xref: /openbmc/linux/kernel/panic.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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/reboot.h>
19 #include <linux/delay.h>
20 #include <linux/kexec.h>
21 #include <linux/sched.h>
22 #include <linux/sysrq.h>
23 #include <linux/init.h>
24 #include <linux/nmi.h>
25 #include <linux/dmi.h>
26 
27 int panic_on_oops;
28 static unsigned long tainted_mask;
29 static int pause_on_oops;
30 static int pause_on_oops_flag;
31 static DEFINE_SPINLOCK(pause_on_oops_lock);
32 
33 int panic_timeout;
34 
35 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
36 
37 EXPORT_SYMBOL(panic_notifier_list);
38 
39 static long no_blink(long time)
40 {
41 	return 0;
42 }
43 
44 /* Returns how long it waited in ms */
45 long (*panic_blink)(long time);
46 EXPORT_SYMBOL(panic_blink);
47 
48 /**
49  *	panic - halt the system
50  *	@fmt: The text string to print
51  *
52  *	Display a message, then perform cleanups.
53  *
54  *	This function never returns.
55  */
56 NORET_TYPE void panic(const char * fmt, ...)
57 {
58 	static char buf[1024];
59 	va_list args;
60 	long i;
61 
62 	/*
63 	 * It's possible to come here directly from a panic-assertion and
64 	 * not have preempt disabled. Some functions called from here want
65 	 * preempt to be disabled. No point enabling it later though...
66 	 */
67 	preempt_disable();
68 
69 	bust_spinlocks(1);
70 	va_start(args, fmt);
71 	vsnprintf(buf, sizeof(buf), fmt, args);
72 	va_end(args);
73 	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
74 #ifdef CONFIG_DEBUG_BUGVERBOSE
75 	dump_stack();
76 #endif
77 
78 	kmsg_dump(KMSG_DUMP_PANIC);
79 	/*
80 	 * If we have crashed and we have a crash kernel loaded let it handle
81 	 * everything else.
82 	 * Do we want to call this before we try to display a message?
83 	 */
84 	crash_kexec(NULL);
85 
86 	/*
87 	 * Note smp_send_stop is the usual smp shutdown function, which
88 	 * unfortunately means it may not be hardened to work in a panic
89 	 * situation.
90 	 */
91 	smp_send_stop();
92 
93 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
94 
95 	bust_spinlocks(0);
96 
97 	if (!panic_blink)
98 		panic_blink = no_blink;
99 
100 	if (panic_timeout > 0) {
101 		/*
102 		 * Delay timeout seconds before rebooting the machine.
103 		 * We can't use the "normal" timers since we just panicked.
104 		 */
105 		printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
106 
107 		for (i = 0; i < panic_timeout*1000; ) {
108 			touch_nmi_watchdog();
109 			i += panic_blink(i);
110 			mdelay(1);
111 			i++;
112 		}
113 		/*
114 		 * This will not be a clean reboot, with everything
115 		 * shutting down.  But if there is a chance of
116 		 * rebooting the system it will be rebooted.
117 		 */
118 		emergency_restart();
119 	}
120 #ifdef __sparc__
121 	{
122 		extern int stop_a_enabled;
123 		/* Make sure the user can actually press Stop-A (L1-A) */
124 		stop_a_enabled = 1;
125 		printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
126 	}
127 #endif
128 #if defined(CONFIG_S390)
129 	{
130 		unsigned long caller;
131 
132 		caller = (unsigned long)__builtin_return_address(0);
133 		disabled_wait(caller);
134 	}
135 #endif
136 	local_irq_enable();
137 	for (i = 0; ; ) {
138 		touch_softlockup_watchdog();
139 		i += panic_blink(i);
140 		mdelay(1);
141 		i++;
142 	}
143 }
144 
145 EXPORT_SYMBOL(panic);
146 
147 
148 struct tnt {
149 	u8	bit;
150 	char	true;
151 	char	false;
152 };
153 
154 static const struct tnt tnts[] = {
155 	{ TAINT_PROPRIETARY_MODULE,	'P', 'G' },
156 	{ TAINT_FORCED_MODULE,		'F', ' ' },
157 	{ TAINT_UNSAFE_SMP,		'S', ' ' },
158 	{ TAINT_FORCED_RMMOD,		'R', ' ' },
159 	{ TAINT_MACHINE_CHECK,		'M', ' ' },
160 	{ TAINT_BAD_PAGE,		'B', ' ' },
161 	{ TAINT_USER,			'U', ' ' },
162 	{ TAINT_DIE,			'D', ' ' },
163 	{ TAINT_OVERRIDDEN_ACPI_TABLE,	'A', ' ' },
164 	{ TAINT_WARN,			'W', ' ' },
165 	{ TAINT_CRAP,			'C', ' ' },
166 };
167 
168 /**
169  *	print_tainted - return a string to represent the kernel taint state.
170  *
171  *  'P' - Proprietary module has been loaded.
172  *  'F' - Module has been forcibly loaded.
173  *  'S' - SMP with CPUs not designed for SMP.
174  *  'R' - User forced a module unload.
175  *  'M' - System experienced a machine check exception.
176  *  'B' - System has hit bad_page.
177  *  'U' - Userspace-defined naughtiness.
178  *  'D' - Kernel has oopsed before
179  *  'A' - ACPI table overridden.
180  *  'W' - Taint on warning.
181  *  'C' - modules from drivers/staging are loaded.
182  *
183  *	The string is overwritten by the next call to print_tainted().
184  */
185 const char *print_tainted(void)
186 {
187 	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
188 
189 	if (tainted_mask) {
190 		char *s;
191 		int i;
192 
193 		s = buf + sprintf(buf, "Tainted: ");
194 		for (i = 0; i < ARRAY_SIZE(tnts); i++) {
195 			const struct tnt *t = &tnts[i];
196 			*s++ = test_bit(t->bit, &tainted_mask) ?
197 					t->true : t->false;
198 		}
199 		*s = 0;
200 	} else
201 		snprintf(buf, sizeof(buf), "Not tainted");
202 
203 	return buf;
204 }
205 
206 int test_taint(unsigned flag)
207 {
208 	return test_bit(flag, &tainted_mask);
209 }
210 EXPORT_SYMBOL(test_taint);
211 
212 unsigned long get_taint(void)
213 {
214 	return tainted_mask;
215 }
216 
217 void add_taint(unsigned flag)
218 {
219 	/*
220 	 * Can't trust the integrity of the kernel anymore.
221 	 * We don't call directly debug_locks_off() because the issue
222 	 * is not necessarily serious enough to set oops_in_progress to 1
223 	 * Also we want to keep up lockdep for staging development and
224 	 * post-warning case.
225 	 */
226 	if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
227 		printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
228 
229 	set_bit(flag, &tainted_mask);
230 }
231 EXPORT_SYMBOL(add_taint);
232 
233 static void spin_msec(int msecs)
234 {
235 	int i;
236 
237 	for (i = 0; i < msecs; i++) {
238 		touch_nmi_watchdog();
239 		mdelay(1);
240 	}
241 }
242 
243 /*
244  * It just happens that oops_enter() and oops_exit() are identically
245  * implemented...
246  */
247 static void do_oops_enter_exit(void)
248 {
249 	unsigned long flags;
250 	static int spin_counter;
251 
252 	if (!pause_on_oops)
253 		return;
254 
255 	spin_lock_irqsave(&pause_on_oops_lock, flags);
256 	if (pause_on_oops_flag == 0) {
257 		/* This CPU may now print the oops message */
258 		pause_on_oops_flag = 1;
259 	} else {
260 		/* We need to stall this CPU */
261 		if (!spin_counter) {
262 			/* This CPU gets to do the counting */
263 			spin_counter = pause_on_oops;
264 			do {
265 				spin_unlock(&pause_on_oops_lock);
266 				spin_msec(MSEC_PER_SEC);
267 				spin_lock(&pause_on_oops_lock);
268 			} while (--spin_counter);
269 			pause_on_oops_flag = 0;
270 		} else {
271 			/* This CPU waits for a different one */
272 			while (spin_counter) {
273 				spin_unlock(&pause_on_oops_lock);
274 				spin_msec(1);
275 				spin_lock(&pause_on_oops_lock);
276 			}
277 		}
278 	}
279 	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
280 }
281 
282 /*
283  * Return true if the calling CPU is allowed to print oops-related info.
284  * This is a bit racy..
285  */
286 int oops_may_print(void)
287 {
288 	return pause_on_oops_flag == 0;
289 }
290 
291 /*
292  * Called when the architecture enters its oops handler, before it prints
293  * anything.  If this is the first CPU to oops, and it's oopsing the first
294  * time then let it proceed.
295  *
296  * This is all enabled by the pause_on_oops kernel boot option.  We do all
297  * this to ensure that oopses don't scroll off the screen.  It has the
298  * side-effect of preventing later-oopsing CPUs from mucking up the display,
299  * too.
300  *
301  * It turns out that the CPU which is allowed to print ends up pausing for
302  * the right duration, whereas all the other CPUs pause for twice as long:
303  * once in oops_enter(), once in oops_exit().
304  */
305 void oops_enter(void)
306 {
307 	tracing_off();
308 	/* can't trust the integrity of the kernel anymore: */
309 	debug_locks_off();
310 	do_oops_enter_exit();
311 }
312 
313 /*
314  * 64-bit random ID for oopses:
315  */
316 static u64 oops_id;
317 
318 static int init_oops_id(void)
319 {
320 	if (!oops_id)
321 		get_random_bytes(&oops_id, sizeof(oops_id));
322 	else
323 		oops_id++;
324 
325 	return 0;
326 }
327 late_initcall(init_oops_id);
328 
329 static void print_oops_end_marker(void)
330 {
331 	init_oops_id();
332 	printk(KERN_WARNING "---[ end trace %016llx ]---\n",
333 		(unsigned long long)oops_id);
334 }
335 
336 /*
337  * Called when the architecture exits its oops handler, after printing
338  * everything.
339  */
340 void oops_exit(void)
341 {
342 	do_oops_enter_exit();
343 	print_oops_end_marker();
344 	kmsg_dump(KMSG_DUMP_OOPS);
345 }
346 
347 #ifdef WANT_WARN_ON_SLOWPATH
348 struct slowpath_args {
349 	const char *fmt;
350 	va_list args;
351 };
352 
353 static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
354 {
355 	const char *board;
356 
357 	printk(KERN_WARNING "------------[ cut here ]------------\n");
358 	printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
359 	board = dmi_get_system_info(DMI_PRODUCT_NAME);
360 	if (board)
361 		printk(KERN_WARNING "Hardware name: %s\n", board);
362 
363 	if (args)
364 		vprintk(args->fmt, args->args);
365 
366 	print_modules();
367 	dump_stack();
368 	print_oops_end_marker();
369 	add_taint(TAINT_WARN);
370 }
371 
372 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
373 {
374 	struct slowpath_args args;
375 
376 	args.fmt = fmt;
377 	va_start(args.args, fmt);
378 	warn_slowpath_common(file, line, __builtin_return_address(0), &args);
379 	va_end(args.args);
380 }
381 EXPORT_SYMBOL(warn_slowpath_fmt);
382 
383 void warn_slowpath_null(const char *file, int line)
384 {
385 	warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
386 }
387 EXPORT_SYMBOL(warn_slowpath_null);
388 #endif
389 
390 #ifdef CONFIG_CC_STACKPROTECTOR
391 
392 /*
393  * Called when gcc's -fstack-protector feature is used, and
394  * gcc detects corruption of the on-stack canary value
395  */
396 void __stack_chk_fail(void)
397 {
398 	panic("stack-protector: Kernel stack is corrupted in: %p\n",
399 		__builtin_return_address(0));
400 }
401 EXPORT_SYMBOL(__stack_chk_fail);
402 
403 #endif
404 
405 core_param(panic, panic_timeout, int, 0644);
406 core_param(pause_on_oops, pause_on_oops, int, 0644);
407