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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/ftrace.h> |
19 | #include <linux/reboot.h> |
20 | #include <linux/delay.h> |
21 | #include <linux/kexec.h> |
22 | #include <linux/sched.h> |
23 | #include <linux/sysrq.h> |
24 | #include <linux/init.h> |
25 | #include <linux/nmi.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 | * Disable local interrupts. This will prevent panic_smp_self_stop |
79 | * from deadlocking the first cpu that invokes the panic, since |
80 | * there is nothing to prevent an interrupt handler (that runs |
81 | * after the panic_lock is acquired) from invoking panic again. |
82 | */ |
83 | local_irq_disable(); |
84 | |
85 | /* |
86 | * It's possible to come here directly from a panic-assertion and |
87 | * not have preempt disabled. Some functions called from here want |
88 | * preempt to be disabled. No point enabling it later though... |
89 | * |
90 | * Only one CPU is allowed to execute the panic code from here. For |
91 | * multiple parallel invocations of panic, all other CPUs either |
92 | * stop themself or will wait until they are stopped by the 1st CPU |
93 | * with smp_send_stop(). |
94 | */ |
95 | if (!spin_trylock(&panic_lock)) |
96 | panic_smp_self_stop(); |
97 | |
98 | console_verbose(); |
99 | bust_spinlocks(1); |
100 | va_start(args, fmt); |
101 | vsnprintf(buf, sizeof(buf), fmt, args); |
102 | va_end(args); |
103 | printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); |
104 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
105 | /* |
106 | * Avoid nested stack-dumping if a panic occurs during oops processing |
107 | */ |
108 | if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
109 | dump_stack(); |
110 | #endif |
111 | |
112 | /* |
113 | * If we have crashed and we have a crash kernel loaded let it handle |
114 | * everything else. |
115 | * Do we want to call this before we try to display a message? |
116 | */ |
117 | crash_kexec(NULL); |
118 | |
119 | /* |
120 | * Note smp_send_stop is the usual smp shutdown function, which |
121 | * unfortunately means it may not be hardened to work in a panic |
122 | * situation. |
123 | */ |
124 | smp_send_stop(); |
125 | |
126 | kmsg_dump(KMSG_DUMP_PANIC); |
127 | |
128 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
129 | |
130 | bust_spinlocks(0); |
131 | |
132 | if (!panic_blink) |
133 | panic_blink = no_blink; |
134 | |
135 | if (panic_timeout > 0) { |
136 | /* |
137 | * Delay timeout seconds before rebooting the machine. |
138 | * We can't use the "normal" timers since we just panicked. |
139 | */ |
140 | printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); |
141 | |
142 | for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
143 | touch_nmi_watchdog(); |
144 | if (i >= i_next) { |
145 | i += panic_blink(state ^= 1); |
146 | i_next = i + 3600 / PANIC_BLINK_SPD; |
147 | } |
148 | mdelay(PANIC_TIMER_STEP); |
149 | } |
150 | } |
151 | if (panic_timeout != 0) { |
152 | /* |
153 | * This will not be a clean reboot, with everything |
154 | * shutting down. But if there is a chance of |
155 | * rebooting the system it will be rebooted. |
156 | */ |
157 | emergency_restart(); |
158 | } |
159 | #ifdef __sparc__ |
160 | { |
161 | extern int stop_a_enabled; |
162 | /* Make sure the user can actually press Stop-A (L1-A) */ |
163 | stop_a_enabled = 1; |
164 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); |
165 | } |
166 | #endif |
167 | #if defined(CONFIG_S390) |
168 | { |
169 | unsigned long caller; |
170 | |
171 | caller = (unsigned long)__builtin_return_address(0); |
172 | disabled_wait(caller); |
173 | } |
174 | #endif |
175 | local_irq_enable(); |
176 | for (i = 0; ; i += PANIC_TIMER_STEP) { |
177 | touch_softlockup_watchdog(); |
178 | if (i >= i_next) { |
179 | i += panic_blink(state ^= 1); |
180 | i_next = i + 3600 / PANIC_BLINK_SPD; |
181 | } |
182 | mdelay(PANIC_TIMER_STEP); |
183 | } |
184 | } |
185 | |
186 | EXPORT_SYMBOL(panic); |
187 | |
188 | |
189 | struct tnt { |
190 | u8 bit; |
191 | char true; |
192 | char false; |
193 | }; |
194 | |
195 | static const struct tnt tnts[] = { |
196 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, |
197 | { TAINT_FORCED_MODULE, 'F', ' ' }, |
198 | { TAINT_UNSAFE_SMP, 'S', ' ' }, |
199 | { TAINT_FORCED_RMMOD, 'R', ' ' }, |
200 | { TAINT_MACHINE_CHECK, 'M', ' ' }, |
201 | { TAINT_BAD_PAGE, 'B', ' ' }, |
202 | { TAINT_USER, 'U', ' ' }, |
203 | { TAINT_DIE, 'D', ' ' }, |
204 | { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, |
205 | { TAINT_WARN, 'W', ' ' }, |
206 | { TAINT_CRAP, 'C', ' ' }, |
207 | { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, |
208 | { TAINT_OOT_MODULE, 'O', ' ' }, |
209 | }; |
210 | |
211 | /** |
212 | * print_tainted - return a string to represent the kernel taint state. |
213 | * |
214 | * 'P' - Proprietary module has been loaded. |
215 | * 'F' - Module has been forcibly loaded. |
216 | * 'S' - SMP with CPUs not designed for SMP. |
217 | * 'R' - User forced a module unload. |
218 | * 'M' - System experienced a machine check exception. |
219 | * 'B' - System has hit bad_page. |
220 | * 'U' - Userspace-defined naughtiness. |
221 | * 'D' - Kernel has oopsed before |
222 | * 'A' - ACPI table overridden. |
223 | * 'W' - Taint on warning. |
224 | * 'C' - modules from drivers/staging are loaded. |
225 | * 'I' - Working around severe firmware bug. |
226 | * 'O' - Out-of-tree module has been loaded. |
227 | * |
228 | * The string is overwritten by the next call to print_tainted(). |
229 | */ |
230 | const char *print_tainted(void) |
231 | { |
232 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; |
233 | |
234 | if (tainted_mask) { |
235 | char *s; |
236 | int i; |
237 | |
238 | s = buf + sprintf(buf, "Tainted: "); |
239 | for (i = 0; i < ARRAY_SIZE(tnts); i++) { |
240 | const struct tnt *t = &tnts[i]; |
241 | *s++ = test_bit(t->bit, &tainted_mask) ? |
242 | t->true : t->false; |
243 | } |
244 | *s = 0; |
245 | } else |
246 | snprintf(buf, sizeof(buf), "Not tainted"); |
247 | |
248 | return buf; |
249 | } |
250 | |
251 | int test_taint(unsigned flag) |
252 | { |
253 | return test_bit(flag, &tainted_mask); |
254 | } |
255 | EXPORT_SYMBOL(test_taint); |
256 | |
257 | unsigned long get_taint(void) |
258 | { |
259 | return tainted_mask; |
260 | } |
261 | |
262 | /** |
263 | * add_taint: add a taint flag if not already set. |
264 | * @flag: one of the TAINT_* constants. |
265 | * @lockdep_ok: whether lock debugging is still OK. |
266 | * |
267 | * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for |
268 | * some notewortht-but-not-corrupting cases, it can be set to true. |
269 | */ |
270 | void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) |
271 | { |
272 | if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) |
273 | printk(KERN_WARNING |
274 | "Disabling lock debugging due to kernel taint\n"); |
275 | |
276 | set_bit(flag, &tainted_mask); |
277 | } |
278 | EXPORT_SYMBOL(add_taint); |
279 | |
280 | static void spin_msec(int msecs) |
281 | { |
282 | int i; |
283 | |
284 | for (i = 0; i < msecs; i++) { |
285 | touch_nmi_watchdog(); |
286 | mdelay(1); |
287 | } |
288 | } |
289 | |
290 | /* |
291 | * It just happens that oops_enter() and oops_exit() are identically |
292 | * implemented... |
293 | */ |
294 | static void do_oops_enter_exit(void) |
295 | { |
296 | unsigned long flags; |
297 | static int spin_counter; |
298 | |
299 | if (!pause_on_oops) |
300 | return; |
301 | |
302 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
303 | if (pause_on_oops_flag == 0) { |
304 | /* This CPU may now print the oops message */ |
305 | pause_on_oops_flag = 1; |
306 | } else { |
307 | /* We need to stall this CPU */ |
308 | if (!spin_counter) { |
309 | /* This CPU gets to do the counting */ |
310 | spin_counter = pause_on_oops; |
311 | do { |
312 | spin_unlock(&pause_on_oops_lock); |
313 | spin_msec(MSEC_PER_SEC); |
314 | spin_lock(&pause_on_oops_lock); |
315 | } while (--spin_counter); |
316 | pause_on_oops_flag = 0; |
317 | } else { |
318 | /* This CPU waits for a different one */ |
319 | while (spin_counter) { |
320 | spin_unlock(&pause_on_oops_lock); |
321 | spin_msec(1); |
322 | spin_lock(&pause_on_oops_lock); |
323 | } |
324 | } |
325 | } |
326 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); |
327 | } |
328 | |
329 | /* |
330 | * Return true if the calling CPU is allowed to print oops-related info. |
331 | * This is a bit racy.. |
332 | */ |
333 | int oops_may_print(void) |
334 | { |
335 | return pause_on_oops_flag == 0; |
336 | } |
337 | |
338 | /* |
339 | * Called when the architecture enters its oops handler, before it prints |
340 | * anything. If this is the first CPU to oops, and it's oopsing the first |
341 | * time then let it proceed. |
342 | * |
343 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
344 | * this to ensure that oopses don't scroll off the screen. It has the |
345 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
346 | * too. |
347 | * |
348 | * It turns out that the CPU which is allowed to print ends up pausing for |
349 | * the right duration, whereas all the other CPUs pause for twice as long: |
350 | * once in oops_enter(), once in oops_exit(). |
351 | */ |
352 | void oops_enter(void) |
353 | { |
354 | tracing_off(); |
355 | /* can't trust the integrity of the kernel anymore: */ |
356 | debug_locks_off(); |
357 | do_oops_enter_exit(); |
358 | } |
359 | |
360 | /* |
361 | * 64-bit random ID for oopses: |
362 | */ |
363 | static u64 oops_id; |
364 | |
365 | static int init_oops_id(void) |
366 | { |
367 | if (!oops_id) |
368 | get_random_bytes(&oops_id, sizeof(oops_id)); |
369 | else |
370 | oops_id++; |
371 | |
372 | return 0; |
373 | } |
374 | late_initcall(init_oops_id); |
375 | |
376 | void print_oops_end_marker(void) |
377 | { |
378 | init_oops_id(); |
379 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", |
380 | (unsigned long long)oops_id); |
381 | } |
382 | |
383 | /* |
384 | * Called when the architecture exits its oops handler, after printing |
385 | * everything. |
386 | */ |
387 | void oops_exit(void) |
388 | { |
389 | do_oops_enter_exit(); |
390 | print_oops_end_marker(); |
391 | kmsg_dump(KMSG_DUMP_OOPS); |
392 | } |
393 | |
394 | #ifdef WANT_WARN_ON_SLOWPATH |
395 | struct slowpath_args { |
396 | const char *fmt; |
397 | va_list args; |
398 | }; |
399 | |
400 | static void warn_slowpath_common(const char *file, int line, void *caller, |
401 | unsigned taint, struct slowpath_args *args) |
402 | { |
403 | disable_trace_on_warning(); |
404 | |
405 | pr_warn("------------[ cut here ]------------\n"); |
406 | pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", |
407 | raw_smp_processor_id(), current->pid, file, line, caller); |
408 | |
409 | if (args) |
410 | vprintk(args->fmt, args->args); |
411 | |
412 | print_modules(); |
413 | dump_stack(); |
414 | print_oops_end_marker(); |
415 | /* Just a warning, don't kill lockdep. */ |
416 | add_taint(taint, LOCKDEP_STILL_OK); |
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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