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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 | 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 | * 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 | */ |
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 | */ |
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 | |
219 | int test_taint(unsigned flag) |
220 | { |
221 | return test_bit(flag, &tainted_mask); |
222 | } |
223 | EXPORT_SYMBOL(test_taint); |
224 | |
225 | unsigned long get_taint(void) |
226 | { |
227 | return tainted_mask; |
228 | } |
229 | |
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 | |
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 | */ |
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 | */ |
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 | */ |
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 | |
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 | |
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 | */ |
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 | |
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 | |
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 | |
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 | |
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 | */ |
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 |
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