush_on_panic(CONSOLE_REPLAY_ALL);
216 return;
217 }
218
219 if (panic_print & PANIC_PRINT_TASK_INFO)
220 show_state();
221
222 if (panic_print & PANIC_PRINT_MEM_INFO)
223 show_mem();
224
225 if (panic_print & PANIC_PRINT_TIMER_INFO)
226 sysrq_timer_list_show();
227
228 if (panic_print & PANIC_PRINT_LOCK_INFO)
229 debug_show_all_locks();
230
231 if (panic_print & PANIC_PRINT_FTRACE_INFO)
232 ftrace_dump(DUMP_ALL);
233
234 if (panic_print & PANIC_PRINT_BLOCKED_TASKS)
235 show_state_filter(TASK_UNINTERRUPTIBLE);
236}
237
238void check_panic_on_warn(const char *origin)
239{
240 unsigned int limit;
241
242 if (panic_on_warn)
243 panic("%s: panic_on_warn set ...\n", origin);
244
245 limit = READ_ONCE(warn_limit);
246 if (atomic_inc_return(&warn_count) >= limit && limit)
247 panic("%s: system warned too often (kernel.warn_limit is %d)",
248 origin, limit);
249}
250
251/*
252 * Helper that triggers the NMI backtrace (if set in panic_print)
253 * and then performs the secondary CPUs shutdown - we cannot have
254 * the NMI backtrace after the CPUs are off!
255 */
256static void panic_other_cpus_shutdown(bool crash_kexec)
257{
258 if (panic_print & PANIC_PRINT_ALL_CPU_BT) {
259 /* Temporary allow non-panic CPUs to write their backtraces. */
260 panic_triggering_all_cpu_backtrace = true;
261 trigger_all_cpu_backtrace();
262 panic_triggering_all_cpu_backtrace = false;
263 }
264
265 /*
266 * Note that smp_send_stop() is the usual SMP shutdown function,
267 * which unfortunately may not be hardened to work in a panic
268 * situation. If we want to do crash dump after notifier calls
269 * and kmsg_dump, we will need architecture dependent extra
270 * bits in addition to stopping other CPUs, hence we rely on
271 * crash_smp_send_stop() for that.
272 */
273 if (!crash_kexec)
274 smp_send_stop();
275 else
276 crash_smp_send_stop();
277}
278
279/**
280 * panic - halt the system
281 * @fmt: The text string to print
282 *
283 * Display a message, then perform cleanups.
284 *
285 * This function never returns.
286 */
287void panic(const char *fmt, ...)
288{
289 static char buf[1024];
290 va_list args;
291 long i, i_next = 0, len;
292 int state = 0;
293 int old_cpu, this_cpu;
294 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
295
296 if (panic_on_warn) {
297 /*
298 * This thread may hit another WARN() in the panic path.
299 * Resetting this prevents additional WARN() from panicking the
300 * system on this thread. Other threads are blocked by the
301 * panic_mutex in panic().
302 */
303 panic_on_warn = 0;
304 }
305
306 /*
307 * Disable local interrupts. This will prevent panic_smp_self_stop
308 * from deadlocking the first cpu that invokes the panic, since
309 * there is nothing to prevent an interrupt handler (that runs
310 * after setting panic_cpu) from invoking panic() again.
311 */
312 local_irq_disable();
313 preempt_disable_notrace();
314
315 /*
316 * It's possible to come here directly from a panic-assertion and
317 * not have preempt disabled. Some functions called from here want
318 * preempt to be disabled. No point enabling it later though...
319 *
320 * Only one CPU is allowed to execute the panic code from here. For
321 * multiple parallel invocations of panic, all other CPUs either
322 * stop themself or will wait until they are stopped by the 1st CPU
323 * with smp_send_stop().
324 *
325 * cmpxchg success means this is the 1st CPU which comes here,
326 * so go ahead.
327 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
328 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
329 */
330 old_cpu = PANIC_CPU_INVALID;
331 this_cpu = raw_smp_processor_id();
332
333 /* atomic_try_cmpxchg updates old_cpu on failure */
334 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
335 /* go ahead */
336 } else if (old_cpu != this_cpu)
337 panic_smp_self_stop();
338
339 console_verbose();
340 bust_spinlocks(1);
341 va_start(args, fmt);
342 len = vscnprintf(buf, sizeof(buf), fmt, args);
343 va_end(args);
344
345 if (len && buf[len - 1] == '\n')
346 buf[len - 1] = '\0';
347
348 pr_emerg("Kernel panic - not syncing: %s\n", buf);
349#ifdef CONFIG_DEBUG_BUGVERBOSE
350 /*
351 * Avoid nested stack-dumping if a panic occurs during oops processing
352 */
353 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
354 dump_stack();
355#endif
356
357 /*
358 * If kgdb is enabled, give it a chance to run before we stop all
359 * the other CPUs or else we won't be able to debug processes left
360 * running on them.
361 */
362 kgdb_panic(buf);
363
364 /*
365 * If we have crashed and we have a crash kernel loaded let it handle
366 * everything else.
367 * If we want to run this after calling panic_notifiers, pass
368 * the "crash_kexec_post_notifiers" option to the kernel.
369 *
370 * Bypass the panic_cpu check and call __crash_kexec directly.
371 */
372 if (!_crash_kexec_post_notifiers)
373 __crash_kexec(NULL);
374
375 panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
376
377 printk_legacy_allow_panic_sync();
378
379 /*
380 * Run any panic handlers, including those that might need to
381 * add information to the kmsg dump output.
382 */
383 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
384
385 panic_print_sys_info(false);
386
387 kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
388
389 /*
390 * If you doubt kdump always works fine in any situation,
391 * "crash_kexec_post_notifiers" offers you a chance to run
392 * panic_notifiers and dumping kmsg before kdump.
393 * Note: since some panic_notifiers can make crashed kernel
394 * more unstable, it can increase risks of the kdump failure too.
395 *
396 * Bypass the panic_cpu check and call __crash_kexec directly.
397 */
398 if (_crash_kexec_post_notifiers)
399 __crash_kexec(NULL);
400
401 console_unblank();
402
403 /*
404 * We may have ended up stopping the CPU holding the lock (in
405 * smp_send_stop()) while still having some valuable data in the console
406 * buffer. Try to acquire the lock then release it regardless of the
407 * result. The release will also print the buffers out. Locks debug
408 * should be disabled to avoid reporting bad unlock balance when
409 * panic() is not being callled from OOPS.
410 */
411 debug_locks_off();
412 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
413
414 panic_print_sys_info(true);
415
416 if (!panic_blink)
417 panic_blink = no_blink;
418
419 if (panic_timeout > 0) {
420 /*
421 * Delay timeout seconds before rebooting the machine.
422 * We can't use the "normal" timers since we just panicked.
423 */
424 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
425
426 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
427 touch_nmi_watchdog();
428 if (i >= i_next) {
429 i += panic_blink(state ^= 1);
430 i_next = i + 3600 / PANIC_BLINK_SPD;
431 }
432 mdelay(PANIC_TIMER_STEP);
433 }
434 }
435 if (panic_timeout != 0) {
436 /*
437 * This will not be a clean reboot, with everything
438 * shutting down. But if there is a chance of
439 * rebooting the system it will be rebooted.
440 */
441 if (panic_reboot_mode != REBOOT_UNDEFINED)
442 reboot_mode = panic_reboot_mode;
443 emergency_restart();
444 }
445#ifdef __sparc__
446 {
447 extern int stop_a_enabled;
448 /* Make sure the user can actually press Stop-A (L1-A) */
449 stop_a_enabled = 1;
450 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
451 "twice on console to return to the boot prom\n");
452 }
453#endif
454#if defined(CONFIG_S390)
455 disabled_wait();
456#endif
457 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
458
459 /* Do not scroll important messages printed above */
460 suppress_printk = 1;
461
462 /*
463 * The final messages may not have been printed if in a context that
464 * defers printing (such as NMI) and irq_work is not available.
465 * Explicitly flush the kernel log buffer one last time.
466 */
467 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
468 nbcon_atomic_flush_unsafe();
469
470 local_irq_enable();
471 for (i = 0; ; i += PANIC_TIMER_STEP) {
472 touch_softlockup_watchdog();
473 if (i >= i_next) {
474 i += panic_blink(state ^= 1);
475 i_next = i + 3600 / PANIC_BLINK_SPD;
476 }
477 mdelay(PANIC_TIMER_STEP);
478 }
479}
480
481EXPORT_SYMBOL(panic);
482
483#define TAINT_FLAG(taint, _c_true, _c_false, _module) \
484 [ TAINT_##taint ] = { \
485 .c_true = _c_true, .c_false = _c_false, \
486 .module = _module, \
487 .desc = #taint, \
488 }
489
490/*
491 * TAINT_FORCED_RMMOD could be a per-module flag but the module
492 * is being removed anyway.
493 */
494const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
495 TAINT_FLAG(PROPRIETARY_MODULE, 'P', 'G', true),
496 TAINT_FLAG(FORCED_MODULE, 'F', ' ', true),
497 TAINT_FLAG(CPU_OUT_OF_SPEC, 'S', ' ', false),
498 TAINT_FLAG(FORCED_RMMOD, 'R', ' ', false),
499 TAINT_FLAG(MACHINE_CHECK, 'M', ' ', false),
500 TAINT_FLAG(BAD_PAGE, 'B', ' ', false),
501 TAINT_FLAG(USER, 'U', ' ', false),
502 TAINT_FLAG(DIE, 'D', ' ', false),
503 TAINT_FLAG(OVERRIDDEN_ACPI_TABLE, 'A', ' ', false),
504 TAINT_FLAG(WARN, 'W', ' ', false),
505 TAINT_FLAG(CRAP, 'C', ' ', true),
506 TAINT_FLAG(FIRMWARE_WORKAROUND, 'I', ' ', false),
507 TAINT_FLAG(OOT_MODULE, 'O', ' ', true),
508 TAINT_FLAG(UNSIGNED_MODULE, 'E', ' ', true),
509 TAINT_FLAG(SOFTLOCKUP, 'L', ' ', false),
510 TAINT_FLAG(LIVEPATCH, 'K', ' ', true),
511 TAINT_FLAG(AUX, 'X', ' ', true),
512 TAINT_FLAG(RANDSTRUCT, 'T', ' ', true),
513 TAINT_FLAG(TEST, 'N', ' ', true),
514};
515
516#undef TAINT_FLAG
517
518static void print_tainted_seq(struct seq_buf *s, bool verbose)
519{
520 const char *sep = "";
521 int i;
522
523 if (!tainted_mask) {
524 seq_buf_puts(s, "Not tainted");
525 return;
526 }
527
528 seq_buf_printf(s, "Tainted: ");
529 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
530 const struct taint_flag *t = &taint_flags[i];
531 bool is_set = test_bit(i, &tainted_mask);
532 char c = is_set ? t->c_true : t->c_false;
533
534 if (verbose) {
535 if (is_set) {
536 seq_buf_printf(s, "%s[%c]=%s", sep, c, t->desc);
537 sep = ", ";
538 }
539 } else {
540 seq_buf_putc(s, c);
541 }
542 }
543}
544
545static const char *_print_tainted(bool verbose)
546{
547 /* FIXME: what should the size be? */
548 static char buf[sizeof(taint_flags)];
549 struct seq_buf s;
550
551 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
552
553 seq_buf_init(&s, buf, sizeof(buf));
554
555 print_tainted_seq(&s, verbose);
556
557 return seq_buf_str(&s);
558}
559
560/**
561 * print_tainted - return a string to represent the kernel taint state.
562 *
563 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
564 *
565 * The string is overwritten by the next call to print_tainted(),
566 * but is always NULL terminated.
567 */
568const char *print_tainted(void)
569{
570 return _print_tainted(false);
571}
572
573/**
574 * print_tainted_verbose - A more verbose version of print_tainted()
575 */
576const char *print_tainted_verbose(void)
577{
578 return _print_tainted(true);
579}
580
581int test_taint(unsigned flag)
582{
583 return test_bit(flag, &tainted_mask);
584}
585EXPORT_SYMBOL(test_taint);
586
587unsigned long get_taint(void)
588{
589 return tainted_mask;
590}
591
592/**
593 * add_taint: add a taint flag if not already set.
594 * @flag: one of the TAINT_* constants.
595 * @lockdep_ok: whether lock debugging is still OK.
596 *
597 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
598 * some notewortht-but-not-corrupting cases, it can be set to true.
599 */
600void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
601{
602 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
603 pr_warn("Disabling lock debugging due to kernel taint\n");
604
605 set_bit(flag, &tainted_mask);
606
607 if (tainted_mask & panic_on_taint) {
608 panic_on_taint = 0;
609 panic("panic_on_taint set ...");
610 }
611}
612EXPORT_SYMBOL(add_taint);
613
614static void spin_msec(int msecs)
615{
616 int i;
617
618 for (i = 0; i < msecs; i++) {
619 touch_nmi_watchdog();
620 mdelay(1);
621 }
622}
623
624/*
625 * It just happens that oops_enter() and oops_exit() are identically
626 * implemented...
627 */
628static void do_oops_enter_exit(void)
629{
630 unsigned long flags;
631 static int spin_counter;
632
633 if (!pause_on_oops)
634 return;
635
636 spin_lock_irqsave(&pause_on_oops_lock, flags);
637 if (pause_on_oops_flag == 0) {
638 /* This CPU may now print the oops message */
639 pause_on_oops_flag = 1;
640 } else {
641 /* We need to stall this CPU */
642 if (!spin_counter) {
643 /* This CPU gets to do the counting */
644 spin_counter = pause_on_oops;
645 do {
646 spin_unlock(&pause_on_oops_lock);
647 spin_msec(MSEC_PER_SEC);
648 spin_lock(&pause_on_oops_lock);
649 } while (--spin_counter);
650 pause_on_oops_flag = 0;
651 } else {
652 /* This CPU waits for a different one */
653 while (spin_counter) {
654 spin_unlock(&pause_on_oops_lock);
655 spin_msec(1);
656 spin_lock(&pause_on_oops_lock);
657 }
658 }
659 }
660 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
661}
662
663/*
664 * Return true if the calling CPU is allowed to print oops-related info.
665 * This is a bit racy..
666 */
667bool oops_may_print(void)
668{
669 return pause_on_oops_flag == 0;
670}
671
672/*
673 * Called when the architecture enters its oops handler, before it prints
674 * anything. If this is the first CPU to oops, and it's oopsing the first
675 * time then let it proceed.
676 *
677 * This is all enabled by the pause_on_oops kernel boot option. We do all
678 * this to ensure that oopses don't scroll off the screen. It has the
679 * side-effect of preventing later-oopsing CPUs from mucking up the display,
680 * too.
681 *
682 * It turns out that the CPU which is allowed to print ends up pausing for
683 * the right duration, whereas all the other CPUs pause for twice as long:
684 * once in oops_enter(), once in oops_exit().
685 */
686void oops_enter(void)
687{
688 nbcon_cpu_emergency_enter();
689 tracing_off();
690 /* can't trust the integrity of the kernel anymore: */
691 debug_locks_off();
692 do_oops_enter_exit();
693
694 if (sysctl_oops_all_cpu_backtrace)
695 trigger_all_cpu_backtrace();
696}
697
698static void print_oops_end_marker(void)
699{
700 pr_warn("---[ end trace %016llx ]---\n", 0ULL);
701}
702
703/*
704 * Called when the architecture exits its oops handler, after printing
705 * everything.
706 */
707void oops_exit(void)
708{
709 do_oops_enter_exit();
710 print_oops_end_marker();
711 nbcon_cpu_emergency_exit();
712 kmsg_dump(KMSG_DUMP_OOPS);
713}
714
715struct warn_args {
716 const char *fmt;
717 va_list args;
718};
719
720void __warn(const char *file, int line, void *caller, unsigned taint,
721 struct pt_regs *regs, struct warn_args *args)
722{
723 nbcon_cpu_emergency_enter();
724
725 disable_trace_on_warning();
726
727 if (file)
728 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
729 raw_smp_processor_id(), current->pid, file, line,
730 caller);
731 else
732 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
733 raw_smp_processor_id(), current->pid, caller);
734
735#pragma GCC diagnostic push
736#ifndef __clang__
737#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
738#endif
739 if (args)
740 vprintk(args->fmt, args->args);
741#pragma GCC diagnostic pop
742
743 print_modules();
744
745 if (regs)
746 show_regs(regs);
747
748 check_panic_on_warn("kernel");
749
750 if (!regs)
751 dump_stack();
752
753 print_irqtrace_events(current);
754
755 print_oops_end_marker();
756 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);
757
758 /* Just a warning, don't kill lockdep. */
759 add_taint(taint, LOCKDEP_STILL_OK);
760
761 nbcon_cpu_emergency_exit();
762}
763
764#ifdef CONFIG_BUG
765#ifndef __WARN_FLAGS
766void warn_slowpath_fmt(const char *file, int line, unsigned taint,
767 const char *fmt, ...)
768{
769 bool rcu = warn_rcu_enter();
770 struct warn_args args;
771
772 pr_warn(CUT_HERE);
773
774 if (!fmt) {
775 __warn(file, line, __builtin_return_address(0), taint,
776 NULL, NULL);
777 warn_rcu_exit(rcu);
778 return;
779 }
780
781 args.fmt = fmt;
782 va_start(args.args, fmt);
783 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
784 va_end(args.args);
785 warn_rcu_exit(rcu);
786}
787EXPORT_SYMBOL(warn_slowpath_fmt);
788#else
789void __warn_printk(const char *fmt, ...)
790{
791 bool rcu = warn_rcu_enter();
792 va_list args;
793
794 pr_warn(CUT_HERE);
795
796 va_start(args, fmt);
797 vprintk(fmt, args);
798 va_end(args);
799 warn_rcu_exit(rcu);
800}
801EXPORT_SYMBOL(__warn_printk);
802#endif
803
804/* Support resetting WARN*_ONCE state */
805
806static int clear_warn_once_set(void *data, u64 val)
807{
808 generic_bug_clear_once();
809 memset(__start_once, 0, __end_once - __start_once);
810 return 0;
811}
812
813DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
814 "%lld\n");
815
816static __init int register_warn_debugfs(void)
817{
818 /* Don't care about failure */
819 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
820 &clear_warn_once_fops);
821 return 0;
822}
823
824device_initcall(register_warn_debugfs);
825#endif
826
827#ifdef CONFIG_STACKPROTECTOR
828
829/*
830 * Called when gcc's -fstack-protector feature is used, and
831 * gcc detects corruption of the on-stack canary value
832 */
833__visible noinstr void __stack_chk_fail(void)
834{
835 instrumentation_begin();
836 panic("stack-protector: Kernel stack is corrupted in: %pB",
837 __builtin_return_address(0));
838 instrumentation_end();
839}
840EXPORT_SYMBOL(__stack_chk_fail);
841
842#endif
843
844core_param(panic, panic_timeout, int, 0644);
845core_param(panic_print, panic_print, ulong, 0644);
846core_param(pause_on_oops, pause_on_oops, int, 0644);
847core_param(panic_on_warn, panic_on_warn, int, 0644);
848core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
849
850static int __init oops_setup(char *s)
851{
852 if (!s)
853 return -EINVAL;
854 if (!strcmp(s, "panic"))
855 panic_on_oops = 1;
856 return 0;
857}
858early_param("oops", oops_setup);
859
860static int __init panic_on_taint_setup(char *s)
861{
862 char *taint_str;
863
864 if (!s)
865 return -EINVAL;
866
867 taint_str = strsep(&s, ",");
868 if (kstrtoul(taint_str, 16, &panic_on_taint))
869 return -EINVAL;
870
871 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
872 panic_on_taint &= TAINT_FLAGS_MAX;
873
874 if (!panic_on_taint)
875 return -EINVAL;
876
877 if (s && !strcmp(s, "nousertaint"))
878 panic_on_taint_nousertaint = true;
879
880 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n",
881 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint));
882
883 return 0;
884}
885early_param("panic_on_taint", panic_on_taint_setup);