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 #define PANIC_TIMER_STEP 100
28 #define PANIC_BLINK_SPD 18
29
30 int panic_on_oops;
31 static unsigned long tainted_mask;
32 static int pause_on_oops;
33 static int pause_on_oops_flag;
34 static DEFINE_SPINLOCK(pause_on_oops_lock);
35
36 int panic_timeout;
37 EXPORT_SYMBOL_GPL(panic_timeout);
38
39 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
40
41 EXPORT_SYMBOL(panic_notifier_list);
42
no_blink(int state)43 static long no_blink(int state)
44 {
45 return 0;
46 }
47
48 /* Returns how long it waited in ms */
49 long (*panic_blink)(int state);
50 EXPORT_SYMBOL(panic_blink);
51
52 /**
53 * panic - halt the system
54 * @fmt: The text string to print
55 *
56 * Display a message, then perform cleanups.
57 *
58 * This function never returns.
59 */
panic(const char * fmt,...)60 NORET_TYPE void panic(const char * fmt, ...)
61 {
62 static char buf[1024];
63 va_list args;
64 long i, i_next = 0;
65 int state = 0;
66
67 /*
68 * It's possible to come here directly from a panic-assertion and
69 * not have preempt disabled. Some functions called from here want
70 * preempt to be disabled. No point enabling it later though...
71 */
72 preempt_disable();
73
74 console_verbose();
75 bust_spinlocks(1);
76 va_start(args, fmt);
77 vsnprintf(buf, sizeof(buf), fmt, args);
78 va_end(args);
79 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
80 #ifdef CONFIG_DEBUG_BUGVERBOSE
81 dump_stack();
82 #endif
83
84 /*
85 * If we have crashed and we have a crash kernel loaded let it handle
86 * everything else.
87 * Do we want to call this before we try to display a message?
88 */
89 crash_kexec(NULL);
90
91 kmsg_dump(KMSG_DUMP_PANIC);
92
93 /*
94 * Note smp_send_stop is the usual smp shutdown function, which
95 * unfortunately means it may not be hardened to work in a panic
96 * situation.
97 */
98 smp_send_stop();
99
100 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
101
102 bust_spinlocks(0);
103
104 if (!panic_blink)
105 panic_blink = no_blink;
106
107 if (panic_timeout > 0) {
108 /*
109 * Delay timeout seconds before rebooting the machine.
110 * We can't use the "normal" timers since we just panicked.
111 */
112 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
113
114 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
115 touch_nmi_watchdog();
116 if (i >= i_next) {
117 i += panic_blink(state ^= 1);
118 i_next = i + 3600 / PANIC_BLINK_SPD;
119 }
120 mdelay(PANIC_TIMER_STEP);
121 }
122 /*
123 * This will not be a clean reboot, with everything
124 * shutting down. But if there is a chance of
125 * rebooting the system it will be rebooted.
126 */
127 emergency_restart();
128 }
129 #ifdef __sparc__
130 {
131 extern int stop_a_enabled;
132 /* Make sure the user can actually press Stop-A (L1-A) */
133 stop_a_enabled = 1;
134 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
135 }
136 #endif
137 #if defined(CONFIG_S390)
138 {
139 unsigned long caller;
140
141 caller = (unsigned long)__builtin_return_address(0);
142 disabled_wait(caller);
143 }
144 #endif
145 local_irq_enable();
146 for (i = 0; ; i += PANIC_TIMER_STEP) {
147 touch_softlockup_watchdog();
148 if (i >= i_next) {
149 i += panic_blink(state ^= 1);
150 i_next = i + 3600 / PANIC_BLINK_SPD;
151 }
152 mdelay(PANIC_TIMER_STEP);
153 }
154 }
155
156 EXPORT_SYMBOL(panic);
157
158
159 struct tnt {
160 u8 bit;
161 char true;
162 char false;
163 };
164
165 static const struct tnt tnts[] = {
166 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
167 { TAINT_FORCED_MODULE, 'F', ' ' },
168 { TAINT_UNSAFE_SMP, 'S', ' ' },
169 { TAINT_FORCED_RMMOD, 'R', ' ' },
170 { TAINT_MACHINE_CHECK, 'M', ' ' },
171 { TAINT_BAD_PAGE, 'B', ' ' },
172 { TAINT_USER, 'U', ' ' },
173 { TAINT_DIE, 'D', ' ' },
174 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
175 { TAINT_WARN, 'W', ' ' },
176 { TAINT_CRAP, 'C', ' ' },
177 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
178 };
179
180 /**
181 * print_tainted - return a string to represent the kernel taint state.
182 *
183 * 'P' - Proprietary module has been loaded.
184 * 'F' - Module has been forcibly loaded.
185 * 'S' - SMP with CPUs not designed for SMP.
186 * 'R' - User forced a module unload.
187 * 'M' - System experienced a machine check exception.
188 * 'B' - System has hit bad_page.
189 * 'U' - Userspace-defined naughtiness.
190 * 'D' - Kernel has oopsed before
191 * 'A' - ACPI table overridden.
192 * 'W' - Taint on warning.
193 * 'C' - modules from drivers/staging are loaded.
194 * 'I' - Working around severe firmware bug.
195 *
196 * The string is overwritten by the next call to print_tainted().
197 */
print_tainted(void)198 const char *print_tainted(void)
199 {
200 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
201
202 if (tainted_mask) {
203 char *s;
204 int i;
205
206 s = buf + sprintf(buf, "Tainted: ");
207 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
208 const struct tnt *t = &tnts[i];
209 *s++ = test_bit(t->bit, &tainted_mask) ?
210 t->true : t->false;
211 }
212 *s = 0;
213 } else
214 snprintf(buf, sizeof(buf), "Not tainted");
215
216 return buf;
217 }
218
test_taint(unsigned flag)219 int test_taint(unsigned flag)
220 {
221 return test_bit(flag, &tainted_mask);
222 }
223 EXPORT_SYMBOL(test_taint);
224
get_taint(void)225 unsigned long get_taint(void)
226 {
227 return tainted_mask;
228 }
229
add_taint(unsigned flag)230 void add_taint(unsigned flag)
231 {
232 /*
233 * Can't trust the integrity of the kernel anymore.
234 * We don't call directly debug_locks_off() because the issue
235 * is not necessarily serious enough to set oops_in_progress to 1
236 * Also we want to keep up lockdep for staging development and
237 * post-warning case.
238 */
239 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
240 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
241
242 set_bit(flag, &tainted_mask);
243 }
244 EXPORT_SYMBOL(add_taint);
245
spin_msec(int msecs)246 static void spin_msec(int msecs)
247 {
248 int i;
249
250 for (i = 0; i < msecs; i++) {
251 touch_nmi_watchdog();
252 mdelay(1);
253 }
254 }
255
256 /*
257 * It just happens that oops_enter() and oops_exit() are identically
258 * implemented...
259 */
do_oops_enter_exit(void)260 static void do_oops_enter_exit(void)
261 {
262 unsigned long flags;
263 static int spin_counter;
264
265 if (!pause_on_oops)
266 return;
267
268 spin_lock_irqsave(&pause_on_oops_lock, flags);
269 if (pause_on_oops_flag == 0) {
270 /* This CPU may now print the oops message */
271 pause_on_oops_flag = 1;
272 } else {
273 /* We need to stall this CPU */
274 if (!spin_counter) {
275 /* This CPU gets to do the counting */
276 spin_counter = pause_on_oops;
277 do {
278 spin_unlock(&pause_on_oops_lock);
279 spin_msec(MSEC_PER_SEC);
280 spin_lock(&pause_on_oops_lock);
281 } while (--spin_counter);
282 pause_on_oops_flag = 0;
283 } else {
284 /* This CPU waits for a different one */
285 while (spin_counter) {
286 spin_unlock(&pause_on_oops_lock);
287 spin_msec(1);
288 spin_lock(&pause_on_oops_lock);
289 }
290 }
291 }
292 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
293 }
294
295 /*
296 * Return true if the calling CPU is allowed to print oops-related info.
297 * This is a bit racy..
298 */
oops_may_print(void)299 int oops_may_print(void)
300 {
301 return pause_on_oops_flag == 0;
302 }
303
304 /*
305 * Called when the architecture enters its oops handler, before it prints
306 * anything. If this is the first CPU to oops, and it's oopsing the first
307 * time then let it proceed.
308 *
309 * This is all enabled by the pause_on_oops kernel boot option. We do all
310 * this to ensure that oopses don't scroll off the screen. It has the
311 * side-effect of preventing later-oopsing CPUs from mucking up the display,
312 * too.
313 *
314 * It turns out that the CPU which is allowed to print ends up pausing for
315 * the right duration, whereas all the other CPUs pause for twice as long:
316 * once in oops_enter(), once in oops_exit().
317 */
oops_enter(void)318 void oops_enter(void)
319 {
320 tracing_off();
321 /* can't trust the integrity of the kernel anymore: */
322 debug_locks_off();
323 do_oops_enter_exit();
324 }
325
326 /*
327 * 64-bit random ID for oopses:
328 */
329 static u64 oops_id;
330
init_oops_id(void)331 static int init_oops_id(void)
332 {
333 if (!oops_id)
334 get_random_bytes(&oops_id, sizeof(oops_id));
335 else
336 oops_id++;
337
338 return 0;
339 }
340 late_initcall(init_oops_id);
341
print_oops_end_marker(void)342 void print_oops_end_marker(void)
343 {
344 init_oops_id();
345 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
346 (unsigned long long)oops_id);
347 }
348
349 /*
350 * Called when the architecture exits its oops handler, after printing
351 * everything.
352 */
oops_exit(void)353 void oops_exit(void)
354 {
355 do_oops_enter_exit();
356 print_oops_end_marker();
357 kmsg_dump(KMSG_DUMP_OOPS);
358 }
359
360 #ifdef WANT_WARN_ON_SLOWPATH
361 struct slowpath_args {
362 const char *fmt;
363 va_list args;
364 };
365
warn_slowpath_common(const char * file,int line,void * caller,unsigned taint,struct slowpath_args * args)366 static void warn_slowpath_common(const char *file, int line, void *caller,
367 unsigned taint, struct slowpath_args *args)
368 {
369 const char *board;
370
371 printk(KERN_WARNING "------------[ cut here ]------------\n");
372 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
373 board = dmi_get_system_info(DMI_PRODUCT_NAME);
374 if (board)
375 printk(KERN_WARNING "Hardware name: %s\n", board);
376
377 if (args)
378 vprintk(args->fmt, args->args);
379
380 print_modules();
381 dump_stack();
382 print_oops_end_marker();
383 add_taint(taint);
384 }
385
warn_slowpath_fmt(const char * file,int line,const char * fmt,...)386 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
387 {
388 struct slowpath_args args;
389
390 args.fmt = fmt;
391 va_start(args.args, fmt);
392 warn_slowpath_common(file, line, __builtin_return_address(0),
393 TAINT_WARN, &args);
394 va_end(args.args);
395 }
396 EXPORT_SYMBOL(warn_slowpath_fmt);
397
warn_slowpath_fmt_taint(const char * file,int line,unsigned taint,const char * fmt,...)398 void warn_slowpath_fmt_taint(const char *file, int line,
399 unsigned taint, const char *fmt, ...)
400 {
401 struct slowpath_args args;
402
403 args.fmt = fmt;
404 va_start(args.args, fmt);
405 warn_slowpath_common(file, line, __builtin_return_address(0),
406 taint, &args);
407 va_end(args.args);
408 }
409 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
410
warn_slowpath_null(const char * file,int line)411 void warn_slowpath_null(const char *file, int line)
412 {
413 warn_slowpath_common(file, line, __builtin_return_address(0),
414 TAINT_WARN, NULL);
415 }
416 EXPORT_SYMBOL(warn_slowpath_null);
417 #endif
418
419 #ifdef CONFIG_CC_STACKPROTECTOR
420
421 /*
422 * Called when gcc's -fstack-protector feature is used, and
423 * gcc detects corruption of the on-stack canary value
424 */
__stack_chk_fail(void)425 void __stack_chk_fail(void)
426 {
427 panic("stack-protector: Kernel stack is corrupted in: %p\n",
428 __builtin_return_address(0));
429 }
430 EXPORT_SYMBOL(__stack_chk_fail);
431
432 #endif
433
434 core_param(panic, panic_timeout, int, 0644);
435 core_param(pause_on_oops, pause_on_oops, int, 0644);
436
oops_setup(char * s)437 static int __init oops_setup(char *s)
438 {
439 if (!s)
440 return -EINVAL;
441 if (!strcmp(s, "panic"))
442 panic_on_oops = 1;
443 return 0;
444 }
445 early_param("oops", oops_setup);
446