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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