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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/kmsg_dump.h>
14#include <linux/kallsyms.h>
15#include <linux/notifier.h>
16#include <linux/module.h>
17#include <linux/random.h>
18#include <linux/reboot.h>
19#include <linux/delay.h>
20#include <linux/kexec.h>
21#include <linux/sched.h>
22#include <linux/sysrq.h>
23#include <linux/init.h>
24#include <linux/nmi.h>
25#include <linux/dmi.h>
26
27#define PANIC_TIMER_STEP 100
28#define PANIC_BLINK_SPD 18
29
30int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
31static unsigned long tainted_mask;
32static int pause_on_oops;
33static int pause_on_oops_flag;
34static DEFINE_SPINLOCK(pause_on_oops_lock);
35
36int panic_timeout;
37EXPORT_SYMBOL_GPL(panic_timeout);
38
39ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
40
41EXPORT_SYMBOL(panic_notifier_list);
42
43static long no_blink(int state)
44{
45 return 0;
46}
47
48/* Returns how long it waited in ms */
49long (*panic_blink)(int state);
50EXPORT_SYMBOL(panic_blink);
51
52/*
53 * Stop ourself in panic -- architecture code may override this
54 */
55void __weak panic_smp_self_stop(void)
56{
57 while (1)
58 cpu_relax();
59}
60
61/**
62 * panic - halt the system
63 * @fmt: The text string to print
64 *
65 * Display a message, then perform cleanups.
66 *
67 * This function never returns.
68 */
69void panic(const char *fmt, ...)
70{
71 static DEFINE_SPINLOCK(panic_lock);
72 static char buf[1024];
73 va_list args;
74 long i, i_next = 0;
75 int state = 0;
76
77 /*
78 * It's possible to come here directly from a panic-assertion and
79 * not have preempt disabled. Some functions called from here want
80 * preempt to be disabled. No point enabling it later though...
81 *
82 * Only one CPU is allowed to execute the panic code from here. For
83 * multiple parallel invocations of panic, all other CPUs either
84 * stop themself or will wait until they are stopped by the 1st CPU
85 * with smp_send_stop().
86 */
87 if (!spin_trylock(&panic_lock))
88 panic_smp_self_stop();
89
90 console_verbose();
91 bust_spinlocks(1);
92 va_start(args, fmt);
93 vsnprintf(buf, sizeof(buf), fmt, args);
94 va_end(args);
95 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
96#ifdef CONFIG_DEBUG_BUGVERBOSE
97 /*
98 * Avoid nested stack-dumping if a panic occurs during oops processing
99 */
100 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
101 dump_stack();
102#endif
103
104 /*
105 * If we have crashed and we have a crash kernel loaded let it handle
106 * everything else.
107 * Do we want to call this before we try to display a message?
108 */
109 crash_kexec(NULL);
110
111 /*
112 * Note smp_send_stop is the usual smp shutdown function, which
113 * unfortunately means it may not be hardened to work in a panic
114 * situation.
115 */
116 smp_send_stop();
117
118 kmsg_dump(KMSG_DUMP_PANIC);
119
120 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
121
122 bust_spinlocks(0);
123
124 if (!panic_blink)
125 panic_blink = no_blink;
126
127 if (panic_timeout > 0) {
128 /*
129 * Delay timeout seconds before rebooting the machine.
130 * We can't use the "normal" timers since we just panicked.
131 */
132 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
133
134 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
135 touch_nmi_watchdog();
136 if (i >= i_next) {
137 i += panic_blink(state ^= 1);
138 i_next = i + 3600 / PANIC_BLINK_SPD;
139 }
140 mdelay(PANIC_TIMER_STEP);
141 }
142 }
143 if (panic_timeout != 0) {
144 /*
145 * This will not be a clean reboot, with everything
146 * shutting down. But if there is a chance of
147 * rebooting the system it will be rebooted.
148 */
149 emergency_restart();
150 }
151#ifdef __sparc__
152 {
153 extern int stop_a_enabled;
154 /* Make sure the user can actually press Stop-A (L1-A) */
155 stop_a_enabled = 1;
156 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
157 }
158#endif
159#if defined(CONFIG_S390)
160 {
161 unsigned long caller;
162
163 caller = (unsigned long)__builtin_return_address(0);
164 disabled_wait(caller);
165 }
166#endif
167 local_irq_enable();
168 for (i = 0; ; i += PANIC_TIMER_STEP) {
169 touch_softlockup_watchdog();
170 if (i >= i_next) {
171 i += panic_blink(state ^= 1);
172 i_next = i + 3600 / PANIC_BLINK_SPD;
173 }
174 mdelay(PANIC_TIMER_STEP);
175 }
176}
177
178EXPORT_SYMBOL(panic);
179
180
181struct tnt {
182 u8 bit;
183 char true;
184 char false;
185};
186
187static const struct tnt tnts[] = {
188 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
189 { TAINT_FORCED_MODULE, 'F', ' ' },
190 { TAINT_UNSAFE_SMP, 'S', ' ' },
191 { TAINT_FORCED_RMMOD, 'R', ' ' },
192 { TAINT_MACHINE_CHECK, 'M', ' ' },
193 { TAINT_BAD_PAGE, 'B', ' ' },
194 { TAINT_USER, 'U', ' ' },
195 { TAINT_DIE, 'D', ' ' },
196 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
197 { TAINT_WARN, 'W', ' ' },
198 { TAINT_CRAP, 'C', ' ' },
199 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
200 { TAINT_OOT_MODULE, 'O', ' ' },
201};
202
203/**
204 * print_tainted - return a string to represent the kernel taint state.
205 *
206 * 'P' - Proprietary module has been loaded.
207 * 'F' - Module has been forcibly loaded.
208 * 'S' - SMP with CPUs not designed for SMP.
209 * 'R' - User forced a module unload.
210 * 'M' - System experienced a machine check exception.
211 * 'B' - System has hit bad_page.
212 * 'U' - Userspace-defined naughtiness.
213 * 'D' - Kernel has oopsed before
214 * 'A' - ACPI table overridden.
215 * 'W' - Taint on warning.
216 * 'C' - modules from drivers/staging are loaded.
217 * 'I' - Working around severe firmware bug.
218 * 'O' - Out-of-tree module has been loaded.
219 *
220 * The string is overwritten by the next call to print_tainted().
221 */
222const char *print_tainted(void)
223{
224 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
225
226 if (tainted_mask) {
227 char *s;
228 int i;
229
230 s = buf + sprintf(buf, "Tainted: ");
231 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
232 const struct tnt *t = &tnts[i];
233 *s++ = test_bit(t->bit, &tainted_mask) ?
234 t->true : t->false;
235 }
236 *s = 0;
237 } else
238 snprintf(buf, sizeof(buf), "Not tainted");
239
240 return buf;
241}
242
243int test_taint(unsigned flag)
244{
245 return test_bit(flag, &tainted_mask);
246}
247EXPORT_SYMBOL(test_taint);
248
249unsigned long get_taint(void)
250{
251 return tainted_mask;
252}
253
254void add_taint(unsigned flag)
255{
256 /*
257 * Can't trust the integrity of the kernel anymore.
258 * We don't call directly debug_locks_off() because the issue
259 * is not necessarily serious enough to set oops_in_progress to 1
260 * Also we want to keep up lockdep for staging/out-of-tree
261 * development and post-warning case.
262 */
263 switch (flag) {
264 case TAINT_CRAP:
265 case TAINT_OOT_MODULE:
266 case TAINT_WARN:
267 case TAINT_FIRMWARE_WORKAROUND:
268 break;
269
270 default:
271 if (__debug_locks_off())
272 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
273 }
274
275 set_bit(flag, &tainted_mask);
276}
277EXPORT_SYMBOL(add_taint);
278
279static void spin_msec(int msecs)
280{
281 int i;
282
283 for (i = 0; i < msecs; i++) {
284 touch_nmi_watchdog();
285 mdelay(1);
286 }
287}
288
289/*
290 * It just happens that oops_enter() and oops_exit() are identically
291 * implemented...
292 */
293static void do_oops_enter_exit(void)
294{
295 unsigned long flags;
296 static int spin_counter;
297
298 if (!pause_on_oops)
299 return;
300
301 spin_lock_irqsave(&pause_on_oops_lock, flags);
302 if (pause_on_oops_flag == 0) {
303 /* This CPU may now print the oops message */
304 pause_on_oops_flag = 1;
305 } else {
306 /* We need to stall this CPU */
307 if (!spin_counter) {
308 /* This CPU gets to do the counting */
309 spin_counter = pause_on_oops;
310 do {
311 spin_unlock(&pause_on_oops_lock);
312 spin_msec(MSEC_PER_SEC);
313 spin_lock(&pause_on_oops_lock);
314 } while (--spin_counter);
315 pause_on_oops_flag = 0;
316 } else {
317 /* This CPU waits for a different one */
318 while (spin_counter) {
319 spin_unlock(&pause_on_oops_lock);
320 spin_msec(1);
321 spin_lock(&pause_on_oops_lock);
322 }
323 }
324 }
325 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
326}
327
328/*
329 * Return true if the calling CPU is allowed to print oops-related info.
330 * This is a bit racy..
331 */
332int oops_may_print(void)
333{
334 return pause_on_oops_flag == 0;
335}
336
337/*
338 * Called when the architecture enters its oops handler, before it prints
339 * anything. If this is the first CPU to oops, and it's oopsing the first
340 * time then let it proceed.
341 *
342 * This is all enabled by the pause_on_oops kernel boot option. We do all
343 * this to ensure that oopses don't scroll off the screen. It has the
344 * side-effect of preventing later-oopsing CPUs from mucking up the display,
345 * too.
346 *
347 * It turns out that the CPU which is allowed to print ends up pausing for
348 * the right duration, whereas all the other CPUs pause for twice as long:
349 * once in oops_enter(), once in oops_exit().
350 */
351void oops_enter(void)
352{
353 tracing_off();
354 /* can't trust the integrity of the kernel anymore: */
355 debug_locks_off();
356 do_oops_enter_exit();
357}
358
359/*
360 * 64-bit random ID for oopses:
361 */
362static u64 oops_id;
363
364static int init_oops_id(void)
365{
366 if (!oops_id)
367 get_random_bytes(&oops_id, sizeof(oops_id));
368 else
369 oops_id++;
370
371 return 0;
372}
373late_initcall(init_oops_id);
374
375void print_oops_end_marker(void)
376{
377 init_oops_id();
378 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
379 (unsigned long long)oops_id);
380}
381
382/*
383 * Called when the architecture exits its oops handler, after printing
384 * everything.
385 */
386void oops_exit(void)
387{
388 do_oops_enter_exit();
389 print_oops_end_marker();
390 kmsg_dump(KMSG_DUMP_OOPS);
391}
392
393#ifdef WANT_WARN_ON_SLOWPATH
394struct slowpath_args {
395 const char *fmt;
396 va_list args;
397};
398
399static void warn_slowpath_common(const char *file, int line, void *caller,
400 unsigned taint, struct slowpath_args *args)
401{
402 const char *board;
403
404 printk(KERN_WARNING "------------[ cut here ]------------\n");
405 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
406 board = dmi_get_system_info(DMI_PRODUCT_NAME);
407 if (board)
408 printk(KERN_WARNING "Hardware name: %s\n", board);
409
410 if (args)
411 vprintk(args->fmt, args->args);
412
413 print_modules();
414 dump_stack();
415 print_oops_end_marker();
416 add_taint(taint);
417}
418
419void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
420{
421 struct slowpath_args args;
422
423 args.fmt = fmt;
424 va_start(args.args, fmt);
425 warn_slowpath_common(file, line, __builtin_return_address(0),
426 TAINT_WARN, &args);
427 va_end(args.args);
428}
429EXPORT_SYMBOL(warn_slowpath_fmt);
430
431void warn_slowpath_fmt_taint(const char *file, int line,
432 unsigned taint, const char *fmt, ...)
433{
434 struct slowpath_args args;
435
436 args.fmt = fmt;
437 va_start(args.args, fmt);
438 warn_slowpath_common(file, line, __builtin_return_address(0),
439 taint, &args);
440 va_end(args.args);
441}
442EXPORT_SYMBOL(warn_slowpath_fmt_taint);
443
444void warn_slowpath_null(const char *file, int line)
445{
446 warn_slowpath_common(file, line, __builtin_return_address(0),
447 TAINT_WARN, NULL);
448}
449EXPORT_SYMBOL(warn_slowpath_null);
450#endif
451
452#ifdef CONFIG_CC_STACKPROTECTOR
453
454/*
455 * Called when gcc's -fstack-protector feature is used, and
456 * gcc detects corruption of the on-stack canary value
457 */
458void __stack_chk_fail(void)
459{
460 panic("stack-protector: Kernel stack is corrupted in: %p\n",
461 __builtin_return_address(0));
462}
463EXPORT_SYMBOL(__stack_chk_fail);
464
465#endif
466
467core_param(panic, panic_timeout, int, 0644);
468core_param(pause_on_oops, pause_on_oops, int, 0644);
469
470static int __init oops_setup(char *s)
471{
472 if (!s)
473 return -EINVAL;
474 if (!strcmp(s, "panic"))
475 panic_on_oops = 1;
476 return 0;
477}
478early_param("oops", oops_setup);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/panic.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * This function is used through-out the kernel (including mm and fs)
10 * to indicate a major problem.
11 */
12#include <linux/debug_locks.h>
13#include <linux/sched/debug.h>
14#include <linux/interrupt.h>
15#include <linux/kgdb.h>
16#include <linux/kmsg_dump.h>
17#include <linux/kallsyms.h>
18#include <linux/notifier.h>
19#include <linux/vt_kern.h>
20#include <linux/module.h>
21#include <linux/random.h>
22#include <linux/ftrace.h>
23#include <linux/reboot.h>
24#include <linux/delay.h>
25#include <linux/kexec.h>
26#include <linux/panic_notifier.h>
27#include <linux/sched.h>
28#include <linux/sysrq.h>
29#include <linux/init.h>
30#include <linux/nmi.h>
31#include <linux/console.h>
32#include <linux/bug.h>
33#include <linux/ratelimit.h>
34#include <linux/debugfs.h>
35#include <asm/sections.h>
36
37#define PANIC_TIMER_STEP 100
38#define PANIC_BLINK_SPD 18
39
40#ifdef CONFIG_SMP
41/*
42 * Should we dump all CPUs backtraces in an oops event?
43 * Defaults to 0, can be changed via sysctl.
44 */
45unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
46#endif /* CONFIG_SMP */
47
48int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
49static unsigned long tainted_mask =
50 IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
51static int pause_on_oops;
52static int pause_on_oops_flag;
53static DEFINE_SPINLOCK(pause_on_oops_lock);
54bool crash_kexec_post_notifiers;
55int panic_on_warn __read_mostly;
56unsigned long panic_on_taint;
57bool panic_on_taint_nousertaint = false;
58
59int panic_timeout = CONFIG_PANIC_TIMEOUT;
60EXPORT_SYMBOL_GPL(panic_timeout);
61
62#define PANIC_PRINT_TASK_INFO 0x00000001
63#define PANIC_PRINT_MEM_INFO 0x00000002
64#define PANIC_PRINT_TIMER_INFO 0x00000004
65#define PANIC_PRINT_LOCK_INFO 0x00000008
66#define PANIC_PRINT_FTRACE_INFO 0x00000010
67#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
68unsigned long panic_print;
69
70ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
71
72EXPORT_SYMBOL(panic_notifier_list);
73
74static long no_blink(int state)
75{
76 return 0;
77}
78
79/* Returns how long it waited in ms */
80long (*panic_blink)(int state);
81EXPORT_SYMBOL(panic_blink);
82
83/*
84 * Stop ourself in panic -- architecture code may override this
85 */
86void __weak panic_smp_self_stop(void)
87{
88 while (1)
89 cpu_relax();
90}
91
92/*
93 * Stop ourselves in NMI context if another CPU has already panicked. Arch code
94 * may override this to prepare for crash dumping, e.g. save regs info.
95 */
96void __weak nmi_panic_self_stop(struct pt_regs *regs)
97{
98 panic_smp_self_stop();
99}
100
101/*
102 * Stop other CPUs in panic. Architecture dependent code may override this
103 * with more suitable version. For example, if the architecture supports
104 * crash dump, it should save registers of each stopped CPU and disable
105 * per-CPU features such as virtualization extensions.
106 */
107void __weak crash_smp_send_stop(void)
108{
109 static int cpus_stopped;
110
111 /*
112 * This function can be called twice in panic path, but obviously
113 * we execute this only once.
114 */
115 if (cpus_stopped)
116 return;
117
118 /*
119 * Note smp_send_stop is the usual smp shutdown function, which
120 * unfortunately means it may not be hardened to work in a panic
121 * situation.
122 */
123 smp_send_stop();
124 cpus_stopped = 1;
125}
126
127atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
128
129/*
130 * A variant of panic() called from NMI context. We return if we've already
131 * panicked on this CPU. If another CPU already panicked, loop in
132 * nmi_panic_self_stop() which can provide architecture dependent code such
133 * as saving register state for crash dump.
134 */
135void nmi_panic(struct pt_regs *regs, const char *msg)
136{
137 int old_cpu, cpu;
138
139 cpu = raw_smp_processor_id();
140 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
141
142 if (old_cpu == PANIC_CPU_INVALID)
143 panic("%s", msg);
144 else if (old_cpu != cpu)
145 nmi_panic_self_stop(regs);
146}
147EXPORT_SYMBOL(nmi_panic);
148
149static void panic_print_sys_info(void)
150{
151 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
152 console_flush_on_panic(CONSOLE_REPLAY_ALL);
153
154 if (panic_print & PANIC_PRINT_TASK_INFO)
155 show_state();
156
157 if (panic_print & PANIC_PRINT_MEM_INFO)
158 show_mem(0, NULL);
159
160 if (panic_print & PANIC_PRINT_TIMER_INFO)
161 sysrq_timer_list_show();
162
163 if (panic_print & PANIC_PRINT_LOCK_INFO)
164 debug_show_all_locks();
165
166 if (panic_print & PANIC_PRINT_FTRACE_INFO)
167 ftrace_dump(DUMP_ALL);
168}
169
170/**
171 * panic - halt the system
172 * @fmt: The text string to print
173 *
174 * Display a message, then perform cleanups.
175 *
176 * This function never returns.
177 */
178void panic(const char *fmt, ...)
179{
180 static char buf[1024];
181 va_list args;
182 long i, i_next = 0, len;
183 int state = 0;
184 int old_cpu, this_cpu;
185 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
186
187 /*
188 * Disable local interrupts. This will prevent panic_smp_self_stop
189 * from deadlocking the first cpu that invokes the panic, since
190 * there is nothing to prevent an interrupt handler (that runs
191 * after setting panic_cpu) from invoking panic() again.
192 */
193 local_irq_disable();
194 preempt_disable_notrace();
195
196 /*
197 * It's possible to come here directly from a panic-assertion and
198 * not have preempt disabled. Some functions called from here want
199 * preempt to be disabled. No point enabling it later though...
200 *
201 * Only one CPU is allowed to execute the panic code from here. For
202 * multiple parallel invocations of panic, all other CPUs either
203 * stop themself or will wait until they are stopped by the 1st CPU
204 * with smp_send_stop().
205 *
206 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
207 * comes here, so go ahead.
208 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
209 * panic_cpu to this CPU. In this case, this is also the 1st CPU.
210 */
211 this_cpu = raw_smp_processor_id();
212 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
213
214 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
215 panic_smp_self_stop();
216
217 console_verbose();
218 bust_spinlocks(1);
219 va_start(args, fmt);
220 len = vscnprintf(buf, sizeof(buf), fmt, args);
221 va_end(args);
222
223 if (len && buf[len - 1] == '\n')
224 buf[len - 1] = '\0';
225
226 pr_emerg("Kernel panic - not syncing: %s\n", buf);
227#ifdef CONFIG_DEBUG_BUGVERBOSE
228 /*
229 * Avoid nested stack-dumping if a panic occurs during oops processing
230 */
231 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
232 dump_stack();
233#endif
234
235 /*
236 * If kgdb is enabled, give it a chance to run before we stop all
237 * the other CPUs or else we won't be able to debug processes left
238 * running on them.
239 */
240 kgdb_panic(buf);
241
242 /*
243 * If we have crashed and we have a crash kernel loaded let it handle
244 * everything else.
245 * If we want to run this after calling panic_notifiers, pass
246 * the "crash_kexec_post_notifiers" option to the kernel.
247 *
248 * Bypass the panic_cpu check and call __crash_kexec directly.
249 */
250 if (!_crash_kexec_post_notifiers) {
251 printk_safe_flush_on_panic();
252 __crash_kexec(NULL);
253
254 /*
255 * Note smp_send_stop is the usual smp shutdown function, which
256 * unfortunately means it may not be hardened to work in a
257 * panic situation.
258 */
259 smp_send_stop();
260 } else {
261 /*
262 * If we want to do crash dump after notifier calls and
263 * kmsg_dump, we will need architecture dependent extra
264 * works in addition to stopping other CPUs.
265 */
266 crash_smp_send_stop();
267 }
268
269 /*
270 * Run any panic handlers, including those that might need to
271 * add information to the kmsg dump output.
272 */
273 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
274
275 /* Call flush even twice. It tries harder with a single online CPU */
276 printk_safe_flush_on_panic();
277 kmsg_dump(KMSG_DUMP_PANIC);
278
279 /*
280 * If you doubt kdump always works fine in any situation,
281 * "crash_kexec_post_notifiers" offers you a chance to run
282 * panic_notifiers and dumping kmsg before kdump.
283 * Note: since some panic_notifiers can make crashed kernel
284 * more unstable, it can increase risks of the kdump failure too.
285 *
286 * Bypass the panic_cpu check and call __crash_kexec directly.
287 */
288 if (_crash_kexec_post_notifiers)
289 __crash_kexec(NULL);
290
291#ifdef CONFIG_VT
292 unblank_screen();
293#endif
294 console_unblank();
295
296 /*
297 * We may have ended up stopping the CPU holding the lock (in
298 * smp_send_stop()) while still having some valuable data in the console
299 * buffer. Try to acquire the lock then release it regardless of the
300 * result. The release will also print the buffers out. Locks debug
301 * should be disabled to avoid reporting bad unlock balance when
302 * panic() is not being callled from OOPS.
303 */
304 debug_locks_off();
305 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
306
307 panic_print_sys_info();
308
309 if (!panic_blink)
310 panic_blink = no_blink;
311
312 if (panic_timeout > 0) {
313 /*
314 * Delay timeout seconds before rebooting the machine.
315 * We can't use the "normal" timers since we just panicked.
316 */
317 pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
318
319 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
320 touch_nmi_watchdog();
321 if (i >= i_next) {
322 i += panic_blink(state ^= 1);
323 i_next = i + 3600 / PANIC_BLINK_SPD;
324 }
325 mdelay(PANIC_TIMER_STEP);
326 }
327 }
328 if (panic_timeout != 0) {
329 /*
330 * This will not be a clean reboot, with everything
331 * shutting down. But if there is a chance of
332 * rebooting the system it will be rebooted.
333 */
334 if (panic_reboot_mode != REBOOT_UNDEFINED)
335 reboot_mode = panic_reboot_mode;
336 emergency_restart();
337 }
338#ifdef __sparc__
339 {
340 extern int stop_a_enabled;
341 /* Make sure the user can actually press Stop-A (L1-A) */
342 stop_a_enabled = 1;
343 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
344 "twice on console to return to the boot prom\n");
345 }
346#endif
347#if defined(CONFIG_S390)
348 disabled_wait();
349#endif
350 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
351
352 /* Do not scroll important messages printed above */
353 suppress_printk = 1;
354 local_irq_enable();
355 for (i = 0; ; i += PANIC_TIMER_STEP) {
356 touch_softlockup_watchdog();
357 if (i >= i_next) {
358 i += panic_blink(state ^= 1);
359 i_next = i + 3600 / PANIC_BLINK_SPD;
360 }
361 mdelay(PANIC_TIMER_STEP);
362 }
363}
364
365EXPORT_SYMBOL(panic);
366
367/*
368 * TAINT_FORCED_RMMOD could be a per-module flag but the module
369 * is being removed anyway.
370 */
371const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
372 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true },
373 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true },
374 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false },
375 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false },
376 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false },
377 [ TAINT_BAD_PAGE ] = { 'B', ' ', false },
378 [ TAINT_USER ] = { 'U', ' ', false },
379 [ TAINT_DIE ] = { 'D', ' ', false },
380 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false },
381 [ TAINT_WARN ] = { 'W', ' ', false },
382 [ TAINT_CRAP ] = { 'C', ' ', true },
383 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false },
384 [ TAINT_OOT_MODULE ] = { 'O', ' ', true },
385 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true },
386 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false },
387 [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
388 [ TAINT_AUX ] = { 'X', ' ', true },
389 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
390};
391
392/**
393 * print_tainted - return a string to represent the kernel taint state.
394 *
395 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
396 *
397 * The string is overwritten by the next call to print_tainted(),
398 * but is always NULL terminated.
399 */
400const char *print_tainted(void)
401{
402 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
403
404 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
405
406 if (tainted_mask) {
407 char *s;
408 int i;
409
410 s = buf + sprintf(buf, "Tainted: ");
411 for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
412 const struct taint_flag *t = &taint_flags[i];
413 *s++ = test_bit(i, &tainted_mask) ?
414 t->c_true : t->c_false;
415 }
416 *s = 0;
417 } else
418 snprintf(buf, sizeof(buf), "Not tainted");
419
420 return buf;
421}
422
423int test_taint(unsigned flag)
424{
425 return test_bit(flag, &tainted_mask);
426}
427EXPORT_SYMBOL(test_taint);
428
429unsigned long get_taint(void)
430{
431 return tainted_mask;
432}
433
434/**
435 * add_taint: add a taint flag if not already set.
436 * @flag: one of the TAINT_* constants.
437 * @lockdep_ok: whether lock debugging is still OK.
438 *
439 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
440 * some notewortht-but-not-corrupting cases, it can be set to true.
441 */
442void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
443{
444 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
445 pr_warn("Disabling lock debugging due to kernel taint\n");
446
447 set_bit(flag, &tainted_mask);
448
449 if (tainted_mask & panic_on_taint) {
450 panic_on_taint = 0;
451 panic("panic_on_taint set ...");
452 }
453}
454EXPORT_SYMBOL(add_taint);
455
456static void spin_msec(int msecs)
457{
458 int i;
459
460 for (i = 0; i < msecs; i++) {
461 touch_nmi_watchdog();
462 mdelay(1);
463 }
464}
465
466/*
467 * It just happens that oops_enter() and oops_exit() are identically
468 * implemented...
469 */
470static void do_oops_enter_exit(void)
471{
472 unsigned long flags;
473 static int spin_counter;
474
475 if (!pause_on_oops)
476 return;
477
478 spin_lock_irqsave(&pause_on_oops_lock, flags);
479 if (pause_on_oops_flag == 0) {
480 /* This CPU may now print the oops message */
481 pause_on_oops_flag = 1;
482 } else {
483 /* We need to stall this CPU */
484 if (!spin_counter) {
485 /* This CPU gets to do the counting */
486 spin_counter = pause_on_oops;
487 do {
488 spin_unlock(&pause_on_oops_lock);
489 spin_msec(MSEC_PER_SEC);
490 spin_lock(&pause_on_oops_lock);
491 } while (--spin_counter);
492 pause_on_oops_flag = 0;
493 } else {
494 /* This CPU waits for a different one */
495 while (spin_counter) {
496 spin_unlock(&pause_on_oops_lock);
497 spin_msec(1);
498 spin_lock(&pause_on_oops_lock);
499 }
500 }
501 }
502 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
503}
504
505/*
506 * Return true if the calling CPU is allowed to print oops-related info.
507 * This is a bit racy..
508 */
509bool oops_may_print(void)
510{
511 return pause_on_oops_flag == 0;
512}
513
514/*
515 * Called when the architecture enters its oops handler, before it prints
516 * anything. If this is the first CPU to oops, and it's oopsing the first
517 * time then let it proceed.
518 *
519 * This is all enabled by the pause_on_oops kernel boot option. We do all
520 * this to ensure that oopses don't scroll off the screen. It has the
521 * side-effect of preventing later-oopsing CPUs from mucking up the display,
522 * too.
523 *
524 * It turns out that the CPU which is allowed to print ends up pausing for
525 * the right duration, whereas all the other CPUs pause for twice as long:
526 * once in oops_enter(), once in oops_exit().
527 */
528void oops_enter(void)
529{
530 tracing_off();
531 /* can't trust the integrity of the kernel anymore: */
532 debug_locks_off();
533 do_oops_enter_exit();
534
535 if (sysctl_oops_all_cpu_backtrace)
536 trigger_all_cpu_backtrace();
537}
538
539/*
540 * 64-bit random ID for oopses:
541 */
542static u64 oops_id;
543
544static int init_oops_id(void)
545{
546 if (!oops_id)
547 get_random_bytes(&oops_id, sizeof(oops_id));
548 else
549 oops_id++;
550
551 return 0;
552}
553late_initcall(init_oops_id);
554
555static void print_oops_end_marker(void)
556{
557 init_oops_id();
558 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
559}
560
561/*
562 * Called when the architecture exits its oops handler, after printing
563 * everything.
564 */
565void oops_exit(void)
566{
567 do_oops_enter_exit();
568 print_oops_end_marker();
569 kmsg_dump(KMSG_DUMP_OOPS);
570}
571
572struct warn_args {
573 const char *fmt;
574 va_list args;
575};
576
577void __warn(const char *file, int line, void *caller, unsigned taint,
578 struct pt_regs *regs, struct warn_args *args)
579{
580 disable_trace_on_warning();
581
582 if (file)
583 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
584 raw_smp_processor_id(), current->pid, file, line,
585 caller);
586 else
587 pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
588 raw_smp_processor_id(), current->pid, caller);
589
590 if (args)
591 vprintk(args->fmt, args->args);
592
593 print_modules();
594
595 if (regs)
596 show_regs(regs);
597
598 if (panic_on_warn) {
599 /*
600 * This thread may hit another WARN() in the panic path.
601 * Resetting this prevents additional WARN() from panicking the
602 * system on this thread. Other threads are blocked by the
603 * panic_mutex in panic().
604 */
605 panic_on_warn = 0;
606 panic("panic_on_warn set ...\n");
607 }
608
609 if (!regs)
610 dump_stack();
611
612 print_irqtrace_events(current);
613
614 print_oops_end_marker();
615
616 /* Just a warning, don't kill lockdep. */
617 add_taint(taint, LOCKDEP_STILL_OK);
618}
619
620#ifndef __WARN_FLAGS
621void warn_slowpath_fmt(const char *file, int line, unsigned taint,
622 const char *fmt, ...)
623{
624 struct warn_args args;
625
626 pr_warn(CUT_HERE);
627
628 if (!fmt) {
629 __warn(file, line, __builtin_return_address(0), taint,
630 NULL, NULL);
631 return;
632 }
633
634 args.fmt = fmt;
635 va_start(args.args, fmt);
636 __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
637 va_end(args.args);
638}
639EXPORT_SYMBOL(warn_slowpath_fmt);
640#else
641void __warn_printk(const char *fmt, ...)
642{
643 va_list args;
644
645 pr_warn(CUT_HERE);
646
647 va_start(args, fmt);
648 vprintk(fmt, args);
649 va_end(args);
650}
651EXPORT_SYMBOL(__warn_printk);
652#endif
653
654#ifdef CONFIG_BUG
655
656/* Support resetting WARN*_ONCE state */
657
658static int clear_warn_once_set(void *data, u64 val)
659{
660 generic_bug_clear_once();
661 memset(__start_once, 0, __end_once - __start_once);
662 return 0;
663}
664
665DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
666 "%lld\n");
667
668static __init int register_warn_debugfs(void)
669{
670 /* Don't care about failure */
671 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
672 &clear_warn_once_fops);
673 return 0;
674}
675
676device_initcall(register_warn_debugfs);
677#endif
678
679#ifdef CONFIG_STACKPROTECTOR
680
681/*
682 * Called when gcc's -fstack-protector feature is used, and
683 * gcc detects corruption of the on-stack canary value
684 */
685__visible noinstr void __stack_chk_fail(void)
686{
687 instrumentation_begin();
688 panic("stack-protector: Kernel stack is corrupted in: %pB",
689 __builtin_return_address(0));
690 instrumentation_end();
691}
692EXPORT_SYMBOL(__stack_chk_fail);
693
694#endif
695
696core_param(panic, panic_timeout, int, 0644);
697core_param(panic_print, panic_print, ulong, 0644);
698core_param(pause_on_oops, pause_on_oops, int, 0644);
699core_param(panic_on_warn, panic_on_warn, int, 0644);
700core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
701
702static int __init oops_setup(char *s)
703{
704 if (!s)
705 return -EINVAL;
706 if (!strcmp(s, "panic"))
707 panic_on_oops = 1;
708 return 0;
709}
710early_param("oops", oops_setup);
711
712static int __init panic_on_taint_setup(char *s)
713{
714 char *taint_str;
715
716 if (!s)
717 return -EINVAL;
718
719 taint_str = strsep(&s, ",");
720 if (kstrtoul(taint_str, 16, &panic_on_taint))
721 return -EINVAL;
722
723 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
724 panic_on_taint &= TAINT_FLAGS_MAX;
725
726 if (!panic_on_taint)
727 return -EINVAL;
728
729 if (s && !strcmp(s, "nousertaint"))
730 panic_on_taint_nousertaint = true;
731
732 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%sabled\n",
733 panic_on_taint, panic_on_taint_nousertaint ? "en" : "dis");
734
735 return 0;
736}
737early_param("panic_on_taint", panic_on_taint_setup);