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