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v4.17
 
  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/sched/debug.h>
 13#include <linux/interrupt.h>
 
 14#include <linux/kmsg_dump.h>
 15#include <linux/kallsyms.h>
 16#include <linux/notifier.h>
 
 17#include <linux/module.h>
 18#include <linux/random.h>
 19#include <linux/ftrace.h>
 20#include <linux/reboot.h>
 21#include <linux/delay.h>
 22#include <linux/kexec.h>
 
 23#include <linux/sched.h>
 
 24#include <linux/sysrq.h>
 25#include <linux/init.h>
 26#include <linux/nmi.h>
 27#include <linux/console.h>
 28#include <linux/bug.h>
 29#include <linux/ratelimit.h>
 30#include <linux/debugfs.h>
 
 
 
 31#include <asm/sections.h>
 32
 33#define PANIC_TIMER_STEP 100
 34#define PANIC_BLINK_SPD 18
 35
 
 
 
 
 
 
 
 
 
 
 36int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
 37static unsigned long tainted_mask =
 38	IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
 39static int pause_on_oops;
 40static int pause_on_oops_flag;
 41static DEFINE_SPINLOCK(pause_on_oops_lock);
 42bool crash_kexec_post_notifiers;
 43int panic_on_warn __read_mostly;
 
 
 
 44
 45int panic_timeout = CONFIG_PANIC_TIMEOUT;
 46EXPORT_SYMBOL_GPL(panic_timeout);
 47
 
 
 
 
 
 
 
 
 
 
 48ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 49
 50EXPORT_SYMBOL(panic_notifier_list);
 51
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 52static long no_blink(int state)
 53{
 54	return 0;
 55}
 56
 57/* Returns how long it waited in ms */
 58long (*panic_blink)(int state);
 59EXPORT_SYMBOL(panic_blink);
 60
 61/*
 62 * Stop ourself in panic -- architecture code may override this
 63 */
 64void __weak panic_smp_self_stop(void)
 65{
 66	while (1)
 67		cpu_relax();
 68}
 69
 70/*
 71 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
 72 * may override this to prepare for crash dumping, e.g. save regs info.
 73 */
 74void __weak nmi_panic_self_stop(struct pt_regs *regs)
 75{
 76	panic_smp_self_stop();
 77}
 78
 79/*
 80 * Stop other CPUs in panic.  Architecture dependent code may override this
 81 * with more suitable version.  For example, if the architecture supports
 82 * crash dump, it should save registers of each stopped CPU and disable
 83 * per-CPU features such as virtualization extensions.
 84 */
 85void __weak crash_smp_send_stop(void)
 86{
 87	static int cpus_stopped;
 88
 89	/*
 90	 * This function can be called twice in panic path, but obviously
 91	 * we execute this only once.
 92	 */
 93	if (cpus_stopped)
 94		return;
 95
 96	/*
 97	 * Note smp_send_stop is the usual smp shutdown function, which
 98	 * unfortunately means it may not be hardened to work in a panic
 99	 * situation.
100	 */
101	smp_send_stop();
102	cpus_stopped = 1;
103}
104
105atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
106
107/*
108 * A variant of panic() called from NMI context. We return if we've already
109 * panicked on this CPU. If another CPU already panicked, loop in
110 * nmi_panic_self_stop() which can provide architecture dependent code such
111 * as saving register state for crash dump.
112 */
113void nmi_panic(struct pt_regs *regs, const char *msg)
114{
115	int old_cpu, cpu;
116
117	cpu = raw_smp_processor_id();
118	old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
119
120	if (old_cpu == PANIC_CPU_INVALID)
 
121		panic("%s", msg);
122	else if (old_cpu != cpu)
123		nmi_panic_self_stop(regs);
124}
125EXPORT_SYMBOL(nmi_panic);
126
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
127/**
128 *	panic - halt the system
129 *	@fmt: The text string to print
130 *
131 *	Display a message, then perform cleanups.
132 *
133 *	This function never returns.
134 */
135void panic(const char *fmt, ...)
136{
137	static char buf[1024];
138	va_list args;
139	long i, i_next = 0;
140	int state = 0;
141	int old_cpu, this_cpu;
142	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
143
 
 
 
 
 
 
 
 
 
 
144	/*
145	 * Disable local interrupts. This will prevent panic_smp_self_stop
146	 * from deadlocking the first cpu that invokes the panic, since
147	 * there is nothing to prevent an interrupt handler (that runs
148	 * after setting panic_cpu) from invoking panic() again.
149	 */
150	local_irq_disable();
 
151
152	/*
153	 * It's possible to come here directly from a panic-assertion and
154	 * not have preempt disabled. Some functions called from here want
155	 * preempt to be disabled. No point enabling it later though...
156	 *
157	 * Only one CPU is allowed to execute the panic code from here. For
158	 * multiple parallel invocations of panic, all other CPUs either
159	 * stop themself or will wait until they are stopped by the 1st CPU
160	 * with smp_send_stop().
161	 *
162	 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
163	 * comes here, so go ahead.
164	 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
165	 * panic_cpu to this CPU.  In this case, this is also the 1st CPU.
166	 */
 
167	this_cpu = raw_smp_processor_id();
168	old_cpu  = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
169
170	if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
 
 
 
171		panic_smp_self_stop();
172
173	console_verbose();
174	bust_spinlocks(1);
175	va_start(args, fmt);
176	vsnprintf(buf, sizeof(buf), fmt, args);
177	va_end(args);
 
 
 
 
178	pr_emerg("Kernel panic - not syncing: %s\n", buf);
179#ifdef CONFIG_DEBUG_BUGVERBOSE
180	/*
181	 * Avoid nested stack-dumping if a panic occurs during oops processing
182	 */
183	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
184		dump_stack();
185#endif
186
187	/*
 
 
 
 
 
 
 
188	 * If we have crashed and we have a crash kernel loaded let it handle
189	 * everything else.
190	 * If we want to run this after calling panic_notifiers, pass
191	 * the "crash_kexec_post_notifiers" option to the kernel.
192	 *
193	 * Bypass the panic_cpu check and call __crash_kexec directly.
194	 */
195	if (!_crash_kexec_post_notifiers) {
196		printk_safe_flush_on_panic();
197		__crash_kexec(NULL);
198
199		/*
200		 * Note smp_send_stop is the usual smp shutdown function, which
201		 * unfortunately means it may not be hardened to work in a
202		 * panic situation.
203		 */
204		smp_send_stop();
205	} else {
206		/*
207		 * If we want to do crash dump after notifier calls and
208		 * kmsg_dump, we will need architecture dependent extra
209		 * works in addition to stopping other CPUs.
210		 */
211		crash_smp_send_stop();
212	}
213
214	/*
215	 * Run any panic handlers, including those that might need to
216	 * add information to the kmsg dump output.
217	 */
218	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
219
220	/* Call flush even twice. It tries harder with a single online CPU */
221	printk_safe_flush_on_panic();
222	kmsg_dump(KMSG_DUMP_PANIC);
223
224	/*
225	 * If you doubt kdump always works fine in any situation,
226	 * "crash_kexec_post_notifiers" offers you a chance to run
227	 * panic_notifiers and dumping kmsg before kdump.
228	 * Note: since some panic_notifiers can make crashed kernel
229	 * more unstable, it can increase risks of the kdump failure too.
230	 *
231	 * Bypass the panic_cpu check and call __crash_kexec directly.
232	 */
233	if (_crash_kexec_post_notifiers)
234		__crash_kexec(NULL);
235
236	bust_spinlocks(0);
237
238	/*
239	 * We may have ended up stopping the CPU holding the lock (in
240	 * smp_send_stop()) while still having some valuable data in the console
241	 * buffer.  Try to acquire the lock then release it regardless of the
242	 * result.  The release will also print the buffers out.  Locks debug
243	 * should be disabled to avoid reporting bad unlock balance when
244	 * panic() is not being callled from OOPS.
245	 */
246	debug_locks_off();
247	console_flush_on_panic();
 
 
248
249	if (!panic_blink)
250		panic_blink = no_blink;
251
252	if (panic_timeout > 0) {
253		/*
254		 * Delay timeout seconds before rebooting the machine.
255		 * We can't use the "normal" timers since we just panicked.
256		 */
257		pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
258
259		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
260			touch_nmi_watchdog();
261			if (i >= i_next) {
262				i += panic_blink(state ^= 1);
263				i_next = i + 3600 / PANIC_BLINK_SPD;
264			}
265			mdelay(PANIC_TIMER_STEP);
266		}
267	}
268	if (panic_timeout != 0) {
269		/*
270		 * This will not be a clean reboot, with everything
271		 * shutting down.  But if there is a chance of
272		 * rebooting the system it will be rebooted.
273		 */
 
 
274		emergency_restart();
275	}
276#ifdef __sparc__
277	{
278		extern int stop_a_enabled;
279		/* Make sure the user can actually press Stop-A (L1-A) */
280		stop_a_enabled = 1;
281		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
282			 "twice on console to return to the boot prom\n");
283	}
284#endif
285#if defined(CONFIG_S390)
286	{
287		unsigned long caller;
288
289		caller = (unsigned long)__builtin_return_address(0);
290		disabled_wait(caller);
291	}
292#endif
293	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
 
 
 
 
 
 
 
 
 
 
 
294	local_irq_enable();
295	for (i = 0; ; i += PANIC_TIMER_STEP) {
296		touch_softlockup_watchdog();
297		if (i >= i_next) {
298			i += panic_blink(state ^= 1);
299			i_next = i + 3600 / PANIC_BLINK_SPD;
300		}
301		mdelay(PANIC_TIMER_STEP);
302	}
303}
304
305EXPORT_SYMBOL(panic);
306
307/*
308 * TAINT_FORCED_RMMOD could be a per-module flag but the module
309 * is being removed anyway.
310 */
311const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
312	[ TAINT_PROPRIETARY_MODULE ]	= { 'P', 'G', true },
313	[ TAINT_FORCED_MODULE ]		= { 'F', ' ', true },
314	[ TAINT_CPU_OUT_OF_SPEC ]	= { 'S', ' ', false },
315	[ TAINT_FORCED_RMMOD ]		= { 'R', ' ', false },
316	[ TAINT_MACHINE_CHECK ]		= { 'M', ' ', false },
317	[ TAINT_BAD_PAGE ]		= { 'B', ' ', false },
318	[ TAINT_USER ]			= { 'U', ' ', false },
319	[ TAINT_DIE ]			= { 'D', ' ', false },
320	[ TAINT_OVERRIDDEN_ACPI_TABLE ]	= { 'A', ' ', false },
321	[ TAINT_WARN ]			= { 'W', ' ', false },
322	[ TAINT_CRAP ]			= { 'C', ' ', true },
323	[ TAINT_FIRMWARE_WORKAROUND ]	= { 'I', ' ', false },
324	[ TAINT_OOT_MODULE ]		= { 'O', ' ', true },
325	[ TAINT_UNSIGNED_MODULE ]	= { 'E', ' ', true },
326	[ TAINT_SOFTLOCKUP ]		= { 'L', ' ', false },
327	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
328	[ TAINT_AUX ]			= { 'X', ' ', true },
329	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
 
330};
331
332/**
333 * print_tainted - return a string to represent the kernel taint state.
334 *
335 * For individual taint flag meanings, see Documentation/sysctl/kernel.txt
336 *
337 * The string is overwritten by the next call to print_tainted(),
338 * but is always NULL terminated.
339 */
340const char *print_tainted(void)
341{
342	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
343
344	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
345
346	if (tainted_mask) {
347		char *s;
348		int i;
349
350		s = buf + sprintf(buf, "Tainted: ");
351		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
352			const struct taint_flag *t = &taint_flags[i];
353			*s++ = test_bit(i, &tainted_mask) ?
354					t->c_true : t->c_false;
355		}
356		*s = 0;
357	} else
358		snprintf(buf, sizeof(buf), "Not tainted");
359
360	return buf;
361}
362
363int test_taint(unsigned flag)
364{
365	return test_bit(flag, &tainted_mask);
366}
367EXPORT_SYMBOL(test_taint);
368
369unsigned long get_taint(void)
370{
371	return tainted_mask;
372}
373
374/**
375 * add_taint: add a taint flag if not already set.
376 * @flag: one of the TAINT_* constants.
377 * @lockdep_ok: whether lock debugging is still OK.
378 *
379 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
380 * some notewortht-but-not-corrupting cases, it can be set to true.
381 */
382void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
383{
384	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
385		pr_warn("Disabling lock debugging due to kernel taint\n");
386
387	set_bit(flag, &tainted_mask);
 
 
 
 
 
388}
389EXPORT_SYMBOL(add_taint);
390
391static void spin_msec(int msecs)
392{
393	int i;
394
395	for (i = 0; i < msecs; i++) {
396		touch_nmi_watchdog();
397		mdelay(1);
398	}
399}
400
401/*
402 * It just happens that oops_enter() and oops_exit() are identically
403 * implemented...
404 */
405static void do_oops_enter_exit(void)
406{
407	unsigned long flags;
408	static int spin_counter;
409
410	if (!pause_on_oops)
411		return;
412
413	spin_lock_irqsave(&pause_on_oops_lock, flags);
414	if (pause_on_oops_flag == 0) {
415		/* This CPU may now print the oops message */
416		pause_on_oops_flag = 1;
417	} else {
418		/* We need to stall this CPU */
419		if (!spin_counter) {
420			/* This CPU gets to do the counting */
421			spin_counter = pause_on_oops;
422			do {
423				spin_unlock(&pause_on_oops_lock);
424				spin_msec(MSEC_PER_SEC);
425				spin_lock(&pause_on_oops_lock);
426			} while (--spin_counter);
427			pause_on_oops_flag = 0;
428		} else {
429			/* This CPU waits for a different one */
430			while (spin_counter) {
431				spin_unlock(&pause_on_oops_lock);
432				spin_msec(1);
433				spin_lock(&pause_on_oops_lock);
434			}
435		}
436	}
437	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
438}
439
440/*
441 * Return true if the calling CPU is allowed to print oops-related info.
442 * This is a bit racy..
443 */
444int oops_may_print(void)
445{
446	return pause_on_oops_flag == 0;
447}
448
449/*
450 * Called when the architecture enters its oops handler, before it prints
451 * anything.  If this is the first CPU to oops, and it's oopsing the first
452 * time then let it proceed.
453 *
454 * This is all enabled by the pause_on_oops kernel boot option.  We do all
455 * this to ensure that oopses don't scroll off the screen.  It has the
456 * side-effect of preventing later-oopsing CPUs from mucking up the display,
457 * too.
458 *
459 * It turns out that the CPU which is allowed to print ends up pausing for
460 * the right duration, whereas all the other CPUs pause for twice as long:
461 * once in oops_enter(), once in oops_exit().
462 */
463void oops_enter(void)
464{
465	tracing_off();
466	/* can't trust the integrity of the kernel anymore: */
467	debug_locks_off();
468	do_oops_enter_exit();
469}
470
471/*
472 * 64-bit random ID for oopses:
473 */
474static u64 oops_id;
475
476static int init_oops_id(void)
477{
478	if (!oops_id)
479		get_random_bytes(&oops_id, sizeof(oops_id));
480	else
481		oops_id++;
482
483	return 0;
 
484}
485late_initcall(init_oops_id);
486
487void print_oops_end_marker(void)
488{
489	init_oops_id();
490	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
491}
492
493/*
494 * Called when the architecture exits its oops handler, after printing
495 * everything.
496 */
497void oops_exit(void)
498{
499	do_oops_enter_exit();
500	print_oops_end_marker();
501	kmsg_dump(KMSG_DUMP_OOPS);
502}
503
504struct warn_args {
505	const char *fmt;
506	va_list args;
507};
508
509void __warn(const char *file, int line, void *caller, unsigned taint,
510	    struct pt_regs *regs, struct warn_args *args)
511{
512	disable_trace_on_warning();
513
514	if (args)
515		pr_warn(CUT_HERE);
516
517	if (file)
518		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
519			raw_smp_processor_id(), current->pid, file, line,
520			caller);
521	else
522		pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
523			raw_smp_processor_id(), current->pid, caller);
524
 
 
 
 
525	if (args)
526		vprintk(args->fmt, args->args);
527
528	if (panic_on_warn) {
529		/*
530		 * This thread may hit another WARN() in the panic path.
531		 * Resetting this prevents additional WARN() from panicking the
532		 * system on this thread.  Other threads are blocked by the
533		 * panic_mutex in panic().
534		 */
535		panic_on_warn = 0;
536		panic("panic_on_warn set ...\n");
537	}
538
539	print_modules();
540
541	if (regs)
542		show_regs(regs);
543	else
 
 
 
544		dump_stack();
545
546	print_irqtrace_events(current);
547
548	print_oops_end_marker();
 
549
550	/* Just a warning, don't kill lockdep. */
551	add_taint(taint, LOCKDEP_STILL_OK);
552}
553
554#ifdef WANT_WARN_ON_SLOWPATH
555void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 
 
556{
 
557	struct warn_args args;
558
559	args.fmt = fmt;
560	va_start(args.args, fmt);
561	__warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
562	       &args);
563	va_end(args.args);
564}
565EXPORT_SYMBOL(warn_slowpath_fmt);
566
567void warn_slowpath_fmt_taint(const char *file, int line,
568			     unsigned taint, const char *fmt, ...)
569{
570	struct warn_args args;
 
 
571
572	args.fmt = fmt;
573	va_start(args.args, fmt);
574	__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
575	va_end(args.args);
 
576}
577EXPORT_SYMBOL(warn_slowpath_fmt_taint);
578
579void warn_slowpath_null(const char *file, int line)
580{
581	pr_warn(CUT_HERE);
582	__warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
583}
584EXPORT_SYMBOL(warn_slowpath_null);
585#else
586void __warn_printk(const char *fmt, ...)
587{
 
588	va_list args;
589
590	pr_warn(CUT_HERE);
591
592	va_start(args, fmt);
593	vprintk(fmt, args);
594	va_end(args);
 
595}
596EXPORT_SYMBOL(__warn_printk);
597#endif
598
599#ifdef CONFIG_BUG
600
601/* Support resetting WARN*_ONCE state */
602
603static int clear_warn_once_set(void *data, u64 val)
604{
605	generic_bug_clear_once();
606	memset(__start_once, 0, __end_once - __start_once);
607	return 0;
608}
609
610DEFINE_SIMPLE_ATTRIBUTE(clear_warn_once_fops,
611			NULL,
612			clear_warn_once_set,
613			"%lld\n");
614
615static __init int register_warn_debugfs(void)
616{
617	/* Don't care about failure */
618	debugfs_create_file("clear_warn_once", 0200, NULL,
619			    NULL, &clear_warn_once_fops);
620	return 0;
621}
622
623device_initcall(register_warn_debugfs);
624#endif
625
626#ifdef CONFIG_CC_STACKPROTECTOR
627
628/*
629 * Called when gcc's -fstack-protector feature is used, and
630 * gcc detects corruption of the on-stack canary value
631 */
632__visible void __stack_chk_fail(void)
633{
634	panic("stack-protector: Kernel stack is corrupted in: %pB\n",
 
635		__builtin_return_address(0));
 
636}
637EXPORT_SYMBOL(__stack_chk_fail);
638
639#endif
640
641#ifdef CONFIG_ARCH_HAS_REFCOUNT
642void refcount_error_report(struct pt_regs *regs, const char *err)
643{
644	WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
645		err, (void *)instruction_pointer(regs),
646		current->comm, task_pid_nr(current),
647		from_kuid_munged(&init_user_ns, current_uid()),
648		from_kuid_munged(&init_user_ns, current_euid()));
649}
650#endif
651
652core_param(panic, panic_timeout, int, 0644);
 
653core_param(pause_on_oops, pause_on_oops, int, 0644);
654core_param(panic_on_warn, panic_on_warn, int, 0644);
655core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
656
657static int __init oops_setup(char *s)
658{
659	if (!s)
660		return -EINVAL;
661	if (!strcmp(s, "panic"))
662		panic_on_oops = 1;
663	return 0;
664}
665early_param("oops", oops_setup);
v6.9.4
  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 <trace/events/error_report.h>
 39#include <asm/sections.h>
 40
 41#define PANIC_TIMER_STEP 100
 42#define PANIC_BLINK_SPD 18
 43
 44#ifdef CONFIG_SMP
 45/*
 46 * Should we dump all CPUs backtraces in an oops event?
 47 * Defaults to 0, can be changed via sysctl.
 48 */
 49static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
 50#else
 51#define sysctl_oops_all_cpu_backtrace 0
 52#endif /* CONFIG_SMP */
 53
 54int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
 55static unsigned long tainted_mask =
 56	IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
 57static int pause_on_oops;
 58static int pause_on_oops_flag;
 59static DEFINE_SPINLOCK(pause_on_oops_lock);
 60bool crash_kexec_post_notifiers;
 61int panic_on_warn __read_mostly;
 62unsigned long panic_on_taint;
 63bool panic_on_taint_nousertaint = false;
 64static unsigned int warn_limit __read_mostly;
 65
 66int panic_timeout = CONFIG_PANIC_TIMEOUT;
 67EXPORT_SYMBOL_GPL(panic_timeout);
 68
 69#define PANIC_PRINT_TASK_INFO		0x00000001
 70#define PANIC_PRINT_MEM_INFO		0x00000002
 71#define PANIC_PRINT_TIMER_INFO		0x00000004
 72#define PANIC_PRINT_LOCK_INFO		0x00000008
 73#define PANIC_PRINT_FTRACE_INFO		0x00000010
 74#define PANIC_PRINT_ALL_PRINTK_MSG	0x00000020
 75#define PANIC_PRINT_ALL_CPU_BT		0x00000040
 76#define PANIC_PRINT_BLOCKED_TASKS	0x00000080
 77unsigned long panic_print;
 78
 79ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 80
 81EXPORT_SYMBOL(panic_notifier_list);
 82
 83#ifdef CONFIG_SYSCTL
 84static struct ctl_table kern_panic_table[] = {
 85#ifdef CONFIG_SMP
 86	{
 87		.procname       = "oops_all_cpu_backtrace",
 88		.data           = &sysctl_oops_all_cpu_backtrace,
 89		.maxlen         = sizeof(int),
 90		.mode           = 0644,
 91		.proc_handler   = proc_dointvec_minmax,
 92		.extra1         = SYSCTL_ZERO,
 93		.extra2         = SYSCTL_ONE,
 94	},
 95#endif
 96	{
 97		.procname       = "warn_limit",
 98		.data           = &warn_limit,
 99		.maxlen         = sizeof(warn_limit),
100		.mode           = 0644,
101		.proc_handler   = proc_douintvec,
102	},
103	{ }
104};
105
106static __init int kernel_panic_sysctls_init(void)
107{
108	register_sysctl_init("kernel", kern_panic_table);
109	return 0;
110}
111late_initcall(kernel_panic_sysctls_init);
112#endif
113
114static atomic_t warn_count = ATOMIC_INIT(0);
115
116#ifdef CONFIG_SYSFS
117static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
118			       char *page)
119{
120	return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
121}
122
123static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
124
125static __init int kernel_panic_sysfs_init(void)
126{
127	sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
128	return 0;
129}
130late_initcall(kernel_panic_sysfs_init);
131#endif
132
133static long no_blink(int state)
134{
135	return 0;
136}
137
138/* Returns how long it waited in ms */
139long (*panic_blink)(int state);
140EXPORT_SYMBOL(panic_blink);
141
142/*
143 * Stop ourself in panic -- architecture code may override this
144 */
145void __weak __noreturn panic_smp_self_stop(void)
146{
147	while (1)
148		cpu_relax();
149}
150
151/*
152 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
153 * may override this to prepare for crash dumping, e.g. save regs info.
154 */
155void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs)
156{
157	panic_smp_self_stop();
158}
159
160/*
161 * Stop other CPUs in panic.  Architecture dependent code may override this
162 * with more suitable version.  For example, if the architecture supports
163 * crash dump, it should save registers of each stopped CPU and disable
164 * per-CPU features such as virtualization extensions.
165 */
166void __weak crash_smp_send_stop(void)
167{
168	static int cpus_stopped;
169
170	/*
171	 * This function can be called twice in panic path, but obviously
172	 * we execute this only once.
173	 */
174	if (cpus_stopped)
175		return;
176
177	/*
178	 * Note smp_send_stop is the usual smp shutdown function, which
179	 * unfortunately means it may not be hardened to work in a panic
180	 * situation.
181	 */
182	smp_send_stop();
183	cpus_stopped = 1;
184}
185
186atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
187
188/*
189 * A variant of panic() called from NMI context. We return if we've already
190 * panicked on this CPU. If another CPU already panicked, loop in
191 * nmi_panic_self_stop() which can provide architecture dependent code such
192 * as saving register state for crash dump.
193 */
194void nmi_panic(struct pt_regs *regs, const char *msg)
195{
196	int old_cpu, this_cpu;
197
198	old_cpu = PANIC_CPU_INVALID;
199	this_cpu = raw_smp_processor_id();
200
201	/* atomic_try_cmpxchg updates old_cpu on failure */
202	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
203		panic("%s", msg);
204	else if (old_cpu != this_cpu)
205		nmi_panic_self_stop(regs);
206}
207EXPORT_SYMBOL(nmi_panic);
208
209static void panic_print_sys_info(bool console_flush)
210{
211	if (console_flush) {
212		if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
213			console_flush_on_panic(CONSOLE_REPLAY_ALL);
214		return;
215	}
216
217	if (panic_print & PANIC_PRINT_TASK_INFO)
218		show_state();
219
220	if (panic_print & PANIC_PRINT_MEM_INFO)
221		show_mem();
222
223	if (panic_print & PANIC_PRINT_TIMER_INFO)
224		sysrq_timer_list_show();
225
226	if (panic_print & PANIC_PRINT_LOCK_INFO)
227		debug_show_all_locks();
228
229	if (panic_print & PANIC_PRINT_FTRACE_INFO)
230		ftrace_dump(DUMP_ALL);
231
232	if (panic_print & PANIC_PRINT_BLOCKED_TASKS)
233		show_state_filter(TASK_UNINTERRUPTIBLE);
234}
235
236void check_panic_on_warn(const char *origin)
237{
238	unsigned int limit;
239
240	if (panic_on_warn)
241		panic("%s: panic_on_warn set ...\n", origin);
242
243	limit = READ_ONCE(warn_limit);
244	if (atomic_inc_return(&warn_count) >= limit && limit)
245		panic("%s: system warned too often (kernel.warn_limit is %d)",
246		      origin, limit);
247}
248
249/*
250 * Helper that triggers the NMI backtrace (if set in panic_print)
251 * and then performs the secondary CPUs shutdown - we cannot have
252 * the NMI backtrace after the CPUs are off!
253 */
254static void panic_other_cpus_shutdown(bool crash_kexec)
255{
256	if (panic_print & PANIC_PRINT_ALL_CPU_BT)
257		trigger_all_cpu_backtrace();
258
259	/*
260	 * Note that smp_send_stop() is the usual SMP shutdown function,
261	 * which unfortunately may not be hardened to work in a panic
262	 * situation. If we want to do crash dump after notifier calls
263	 * and kmsg_dump, we will need architecture dependent extra
264	 * bits in addition to stopping other CPUs, hence we rely on
265	 * crash_smp_send_stop() for that.
266	 */
267	if (!crash_kexec)
268		smp_send_stop();
269	else
270		crash_smp_send_stop();
271}
272
273/**
274 *	panic - halt the system
275 *	@fmt: The text string to print
276 *
277 *	Display a message, then perform cleanups.
278 *
279 *	This function never returns.
280 */
281void panic(const char *fmt, ...)
282{
283	static char buf[1024];
284	va_list args;
285	long i, i_next = 0, len;
286	int state = 0;
287	int old_cpu, this_cpu;
288	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
289
290	if (panic_on_warn) {
291		/*
292		 * This thread may hit another WARN() in the panic path.
293		 * Resetting this prevents additional WARN() from panicking the
294		 * system on this thread.  Other threads are blocked by the
295		 * panic_mutex in panic().
296		 */
297		panic_on_warn = 0;
298	}
299
300	/*
301	 * Disable local interrupts. This will prevent panic_smp_self_stop
302	 * from deadlocking the first cpu that invokes the panic, since
303	 * there is nothing to prevent an interrupt handler (that runs
304	 * after setting panic_cpu) from invoking panic() again.
305	 */
306	local_irq_disable();
307	preempt_disable_notrace();
308
309	/*
310	 * It's possible to come here directly from a panic-assertion and
311	 * not have preempt disabled. Some functions called from here want
312	 * preempt to be disabled. No point enabling it later though...
313	 *
314	 * Only one CPU is allowed to execute the panic code from here. For
315	 * multiple parallel invocations of panic, all other CPUs either
316	 * stop themself or will wait until they are stopped by the 1st CPU
317	 * with smp_send_stop().
318	 *
319	 * cmpxchg success means this is the 1st CPU which comes here,
320	 * so go ahead.
321	 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
322	 * panic_cpu to this CPU.  In this case, this is also the 1st CPU.
323	 */
324	old_cpu = PANIC_CPU_INVALID;
325	this_cpu = raw_smp_processor_id();
 
326
327	/* atomic_try_cmpxchg updates old_cpu on failure */
328	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
329		/* go ahead */
330	} else if (old_cpu != this_cpu)
331		panic_smp_self_stop();
332
333	console_verbose();
334	bust_spinlocks(1);
335	va_start(args, fmt);
336	len = vscnprintf(buf, sizeof(buf), fmt, args);
337	va_end(args);
338
339	if (len && buf[len - 1] == '\n')
340		buf[len - 1] = '\0';
341
342	pr_emerg("Kernel panic - not syncing: %s\n", buf);
343#ifdef CONFIG_DEBUG_BUGVERBOSE
344	/*
345	 * Avoid nested stack-dumping if a panic occurs during oops processing
346	 */
347	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
348		dump_stack();
349#endif
350
351	/*
352	 * If kgdb is enabled, give it a chance to run before we stop all
353	 * the other CPUs or else we won't be able to debug processes left
354	 * running on them.
355	 */
356	kgdb_panic(buf);
357
358	/*
359	 * If we have crashed and we have a crash kernel loaded let it handle
360	 * everything else.
361	 * If we want to run this after calling panic_notifiers, pass
362	 * the "crash_kexec_post_notifiers" option to the kernel.
363	 *
364	 * Bypass the panic_cpu check and call __crash_kexec directly.
365	 */
366	if (!_crash_kexec_post_notifiers)
 
367		__crash_kexec(NULL);
368
369	panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
 
 
 
 
 
 
 
 
 
 
 
 
 
370
371	/*
372	 * Run any panic handlers, including those that might need to
373	 * add information to the kmsg dump output.
374	 */
375	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
376
377	panic_print_sys_info(false);
378
379	kmsg_dump(KMSG_DUMP_PANIC);
380
381	/*
382	 * If you doubt kdump always works fine in any situation,
383	 * "crash_kexec_post_notifiers" offers you a chance to run
384	 * panic_notifiers and dumping kmsg before kdump.
385	 * Note: since some panic_notifiers can make crashed kernel
386	 * more unstable, it can increase risks of the kdump failure too.
387	 *
388	 * Bypass the panic_cpu check and call __crash_kexec directly.
389	 */
390	if (_crash_kexec_post_notifiers)
391		__crash_kexec(NULL);
392
393	console_unblank();
394
395	/*
396	 * We may have ended up stopping the CPU holding the lock (in
397	 * smp_send_stop()) while still having some valuable data in the console
398	 * buffer.  Try to acquire the lock then release it regardless of the
399	 * result.  The release will also print the buffers out.  Locks debug
400	 * should be disabled to avoid reporting bad unlock balance when
401	 * panic() is not being callled from OOPS.
402	 */
403	debug_locks_off();
404	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
405
406	panic_print_sys_info(true);
407
408	if (!panic_blink)
409		panic_blink = no_blink;
410
411	if (panic_timeout > 0) {
412		/*
413		 * Delay timeout seconds before rebooting the machine.
414		 * We can't use the "normal" timers since we just panicked.
415		 */
416		pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
417
418		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
419			touch_nmi_watchdog();
420			if (i >= i_next) {
421				i += panic_blink(state ^= 1);
422				i_next = i + 3600 / PANIC_BLINK_SPD;
423			}
424			mdelay(PANIC_TIMER_STEP);
425		}
426	}
427	if (panic_timeout != 0) {
428		/*
429		 * This will not be a clean reboot, with everything
430		 * shutting down.  But if there is a chance of
431		 * rebooting the system it will be rebooted.
432		 */
433		if (panic_reboot_mode != REBOOT_UNDEFINED)
434			reboot_mode = panic_reboot_mode;
435		emergency_restart();
436	}
437#ifdef __sparc__
438	{
439		extern int stop_a_enabled;
440		/* Make sure the user can actually press Stop-A (L1-A) */
441		stop_a_enabled = 1;
442		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
443			 "twice on console to return to the boot prom\n");
444	}
445#endif
446#if defined(CONFIG_S390)
447	disabled_wait();
 
 
 
 
 
448#endif
449	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
450
451	/* Do not scroll important messages printed above */
452	suppress_printk = 1;
453
454	/*
455	 * The final messages may not have been printed if in a context that
456	 * defers printing (such as NMI) and irq_work is not available.
457	 * Explicitly flush the kernel log buffer one last time.
458	 */
459	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
460
461	local_irq_enable();
462	for (i = 0; ; i += PANIC_TIMER_STEP) {
463		touch_softlockup_watchdog();
464		if (i >= i_next) {
465			i += panic_blink(state ^= 1);
466			i_next = i + 3600 / PANIC_BLINK_SPD;
467		}
468		mdelay(PANIC_TIMER_STEP);
469	}
470}
471
472EXPORT_SYMBOL(panic);
473
474/*
475 * TAINT_FORCED_RMMOD could be a per-module flag but the module
476 * is being removed anyway.
477 */
478const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
479	[ TAINT_PROPRIETARY_MODULE ]	= { 'P', 'G', true },
480	[ TAINT_FORCED_MODULE ]		= { 'F', ' ', true },
481	[ TAINT_CPU_OUT_OF_SPEC ]	= { 'S', ' ', false },
482	[ TAINT_FORCED_RMMOD ]		= { 'R', ' ', false },
483	[ TAINT_MACHINE_CHECK ]		= { 'M', ' ', false },
484	[ TAINT_BAD_PAGE ]		= { 'B', ' ', false },
485	[ TAINT_USER ]			= { 'U', ' ', false },
486	[ TAINT_DIE ]			= { 'D', ' ', false },
487	[ TAINT_OVERRIDDEN_ACPI_TABLE ]	= { 'A', ' ', false },
488	[ TAINT_WARN ]			= { 'W', ' ', false },
489	[ TAINT_CRAP ]			= { 'C', ' ', true },
490	[ TAINT_FIRMWARE_WORKAROUND ]	= { 'I', ' ', false },
491	[ TAINT_OOT_MODULE ]		= { 'O', ' ', true },
492	[ TAINT_UNSIGNED_MODULE ]	= { 'E', ' ', true },
493	[ TAINT_SOFTLOCKUP ]		= { 'L', ' ', false },
494	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
495	[ TAINT_AUX ]			= { 'X', ' ', true },
496	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
497	[ TAINT_TEST ]			= { 'N', ' ', true },
498};
499
500/**
501 * print_tainted - return a string to represent the kernel taint state.
502 *
503 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
504 *
505 * The string is overwritten by the next call to print_tainted(),
506 * but is always NULL terminated.
507 */
508const char *print_tainted(void)
509{
510	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
511
512	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
513
514	if (tainted_mask) {
515		char *s;
516		int i;
517
518		s = buf + sprintf(buf, "Tainted: ");
519		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
520			const struct taint_flag *t = &taint_flags[i];
521			*s++ = test_bit(i, &tainted_mask) ?
522					t->c_true : t->c_false;
523		}
524		*s = 0;
525	} else
526		snprintf(buf, sizeof(buf), "Not tainted");
527
528	return buf;
529}
530
531int test_taint(unsigned flag)
532{
533	return test_bit(flag, &tainted_mask);
534}
535EXPORT_SYMBOL(test_taint);
536
537unsigned long get_taint(void)
538{
539	return tainted_mask;
540}
541
542/**
543 * add_taint: add a taint flag if not already set.
544 * @flag: one of the TAINT_* constants.
545 * @lockdep_ok: whether lock debugging is still OK.
546 *
547 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
548 * some notewortht-but-not-corrupting cases, it can be set to true.
549 */
550void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
551{
552	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
553		pr_warn("Disabling lock debugging due to kernel taint\n");
554
555	set_bit(flag, &tainted_mask);
556
557	if (tainted_mask & panic_on_taint) {
558		panic_on_taint = 0;
559		panic("panic_on_taint set ...");
560	}
561}
562EXPORT_SYMBOL(add_taint);
563
564static void spin_msec(int msecs)
565{
566	int i;
567
568	for (i = 0; i < msecs; i++) {
569		touch_nmi_watchdog();
570		mdelay(1);
571	}
572}
573
574/*
575 * It just happens that oops_enter() and oops_exit() are identically
576 * implemented...
577 */
578static void do_oops_enter_exit(void)
579{
580	unsigned long flags;
581	static int spin_counter;
582
583	if (!pause_on_oops)
584		return;
585
586	spin_lock_irqsave(&pause_on_oops_lock, flags);
587	if (pause_on_oops_flag == 0) {
588		/* This CPU may now print the oops message */
589		pause_on_oops_flag = 1;
590	} else {
591		/* We need to stall this CPU */
592		if (!spin_counter) {
593			/* This CPU gets to do the counting */
594			spin_counter = pause_on_oops;
595			do {
596				spin_unlock(&pause_on_oops_lock);
597				spin_msec(MSEC_PER_SEC);
598				spin_lock(&pause_on_oops_lock);
599			} while (--spin_counter);
600			pause_on_oops_flag = 0;
601		} else {
602			/* This CPU waits for a different one */
603			while (spin_counter) {
604				spin_unlock(&pause_on_oops_lock);
605				spin_msec(1);
606				spin_lock(&pause_on_oops_lock);
607			}
608		}
609	}
610	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
611}
612
613/*
614 * Return true if the calling CPU is allowed to print oops-related info.
615 * This is a bit racy..
616 */
617bool oops_may_print(void)
618{
619	return pause_on_oops_flag == 0;
620}
621
622/*
623 * Called when the architecture enters its oops handler, before it prints
624 * anything.  If this is the first CPU to oops, and it's oopsing the first
625 * time then let it proceed.
626 *
627 * This is all enabled by the pause_on_oops kernel boot option.  We do all
628 * this to ensure that oopses don't scroll off the screen.  It has the
629 * side-effect of preventing later-oopsing CPUs from mucking up the display,
630 * too.
631 *
632 * It turns out that the CPU which is allowed to print ends up pausing for
633 * the right duration, whereas all the other CPUs pause for twice as long:
634 * once in oops_enter(), once in oops_exit().
635 */
636void oops_enter(void)
637{
638	tracing_off();
639	/* can't trust the integrity of the kernel anymore: */
640	debug_locks_off();
641	do_oops_enter_exit();
 
 
 
 
 
 
 
 
 
 
 
 
 
642
643	if (sysctl_oops_all_cpu_backtrace)
644		trigger_all_cpu_backtrace();
645}
 
646
647static void print_oops_end_marker(void)
648{
649	pr_warn("---[ end trace %016llx ]---\n", 0ULL);
 
650}
651
652/*
653 * Called when the architecture exits its oops handler, after printing
654 * everything.
655 */
656void oops_exit(void)
657{
658	do_oops_enter_exit();
659	print_oops_end_marker();
660	kmsg_dump(KMSG_DUMP_OOPS);
661}
662
663struct warn_args {
664	const char *fmt;
665	va_list args;
666};
667
668void __warn(const char *file, int line, void *caller, unsigned taint,
669	    struct pt_regs *regs, struct warn_args *args)
670{
671	disable_trace_on_warning();
672
 
 
 
673	if (file)
674		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
675			raw_smp_processor_id(), current->pid, file, line,
676			caller);
677	else
678		pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
679			raw_smp_processor_id(), current->pid, caller);
680
681#pragma GCC diagnostic push
682#ifndef __clang__
683#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
684#endif
685	if (args)
686		vprintk(args->fmt, args->args);
687#pragma GCC diagnostic pop
 
 
 
 
 
 
 
 
 
 
688
689	print_modules();
690
691	if (regs)
692		show_regs(regs);
693
694	check_panic_on_warn("kernel");
695
696	if (!regs)
697		dump_stack();
698
699	print_irqtrace_events(current);
700
701	print_oops_end_marker();
702	trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);
703
704	/* Just a warning, don't kill lockdep. */
705	add_taint(taint, LOCKDEP_STILL_OK);
706}
707
708#ifdef CONFIG_BUG
709#ifndef __WARN_FLAGS
710void warn_slowpath_fmt(const char *file, int line, unsigned taint,
711		       const char *fmt, ...)
712{
713	bool rcu = warn_rcu_enter();
714	struct warn_args args;
715
716	pr_warn(CUT_HERE);
 
 
 
 
 
 
717
718	if (!fmt) {
719		__warn(file, line, __builtin_return_address(0), taint,
720		       NULL, NULL);
721		warn_rcu_exit(rcu);
722		return;
723	}
724
725	args.fmt = fmt;
726	va_start(args.args, fmt);
727	__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
728	va_end(args.args);
729	warn_rcu_exit(rcu);
730}
731EXPORT_SYMBOL(warn_slowpath_fmt);
 
 
 
 
 
 
 
732#else
733void __warn_printk(const char *fmt, ...)
734{
735	bool rcu = warn_rcu_enter();
736	va_list args;
737
738	pr_warn(CUT_HERE);
739
740	va_start(args, fmt);
741	vprintk(fmt, args);
742	va_end(args);
743	warn_rcu_exit(rcu);
744}
745EXPORT_SYMBOL(__warn_printk);
746#endif
747
 
 
748/* Support resetting WARN*_ONCE state */
749
750static int clear_warn_once_set(void *data, u64 val)
751{
752	generic_bug_clear_once();
753	memset(__start_once, 0, __end_once - __start_once);
754	return 0;
755}
756
757DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
758			 "%lld\n");
 
 
759
760static __init int register_warn_debugfs(void)
761{
762	/* Don't care about failure */
763	debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
764				   &clear_warn_once_fops);
765	return 0;
766}
767
768device_initcall(register_warn_debugfs);
769#endif
770
771#ifdef CONFIG_STACKPROTECTOR
772
773/*
774 * Called when gcc's -fstack-protector feature is used, and
775 * gcc detects corruption of the on-stack canary value
776 */
777__visible noinstr void __stack_chk_fail(void)
778{
779	instrumentation_begin();
780	panic("stack-protector: Kernel stack is corrupted in: %pB",
781		__builtin_return_address(0));
782	instrumentation_end();
783}
784EXPORT_SYMBOL(__stack_chk_fail);
785
786#endif
787
 
 
 
 
 
 
 
 
 
 
 
788core_param(panic, panic_timeout, int, 0644);
789core_param(panic_print, panic_print, ulong, 0644);
790core_param(pause_on_oops, pause_on_oops, int, 0644);
791core_param(panic_on_warn, panic_on_warn, int, 0644);
792core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
793
794static int __init oops_setup(char *s)
795{
796	if (!s)
797		return -EINVAL;
798	if (!strcmp(s, "panic"))
799		panic_on_oops = 1;
800	return 0;
801}
802early_param("oops", oops_setup);
803
804static int __init panic_on_taint_setup(char *s)
805{
806	char *taint_str;
807
808	if (!s)
809		return -EINVAL;
810
811	taint_str = strsep(&s, ",");
812	if (kstrtoul(taint_str, 16, &panic_on_taint))
813		return -EINVAL;
814
815	/* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
816	panic_on_taint &= TAINT_FLAGS_MAX;
817
818	if (!panic_on_taint)
819		return -EINVAL;
820
821	if (s && !strcmp(s, "nousertaint"))
822		panic_on_taint_nousertaint = true;
823
824	pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n",
825		panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint));
826
827	return 0;
828}
829early_param("panic_on_taint", panic_on_taint_setup);