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1da177e4
LT
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 */
c95dbf27
IM
11#include <linux/debug_locks.h>
12#include <linux/interrupt.h>
13#include <linux/kallsyms.h>
14#include <linux/notifier.h>
1da177e4 15#include <linux/module.h>
c95dbf27 16#include <linux/random.h>
1da177e4 17#include <linux/reboot.h>
c95dbf27
IM
18#include <linux/delay.h>
19#include <linux/kexec.h>
20#include <linux/sched.h>
1da177e4 21#include <linux/sysrq.h>
c95dbf27 22#include <linux/init.h>
1da177e4 23#include <linux/nmi.h>
bd89bb29 24#include <linux/dmi.h>
1da177e4 25
1da177e4 26int panic_on_oops;
25ddbb18 27static unsigned long tainted_mask;
dd287796
AM
28static int pause_on_oops;
29static int pause_on_oops_flag;
30static DEFINE_SPINLOCK(pause_on_oops_lock);
1da177e4 31
dd287796 32int panic_timeout;
1da177e4 33
e041c683 34ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4
LT
35
36EXPORT_SYMBOL(panic_notifier_list);
37
1da177e4
LT
38static long no_blink(long time)
39{
40 return 0;
41}
42
43/* Returns how long it waited in ms */
44long (*panic_blink)(long time);
45EXPORT_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 */
1da177e4
LT
55NORET_TYPE void panic(const char * fmt, ...)
56{
1da177e4
LT
57 static char buf[1024];
58 va_list args;
c95dbf27 59 long i;
1da177e4 60
dc009d92 61 /*
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IM
62 * It's possible to come here directly from a panic-assertion and
63 * not have preempt disabled. Some functions called from here want
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EB
64 * preempt to be disabled. No point enabling it later though...
65 */
66 preempt_disable();
67
1da177e4
LT
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);
5cb27301
IM
73#ifdef CONFIG_DEBUG_BUGVERBOSE
74 dump_stack();
75#endif
1da177e4 76
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EB
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 */
6e274d14 82 crash_kexec(NULL);
dc009d92 83
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EB
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 */
1da177e4 89 smp_send_stop();
1da177e4 90
e041c683 91 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4
LT
92
93 if (!panic_blink)
94 panic_blink = no_blink;
95
dc009d92 96 if (panic_timeout > 0) {
1da177e4 97 /*
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IM
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
1da177e4
LT
103 for (i = 0; i < panic_timeout*1000; ) {
104 touch_nmi_watchdog();
105 i += panic_blink(i);
106 mdelay(1);
107 i++;
108 }
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IM
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.
1da177e4 113 */
2f048ea8 114 emergency_restart();
1da177e4
LT
115 }
116#ifdef __sparc__
117 {
118 extern int stop_a_enabled;
a271c241 119 /* Make sure the user can actually press Stop-A (L1-A) */
1da177e4 120 stop_a_enabled = 1;
a271c241 121 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4
LT
122 }
123#endif
347a8dc3 124#if defined(CONFIG_S390)
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IM
125 {
126 unsigned long caller;
127
128 caller = (unsigned long)__builtin_return_address(0);
129 disabled_wait(caller);
130 }
1da177e4
LT
131#endif
132 local_irq_enable();
c95dbf27 133 for (i = 0; ; ) {
c22db941 134 touch_softlockup_watchdog();
1da177e4
LT
135 i += panic_blink(i);
136 mdelay(1);
137 i++;
138 }
ffd71da4 139 bust_spinlocks(0);
1da177e4
LT
140}
141
142EXPORT_SYMBOL(panic);
143
c277e63f 144
25ddbb18 145struct tnt {
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IM
146 u8 bit;
147 char true;
148 char false;
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AK
149};
150
151static const struct tnt tnts[] = {
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IM
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', ' ' },
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AK
163};
164
1da177e4
LT
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.
9aa5e993 172 * 'M' - System experienced a machine check exception.
1da177e4 173 * 'B' - System has hit bad_page.
34f5a398 174 * 'U' - Userspace-defined naughtiness.
a8005992 175 * 'D' - Kernel has oopsed before
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NH
176 * 'A' - ACPI table overridden.
177 * 'W' - Taint on warning.
061b1bd3 178 * 'C' - modules from drivers/staging are loaded.
1da177e4
LT
179 *
180 * The string is overwritten by the next call to print_taint().
181 */
1da177e4
LT
182const char *print_tainted(void)
183{
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AK
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
1da177e4 198 snprintf(buf, sizeof(buf), "Not tainted");
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IM
199
200 return buf;
1da177e4
LT
201}
202
25ddbb18 203int test_taint(unsigned flag)
1da177e4 204{
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AK
205 return test_bit(flag, &tainted_mask);
206}
207EXPORT_SYMBOL(test_taint);
208
209unsigned long get_taint(void)
210{
211 return tainted_mask;
1da177e4 212}
dd287796 213
1da177e4 214void add_taint(unsigned flag)
dd287796 215{
9eeba613
FW
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
574bbe78
FW
220 * Also we want to keep up lockdep for staging development and
221 * post-warning case.
9eeba613 222 */
574bbe78 223 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
b48ccb09 224 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
9eeba613 225
25ddbb18 226 set_bit(flag, &tainted_mask);
dd287796 227}
1da177e4 228EXPORT_SYMBOL(add_taint);
dd287796
AM
229
230static 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 */
244static 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/*
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280 * Return true if the calling CPU is allowed to print oops-related info.
281 * This is a bit racy..
dd287796
AM
282 */
283int 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
c95dbf27
IM
290 * anything. If this is the first CPU to oops, and it's oopsing the first
291 * time then let it proceed.
dd287796 292 *
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IM
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.
dd287796 297 *
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IM
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().
dd287796
AM
301 */
302void oops_enter(void)
303{
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IM
304 /* can't trust the integrity of the kernel anymore: */
305 debug_locks_off();
dd287796
AM
306 do_oops_enter_exit();
307}
308
2c3b20e9
AV
309/*
310 * 64-bit random ID for oopses:
311 */
312static u64 oops_id;
313
314static int init_oops_id(void)
315{
316 if (!oops_id)
317 get_random_bytes(&oops_id, sizeof(oops_id));
d6624f99
AV
318 else
319 oops_id++;
2c3b20e9
AV
320
321 return 0;
322}
323late_initcall(init_oops_id);
324
71c33911
AV
325static 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
dd287796
AM
332/*
333 * Called when the architecture exits its oops handler, after printing
334 * everything.
335 */
336void oops_exit(void)
337{
338 do_oops_enter_exit();
71c33911 339 print_oops_end_marker();
dd287796 340}
3162f751 341
79b4cc5e 342#ifdef WANT_WARN_ON_SLOWPATH
0f6f49a8
LT
343struct slowpath_args {
344 const char *fmt;
a8f18b90 345 va_list args;
0f6f49a8 346};
bd89bb29 347
0f6f49a8
LT
348static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
349{
350 const char *board;
a8f18b90
AV
351
352 printk(KERN_WARNING "------------[ cut here ]------------\n");
0f6f49a8 353 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
bd89bb29
AV
354 board = dmi_get_system_info(DMI_PRODUCT_NAME);
355 if (board)
356 printk(KERN_WARNING "Hardware name: %s\n", board);
74853dba 357
0f6f49a8
LT
358 if (args)
359 vprintk(args->fmt, args->args);
a8f18b90
AV
360
361 print_modules();
362 dump_stack();
363 print_oops_end_marker();
364 add_taint(TAINT_WARN);
365}
0f6f49a8
LT
366
367void 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}
57adc4d2
AK
376EXPORT_SYMBOL(warn_slowpath_fmt);
377
378void warn_slowpath_null(const char *file, int line)
379{
0f6f49a8 380 warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
57adc4d2
AK
381}
382EXPORT_SYMBOL(warn_slowpath_null);
79b4cc5e
AV
383#endif
384
3162f751 385#ifdef CONFIG_CC_STACKPROTECTOR
54371a43 386
3162f751
AV
387/*
388 * Called when gcc's -fstack-protector feature is used, and
389 * gcc detects corruption of the on-stack canary value
390 */
391void __stack_chk_fail(void)
392{
517a92c4
IM
393 panic("stack-protector: Kernel stack is corrupted in: %p\n",
394 __builtin_return_address(0));
3162f751
AV
395}
396EXPORT_SYMBOL(__stack_chk_fail);
54371a43 397
3162f751 398#endif
f44dd164
RR
399
400core_param(panic, panic_timeout, int, 0644);
401core_param(pause_on_oops, pause_on_oops, int, 0644);