xref: /openbmc/linux/kernel/panic.c (revision e7f127b2)
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 <trace/events/error_report.h>
36 #include <asm/sections.h>
37 
38 #define PANIC_TIMER_STEP 100
39 #define PANIC_BLINK_SPD 18
40 
41 #ifdef CONFIG_SMP
42 /*
43  * Should we dump all CPUs backtraces in an oops event?
44  * Defaults to 0, can be changed via sysctl.
45  */
46 unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
47 #endif /* CONFIG_SMP */
48 
49 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
50 static unsigned long tainted_mask =
51 	IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
52 static int pause_on_oops;
53 static int pause_on_oops_flag;
54 static DEFINE_SPINLOCK(pause_on_oops_lock);
55 bool crash_kexec_post_notifiers;
56 int panic_on_warn __read_mostly;
57 unsigned long panic_on_taint;
58 bool panic_on_taint_nousertaint = false;
59 
60 int panic_timeout = CONFIG_PANIC_TIMEOUT;
61 EXPORT_SYMBOL_GPL(panic_timeout);
62 
63 #define PANIC_PRINT_TASK_INFO		0x00000001
64 #define PANIC_PRINT_MEM_INFO		0x00000002
65 #define PANIC_PRINT_TIMER_INFO		0x00000004
66 #define PANIC_PRINT_LOCK_INFO		0x00000008
67 #define PANIC_PRINT_FTRACE_INFO		0x00000010
68 #define PANIC_PRINT_ALL_PRINTK_MSG	0x00000020
69 unsigned long panic_print;
70 
71 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
72 
73 EXPORT_SYMBOL(panic_notifier_list);
74 
75 static long no_blink(int state)
76 {
77 	return 0;
78 }
79 
80 /* Returns how long it waited in ms */
81 long (*panic_blink)(int state);
82 EXPORT_SYMBOL(panic_blink);
83 
84 /*
85  * Stop ourself in panic -- architecture code may override this
86  */
87 void __weak panic_smp_self_stop(void)
88 {
89 	while (1)
90 		cpu_relax();
91 }
92 
93 /*
94  * Stop ourselves in NMI context if another CPU has already panicked. Arch code
95  * may override this to prepare for crash dumping, e.g. save regs info.
96  */
97 void __weak nmi_panic_self_stop(struct pt_regs *regs)
98 {
99 	panic_smp_self_stop();
100 }
101 
102 /*
103  * Stop other CPUs in panic.  Architecture dependent code may override this
104  * with more suitable version.  For example, if the architecture supports
105  * crash dump, it should save registers of each stopped CPU and disable
106  * per-CPU features such as virtualization extensions.
107  */
108 void __weak crash_smp_send_stop(void)
109 {
110 	static int cpus_stopped;
111 
112 	/*
113 	 * This function can be called twice in panic path, but obviously
114 	 * we execute this only once.
115 	 */
116 	if (cpus_stopped)
117 		return;
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 	cpus_stopped = 1;
126 }
127 
128 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
129 
130 /*
131  * A variant of panic() called from NMI context. We return if we've already
132  * panicked on this CPU. If another CPU already panicked, loop in
133  * nmi_panic_self_stop() which can provide architecture dependent code such
134  * as saving register state for crash dump.
135  */
136 void nmi_panic(struct pt_regs *regs, const char *msg)
137 {
138 	int old_cpu, cpu;
139 
140 	cpu = raw_smp_processor_id();
141 	old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
142 
143 	if (old_cpu == PANIC_CPU_INVALID)
144 		panic("%s", msg);
145 	else if (old_cpu != cpu)
146 		nmi_panic_self_stop(regs);
147 }
148 EXPORT_SYMBOL(nmi_panic);
149 
150 static void panic_print_sys_info(void)
151 {
152 	if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
153 		console_flush_on_panic(CONSOLE_REPLAY_ALL);
154 
155 	if (panic_print & PANIC_PRINT_TASK_INFO)
156 		show_state();
157 
158 	if (panic_print & PANIC_PRINT_MEM_INFO)
159 		show_mem(0, NULL);
160 
161 	if (panic_print & PANIC_PRINT_TIMER_INFO)
162 		sysrq_timer_list_show();
163 
164 	if (panic_print & PANIC_PRINT_LOCK_INFO)
165 		debug_show_all_locks();
166 
167 	if (panic_print & PANIC_PRINT_FTRACE_INFO)
168 		ftrace_dump(DUMP_ALL);
169 }
170 
171 /**
172  *	panic - halt the system
173  *	@fmt: The text string to print
174  *
175  *	Display a message, then perform cleanups.
176  *
177  *	This function never returns.
178  */
179 void panic(const char *fmt, ...)
180 {
181 	static char buf[1024];
182 	va_list args;
183 	long i, i_next = 0, len;
184 	int state = 0;
185 	int old_cpu, this_cpu;
186 	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
187 
188 	/*
189 	 * Disable local interrupts. This will prevent panic_smp_self_stop
190 	 * from deadlocking the first cpu that invokes the panic, since
191 	 * there is nothing to prevent an interrupt handler (that runs
192 	 * after setting panic_cpu) from invoking panic() again.
193 	 */
194 	local_irq_disable();
195 	preempt_disable_notrace();
196 
197 	/*
198 	 * It's possible to come here directly from a panic-assertion and
199 	 * not have preempt disabled. Some functions called from here want
200 	 * preempt to be disabled. No point enabling it later though...
201 	 *
202 	 * Only one CPU is allowed to execute the panic code from here. For
203 	 * multiple parallel invocations of panic, all other CPUs either
204 	 * stop themself or will wait until they are stopped by the 1st CPU
205 	 * with smp_send_stop().
206 	 *
207 	 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
208 	 * comes here, so go ahead.
209 	 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
210 	 * panic_cpu to this CPU.  In this case, this is also the 1st CPU.
211 	 */
212 	this_cpu = raw_smp_processor_id();
213 	old_cpu  = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
214 
215 	if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
216 		panic_smp_self_stop();
217 
218 	console_verbose();
219 	bust_spinlocks(1);
220 	va_start(args, fmt);
221 	len = vscnprintf(buf, sizeof(buf), fmt, args);
222 	va_end(args);
223 
224 	if (len && buf[len - 1] == '\n')
225 		buf[len - 1] = '\0';
226 
227 	pr_emerg("Kernel panic - not syncing: %s\n", buf);
228 #ifdef CONFIG_DEBUG_BUGVERBOSE
229 	/*
230 	 * Avoid nested stack-dumping if a panic occurs during oops processing
231 	 */
232 	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
233 		dump_stack();
234 #endif
235 
236 	/*
237 	 * If kgdb is enabled, give it a chance to run before we stop all
238 	 * the other CPUs or else we won't be able to debug processes left
239 	 * running on them.
240 	 */
241 	kgdb_panic(buf);
242 
243 	/*
244 	 * If we have crashed and we have a crash kernel loaded let it handle
245 	 * everything else.
246 	 * If we want to run this after calling panic_notifiers, pass
247 	 * the "crash_kexec_post_notifiers" option to the kernel.
248 	 *
249 	 * Bypass the panic_cpu check and call __crash_kexec directly.
250 	 */
251 	if (!_crash_kexec_post_notifiers) {
252 		__crash_kexec(NULL);
253 
254 		/*
255 		 * Note smp_send_stop is the usual smp shutdown function, which
256 		 * unfortunately means it may not be hardened to work in a
257 		 * panic situation.
258 		 */
259 		smp_send_stop();
260 	} else {
261 		/*
262 		 * If we want to do crash dump after notifier calls and
263 		 * kmsg_dump, we will need architecture dependent extra
264 		 * works in addition to stopping other CPUs.
265 		 */
266 		crash_smp_send_stop();
267 	}
268 
269 	/*
270 	 * Run any panic handlers, including those that might need to
271 	 * add information to the kmsg dump output.
272 	 */
273 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
274 
275 	kmsg_dump(KMSG_DUMP_PANIC);
276 
277 	/*
278 	 * If you doubt kdump always works fine in any situation,
279 	 * "crash_kexec_post_notifiers" offers you a chance to run
280 	 * panic_notifiers and dumping kmsg before kdump.
281 	 * Note: since some panic_notifiers can make crashed kernel
282 	 * more unstable, it can increase risks of the kdump failure too.
283 	 *
284 	 * Bypass the panic_cpu check and call __crash_kexec directly.
285 	 */
286 	if (_crash_kexec_post_notifiers)
287 		__crash_kexec(NULL);
288 
289 #ifdef CONFIG_VT
290 	unblank_screen();
291 #endif
292 	console_unblank();
293 
294 	/*
295 	 * We may have ended up stopping the CPU holding the lock (in
296 	 * smp_send_stop()) while still having some valuable data in the console
297 	 * buffer.  Try to acquire the lock then release it regardless of the
298 	 * result.  The release will also print the buffers out.  Locks debug
299 	 * should be disabled to avoid reporting bad unlock balance when
300 	 * panic() is not being callled from OOPS.
301 	 */
302 	debug_locks_off();
303 	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
304 
305 	panic_print_sys_info();
306 
307 	if (!panic_blink)
308 		panic_blink = no_blink;
309 
310 	if (panic_timeout > 0) {
311 		/*
312 		 * Delay timeout seconds before rebooting the machine.
313 		 * We can't use the "normal" timers since we just panicked.
314 		 */
315 		pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
316 
317 		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
318 			touch_nmi_watchdog();
319 			if (i >= i_next) {
320 				i += panic_blink(state ^= 1);
321 				i_next = i + 3600 / PANIC_BLINK_SPD;
322 			}
323 			mdelay(PANIC_TIMER_STEP);
324 		}
325 	}
326 	if (panic_timeout != 0) {
327 		/*
328 		 * This will not be a clean reboot, with everything
329 		 * shutting down.  But if there is a chance of
330 		 * rebooting the system it will be rebooted.
331 		 */
332 		if (panic_reboot_mode != REBOOT_UNDEFINED)
333 			reboot_mode = panic_reboot_mode;
334 		emergency_restart();
335 	}
336 #ifdef __sparc__
337 	{
338 		extern int stop_a_enabled;
339 		/* Make sure the user can actually press Stop-A (L1-A) */
340 		stop_a_enabled = 1;
341 		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
342 			 "twice on console to return to the boot prom\n");
343 	}
344 #endif
345 #if defined(CONFIG_S390)
346 	disabled_wait();
347 #endif
348 	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
349 
350 	/* Do not scroll important messages printed above */
351 	suppress_printk = 1;
352 	local_irq_enable();
353 	for (i = 0; ; i += PANIC_TIMER_STEP) {
354 		touch_softlockup_watchdog();
355 		if (i >= i_next) {
356 			i += panic_blink(state ^= 1);
357 			i_next = i + 3600 / PANIC_BLINK_SPD;
358 		}
359 		mdelay(PANIC_TIMER_STEP);
360 	}
361 }
362 
363 EXPORT_SYMBOL(panic);
364 
365 /*
366  * TAINT_FORCED_RMMOD could be a per-module flag but the module
367  * is being removed anyway.
368  */
369 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
370 	[ TAINT_PROPRIETARY_MODULE ]	= { 'P', 'G', true },
371 	[ TAINT_FORCED_MODULE ]		= { 'F', ' ', true },
372 	[ TAINT_CPU_OUT_OF_SPEC ]	= { 'S', ' ', false },
373 	[ TAINT_FORCED_RMMOD ]		= { 'R', ' ', false },
374 	[ TAINT_MACHINE_CHECK ]		= { 'M', ' ', false },
375 	[ TAINT_BAD_PAGE ]		= { 'B', ' ', false },
376 	[ TAINT_USER ]			= { 'U', ' ', false },
377 	[ TAINT_DIE ]			= { 'D', ' ', false },
378 	[ TAINT_OVERRIDDEN_ACPI_TABLE ]	= { 'A', ' ', false },
379 	[ TAINT_WARN ]			= { 'W', ' ', false },
380 	[ TAINT_CRAP ]			= { 'C', ' ', true },
381 	[ TAINT_FIRMWARE_WORKAROUND ]	= { 'I', ' ', false },
382 	[ TAINT_OOT_MODULE ]		= { 'O', ' ', true },
383 	[ TAINT_UNSIGNED_MODULE ]	= { 'E', ' ', true },
384 	[ TAINT_SOFTLOCKUP ]		= { 'L', ' ', false },
385 	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
386 	[ TAINT_AUX ]			= { 'X', ' ', true },
387 	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
388 };
389 
390 /**
391  * print_tainted - return a string to represent the kernel taint state.
392  *
393  * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
394  *
395  * The string is overwritten by the next call to print_tainted(),
396  * but is always NULL terminated.
397  */
398 const char *print_tainted(void)
399 {
400 	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
401 
402 	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
403 
404 	if (tainted_mask) {
405 		char *s;
406 		int i;
407 
408 		s = buf + sprintf(buf, "Tainted: ");
409 		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
410 			const struct taint_flag *t = &taint_flags[i];
411 			*s++ = test_bit(i, &tainted_mask) ?
412 					t->c_true : t->c_false;
413 		}
414 		*s = 0;
415 	} else
416 		snprintf(buf, sizeof(buf), "Not tainted");
417 
418 	return buf;
419 }
420 
421 int test_taint(unsigned flag)
422 {
423 	return test_bit(flag, &tainted_mask);
424 }
425 EXPORT_SYMBOL(test_taint);
426 
427 unsigned long get_taint(void)
428 {
429 	return tainted_mask;
430 }
431 
432 /**
433  * add_taint: add a taint flag if not already set.
434  * @flag: one of the TAINT_* constants.
435  * @lockdep_ok: whether lock debugging is still OK.
436  *
437  * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
438  * some notewortht-but-not-corrupting cases, it can be set to true.
439  */
440 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
441 {
442 	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
443 		pr_warn("Disabling lock debugging due to kernel taint\n");
444 
445 	set_bit(flag, &tainted_mask);
446 
447 	if (tainted_mask & panic_on_taint) {
448 		panic_on_taint = 0;
449 		panic("panic_on_taint set ...");
450 	}
451 }
452 EXPORT_SYMBOL(add_taint);
453 
454 static void spin_msec(int msecs)
455 {
456 	int i;
457 
458 	for (i = 0; i < msecs; i++) {
459 		touch_nmi_watchdog();
460 		mdelay(1);
461 	}
462 }
463 
464 /*
465  * It just happens that oops_enter() and oops_exit() are identically
466  * implemented...
467  */
468 static void do_oops_enter_exit(void)
469 {
470 	unsigned long flags;
471 	static int spin_counter;
472 
473 	if (!pause_on_oops)
474 		return;
475 
476 	spin_lock_irqsave(&pause_on_oops_lock, flags);
477 	if (pause_on_oops_flag == 0) {
478 		/* This CPU may now print the oops message */
479 		pause_on_oops_flag = 1;
480 	} else {
481 		/* We need to stall this CPU */
482 		if (!spin_counter) {
483 			/* This CPU gets to do the counting */
484 			spin_counter = pause_on_oops;
485 			do {
486 				spin_unlock(&pause_on_oops_lock);
487 				spin_msec(MSEC_PER_SEC);
488 				spin_lock(&pause_on_oops_lock);
489 			} while (--spin_counter);
490 			pause_on_oops_flag = 0;
491 		} else {
492 			/* This CPU waits for a different one */
493 			while (spin_counter) {
494 				spin_unlock(&pause_on_oops_lock);
495 				spin_msec(1);
496 				spin_lock(&pause_on_oops_lock);
497 			}
498 		}
499 	}
500 	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
501 }
502 
503 /*
504  * Return true if the calling CPU is allowed to print oops-related info.
505  * This is a bit racy..
506  */
507 bool oops_may_print(void)
508 {
509 	return pause_on_oops_flag == 0;
510 }
511 
512 /*
513  * Called when the architecture enters its oops handler, before it prints
514  * anything.  If this is the first CPU to oops, and it's oopsing the first
515  * time then let it proceed.
516  *
517  * This is all enabled by the pause_on_oops kernel boot option.  We do all
518  * this to ensure that oopses don't scroll off the screen.  It has the
519  * side-effect of preventing later-oopsing CPUs from mucking up the display,
520  * too.
521  *
522  * It turns out that the CPU which is allowed to print ends up pausing for
523  * the right duration, whereas all the other CPUs pause for twice as long:
524  * once in oops_enter(), once in oops_exit().
525  */
526 void oops_enter(void)
527 {
528 	tracing_off();
529 	/* can't trust the integrity of the kernel anymore: */
530 	debug_locks_off();
531 	do_oops_enter_exit();
532 
533 	if (sysctl_oops_all_cpu_backtrace)
534 		trigger_all_cpu_backtrace();
535 }
536 
537 static void print_oops_end_marker(void)
538 {
539 	pr_warn("---[ end trace %016llx ]---\n", 0ULL);
540 }
541 
542 /*
543  * Called when the architecture exits its oops handler, after printing
544  * everything.
545  */
546 void oops_exit(void)
547 {
548 	do_oops_enter_exit();
549 	print_oops_end_marker();
550 	kmsg_dump(KMSG_DUMP_OOPS);
551 }
552 
553 struct warn_args {
554 	const char *fmt;
555 	va_list args;
556 };
557 
558 void __warn(const char *file, int line, void *caller, unsigned taint,
559 	    struct pt_regs *regs, struct warn_args *args)
560 {
561 	disable_trace_on_warning();
562 
563 	if (file)
564 		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
565 			raw_smp_processor_id(), current->pid, file, line,
566 			caller);
567 	else
568 		pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
569 			raw_smp_processor_id(), current->pid, caller);
570 
571 	if (args)
572 		vprintk(args->fmt, args->args);
573 
574 	print_modules();
575 
576 	if (regs)
577 		show_regs(regs);
578 
579 	if (panic_on_warn) {
580 		/*
581 		 * This thread may hit another WARN() in the panic path.
582 		 * Resetting this prevents additional WARN() from panicking the
583 		 * system on this thread.  Other threads are blocked by the
584 		 * panic_mutex in panic().
585 		 */
586 		panic_on_warn = 0;
587 		panic("panic_on_warn set ...\n");
588 	}
589 
590 	if (!regs)
591 		dump_stack();
592 
593 	print_irqtrace_events(current);
594 
595 	print_oops_end_marker();
596 	trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);
597 
598 	/* Just a warning, don't kill lockdep. */
599 	add_taint(taint, LOCKDEP_STILL_OK);
600 }
601 
602 #ifndef __WARN_FLAGS
603 void warn_slowpath_fmt(const char *file, int line, unsigned taint,
604 		       const char *fmt, ...)
605 {
606 	struct warn_args args;
607 
608 	pr_warn(CUT_HERE);
609 
610 	if (!fmt) {
611 		__warn(file, line, __builtin_return_address(0), taint,
612 		       NULL, NULL);
613 		return;
614 	}
615 
616 	args.fmt = fmt;
617 	va_start(args.args, fmt);
618 	__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
619 	va_end(args.args);
620 }
621 EXPORT_SYMBOL(warn_slowpath_fmt);
622 #else
623 void __warn_printk(const char *fmt, ...)
624 {
625 	va_list args;
626 
627 	pr_warn(CUT_HERE);
628 
629 	va_start(args, fmt);
630 	vprintk(fmt, args);
631 	va_end(args);
632 }
633 EXPORT_SYMBOL(__warn_printk);
634 #endif
635 
636 #ifdef CONFIG_BUG
637 
638 /* Support resetting WARN*_ONCE state */
639 
640 static int clear_warn_once_set(void *data, u64 val)
641 {
642 	generic_bug_clear_once();
643 	memset(__start_once, 0, __end_once - __start_once);
644 	return 0;
645 }
646 
647 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
648 			 "%lld\n");
649 
650 static __init int register_warn_debugfs(void)
651 {
652 	/* Don't care about failure */
653 	debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
654 				   &clear_warn_once_fops);
655 	return 0;
656 }
657 
658 device_initcall(register_warn_debugfs);
659 #endif
660 
661 #ifdef CONFIG_STACKPROTECTOR
662 
663 /*
664  * Called when gcc's -fstack-protector feature is used, and
665  * gcc detects corruption of the on-stack canary value
666  */
667 __visible noinstr void __stack_chk_fail(void)
668 {
669 	instrumentation_begin();
670 	panic("stack-protector: Kernel stack is corrupted in: %pB",
671 		__builtin_return_address(0));
672 	instrumentation_end();
673 }
674 EXPORT_SYMBOL(__stack_chk_fail);
675 
676 #endif
677 
678 core_param(panic, panic_timeout, int, 0644);
679 core_param(panic_print, panic_print, ulong, 0644);
680 core_param(pause_on_oops, pause_on_oops, int, 0644);
681 core_param(panic_on_warn, panic_on_warn, int, 0644);
682 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
683 
684 static int __init oops_setup(char *s)
685 {
686 	if (!s)
687 		return -EINVAL;
688 	if (!strcmp(s, "panic"))
689 		panic_on_oops = 1;
690 	return 0;
691 }
692 early_param("oops", oops_setup);
693 
694 static int __init panic_on_taint_setup(char *s)
695 {
696 	char *taint_str;
697 
698 	if (!s)
699 		return -EINVAL;
700 
701 	taint_str = strsep(&s, ",");
702 	if (kstrtoul(taint_str, 16, &panic_on_taint))
703 		return -EINVAL;
704 
705 	/* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
706 	panic_on_taint &= TAINT_FLAGS_MAX;
707 
708 	if (!panic_on_taint)
709 		return -EINVAL;
710 
711 	if (s && !strcmp(s, "nousertaint"))
712 		panic_on_taint_nousertaint = true;
713 
714 	pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
715 		panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
716 
717 	return 0;
718 }
719 early_param("panic_on_taint", panic_on_taint_setup);
720