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  */
45 unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
46 #endif /* CONFIG_SMP */
47 
48 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
49 static unsigned long tainted_mask =
50 	IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
51 static int pause_on_oops;
52 static int pause_on_oops_flag;
53 static DEFINE_SPINLOCK(pause_on_oops_lock);
54 bool crash_kexec_post_notifiers;
55 int panic_on_warn __read_mostly;
56 unsigned long panic_on_taint;
57 bool panic_on_taint_nousertaint = false;
58 
59 int panic_timeout = CONFIG_PANIC_TIMEOUT;
60 EXPORT_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
68 unsigned long panic_print;
69 
70 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
71 
72 EXPORT_SYMBOL(panic_notifier_list);
73 
no_blink(int state)74 static long no_blink(int state)
75 {
76 	return 0;
77 }
78 
79 /* Returns how long it waited in ms */
80 long (*panic_blink)(int state);
81 EXPORT_SYMBOL(panic_blink);
82 
83 /*
84  * Stop ourself in panic -- architecture code may override this
85  */
panic_smp_self_stop(void)86 void __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  */
nmi_panic_self_stop(struct pt_regs * regs)96 void __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  */
crash_smp_send_stop(void)107 void __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 
127 atomic_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  */
nmi_panic(struct pt_regs * regs,const char * msg)135 void 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 }
147 EXPORT_SYMBOL(nmi_panic);
148 
panic_print_sys_info(void)149 static 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  */
panic(const char * fmt,...)178 void 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 		__crash_kexec(NULL);
252 
253 		/*
254 		 * Note smp_send_stop is the usual smp shutdown function, which
255 		 * unfortunately means it may not be hardened to work in a
256 		 * panic situation.
257 		 */
258 		smp_send_stop();
259 	} else {
260 		/*
261 		 * If we want to do crash dump after notifier calls and
262 		 * kmsg_dump, we will need architecture dependent extra
263 		 * works in addition to stopping other CPUs.
264 		 */
265 		crash_smp_send_stop();
266 	}
267 
268 	/*
269 	 * Run any panic handlers, including those that might need to
270 	 * add information to the kmsg dump output.
271 	 */
272 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
273 
274 	kmsg_dump(KMSG_DUMP_PANIC);
275 
276 	/*
277 	 * If you doubt kdump always works fine in any situation,
278 	 * "crash_kexec_post_notifiers" offers you a chance to run
279 	 * panic_notifiers and dumping kmsg before kdump.
280 	 * Note: since some panic_notifiers can make crashed kernel
281 	 * more unstable, it can increase risks of the kdump failure too.
282 	 *
283 	 * Bypass the panic_cpu check and call __crash_kexec directly.
284 	 */
285 	if (_crash_kexec_post_notifiers)
286 		__crash_kexec(NULL);
287 
288 #ifdef CONFIG_VT
289 	unblank_screen();
290 #endif
291 	console_unblank();
292 
293 	/*
294 	 * We may have ended up stopping the CPU holding the lock (in
295 	 * smp_send_stop()) while still having some valuable data in the console
296 	 * buffer.  Try to acquire the lock then release it regardless of the
297 	 * result.  The release will also print the buffers out.  Locks debug
298 	 * should be disabled to avoid reporting bad unlock balance when
299 	 * panic() is not being callled from OOPS.
300 	 */
301 	debug_locks_off();
302 	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
303 
304 	panic_print_sys_info();
305 
306 	if (!panic_blink)
307 		panic_blink = no_blink;
308 
309 	if (panic_timeout > 0) {
310 		/*
311 		 * Delay timeout seconds before rebooting the machine.
312 		 * We can't use the "normal" timers since we just panicked.
313 		 */
314 		pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
315 
316 		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
317 			touch_nmi_watchdog();
318 			if (i >= i_next) {
319 				i += panic_blink(state ^= 1);
320 				i_next = i + 3600 / PANIC_BLINK_SPD;
321 			}
322 			mdelay(PANIC_TIMER_STEP);
323 		}
324 	}
325 	if (panic_timeout != 0) {
326 		/*
327 		 * This will not be a clean reboot, with everything
328 		 * shutting down.  But if there is a chance of
329 		 * rebooting the system it will be rebooted.
330 		 */
331 		if (panic_reboot_mode != REBOOT_UNDEFINED)
332 			reboot_mode = panic_reboot_mode;
333 		emergency_restart();
334 	}
335 #ifdef __sparc__
336 	{
337 		extern int stop_a_enabled;
338 		/* Make sure the user can actually press Stop-A (L1-A) */
339 		stop_a_enabled = 1;
340 		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
341 			 "twice on console to return to the boot prom\n");
342 	}
343 #endif
344 #if defined(CONFIG_S390)
345 	disabled_wait();
346 #endif
347 	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
348 
349 	/* Do not scroll important messages printed above */
350 	suppress_printk = 1;
351 	local_irq_enable();
352 	for (i = 0; ; i += PANIC_TIMER_STEP) {
353 		touch_softlockup_watchdog();
354 		if (i >= i_next) {
355 			i += panic_blink(state ^= 1);
356 			i_next = i + 3600 / PANIC_BLINK_SPD;
357 		}
358 		mdelay(PANIC_TIMER_STEP);
359 	}
360 }
361 
362 EXPORT_SYMBOL(panic);
363 
364 /*
365  * TAINT_FORCED_RMMOD could be a per-module flag but the module
366  * is being removed anyway.
367  */
368 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
369 	[ TAINT_PROPRIETARY_MODULE ]	= { 'P', 'G', true },
370 	[ TAINT_FORCED_MODULE ]		= { 'F', ' ', true },
371 	[ TAINT_CPU_OUT_OF_SPEC ]	= { 'S', ' ', false },
372 	[ TAINT_FORCED_RMMOD ]		= { 'R', ' ', false },
373 	[ TAINT_MACHINE_CHECK ]		= { 'M', ' ', false },
374 	[ TAINT_BAD_PAGE ]		= { 'B', ' ', false },
375 	[ TAINT_USER ]			= { 'U', ' ', false },
376 	[ TAINT_DIE ]			= { 'D', ' ', false },
377 	[ TAINT_OVERRIDDEN_ACPI_TABLE ]	= { 'A', ' ', false },
378 	[ TAINT_WARN ]			= { 'W', ' ', false },
379 	[ TAINT_CRAP ]			= { 'C', ' ', true },
380 	[ TAINT_FIRMWARE_WORKAROUND ]	= { 'I', ' ', false },
381 	[ TAINT_OOT_MODULE ]		= { 'O', ' ', true },
382 	[ TAINT_UNSIGNED_MODULE ]	= { 'E', ' ', true },
383 	[ TAINT_SOFTLOCKUP ]		= { 'L', ' ', false },
384 	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
385 	[ TAINT_AUX ]			= { 'X', ' ', true },
386 	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
387 };
388 
389 /**
390  * print_tainted - return a string to represent the kernel taint state.
391  *
392  * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
393  *
394  * The string is overwritten by the next call to print_tainted(),
395  * but is always NULL terminated.
396  */
print_tainted(void)397 const char *print_tainted(void)
398 {
399 	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
400 
401 	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
402 
403 	if (tainted_mask) {
404 		char *s;
405 		int i;
406 
407 		s = buf + sprintf(buf, "Tainted: ");
408 		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
409 			const struct taint_flag *t = &taint_flags[i];
410 			*s++ = test_bit(i, &tainted_mask) ?
411 					t->c_true : t->c_false;
412 		}
413 		*s = 0;
414 	} else
415 		snprintf(buf, sizeof(buf), "Not tainted");
416 
417 	return buf;
418 }
419 
test_taint(unsigned flag)420 int test_taint(unsigned flag)
421 {
422 	return test_bit(flag, &tainted_mask);
423 }
424 EXPORT_SYMBOL(test_taint);
425 
get_taint(void)426 unsigned long get_taint(void)
427 {
428 	return tainted_mask;
429 }
430 
431 /**
432  * add_taint: add a taint flag if not already set.
433  * @flag: one of the TAINT_* constants.
434  * @lockdep_ok: whether lock debugging is still OK.
435  *
436  * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
437  * some notewortht-but-not-corrupting cases, it can be set to true.
438  */
add_taint(unsigned flag,enum lockdep_ok lockdep_ok)439 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
440 {
441 	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
442 		pr_warn("Disabling lock debugging due to kernel taint\n");
443 
444 	set_bit(flag, &tainted_mask);
445 
446 	if (tainted_mask & panic_on_taint) {
447 		panic_on_taint = 0;
448 		panic("panic_on_taint set ...");
449 	}
450 }
451 EXPORT_SYMBOL(add_taint);
452 
spin_msec(int msecs)453 static void spin_msec(int msecs)
454 {
455 	int i;
456 
457 	for (i = 0; i < msecs; i++) {
458 		touch_nmi_watchdog();
459 		mdelay(1);
460 	}
461 }
462 
463 /*
464  * It just happens that oops_enter() and oops_exit() are identically
465  * implemented...
466  */
do_oops_enter_exit(void)467 static void do_oops_enter_exit(void)
468 {
469 	unsigned long flags;
470 	static int spin_counter;
471 
472 	if (!pause_on_oops)
473 		return;
474 
475 	spin_lock_irqsave(&pause_on_oops_lock, flags);
476 	if (pause_on_oops_flag == 0) {
477 		/* This CPU may now print the oops message */
478 		pause_on_oops_flag = 1;
479 	} else {
480 		/* We need to stall this CPU */
481 		if (!spin_counter) {
482 			/* This CPU gets to do the counting */
483 			spin_counter = pause_on_oops;
484 			do {
485 				spin_unlock(&pause_on_oops_lock);
486 				spin_msec(MSEC_PER_SEC);
487 				spin_lock(&pause_on_oops_lock);
488 			} while (--spin_counter);
489 			pause_on_oops_flag = 0;
490 		} else {
491 			/* This CPU waits for a different one */
492 			while (spin_counter) {
493 				spin_unlock(&pause_on_oops_lock);
494 				spin_msec(1);
495 				spin_lock(&pause_on_oops_lock);
496 			}
497 		}
498 	}
499 	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
500 }
501 
502 /*
503  * Return true if the calling CPU is allowed to print oops-related info.
504  * This is a bit racy..
505  */
oops_may_print(void)506 bool oops_may_print(void)
507 {
508 	return pause_on_oops_flag == 0;
509 }
510 
511 /*
512  * Called when the architecture enters its oops handler, before it prints
513  * anything.  If this is the first CPU to oops, and it's oopsing the first
514  * time then let it proceed.
515  *
516  * This is all enabled by the pause_on_oops kernel boot option.  We do all
517  * this to ensure that oopses don't scroll off the screen.  It has the
518  * side-effect of preventing later-oopsing CPUs from mucking up the display,
519  * too.
520  *
521  * It turns out that the CPU which is allowed to print ends up pausing for
522  * the right duration, whereas all the other CPUs pause for twice as long:
523  * once in oops_enter(), once in oops_exit().
524  */
oops_enter(void)525 void oops_enter(void)
526 {
527 	tracing_off();
528 	/* can't trust the integrity of the kernel anymore: */
529 	debug_locks_off();
530 	do_oops_enter_exit();
531 
532 	if (sysctl_oops_all_cpu_backtrace)
533 		trigger_all_cpu_backtrace();
534 }
535 
536 /*
537  * 64-bit random ID for oopses:
538  */
539 static u64 oops_id;
540 
init_oops_id(void)541 static int init_oops_id(void)
542 {
543 	if (!oops_id)
544 		get_random_bytes(&oops_id, sizeof(oops_id));
545 	else
546 		oops_id++;
547 
548 	return 0;
549 }
550 late_initcall(init_oops_id);
551 
print_oops_end_marker(void)552 static void print_oops_end_marker(void)
553 {
554 	init_oops_id();
555 	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
556 }
557 
558 /*
559  * Called when the architecture exits its oops handler, after printing
560  * everything.
561  */
oops_exit(void)562 void oops_exit(void)
563 {
564 	do_oops_enter_exit();
565 	print_oops_end_marker();
566 	kmsg_dump(KMSG_DUMP_OOPS);
567 }
568 
569 struct warn_args {
570 	const char *fmt;
571 	va_list args;
572 };
573 
__warn(const char * file,int line,void * caller,unsigned taint,struct pt_regs * regs,struct warn_args * args)574 void __warn(const char *file, int line, void *caller, unsigned taint,
575 	    struct pt_regs *regs, struct warn_args *args)
576 {
577 	disable_trace_on_warning();
578 
579 	if (file)
580 		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
581 			raw_smp_processor_id(), current->pid, file, line,
582 			caller);
583 	else
584 		pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
585 			raw_smp_processor_id(), current->pid, caller);
586 
587 	if (args)
588 		vprintk(args->fmt, args->args);
589 
590 	print_modules();
591 
592 	if (regs)
593 		show_regs(regs);
594 
595 	if (panic_on_warn) {
596 		/*
597 		 * This thread may hit another WARN() in the panic path.
598 		 * Resetting this prevents additional WARN() from panicking the
599 		 * system on this thread.  Other threads are blocked by the
600 		 * panic_mutex in panic().
601 		 */
602 		panic_on_warn = 0;
603 		panic("panic_on_warn set ...\n");
604 	}
605 
606 	if (!regs)
607 		dump_stack();
608 
609 	print_irqtrace_events(current);
610 
611 	print_oops_end_marker();
612 
613 	/* Just a warning, don't kill lockdep. */
614 	add_taint(taint, LOCKDEP_STILL_OK);
615 }
616 
617 #ifndef __WARN_FLAGS
warn_slowpath_fmt(const char * file,int line,unsigned taint,const char * fmt,...)618 void warn_slowpath_fmt(const char *file, int line, unsigned taint,
619 		       const char *fmt, ...)
620 {
621 	struct warn_args args;
622 
623 	pr_warn(CUT_HERE);
624 
625 	if (!fmt) {
626 		__warn(file, line, __builtin_return_address(0), taint,
627 		       NULL, NULL);
628 		return;
629 	}
630 
631 	args.fmt = fmt;
632 	va_start(args.args, fmt);
633 	__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
634 	va_end(args.args);
635 }
636 EXPORT_SYMBOL(warn_slowpath_fmt);
637 #else
__warn_printk(const char * fmt,...)638 void __warn_printk(const char *fmt, ...)
639 {
640 	va_list args;
641 
642 	pr_warn(CUT_HERE);
643 
644 	va_start(args, fmt);
645 	vprintk(fmt, args);
646 	va_end(args);
647 }
648 EXPORT_SYMBOL(__warn_printk);
649 #endif
650 
651 #ifdef CONFIG_BUG
652 
653 /* Support resetting WARN*_ONCE state */
654 
clear_warn_once_set(void * data,u64 val)655 static int clear_warn_once_set(void *data, u64 val)
656 {
657 	generic_bug_clear_once();
658 	memset(__start_once, 0, __end_once - __start_once);
659 	return 0;
660 }
661 
662 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
663 			 "%lld\n");
664 
register_warn_debugfs(void)665 static __init int register_warn_debugfs(void)
666 {
667 	/* Don't care about failure */
668 	debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
669 				   &clear_warn_once_fops);
670 	return 0;
671 }
672 
673 device_initcall(register_warn_debugfs);
674 #endif
675 
676 #ifdef CONFIG_STACKPROTECTOR
677 
678 /*
679  * Called when gcc's -fstack-protector feature is used, and
680  * gcc detects corruption of the on-stack canary value
681  */
__stack_chk_fail(void)682 __visible noinstr void __stack_chk_fail(void)
683 {
684 	instrumentation_begin();
685 	panic("stack-protector: Kernel stack is corrupted in: %pB",
686 		__builtin_return_address(0));
687 	instrumentation_end();
688 }
689 EXPORT_SYMBOL(__stack_chk_fail);
690 
691 #endif
692 
693 core_param(panic, panic_timeout, int, 0644);
694 core_param(panic_print, panic_print, ulong, 0644);
695 core_param(pause_on_oops, pause_on_oops, int, 0644);
696 core_param(panic_on_warn, panic_on_warn, int, 0644);
697 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
698 
oops_setup(char * s)699 static int __init oops_setup(char *s)
700 {
701 	if (!s)
702 		return -EINVAL;
703 	if (!strcmp(s, "panic"))
704 		panic_on_oops = 1;
705 	return 0;
706 }
707 early_param("oops", oops_setup);
708 
panic_on_taint_setup(char * s)709 static int __init panic_on_taint_setup(char *s)
710 {
711 	char *taint_str;
712 
713 	if (!s)
714 		return -EINVAL;
715 
716 	taint_str = strsep(&s, ",");
717 	if (kstrtoul(taint_str, 16, &panic_on_taint))
718 		return -EINVAL;
719 
720 	/* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
721 	panic_on_taint &= TAINT_FLAGS_MAX;
722 
723 	if (!panic_on_taint)
724 		return -EINVAL;
725 
726 	if (s && !strcmp(s, "nousertaint"))
727 		panic_on_taint_nousertaint = true;
728 
729 	pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
730 		panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
731 
732 	return 0;
733 }
734 early_param("panic_on_taint", panic_on_taint_setup);
735