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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 | 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 | /* Returns how long it waited in ms */ |
40 | long (*panic_blink)(long time); |
41 | EXPORT_SYMBOL(panic_blink); |
42 | |
43 | static void panic_blink_one_second(void) |
44 | { |
45 | static long i = 0, end; |
46 | |
47 | if (panic_blink) { |
48 | end = i + MSEC_PER_SEC; |
49 | |
50 | while (i < end) { |
51 | i += panic_blink(i); |
52 | mdelay(1); |
53 | i++; |
54 | } |
55 | } else { |
56 | /* |
57 | * When running under a hypervisor a small mdelay may get |
58 | * rounded up to the hypervisor timeslice. For example, with |
59 | * a 1ms in 10ms hypervisor timeslice we might inflate a |
60 | * mdelay(1) loop by 10x. |
61 | * |
62 | * If we have nothing to blink, spin on 1 second calls to |
63 | * mdelay to avoid this. |
64 | */ |
65 | mdelay(MSEC_PER_SEC); |
66 | } |
67 | } |
68 | |
69 | /** |
70 | * panic - halt the system |
71 | * @fmt: The text string to print |
72 | * |
73 | * Display a message, then perform cleanups. |
74 | * |
75 | * This function never returns. |
76 | */ |
77 | NORET_TYPE void panic(const char * fmt, ...) |
78 | { |
79 | static char buf[1024]; |
80 | va_list args; |
81 | long i; |
82 | |
83 | /* |
84 | * It's possible to come here directly from a panic-assertion and |
85 | * not have preempt disabled. Some functions called from here want |
86 | * preempt to be disabled. No point enabling it later though... |
87 | */ |
88 | preempt_disable(); |
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 | dump_stack(); |
98 | #endif |
99 | |
100 | /* |
101 | * If we have crashed and we have a crash kernel loaded let it handle |
102 | * everything else. |
103 | * Do we want to call this before we try to display a message? |
104 | */ |
105 | crash_kexec(NULL); |
106 | |
107 | kmsg_dump(KMSG_DUMP_PANIC); |
108 | |
109 | /* |
110 | * Note smp_send_stop is the usual smp shutdown function, which |
111 | * unfortunately means it may not be hardened to work in a panic |
112 | * situation. |
113 | */ |
114 | smp_send_stop(); |
115 | |
116 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
117 | |
118 | bust_spinlocks(0); |
119 | |
120 | if (panic_timeout > 0) { |
121 | /* |
122 | * Delay timeout seconds before rebooting the machine. |
123 | * We can't use the "normal" timers since we just panicked. |
124 | */ |
125 | printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); |
126 | |
127 | for (i = 0; i < panic_timeout; i++) { |
128 | touch_nmi_watchdog(); |
129 | panic_blink_one_second(); |
130 | } |
131 | /* |
132 | * This will not be a clean reboot, with everything |
133 | * shutting down. But if there is a chance of |
134 | * rebooting the system it will be rebooted. |
135 | */ |
136 | emergency_restart(); |
137 | } |
138 | #ifdef __sparc__ |
139 | { |
140 | extern int stop_a_enabled; |
141 | /* Make sure the user can actually press Stop-A (L1-A) */ |
142 | stop_a_enabled = 1; |
143 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); |
144 | } |
145 | #endif |
146 | #if defined(CONFIG_S390) |
147 | { |
148 | unsigned long caller; |
149 | |
150 | caller = (unsigned long)__builtin_return_address(0); |
151 | disabled_wait(caller); |
152 | } |
153 | #endif |
154 | local_irq_enable(); |
155 | while (1) { |
156 | touch_softlockup_watchdog(); |
157 | panic_blink_one_second(); |
158 | } |
159 | } |
160 | |
161 | EXPORT_SYMBOL(panic); |
162 | |
163 | |
164 | struct tnt { |
165 | u8 bit; |
166 | char true; |
167 | char false; |
168 | }; |
169 | |
170 | static const struct tnt tnts[] = { |
171 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, |
172 | { TAINT_FORCED_MODULE, 'F', ' ' }, |
173 | { TAINT_UNSAFE_SMP, 'S', ' ' }, |
174 | { TAINT_FORCED_RMMOD, 'R', ' ' }, |
175 | { TAINT_MACHINE_CHECK, 'M', ' ' }, |
176 | { TAINT_BAD_PAGE, 'B', ' ' }, |
177 | { TAINT_USER, 'U', ' ' }, |
178 | { TAINT_DIE, 'D', ' ' }, |
179 | { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, |
180 | { TAINT_WARN, 'W', ' ' }, |
181 | { TAINT_CRAP, 'C', ' ' }, |
182 | { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, |
183 | }; |
184 | |
185 | /** |
186 | * print_tainted - return a string to represent the kernel taint state. |
187 | * |
188 | * 'P' - Proprietary module has been loaded. |
189 | * 'F' - Module has been forcibly loaded. |
190 | * 'S' - SMP with CPUs not designed for SMP. |
191 | * 'R' - User forced a module unload. |
192 | * 'M' - System experienced a machine check exception. |
193 | * 'B' - System has hit bad_page. |
194 | * 'U' - Userspace-defined naughtiness. |
195 | * 'D' - Kernel has oopsed before |
196 | * 'A' - ACPI table overridden. |
197 | * 'W' - Taint on warning. |
198 | * 'C' - modules from drivers/staging are loaded. |
199 | * 'I' - Working around severe firmware bug. |
200 | * |
201 | * The string is overwritten by the next call to print_tainted(). |
202 | */ |
203 | const char *print_tainted(void) |
204 | { |
205 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; |
206 | |
207 | if (tainted_mask) { |
208 | char *s; |
209 | int i; |
210 | |
211 | s = buf + sprintf(buf, "Tainted: "); |
212 | for (i = 0; i < ARRAY_SIZE(tnts); i++) { |
213 | const struct tnt *t = &tnts[i]; |
214 | *s++ = test_bit(t->bit, &tainted_mask) ? |
215 | t->true : t->false; |
216 | } |
217 | *s = 0; |
218 | } else |
219 | snprintf(buf, sizeof(buf), "Not tainted"); |
220 | |
221 | return buf; |
222 | } |
223 | |
224 | int test_taint(unsigned flag) |
225 | { |
226 | return test_bit(flag, &tainted_mask); |
227 | } |
228 | EXPORT_SYMBOL(test_taint); |
229 | |
230 | unsigned long get_taint(void) |
231 | { |
232 | return tainted_mask; |
233 | } |
234 | |
235 | void add_taint(unsigned flag) |
236 | { |
237 | /* |
238 | * Can't trust the integrity of the kernel anymore. |
239 | * We don't call directly debug_locks_off() because the issue |
240 | * is not necessarily serious enough to set oops_in_progress to 1 |
241 | * Also we want to keep up lockdep for staging development and |
242 | * post-warning case. |
243 | */ |
244 | if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) |
245 | printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); |
246 | |
247 | set_bit(flag, &tainted_mask); |
248 | } |
249 | EXPORT_SYMBOL(add_taint); |
250 | |
251 | static void spin_msec(int msecs) |
252 | { |
253 | int i; |
254 | |
255 | for (i = 0; i < msecs; i++) { |
256 | touch_nmi_watchdog(); |
257 | mdelay(1); |
258 | } |
259 | } |
260 | |
261 | /* |
262 | * It just happens that oops_enter() and oops_exit() are identically |
263 | * implemented... |
264 | */ |
265 | static void do_oops_enter_exit(void) |
266 | { |
267 | unsigned long flags; |
268 | static int spin_counter; |
269 | |
270 | if (!pause_on_oops) |
271 | return; |
272 | |
273 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
274 | if (pause_on_oops_flag == 0) { |
275 | /* This CPU may now print the oops message */ |
276 | pause_on_oops_flag = 1; |
277 | } else { |
278 | /* We need to stall this CPU */ |
279 | if (!spin_counter) { |
280 | /* This CPU gets to do the counting */ |
281 | spin_counter = pause_on_oops; |
282 | do { |
283 | spin_unlock(&pause_on_oops_lock); |
284 | spin_msec(MSEC_PER_SEC); |
285 | spin_lock(&pause_on_oops_lock); |
286 | } while (--spin_counter); |
287 | pause_on_oops_flag = 0; |
288 | } else { |
289 | /* This CPU waits for a different one */ |
290 | while (spin_counter) { |
291 | spin_unlock(&pause_on_oops_lock); |
292 | spin_msec(1); |
293 | spin_lock(&pause_on_oops_lock); |
294 | } |
295 | } |
296 | } |
297 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); |
298 | } |
299 | |
300 | /* |
301 | * Return true if the calling CPU is allowed to print oops-related info. |
302 | * This is a bit racy.. |
303 | */ |
304 | int oops_may_print(void) |
305 | { |
306 | return pause_on_oops_flag == 0; |
307 | } |
308 | |
309 | /* |
310 | * Called when the architecture enters its oops handler, before it prints |
311 | * anything. If this is the first CPU to oops, and it's oopsing the first |
312 | * time then let it proceed. |
313 | * |
314 | * This is all enabled by the pause_on_oops kernel boot option. We do all |
315 | * this to ensure that oopses don't scroll off the screen. It has the |
316 | * side-effect of preventing later-oopsing CPUs from mucking up the display, |
317 | * too. |
318 | * |
319 | * It turns out that the CPU which is allowed to print ends up pausing for |
320 | * the right duration, whereas all the other CPUs pause for twice as long: |
321 | * once in oops_enter(), once in oops_exit(). |
322 | */ |
323 | void oops_enter(void) |
324 | { |
325 | tracing_off(); |
326 | /* can't trust the integrity of the kernel anymore: */ |
327 | debug_locks_off(); |
328 | do_oops_enter_exit(); |
329 | } |
330 | |
331 | /* |
332 | * 64-bit random ID for oopses: |
333 | */ |
334 | static u64 oops_id; |
335 | |
336 | static int init_oops_id(void) |
337 | { |
338 | if (!oops_id) |
339 | get_random_bytes(&oops_id, sizeof(oops_id)); |
340 | else |
341 | oops_id++; |
342 | |
343 | return 0; |
344 | } |
345 | late_initcall(init_oops_id); |
346 | |
347 | static void print_oops_end_marker(void) |
348 | { |
349 | init_oops_id(); |
350 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", |
351 | (unsigned long long)oops_id); |
352 | } |
353 | |
354 | /* |
355 | * Called when the architecture exits its oops handler, after printing |
356 | * everything. |
357 | */ |
358 | void oops_exit(void) |
359 | { |
360 | do_oops_enter_exit(); |
361 | print_oops_end_marker(); |
362 | kmsg_dump(KMSG_DUMP_OOPS); |
363 | } |
364 | |
365 | #ifdef WANT_WARN_ON_SLOWPATH |
366 | struct slowpath_args { |
367 | const char *fmt; |
368 | va_list args; |
369 | }; |
370 | |
371 | static void warn_slowpath_common(const char *file, int line, void *caller, |
372 | unsigned taint, struct slowpath_args *args) |
373 | { |
374 | const char *board; |
375 | |
376 | printk(KERN_WARNING "------------[ cut here ]------------\n"); |
377 | printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); |
378 | board = dmi_get_system_info(DMI_PRODUCT_NAME); |
379 | if (board) |
380 | printk(KERN_WARNING "Hardware name: %s\n", board); |
381 | |
382 | if (args) |
383 | vprintk(args->fmt, args->args); |
384 | |
385 | print_modules(); |
386 | dump_stack(); |
387 | print_oops_end_marker(); |
388 | add_taint(taint); |
389 | } |
390 | |
391 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) |
392 | { |
393 | struct slowpath_args args; |
394 | |
395 | args.fmt = fmt; |
396 | va_start(args.args, fmt); |
397 | warn_slowpath_common(file, line, __builtin_return_address(0), |
398 | TAINT_WARN, &args); |
399 | va_end(args.args); |
400 | } |
401 | EXPORT_SYMBOL(warn_slowpath_fmt); |
402 | |
403 | void warn_slowpath_fmt_taint(const char *file, int line, |
404 | unsigned taint, const char *fmt, ...) |
405 | { |
406 | struct slowpath_args args; |
407 | |
408 | args.fmt = fmt; |
409 | va_start(args.args, fmt); |
410 | warn_slowpath_common(file, line, __builtin_return_address(0), |
411 | taint, &args); |
412 | va_end(args.args); |
413 | } |
414 | EXPORT_SYMBOL(warn_slowpath_fmt_taint); |
415 | |
416 | void warn_slowpath_null(const char *file, int line) |
417 | { |
418 | warn_slowpath_common(file, line, __builtin_return_address(0), |
419 | TAINT_WARN, NULL); |
420 | } |
421 | EXPORT_SYMBOL(warn_slowpath_null); |
422 | #endif |
423 | |
424 | #ifdef CONFIG_CC_STACKPROTECTOR |
425 | |
426 | /* |
427 | * Called when gcc's -fstack-protector feature is used, and |
428 | * gcc detects corruption of the on-stack canary value |
429 | */ |
430 | void __stack_chk_fail(void) |
431 | { |
432 | panic("stack-protector: Kernel stack is corrupted in: %p\n", |
433 | __builtin_return_address(0)); |
434 | } |
435 | EXPORT_SYMBOL(__stack_chk_fail); |
436 | |
437 | #endif |
438 | |
439 | core_param(panic, panic_timeout, int, 0644); |
440 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
441 |
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