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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/kallsyms.h> | |
14 | #include <linux/notifier.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/random.h> | |
17 | #include <linux/reboot.h> | |
18 | #include <linux/delay.h> | |
19 | #include <linux/kexec.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/sysrq.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/nmi.h> | |
24 | #include <linux/dmi.h> | |
25 | ||
26 | int panic_on_oops; | |
27 | static unsigned long tainted_mask; | |
28 | static int pause_on_oops; | |
29 | static int pause_on_oops_flag; | |
30 | static DEFINE_SPINLOCK(pause_on_oops_lock); | |
31 | ||
32 | int panic_timeout; | |
33 | ||
34 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); | |
35 | ||
36 | EXPORT_SYMBOL(panic_notifier_list); | |
37 | ||
38 | static long no_blink(long time) | |
39 | { | |
40 | return 0; | |
41 | } | |
42 | ||
43 | /* Returns how long it waited in ms */ | |
44 | long (*panic_blink)(long time); | |
45 | EXPORT_SYMBOL(panic_blink); | |
46 | ||
47 | /** | |
48 | * panic - halt the system | |
49 | * @fmt: The text string to print | |
50 | * | |
51 | * Display a message, then perform cleanups. | |
52 | * | |
53 | * This function never returns. | |
54 | */ | |
55 | NORET_TYPE void panic(const char * fmt, ...) | |
56 | { | |
57 | static char buf[1024]; | |
58 | va_list args; | |
59 | long i; | |
60 | ||
61 | /* | |
62 | * It's possible to come here directly from a panic-assertion and | |
63 | * not have preempt disabled. Some functions called from here want | |
64 | * preempt to be disabled. No point enabling it later though... | |
65 | */ | |
66 | preempt_disable(); | |
67 | ||
68 | bust_spinlocks(1); | |
69 | va_start(args, fmt); | |
70 | vsnprintf(buf, sizeof(buf), fmt, args); | |
71 | va_end(args); | |
72 | printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); | |
73 | #ifdef CONFIG_DEBUG_BUGVERBOSE | |
74 | dump_stack(); | |
75 | #endif | |
76 | ||
77 | /* | |
78 | * If we have crashed and we have a crash kernel loaded let it handle | |
79 | * everything else. | |
80 | * Do we want to call this before we try to display a message? | |
81 | */ | |
82 | crash_kexec(NULL); | |
83 | ||
84 | /* | |
85 | * Note smp_send_stop is the usual smp shutdown function, which | |
86 | * unfortunately means it may not be hardened to work in a panic | |
87 | * situation. | |
88 | */ | |
89 | smp_send_stop(); | |
90 | ||
91 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); | |
92 | ||
93 | if (!panic_blink) | |
94 | panic_blink = no_blink; | |
95 | ||
96 | if (panic_timeout > 0) { | |
97 | /* | |
98 | * Delay timeout seconds before rebooting the machine. | |
99 | * We can't use the "normal" timers since we just panicked. | |
100 | */ | |
101 | printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); | |
102 | ||
103 | for (i = 0; i < panic_timeout*1000; ) { | |
104 | touch_nmi_watchdog(); | |
105 | i += panic_blink(i); | |
106 | mdelay(1); | |
107 | i++; | |
108 | } | |
109 | /* | |
110 | * This will not be a clean reboot, with everything | |
111 | * shutting down. But if there is a chance of | |
112 | * rebooting the system it will be rebooted. | |
113 | */ | |
114 | emergency_restart(); | |
115 | } | |
116 | #ifdef __sparc__ | |
117 | { | |
118 | extern int stop_a_enabled; | |
119 | /* Make sure the user can actually press Stop-A (L1-A) */ | |
120 | stop_a_enabled = 1; | |
121 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); | |
122 | } | |
123 | #endif | |
124 | #if defined(CONFIG_S390) | |
125 | { | |
126 | unsigned long caller; | |
127 | ||
128 | caller = (unsigned long)__builtin_return_address(0); | |
129 | disabled_wait(caller); | |
130 | } | |
131 | #endif | |
132 | local_irq_enable(); | |
133 | for (i = 0; ; ) { | |
134 | touch_softlockup_watchdog(); | |
135 | i += panic_blink(i); | |
136 | mdelay(1); | |
137 | i++; | |
138 | } | |
139 | bust_spinlocks(0); | |
140 | } | |
141 | ||
142 | EXPORT_SYMBOL(panic); | |
143 | ||
144 | ||
145 | struct tnt { | |
146 | u8 bit; | |
147 | char true; | |
148 | char false; | |
149 | }; | |
150 | ||
151 | static const struct tnt tnts[] = { | |
152 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, | |
153 | { TAINT_FORCED_MODULE, 'F', ' ' }, | |
154 | { TAINT_UNSAFE_SMP, 'S', ' ' }, | |
155 | { TAINT_FORCED_RMMOD, 'R', ' ' }, | |
156 | { TAINT_MACHINE_CHECK, 'M', ' ' }, | |
157 | { TAINT_BAD_PAGE, 'B', ' ' }, | |
158 | { TAINT_USER, 'U', ' ' }, | |
159 | { TAINT_DIE, 'D', ' ' }, | |
160 | { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, | |
161 | { TAINT_WARN, 'W', ' ' }, | |
162 | { TAINT_CRAP, 'C', ' ' }, | |
163 | }; | |
164 | ||
165 | /** | |
166 | * print_tainted - return a string to represent the kernel taint state. | |
167 | * | |
168 | * 'P' - Proprietary module has been loaded. | |
169 | * 'F' - Module has been forcibly loaded. | |
170 | * 'S' - SMP with CPUs not designed for SMP. | |
171 | * 'R' - User forced a module unload. | |
172 | * 'M' - System experienced a machine check exception. | |
173 | * 'B' - System has hit bad_page. | |
174 | * 'U' - Userspace-defined naughtiness. | |
175 | * 'D' - Kernel has oopsed before | |
176 | * 'A' - ACPI table overridden. | |
177 | * 'W' - Taint on warning. | |
178 | * 'C' - modules from drivers/staging are loaded. | |
179 | * | |
180 | * The string is overwritten by the next call to print_taint(). | |
181 | */ | |
182 | const char *print_tainted(void) | |
183 | { | |
184 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; | |
185 | ||
186 | if (tainted_mask) { | |
187 | char *s; | |
188 | int i; | |
189 | ||
190 | s = buf + sprintf(buf, "Tainted: "); | |
191 | for (i = 0; i < ARRAY_SIZE(tnts); i++) { | |
192 | const struct tnt *t = &tnts[i]; | |
193 | *s++ = test_bit(t->bit, &tainted_mask) ? | |
194 | t->true : t->false; | |
195 | } | |
196 | *s = 0; | |
197 | } else | |
198 | snprintf(buf, sizeof(buf), "Not tainted"); | |
199 | ||
200 | return buf; | |
201 | } | |
202 | ||
203 | int test_taint(unsigned flag) | |
204 | { | |
205 | return test_bit(flag, &tainted_mask); | |
206 | } | |
207 | EXPORT_SYMBOL(test_taint); | |
208 | ||
209 | unsigned long get_taint(void) | |
210 | { | |
211 | return tainted_mask; | |
212 | } | |
213 | ||
214 | void add_taint(unsigned flag) | |
215 | { | |
216 | /* | |
217 | * Can't trust the integrity of the kernel anymore. | |
218 | * We don't call directly debug_locks_off() because the issue | |
219 | * is not necessarily serious enough to set oops_in_progress to 1 | |
220 | * Also we want to keep up lockdep for staging development and | |
221 | * post-warning case. | |
222 | */ | |
223 | if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) | |
224 | printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); | |
225 | ||
226 | set_bit(flag, &tainted_mask); | |
227 | } | |
228 | EXPORT_SYMBOL(add_taint); | |
229 | ||
230 | static void spin_msec(int msecs) | |
231 | { | |
232 | int i; | |
233 | ||
234 | for (i = 0; i < msecs; i++) { | |
235 | touch_nmi_watchdog(); | |
236 | mdelay(1); | |
237 | } | |
238 | } | |
239 | ||
240 | /* | |
241 | * It just happens that oops_enter() and oops_exit() are identically | |
242 | * implemented... | |
243 | */ | |
244 | static void do_oops_enter_exit(void) | |
245 | { | |
246 | unsigned long flags; | |
247 | static int spin_counter; | |
248 | ||
249 | if (!pause_on_oops) | |
250 | return; | |
251 | ||
252 | spin_lock_irqsave(&pause_on_oops_lock, flags); | |
253 | if (pause_on_oops_flag == 0) { | |
254 | /* This CPU may now print the oops message */ | |
255 | pause_on_oops_flag = 1; | |
256 | } else { | |
257 | /* We need to stall this CPU */ | |
258 | if (!spin_counter) { | |
259 | /* This CPU gets to do the counting */ | |
260 | spin_counter = pause_on_oops; | |
261 | do { | |
262 | spin_unlock(&pause_on_oops_lock); | |
263 | spin_msec(MSEC_PER_SEC); | |
264 | spin_lock(&pause_on_oops_lock); | |
265 | } while (--spin_counter); | |
266 | pause_on_oops_flag = 0; | |
267 | } else { | |
268 | /* This CPU waits for a different one */ | |
269 | while (spin_counter) { | |
270 | spin_unlock(&pause_on_oops_lock); | |
271 | spin_msec(1); | |
272 | spin_lock(&pause_on_oops_lock); | |
273 | } | |
274 | } | |
275 | } | |
276 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); | |
277 | } | |
278 | ||
279 | /* | |
280 | * Return true if the calling CPU is allowed to print oops-related info. | |
281 | * This is a bit racy.. | |
282 | */ | |
283 | int oops_may_print(void) | |
284 | { | |
285 | return pause_on_oops_flag == 0; | |
286 | } | |
287 | ||
288 | /* | |
289 | * Called when the architecture enters its oops handler, before it prints | |
290 | * anything. If this is the first CPU to oops, and it's oopsing the first | |
291 | * time then let it proceed. | |
292 | * | |
293 | * This is all enabled by the pause_on_oops kernel boot option. We do all | |
294 | * this to ensure that oopses don't scroll off the screen. It has the | |
295 | * side-effect of preventing later-oopsing CPUs from mucking up the display, | |
296 | * too. | |
297 | * | |
298 | * It turns out that the CPU which is allowed to print ends up pausing for | |
299 | * the right duration, whereas all the other CPUs pause for twice as long: | |
300 | * once in oops_enter(), once in oops_exit(). | |
301 | */ | |
302 | void oops_enter(void) | |
303 | { | |
304 | /* can't trust the integrity of the kernel anymore: */ | |
305 | debug_locks_off(); | |
306 | do_oops_enter_exit(); | |
307 | } | |
308 | ||
309 | /* | |
310 | * 64-bit random ID for oopses: | |
311 | */ | |
312 | static u64 oops_id; | |
313 | ||
314 | static int init_oops_id(void) | |
315 | { | |
316 | if (!oops_id) | |
317 | get_random_bytes(&oops_id, sizeof(oops_id)); | |
318 | else | |
319 | oops_id++; | |
320 | ||
321 | return 0; | |
322 | } | |
323 | late_initcall(init_oops_id); | |
324 | ||
325 | static void print_oops_end_marker(void) | |
326 | { | |
327 | init_oops_id(); | |
328 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", | |
329 | (unsigned long long)oops_id); | |
330 | } | |
331 | ||
332 | /* | |
333 | * Called when the architecture exits its oops handler, after printing | |
334 | * everything. | |
335 | */ | |
336 | void oops_exit(void) | |
337 | { | |
338 | do_oops_enter_exit(); | |
339 | print_oops_end_marker(); | |
340 | } | |
341 | ||
342 | #ifdef WANT_WARN_ON_SLOWPATH | |
343 | struct slowpath_args { | |
344 | const char *fmt; | |
345 | va_list args; | |
346 | }; | |
347 | ||
348 | static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) | |
349 | { | |
350 | const char *board; | |
351 | ||
352 | printk(KERN_WARNING "------------[ cut here ]------------\n"); | |
353 | printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); | |
354 | board = dmi_get_system_info(DMI_PRODUCT_NAME); | |
355 | if (board) | |
356 | printk(KERN_WARNING "Hardware name: %s\n", board); | |
357 | ||
358 | if (args) | |
359 | vprintk(args->fmt, args->args); | |
360 | ||
361 | print_modules(); | |
362 | dump_stack(); | |
363 | print_oops_end_marker(); | |
364 | add_taint(TAINT_WARN); | |
365 | } | |
366 | ||
367 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) | |
368 | { | |
369 | struct slowpath_args args; | |
370 | ||
371 | args.fmt = fmt; | |
372 | va_start(args.args, fmt); | |
373 | warn_slowpath_common(file, line, __builtin_return_address(0), &args); | |
374 | va_end(args.args); | |
375 | } | |
376 | EXPORT_SYMBOL(warn_slowpath_fmt); | |
377 | ||
378 | void warn_slowpath_null(const char *file, int line) | |
379 | { | |
380 | warn_slowpath_common(file, line, __builtin_return_address(0), NULL); | |
381 | } | |
382 | EXPORT_SYMBOL(warn_slowpath_null); | |
383 | #endif | |
384 | ||
385 | #ifdef CONFIG_CC_STACKPROTECTOR | |
386 | ||
387 | /* | |
388 | * Called when gcc's -fstack-protector feature is used, and | |
389 | * gcc detects corruption of the on-stack canary value | |
390 | */ | |
391 | void __stack_chk_fail(void) | |
392 | { | |
393 | panic("stack-protector: Kernel stack is corrupted in: %p\n", | |
394 | __builtin_return_address(0)); | |
395 | } | |
396 | EXPORT_SYMBOL(__stack_chk_fail); | |
397 | ||
398 | #endif | |
399 | ||
400 | core_param(panic, panic_timeout, int, 0644); | |
401 | core_param(pause_on_oops, pause_on_oops, int, 0644); |