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