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