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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
74atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
75
76/*
77 * A variant of panic() called from NMI context. We return if we've already
78 * panicked on this CPU. If another CPU already panicked, loop in
79 * nmi_panic_self_stop() which can provide architecture dependent code such
80 * as saving register state for crash dump.
81 */
82void nmi_panic(struct pt_regs *regs, const char *msg)
83{
84 int old_cpu, cpu;
85
86 cpu = raw_smp_processor_id();
87 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
88
89 if (old_cpu == PANIC_CPU_INVALID)
90 panic("%s", msg);
91 else if (old_cpu != cpu)
92 nmi_panic_self_stop(regs);
93}
94EXPORT_SYMBOL(nmi_panic);
95
96/**
97 * panic - halt the system
98 * @fmt: The text string to print
99 *
100 * Display a message, then perform cleanups.
101 *
102 * This function never returns.
103 */
104void panic(const char *fmt, ...)
105{
106 static char buf[1024];
107 va_list args;
108 long i, i_next = 0;
109 int state = 0;
110 int old_cpu, this_cpu;
111
112 /*
113 * Disable local interrupts. This will prevent panic_smp_self_stop
114 * from deadlocking the first cpu that invokes the panic, since
115 * there is nothing to prevent an interrupt handler (that runs
116 * after setting panic_cpu) from invoking panic() again.
117 */
118 local_irq_disable();
119
120 /*
121 * It's possible to come here directly from a panic-assertion and
122 * not have preempt disabled. Some functions called from here want
123 * preempt to be disabled. No point enabling it later though...
124 *
125 * Only one CPU is allowed to execute the panic code from here. For
126 * multiple parallel invocations of panic, all other CPUs either
127 * stop themself or will wait until they are stopped by the 1st CPU
128 * with smp_send_stop().
129 *
130 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
131 * comes here, so go ahead.
132 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
133 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
134 */
135 this_cpu = raw_smp_processor_id();
136 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
137
138 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
139 panic_smp_self_stop();
140
141 console_verbose();
142 bust_spinlocks(1);
143 va_start(args, fmt);
144 vsnprintf(buf, sizeof(buf), fmt, args);
145 va_end(args);
146 pr_emerg("Kernel panic - not syncing: %s\n", buf);
147#ifdef CONFIG_DEBUG_BUGVERBOSE
148 /*
149 * Avoid nested stack-dumping if a panic occurs during oops processing
150 */
151 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
152 dump_stack();
153#endif
154
155 /*
156 * If we have crashed and we have a crash kernel loaded let it handle
157 * everything else.
158 * If we want to run this after calling panic_notifiers, pass
159 * the "crash_kexec_post_notifiers" option to the kernel.
160 *
161 * Bypass the panic_cpu check and call __crash_kexec directly.
162 */
163 if (!crash_kexec_post_notifiers)
164 __crash_kexec(NULL);
165
166 /*
167 * Note smp_send_stop is the usual smp shutdown function, which
168 * unfortunately means it may not be hardened to work in a panic
169 * situation.
170 */
171 smp_send_stop();
172
173 /*
174 * Run any panic handlers, including those that might need to
175 * add information to the kmsg dump output.
176 */
177 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
178
179 kmsg_dump(KMSG_DUMP_PANIC);
180
181 /*
182 * If you doubt kdump always works fine in any situation,
183 * "crash_kexec_post_notifiers" offers you a chance to run
184 * panic_notifiers and dumping kmsg before kdump.
185 * Note: since some panic_notifiers can make crashed kernel
186 * more unstable, it can increase risks of the kdump failure too.
187 *
188 * Bypass the panic_cpu check and call __crash_kexec directly.
189 */
190 if (crash_kexec_post_notifiers)
191 __crash_kexec(NULL);
192
193 bust_spinlocks(0);
194
195 /*
196 * We may have ended up stopping the CPU holding the lock (in
197 * smp_send_stop()) while still having some valuable data in the console
198 * buffer. Try to acquire the lock then release it regardless of the
199 * result. The release will also print the buffers out. Locks debug
200 * should be disabled to avoid reporting bad unlock balance when
201 * panic() is not being callled from OOPS.
202 */
203 debug_locks_off();
204 console_flush_on_panic();
205
206 if (!panic_blink)
207 panic_blink = no_blink;
208
209 if (panic_timeout > 0) {
210 /*
211 * Delay timeout seconds before rebooting the machine.
212 * We can't use the "normal" timers since we just panicked.
213 */
214 pr_emerg("Rebooting in %d seconds..", panic_timeout);
215
216 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
217 touch_nmi_watchdog();
218 if (i >= i_next) {
219 i += panic_blink(state ^= 1);
220 i_next = i + 3600 / PANIC_BLINK_SPD;
221 }
222 mdelay(PANIC_TIMER_STEP);
223 }
224 }
225 if (panic_timeout != 0) {
226 /*
227 * This will not be a clean reboot, with everything
228 * shutting down. But if there is a chance of
229 * rebooting the system it will be rebooted.
230 */
231 emergency_restart();
232 }
233#ifdef __sparc__
234 {
235 extern int stop_a_enabled;
236 /* Make sure the user can actually press Stop-A (L1-A) */
237 stop_a_enabled = 1;
238 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
239 }
240#endif
241#if defined(CONFIG_S390)
242 {
243 unsigned long caller;
244
245 caller = (unsigned long)__builtin_return_address(0);
246 disabled_wait(caller);
247 }
248#endif
249 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
250 local_irq_enable();
251 for (i = 0; ; i += PANIC_TIMER_STEP) {
252 touch_softlockup_watchdog();
253 if (i >= i_next) {
254 i += panic_blink(state ^= 1);
255 i_next = i + 3600 / PANIC_BLINK_SPD;
256 }
257 mdelay(PANIC_TIMER_STEP);
258 }
259}
260
261EXPORT_SYMBOL(panic);
262
263
264struct tnt {
265 u8 bit;
266 char true;
267 char false;
268};
269
270static const struct tnt tnts[] = {
271 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
272 { TAINT_FORCED_MODULE, 'F', ' ' },
273 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
274 { TAINT_FORCED_RMMOD, 'R', ' ' },
275 { TAINT_MACHINE_CHECK, 'M', ' ' },
276 { TAINT_BAD_PAGE, 'B', ' ' },
277 { TAINT_USER, 'U', ' ' },
278 { TAINT_DIE, 'D', ' ' },
279 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
280 { TAINT_WARN, 'W', ' ' },
281 { TAINT_CRAP, 'C', ' ' },
282 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
283 { TAINT_OOT_MODULE, 'O', ' ' },
284 { TAINT_UNSIGNED_MODULE, 'E', ' ' },
285 { TAINT_SOFTLOCKUP, 'L', ' ' },
286 { TAINT_LIVEPATCH, 'K', ' ' },
287};
288
289/**
290 * print_tainted - return a string to represent the kernel taint state.
291 *
292 * 'P' - Proprietary module has been loaded.
293 * 'F' - Module has been forcibly loaded.
294 * 'S' - SMP with CPUs not designed for SMP.
295 * 'R' - User forced a module unload.
296 * 'M' - System experienced a machine check exception.
297 * 'B' - System has hit bad_page.
298 * 'U' - Userspace-defined naughtiness.
299 * 'D' - Kernel has oopsed before
300 * 'A' - ACPI table overridden.
301 * 'W' - Taint on warning.
302 * 'C' - modules from drivers/staging are loaded.
303 * 'I' - Working around severe firmware bug.
304 * 'O' - Out-of-tree module has been loaded.
305 * 'E' - Unsigned module has been loaded.
306 * 'L' - A soft lockup has previously occurred.
307 * 'K' - Kernel has been live patched.
308 *
309 * The string is overwritten by the next call to print_tainted().
310 */
311const char *print_tainted(void)
312{
313 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
314
315 if (tainted_mask) {
316 char *s;
317 int i;
318
319 s = buf + sprintf(buf, "Tainted: ");
320 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
321 const struct tnt *t = &tnts[i];
322 *s++ = test_bit(t->bit, &tainted_mask) ?
323 t->true : t->false;
324 }
325 *s = 0;
326 } else
327 snprintf(buf, sizeof(buf), "Not tainted");
328
329 return buf;
330}
331
332int test_taint(unsigned flag)
333{
334 return test_bit(flag, &tainted_mask);
335}
336EXPORT_SYMBOL(test_taint);
337
338unsigned long get_taint(void)
339{
340 return tainted_mask;
341}
342
343/**
344 * add_taint: add a taint flag if not already set.
345 * @flag: one of the TAINT_* constants.
346 * @lockdep_ok: whether lock debugging is still OK.
347 *
348 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
349 * some notewortht-but-not-corrupting cases, it can be set to true.
350 */
351void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
352{
353 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
354 pr_warn("Disabling lock debugging due to kernel taint\n");
355
356 set_bit(flag, &tainted_mask);
357}
358EXPORT_SYMBOL(add_taint);
359
360static void spin_msec(int msecs)
361{
362 int i;
363
364 for (i = 0; i < msecs; i++) {
365 touch_nmi_watchdog();
366 mdelay(1);
367 }
368}
369
370/*
371 * It just happens that oops_enter() and oops_exit() are identically
372 * implemented...
373 */
374static void do_oops_enter_exit(void)
375{
376 unsigned long flags;
377 static int spin_counter;
378
379 if (!pause_on_oops)
380 return;
381
382 spin_lock_irqsave(&pause_on_oops_lock, flags);
383 if (pause_on_oops_flag == 0) {
384 /* This CPU may now print the oops message */
385 pause_on_oops_flag = 1;
386 } else {
387 /* We need to stall this CPU */
388 if (!spin_counter) {
389 /* This CPU gets to do the counting */
390 spin_counter = pause_on_oops;
391 do {
392 spin_unlock(&pause_on_oops_lock);
393 spin_msec(MSEC_PER_SEC);
394 spin_lock(&pause_on_oops_lock);
395 } while (--spin_counter);
396 pause_on_oops_flag = 0;
397 } else {
398 /* This CPU waits for a different one */
399 while (spin_counter) {
400 spin_unlock(&pause_on_oops_lock);
401 spin_msec(1);
402 spin_lock(&pause_on_oops_lock);
403 }
404 }
405 }
406 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
407}
408
409/*
410 * Return true if the calling CPU is allowed to print oops-related info.
411 * This is a bit racy..
412 */
413int oops_may_print(void)
414{
415 return pause_on_oops_flag == 0;
416}
417
418/*
419 * Called when the architecture enters its oops handler, before it prints
420 * anything. If this is the first CPU to oops, and it's oopsing the first
421 * time then let it proceed.
422 *
423 * This is all enabled by the pause_on_oops kernel boot option. We do all
424 * this to ensure that oopses don't scroll off the screen. It has the
425 * side-effect of preventing later-oopsing CPUs from mucking up the display,
426 * too.
427 *
428 * It turns out that the CPU which is allowed to print ends up pausing for
429 * the right duration, whereas all the other CPUs pause for twice as long:
430 * once in oops_enter(), once in oops_exit().
431 */
432void oops_enter(void)
433{
434 tracing_off();
435 /* can't trust the integrity of the kernel anymore: */
436 debug_locks_off();
437 do_oops_enter_exit();
438}
439
440/*
441 * 64-bit random ID for oopses:
442 */
443static u64 oops_id;
444
445static int init_oops_id(void)
446{
447 if (!oops_id)
448 get_random_bytes(&oops_id, sizeof(oops_id));
449 else
450 oops_id++;
451
452 return 0;
453}
454late_initcall(init_oops_id);
455
456void print_oops_end_marker(void)
457{
458 init_oops_id();
459 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
460}
461
462/*
463 * Called when the architecture exits its oops handler, after printing
464 * everything.
465 */
466void oops_exit(void)
467{
468 do_oops_enter_exit();
469 print_oops_end_marker();
470 kmsg_dump(KMSG_DUMP_OOPS);
471}
472
473struct warn_args {
474 const char *fmt;
475 va_list args;
476};
477
478void __warn(const char *file, int line, void *caller, unsigned taint,
479 struct pt_regs *regs, struct warn_args *args)
480{
481 disable_trace_on_warning();
482
483 pr_warn("------------[ cut here ]------------\n");
484
485 if (file)
486 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
487 raw_smp_processor_id(), current->pid, file, line,
488 caller);
489 else
490 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
491 raw_smp_processor_id(), current->pid, caller);
492
493 if (args)
494 vprintk(args->fmt, args->args);
495
496 if (panic_on_warn) {
497 /*
498 * This thread may hit another WARN() in the panic path.
499 * Resetting this prevents additional WARN() from panicking the
500 * system on this thread. Other threads are blocked by the
501 * panic_mutex in panic().
502 */
503 panic_on_warn = 0;
504 panic("panic_on_warn set ...\n");
505 }
506
507 print_modules();
508
509 if (regs)
510 show_regs(regs);
511 else
512 dump_stack();
513
514 print_oops_end_marker();
515
516 /* Just a warning, don't kill lockdep. */
517 add_taint(taint, LOCKDEP_STILL_OK);
518}
519
520#ifdef WANT_WARN_ON_SLOWPATH
521void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
522{
523 struct warn_args args;
524
525 args.fmt = fmt;
526 va_start(args.args, fmt);
527 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
528 &args);
529 va_end(args.args);
530}
531EXPORT_SYMBOL(warn_slowpath_fmt);
532
533void warn_slowpath_fmt_taint(const char *file, int line,
534 unsigned taint, const char *fmt, ...)
535{
536 struct warn_args args;
537
538 args.fmt = fmt;
539 va_start(args.args, fmt);
540 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
541 va_end(args.args);
542}
543EXPORT_SYMBOL(warn_slowpath_fmt_taint);
544
545void warn_slowpath_null(const char *file, int line)
546{
547 __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
548}
549EXPORT_SYMBOL(warn_slowpath_null);
550#endif
551
552#ifdef CONFIG_CC_STACKPROTECTOR
553
554/*
555 * Called when gcc's -fstack-protector feature is used, and
556 * gcc detects corruption of the on-stack canary value
557 */
558__visible void __stack_chk_fail(void)
559{
560 panic("stack-protector: Kernel stack is corrupted in: %p\n",
561 __builtin_return_address(0));
562}
563EXPORT_SYMBOL(__stack_chk_fail);
564
565#endif
566
567core_param(panic, panic_timeout, int, 0644);
568core_param(pause_on_oops, pause_on_oops, int, 0644);
569core_param(panic_on_warn, panic_on_warn, int, 0644);
570
571static int __init setup_crash_kexec_post_notifiers(char *s)
572{
573 crash_kexec_post_notifiers = true;
574 return 0;
575}
576early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
577
578static int __init oops_setup(char *s)
579{
580 if (!s)
581 return -EINVAL;
582 if (!strcmp(s, "panic"))
583 panic_on_oops = 1;
584 return 0;
585}
586early_param("oops", oops_setup);
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);