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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 | tracing_off(); |
305 | /* can't trust the integrity of the kernel anymore: */ |
306 | debug_locks_off(); |
307 | do_oops_enter_exit(); |
308 | } |
309 | |
310 | /* |
311 | * 64-bit random ID for oopses: |
312 | */ |
313 | static u64 oops_id; |
314 | |
315 | static int init_oops_id(void) |
316 | { |
317 | if (!oops_id) |
318 | get_random_bytes(&oops_id, sizeof(oops_id)); |
319 | else |
320 | oops_id++; |
321 | |
322 | return 0; |
323 | } |
324 | late_initcall(init_oops_id); |
325 | |
326 | static void print_oops_end_marker(void) |
327 | { |
328 | init_oops_id(); |
329 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", |
330 | (unsigned long long)oops_id); |
331 | } |
332 | |
333 | /* |
334 | * Called when the architecture exits its oops handler, after printing |
335 | * everything. |
336 | */ |
337 | void oops_exit(void) |
338 | { |
339 | do_oops_enter_exit(); |
340 | print_oops_end_marker(); |
341 | } |
342 | |
343 | #ifdef WANT_WARN_ON_SLOWPATH |
344 | struct slowpath_args { |
345 | const char *fmt; |
346 | va_list args; |
347 | }; |
348 | |
349 | static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) |
350 | { |
351 | const char *board; |
352 | |
353 | printk(KERN_WARNING "------------[ cut here ]------------\n"); |
354 | printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); |
355 | board = dmi_get_system_info(DMI_PRODUCT_NAME); |
356 | if (board) |
357 | printk(KERN_WARNING "Hardware name: %s\n", board); |
358 | |
359 | if (args) |
360 | vprintk(args->fmt, args->args); |
361 | |
362 | print_modules(); |
363 | dump_stack(); |
364 | print_oops_end_marker(); |
365 | add_taint(TAINT_WARN); |
366 | } |
367 | |
368 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) |
369 | { |
370 | struct slowpath_args args; |
371 | |
372 | args.fmt = fmt; |
373 | va_start(args.args, fmt); |
374 | warn_slowpath_common(file, line, __builtin_return_address(0), &args); |
375 | va_end(args.args); |
376 | } |
377 | EXPORT_SYMBOL(warn_slowpath_fmt); |
378 | |
379 | void warn_slowpath_null(const char *file, int line) |
380 | { |
381 | warn_slowpath_common(file, line, __builtin_return_address(0), NULL); |
382 | } |
383 | EXPORT_SYMBOL(warn_slowpath_null); |
384 | #endif |
385 | |
386 | #ifdef CONFIG_CC_STACKPROTECTOR |
387 | |
388 | /* |
389 | * Called when gcc's -fstack-protector feature is used, and |
390 | * gcc detects corruption of the on-stack canary value |
391 | */ |
392 | void __stack_chk_fail(void) |
393 | { |
394 | panic("stack-protector: Kernel stack is corrupted in: %p\n", |
395 | __builtin_return_address(0)); |
396 | } |
397 | EXPORT_SYMBOL(__stack_chk_fail); |
398 | |
399 | #endif |
400 | |
401 | core_param(panic, panic_timeout, int, 0644); |
402 | core_param(pause_on_oops, pause_on_oops, int, 0644); |
403 |
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