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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 = CONFIG_PANIC_ON_OOPS_VALUE; |
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 | |
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 | * Stop ourself in panic -- architecture code may override this |
54 | */ |
55 | void __weak panic_smp_self_stop(void) |
56 | { |
57 | while (1) |
58 | cpu_relax(); |
59 | } |
60 | |
61 | /** |
62 | * panic - halt the system |
63 | * @fmt: The text string to print |
64 | * |
65 | * Display a message, then perform cleanups. |
66 | * |
67 | * This function never returns. |
68 | */ |
69 | void panic(const char *fmt, ...) |
70 | { |
71 | static DEFINE_SPINLOCK(panic_lock); |
72 | static char buf[1024]; |
73 | va_list args; |
74 | long i, i_next = 0; |
75 | int state = 0; |
76 | |
77 | /* |
78 | * It's possible to come here directly from a panic-assertion and |
79 | * not have preempt disabled. Some functions called from here want |
80 | * preempt to be disabled. No point enabling it later though... |
81 | * |
82 | * Only one CPU is allowed to execute the panic code from here. For |
83 | * multiple parallel invocations of panic, all other CPUs either |
84 | * stop themself or will wait until they are stopped by the 1st CPU |
85 | * with smp_send_stop(). |
86 | */ |
87 | if (!spin_trylock(&panic_lock)) |
88 | panic_smp_self_stop(); |
89 | |
90 | console_verbose(); |
91 | bust_spinlocks(1); |
92 | va_start(args, fmt); |
93 | vsnprintf(buf, sizeof(buf), fmt, args); |
94 | va_end(args); |
95 | printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); |
96 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
97 | /* |
98 | * Avoid nested stack-dumping if a panic occurs during oops processing |
99 | */ |
100 | if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
101 | dump_stack(); |
102 | #endif |
103 | |
104 | /* |
105 | * If we have crashed and we have a crash kernel loaded let it handle |
106 | * everything else. |
107 | * Do we want to call this before we try to display a message? |
108 | */ |
109 | crash_kexec(NULL); |
110 | |
111 | /* |
112 | * Note smp_send_stop is the usual smp shutdown function, which |
113 | * unfortunately means it may not be hardened to work in a panic |
114 | * situation. |
115 | */ |
116 | smp_send_stop(); |
117 | |
118 | kmsg_dump(KMSG_DUMP_PANIC); |
119 | |
120 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
121 | |
122 | bust_spinlocks(0); |
123 | |
124 | if (!panic_blink) |
125 | panic_blink = no_blink; |
126 | |
127 | if (panic_timeout > 0) { |
128 | /* |
129 | * Delay timeout seconds before rebooting the machine. |
130 | * We can't use the "normal" timers since we just panicked. |
131 | */ |
132 | printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); |
133 | |
134 | for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
135 | touch_nmi_watchdog(); |
136 | if (i >= i_next) { |
137 | i += panic_blink(state ^= 1); |
138 | i_next = i + 3600 / PANIC_BLINK_SPD; |
139 | } |
140 | mdelay(PANIC_TIMER_STEP); |
141 | } |
142 | } |
143 | if (panic_timeout != 0) { |
144 | /* |
145 | * This will not be a clean reboot, with everything |
146 | * shutting down. But if there is a chance of |
147 | * rebooting the system it will be rebooted. |
148 | */ |
149 | emergency_restart(); |
150 | } |
151 | #ifdef __sparc__ |
152 | { |
153 | extern int stop_a_enabled; |
154 | /* Make sure the user can actually press Stop-A (L1-A) */ |
155 | stop_a_enabled = 1; |
156 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); |
157 | } |
158 | #endif |
159 | #if defined(CONFIG_S390) |
160 | { |
161 | unsigned long caller; |
162 | |
163 | caller = (unsigned long)__builtin_return_address(0); |
164 | disabled_wait(caller); |
165 | } |
166 | #endif |
167 | local_irq_enable(); |
168 | for (i = 0; ; i += PANIC_TIMER_STEP) { |
169 | touch_softlockup_watchdog(); |
170 | if (i >= i_next) { |
171 | i += panic_blink(state ^= 1); |
172 | i_next = i + 3600 / PANIC_BLINK_SPD; |
173 | } |
174 | mdelay(PANIC_TIMER_STEP); |
175 | } |
176 | } |
177 | |
178 | EXPORT_SYMBOL(panic); |
179 | |
180 | |
181 | struct tnt { |
182 | u8 bit; |
183 | char true; |
184 | char false; |
185 | }; |
186 | |
187 | static const struct tnt tnts[] = { |
188 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, |
189 | { TAINT_FORCED_MODULE, 'F', ' ' }, |
190 | { TAINT_UNSAFE_SMP, 'S', ' ' }, |
191 | { TAINT_FORCED_RMMOD, 'R', ' ' }, |
192 | { TAINT_MACHINE_CHECK, 'M', ' ' }, |
193 | { TAINT_BAD_PAGE, 'B', ' ' }, |
194 | { TAINT_USER, 'U', ' ' }, |
195 | { TAINT_DIE, 'D', ' ' }, |
196 | { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, |
197 | { TAINT_WARN, 'W', ' ' }, |
198 | { TAINT_CRAP, 'C', ' ' }, |
199 | { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, |
200 | { TAINT_OOT_MODULE, 'O', ' ' }, |
201 | }; |
202 | |
203 | /** |
204 | * print_tainted - return a string to represent the kernel taint state. |
205 | * |
206 | * 'P' - Proprietary module has been loaded. |
207 | * 'F' - Module has been forcibly loaded. |
208 | * 'S' - SMP with CPUs not designed for SMP. |
209 | * 'R' - User forced a module unload. |
210 | * 'M' - System experienced a machine check exception. |
211 | * 'B' - System has hit bad_page. |
212 | * 'U' - Userspace-defined naughtiness. |
213 | * 'D' - Kernel has oopsed before |
214 | * 'A' - ACPI table overridden. |
215 | * 'W' - Taint on warning. |
216 | * 'C' - modules from drivers/staging are loaded. |
217 | * 'I' - Working around severe firmware bug. |
218 | * 'O' - Out-of-tree module has been loaded. |
219 | * |
220 | * The string is overwritten by the next call to print_tainted(). |
221 | */ |
222 | const char *print_tainted(void) |
223 | { |
224 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; |
225 | |
226 | if (tainted_mask) { |
227 | char *s; |
228 | int i; |
229 | |
230 | s = buf + sprintf(buf, "Tainted: "); |
231 | for (i = 0; i < ARRAY_SIZE(tnts); i++) { |
232 | const struct tnt *t = &tnts[i]; |
233 | *s++ = test_bit(t->bit, &tainted_mask) ? |
234 | t->true : t->false; |
235 | } |
236 | *s = 0; |
237 | } else |
238 | snprintf(buf, sizeof(buf), "Not tainted"); |
239 | |
240 | return buf; |
241 | } |
242 | |
243 | int test_taint(unsigned flag) |
244 | { |
245 | return test_bit(flag, &tainted_mask); |
246 | } |
247 | EXPORT_SYMBOL(test_taint); |
248 | |
249 | unsigned long get_taint(void) |
250 | { |
251 | return tainted_mask; |
252 | } |
253 | |
254 | void add_taint(unsigned flag) |
255 | { |
256 | /* |
257 | * Can't trust the integrity of the kernel anymore. |
258 | * We don't call directly debug_locks_off() because the issue |
259 | * is not necessarily serious enough to set oops_in_progress to 1 |
260 | * Also we want to keep up lockdep for staging/out-of-tree |
261 | * development and post-warning case. |
262 | */ |
263 | switch (flag) { |
264 | case TAINT_CRAP: |
265 | case TAINT_OOT_MODULE: |
266 | case TAINT_WARN: |
267 | case TAINT_FIRMWARE_WORKAROUND: |
268 | break; |
269 | |
270 | default: |
271 | if (__debug_locks_off()) |
272 | printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); |
273 | } |
274 | |
275 | set_bit(flag, &tainted_mask); |
276 | } |
277 | EXPORT_SYMBOL(add_taint); |
278 | |
279 | static void spin_msec(int msecs) |
280 | { |
281 | int i; |
282 | |
283 | for (i = 0; i < msecs; i++) { |
284 | touch_nmi_watchdog(); |
285 | mdelay(1); |
286 | } |
287 | } |
288 | |
289 | /* |
290 | * It just happens that oops_enter() and oops_exit() are identically |
291 | * implemented... |
292 | */ |
293 | static void do_oops_enter_exit(void) |
294 | { |
295 | unsigned long flags; |
296 | static int spin_counter; |
297 | |
298 | if (!pause_on_oops) |
299 | return; |
300 | |
301 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
302 | if (pause_on_oops_flag == 0) { |
303 | /* This CPU may now print the oops message */ |
304 | pause_on_oops_flag = 1; |
305 | } else { |
306 | /* We need to stall this CPU */ |
307 | if (!spin_counter) { |
308 | /* This CPU gets to do the counting */ |
309 | spin_counter = pause_on_oops; |
310 | do { |
311 | spin_unlock(&pause_on_oops_lock); |
312 | spin_msec(MSEC_PER_SEC); |
313 | spin_lock(&pause_on_oops_lock); |
314 | } while (--spin_counter); |
315 | pause_on_oops_flag = 0; |
316 | } else { |
317 | /* This CPU waits for a different one */ |
318 | while (spin_counter) { |
319 | spin_unlock(&pause_on_oops_lock); |
320 | spin_msec(1); |
321 | spin_lock(&pause_on_oops_lock); |
322 | } |
323 | } |
324 | } |
325 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); |
326 | } |
327 | |
328 | /* |
329 | * Return true if the calling CPU is allowed to print oops-related info. |
330 | * This is a bit racy.. |
331 | */ |
332 | int oops_may_print(void) |
333 | { |
334 | return pause_on_oops_flag == 0; |
335 | } |
336 | |
337 | /* |
338 | * Called when the architecture enters its oops handler, before it prints |
339 | * anything. If this is the first CPU to oops, and it's oopsing the first |
340 | * time then let it proceed. |
341 | * |
342 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
343 | * this to ensure that oopses don't scroll off the screen. It has the |
344 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
345 | * too. |
346 | * |
347 | * It turns out that the CPU which is allowed to print ends up pausing for |
348 | * the right duration, whereas all the other CPUs pause for twice as long: |
349 | * once in oops_enter(), once in oops_exit(). |
350 | */ |
351 | void oops_enter(void) |
352 | { |
353 | tracing_off(); |
354 | /* can't trust the integrity of the kernel anymore: */ |
355 | debug_locks_off(); |
356 | do_oops_enter_exit(); |
357 | } |
358 | |
359 | /* |
360 | * 64-bit random ID for oopses: |
361 | */ |
362 | static u64 oops_id; |
363 | |
364 | static int init_oops_id(void) |
365 | { |
366 | if (!oops_id) |
367 | get_random_bytes(&oops_id, sizeof(oops_id)); |
368 | else |
369 | oops_id++; |
370 | |
371 | return 0; |
372 | } |
373 | late_initcall(init_oops_id); |
374 | |
375 | void print_oops_end_marker(void) |
376 | { |
377 | init_oops_id(); |
378 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", |
379 | (unsigned long long)oops_id); |
380 | } |
381 | |
382 | /* |
383 | * Called when the architecture exits its oops handler, after printing |
384 | * everything. |
385 | */ |
386 | void oops_exit(void) |
387 | { |
388 | do_oops_enter_exit(); |
389 | print_oops_end_marker(); |
390 | kmsg_dump(KMSG_DUMP_OOPS); |
391 | } |
392 | |
393 | #ifdef WANT_WARN_ON_SLOWPATH |
394 | struct slowpath_args { |
395 | const char *fmt; |
396 | va_list args; |
397 | }; |
398 | |
399 | static void warn_slowpath_common(const char *file, int line, void *caller, |
400 | unsigned taint, struct slowpath_args *args) |
401 | { |
402 | const char *board; |
403 | |
404 | printk(KERN_WARNING "------------[ cut here ]------------\n"); |
405 | printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); |
406 | board = dmi_get_system_info(DMI_PRODUCT_NAME); |
407 | if (board) |
408 | printk(KERN_WARNING "Hardware name: %s\n", board); |
409 | |
410 | if (args) |
411 | vprintk(args->fmt, args->args); |
412 | |
413 | print_modules(); |
414 | dump_stack(); |
415 | print_oops_end_marker(); |
416 | add_taint(taint); |
417 | } |
418 | |
419 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) |
420 | { |
421 | struct slowpath_args args; |
422 | |
423 | args.fmt = fmt; |
424 | va_start(args.args, fmt); |
425 | warn_slowpath_common(file, line, __builtin_return_address(0), |
426 | TAINT_WARN, &args); |
427 | va_end(args.args); |
428 | } |
429 | EXPORT_SYMBOL(warn_slowpath_fmt); |
430 | |
431 | void warn_slowpath_fmt_taint(const char *file, int line, |
432 | unsigned taint, const char *fmt, ...) |
433 | { |
434 | struct slowpath_args args; |
435 | |
436 | args.fmt = fmt; |
437 | va_start(args.args, fmt); |
438 | warn_slowpath_common(file, line, __builtin_return_address(0), |
439 | taint, &args); |
440 | va_end(args.args); |
441 | } |
442 | EXPORT_SYMBOL(warn_slowpath_fmt_taint); |
443 | |
444 | void warn_slowpath_null(const char *file, int line) |
445 | { |
446 | warn_slowpath_common(file, line, __builtin_return_address(0), |
447 | TAINT_WARN, NULL); |
448 | } |
449 | EXPORT_SYMBOL(warn_slowpath_null); |
450 | #endif |
451 | |
452 | #ifdef CONFIG_CC_STACKPROTECTOR |
453 | |
454 | /* |
455 | * Called when gcc's -fstack-protector feature is used, and |
456 | * gcc detects corruption of the on-stack canary value |
457 | */ |
458 | void __stack_chk_fail(void) |
459 | { |
460 | panic("stack-protector: Kernel stack is corrupted in: %p\n", |
461 | __builtin_return_address(0)); |
462 | } |
463 | EXPORT_SYMBOL(__stack_chk_fail); |
464 | |
465 | #endif |
466 | |
467 | core_param(panic, panic_timeout, int, 0644); |
468 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
469 | |
470 | static int __init oops_setup(char *s) |
471 | { |
472 | if (!s) |
473 | return -EINVAL; |
474 | if (!strcmp(s, "panic")) |
475 | panic_on_oops = 1; |
476 | return 0; |
477 | } |
478 | early_param("oops", oops_setup); |
479 |
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