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/string_helpers.h> 29 #include <linux/sysrq.h> 30 #include <linux/init.h> 31 #include <linux/nmi.h> 32 #include <linux/console.h> 33 #include <linux/bug.h> 34 #include <linux/ratelimit.h> 35 #include <linux/debugfs.h> 36 #include <linux/sysfs.h> 37 #include <linux/context_tracking.h> 38 #include <trace/events/error_report.h> 39 #include <asm/sections.h> 40 41 #define PANIC_TIMER_STEP 100 42 #define PANIC_BLINK_SPD 18 43 44 #ifdef CONFIG_SMP 45 /* 46 * Should we dump all CPUs backtraces in an oops event? 47 * Defaults to 0, can be changed via sysctl. 48 */ 49 static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; 50 #else 51 #define sysctl_oops_all_cpu_backtrace 0 52 #endif /* CONFIG_SMP */ 53 54 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; 55 static unsigned long tainted_mask = 56 IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0; 57 static int pause_on_oops; 58 static int pause_on_oops_flag; 59 static DEFINE_SPINLOCK(pause_on_oops_lock); 60 bool crash_kexec_post_notifiers; 61 int panic_on_warn __read_mostly; 62 unsigned long panic_on_taint; 63 bool panic_on_taint_nousertaint = false; 64 static unsigned int warn_limit __read_mostly; 65 66 int panic_timeout = CONFIG_PANIC_TIMEOUT; 67 EXPORT_SYMBOL_GPL(panic_timeout); 68 69 #define PANIC_PRINT_TASK_INFO 0x00000001 70 #define PANIC_PRINT_MEM_INFO 0x00000002 71 #define PANIC_PRINT_TIMER_INFO 0x00000004 72 #define PANIC_PRINT_LOCK_INFO 0x00000008 73 #define PANIC_PRINT_FTRACE_INFO 0x00000010 74 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 75 #define PANIC_PRINT_ALL_CPU_BT 0x00000040 76 unsigned long panic_print; 77 78 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 79 80 EXPORT_SYMBOL(panic_notifier_list); 81 82 #ifdef CONFIG_SYSCTL 83 static struct ctl_table kern_panic_table[] = { 84 #ifdef CONFIG_SMP 85 { 86 .procname = "oops_all_cpu_backtrace", 87 .data = &sysctl_oops_all_cpu_backtrace, 88 .maxlen = sizeof(int), 89 .mode = 0644, 90 .proc_handler = proc_dointvec_minmax, 91 .extra1 = SYSCTL_ZERO, 92 .extra2 = SYSCTL_ONE, 93 }, 94 #endif 95 { 96 .procname = "warn_limit", 97 .data = &warn_limit, 98 .maxlen = sizeof(warn_limit), 99 .mode = 0644, 100 .proc_handler = proc_douintvec, 101 }, 102 { } 103 }; 104 105 static __init int kernel_panic_sysctls_init(void) 106 { 107 register_sysctl_init("kernel", kern_panic_table); 108 return 0; 109 } 110 late_initcall(kernel_panic_sysctls_init); 111 #endif 112 113 static atomic_t warn_count = ATOMIC_INIT(0); 114 115 #ifdef CONFIG_SYSFS 116 static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, 117 char *page) 118 { 119 return sysfs_emit(page, "%d\n", atomic_read(&warn_count)); 120 } 121 122 static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); 123 124 static __init int kernel_panic_sysfs_init(void) 125 { 126 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL); 127 return 0; 128 } 129 late_initcall(kernel_panic_sysfs_init); 130 #endif 131 132 static long no_blink(int state) 133 { 134 return 0; 135 } 136 137 /* Returns how long it waited in ms */ 138 long (*panic_blink)(int state); 139 EXPORT_SYMBOL(panic_blink); 140 141 /* 142 * Stop ourself in panic -- architecture code may override this 143 */ 144 void __weak panic_smp_self_stop(void) 145 { 146 while (1) 147 cpu_relax(); 148 } 149 150 /* 151 * Stop ourselves in NMI context if another CPU has already panicked. Arch code 152 * may override this to prepare for crash dumping, e.g. save regs info. 153 */ 154 void __weak nmi_panic_self_stop(struct pt_regs *regs) 155 { 156 panic_smp_self_stop(); 157 } 158 159 /* 160 * Stop other CPUs in panic. Architecture dependent code may override this 161 * with more suitable version. For example, if the architecture supports 162 * crash dump, it should save registers of each stopped CPU and disable 163 * per-CPU features such as virtualization extensions. 164 */ 165 void __weak crash_smp_send_stop(void) 166 { 167 static int cpus_stopped; 168 169 /* 170 * This function can be called twice in panic path, but obviously 171 * we execute this only once. 172 */ 173 if (cpus_stopped) 174 return; 175 176 /* 177 * Note smp_send_stop is the usual smp shutdown function, which 178 * unfortunately means it may not be hardened to work in a panic 179 * situation. 180 */ 181 smp_send_stop(); 182 cpus_stopped = 1; 183 } 184 185 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); 186 187 /* 188 * A variant of panic() called from NMI context. We return if we've already 189 * panicked on this CPU. If another CPU already panicked, loop in 190 * nmi_panic_self_stop() which can provide architecture dependent code such 191 * as saving register state for crash dump. 192 */ 193 void nmi_panic(struct pt_regs *regs, const char *msg) 194 { 195 int old_cpu, cpu; 196 197 cpu = raw_smp_processor_id(); 198 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); 199 200 if (old_cpu == PANIC_CPU_INVALID) 201 panic("%s", msg); 202 else if (old_cpu != cpu) 203 nmi_panic_self_stop(regs); 204 } 205 EXPORT_SYMBOL(nmi_panic); 206 207 static void panic_print_sys_info(bool console_flush) 208 { 209 if (console_flush) { 210 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) 211 console_flush_on_panic(CONSOLE_REPLAY_ALL); 212 return; 213 } 214 215 if (panic_print & PANIC_PRINT_ALL_CPU_BT) 216 trigger_all_cpu_backtrace(); 217 218 if (panic_print & PANIC_PRINT_TASK_INFO) 219 show_state(); 220 221 if (panic_print & PANIC_PRINT_MEM_INFO) 222 show_mem(0, NULL); 223 224 if (panic_print & PANIC_PRINT_TIMER_INFO) 225 sysrq_timer_list_show(); 226 227 if (panic_print & PANIC_PRINT_LOCK_INFO) 228 debug_show_all_locks(); 229 230 if (panic_print & PANIC_PRINT_FTRACE_INFO) 231 ftrace_dump(DUMP_ALL); 232 } 233 234 void check_panic_on_warn(const char *origin) 235 { 236 unsigned int limit; 237 238 if (panic_on_warn) 239 panic("%s: panic_on_warn set ...\n", origin); 240 241 limit = READ_ONCE(warn_limit); 242 if (atomic_inc_return(&warn_count) >= limit && limit) 243 panic("%s: system warned too often (kernel.warn_limit is %d)", 244 origin, limit); 245 } 246 247 /** 248 * panic - halt the system 249 * @fmt: The text string to print 250 * 251 * Display a message, then perform cleanups. 252 * 253 * This function never returns. 254 */ 255 void panic(const char *fmt, ...) 256 { 257 static char buf[1024]; 258 va_list args; 259 long i, i_next = 0, len; 260 int state = 0; 261 int old_cpu, this_cpu; 262 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; 263 264 if (panic_on_warn) { 265 /* 266 * This thread may hit another WARN() in the panic path. 267 * Resetting this prevents additional WARN() from panicking the 268 * system on this thread. Other threads are blocked by the 269 * panic_mutex in panic(). 270 */ 271 panic_on_warn = 0; 272 } 273 274 /* 275 * Disable local interrupts. This will prevent panic_smp_self_stop 276 * from deadlocking the first cpu that invokes the panic, since 277 * there is nothing to prevent an interrupt handler (that runs 278 * after setting panic_cpu) from invoking panic() again. 279 */ 280 local_irq_disable(); 281 preempt_disable_notrace(); 282 283 /* 284 * It's possible to come here directly from a panic-assertion and 285 * not have preempt disabled. Some functions called from here want 286 * preempt to be disabled. No point enabling it later though... 287 * 288 * Only one CPU is allowed to execute the panic code from here. For 289 * multiple parallel invocations of panic, all other CPUs either 290 * stop themself or will wait until they are stopped by the 1st CPU 291 * with smp_send_stop(). 292 * 293 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which 294 * comes here, so go ahead. 295 * `old_cpu == this_cpu' means we came from nmi_panic() which sets 296 * panic_cpu to this CPU. In this case, this is also the 1st CPU. 297 */ 298 this_cpu = raw_smp_processor_id(); 299 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); 300 301 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu) 302 panic_smp_self_stop(); 303 304 console_verbose(); 305 bust_spinlocks(1); 306 va_start(args, fmt); 307 len = vscnprintf(buf, sizeof(buf), fmt, args); 308 va_end(args); 309 310 if (len && buf[len - 1] == '\n') 311 buf[len - 1] = '\0'; 312 313 pr_emerg("Kernel panic - not syncing: %s\n", buf); 314 #ifdef CONFIG_DEBUG_BUGVERBOSE 315 /* 316 * Avoid nested stack-dumping if a panic occurs during oops processing 317 */ 318 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 319 dump_stack(); 320 #endif 321 322 /* 323 * If kgdb is enabled, give it a chance to run before we stop all 324 * the other CPUs or else we won't be able to debug processes left 325 * running on them. 326 */ 327 kgdb_panic(buf); 328 329 /* 330 * If we have crashed and we have a crash kernel loaded let it handle 331 * everything else. 332 * If we want to run this after calling panic_notifiers, pass 333 * the "crash_kexec_post_notifiers" option to the kernel. 334 * 335 * Bypass the panic_cpu check and call __crash_kexec directly. 336 */ 337 if (!_crash_kexec_post_notifiers) { 338 __crash_kexec(NULL); 339 340 /* 341 * Note smp_send_stop is the usual smp shutdown function, which 342 * unfortunately means it may not be hardened to work in a 343 * panic situation. 344 */ 345 smp_send_stop(); 346 } else { 347 /* 348 * If we want to do crash dump after notifier calls and 349 * kmsg_dump, we will need architecture dependent extra 350 * works in addition to stopping other CPUs. 351 */ 352 crash_smp_send_stop(); 353 } 354 355 /* 356 * Run any panic handlers, including those that might need to 357 * add information to the kmsg dump output. 358 */ 359 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 360 361 panic_print_sys_info(false); 362 363 kmsg_dump(KMSG_DUMP_PANIC); 364 365 /* 366 * If you doubt kdump always works fine in any situation, 367 * "crash_kexec_post_notifiers" offers you a chance to run 368 * panic_notifiers and dumping kmsg before kdump. 369 * Note: since some panic_notifiers can make crashed kernel 370 * more unstable, it can increase risks of the kdump failure too. 371 * 372 * Bypass the panic_cpu check and call __crash_kexec directly. 373 */ 374 if (_crash_kexec_post_notifiers) 375 __crash_kexec(NULL); 376 377 console_unblank(); 378 379 /* 380 * We may have ended up stopping the CPU holding the lock (in 381 * smp_send_stop()) while still having some valuable data in the console 382 * buffer. Try to acquire the lock then release it regardless of the 383 * result. The release will also print the buffers out. Locks debug 384 * should be disabled to avoid reporting bad unlock balance when 385 * panic() is not being callled from OOPS. 386 */ 387 debug_locks_off(); 388 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 389 390 panic_print_sys_info(true); 391 392 if (!panic_blink) 393 panic_blink = no_blink; 394 395 if (panic_timeout > 0) { 396 /* 397 * Delay timeout seconds before rebooting the machine. 398 * We can't use the "normal" timers since we just panicked. 399 */ 400 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 401 402 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 403 touch_nmi_watchdog(); 404 if (i >= i_next) { 405 i += panic_blink(state ^= 1); 406 i_next = i + 3600 / PANIC_BLINK_SPD; 407 } 408 mdelay(PANIC_TIMER_STEP); 409 } 410 } 411 if (panic_timeout != 0) { 412 /* 413 * This will not be a clean reboot, with everything 414 * shutting down. But if there is a chance of 415 * rebooting the system it will be rebooted. 416 */ 417 if (panic_reboot_mode != REBOOT_UNDEFINED) 418 reboot_mode = panic_reboot_mode; 419 emergency_restart(); 420 } 421 #ifdef __sparc__ 422 { 423 extern int stop_a_enabled; 424 /* Make sure the user can actually press Stop-A (L1-A) */ 425 stop_a_enabled = 1; 426 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 427 "twice on console to return to the boot prom\n"); 428 } 429 #endif 430 #if defined(CONFIG_S390) 431 disabled_wait(); 432 #endif 433 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 434 435 /* Do not scroll important messages printed above */ 436 suppress_printk = 1; 437 local_irq_enable(); 438 for (i = 0; ; i += PANIC_TIMER_STEP) { 439 touch_softlockup_watchdog(); 440 if (i >= i_next) { 441 i += panic_blink(state ^= 1); 442 i_next = i + 3600 / PANIC_BLINK_SPD; 443 } 444 mdelay(PANIC_TIMER_STEP); 445 } 446 } 447 448 EXPORT_SYMBOL(panic); 449 450 /* 451 * TAINT_FORCED_RMMOD could be a per-module flag but the module 452 * is being removed anyway. 453 */ 454 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { 455 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true }, 456 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true }, 457 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false }, 458 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false }, 459 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false }, 460 [ TAINT_BAD_PAGE ] = { 'B', ' ', false }, 461 [ TAINT_USER ] = { 'U', ' ', false }, 462 [ TAINT_DIE ] = { 'D', ' ', false }, 463 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false }, 464 [ TAINT_WARN ] = { 'W', ' ', false }, 465 [ TAINT_CRAP ] = { 'C', ' ', true }, 466 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false }, 467 [ TAINT_OOT_MODULE ] = { 'O', ' ', true }, 468 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true }, 469 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false }, 470 [ TAINT_LIVEPATCH ] = { 'K', ' ', true }, 471 [ TAINT_AUX ] = { 'X', ' ', true }, 472 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true }, 473 [ TAINT_TEST ] = { 'N', ' ', true }, 474 }; 475 476 /** 477 * print_tainted - return a string to represent the kernel taint state. 478 * 479 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst 480 * 481 * The string is overwritten by the next call to print_tainted(), 482 * but is always NULL terminated. 483 */ 484 const char *print_tainted(void) 485 { 486 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")]; 487 488 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); 489 490 if (tainted_mask) { 491 char *s; 492 int i; 493 494 s = buf + sprintf(buf, "Tainted: "); 495 for (i = 0; i < TAINT_FLAGS_COUNT; i++) { 496 const struct taint_flag *t = &taint_flags[i]; 497 *s++ = test_bit(i, &tainted_mask) ? 498 t->c_true : t->c_false; 499 } 500 *s = 0; 501 } else 502 snprintf(buf, sizeof(buf), "Not tainted"); 503 504 return buf; 505 } 506 507 int test_taint(unsigned flag) 508 { 509 return test_bit(flag, &tainted_mask); 510 } 511 EXPORT_SYMBOL(test_taint); 512 513 unsigned long get_taint(void) 514 { 515 return tainted_mask; 516 } 517 518 /** 519 * add_taint: add a taint flag if not already set. 520 * @flag: one of the TAINT_* constants. 521 * @lockdep_ok: whether lock debugging is still OK. 522 * 523 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 524 * some notewortht-but-not-corrupting cases, it can be set to true. 525 */ 526 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 527 { 528 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 529 pr_warn("Disabling lock debugging due to kernel taint\n"); 530 531 set_bit(flag, &tainted_mask); 532 533 if (tainted_mask & panic_on_taint) { 534 panic_on_taint = 0; 535 panic("panic_on_taint set ..."); 536 } 537 } 538 EXPORT_SYMBOL(add_taint); 539 540 static void spin_msec(int msecs) 541 { 542 int i; 543 544 for (i = 0; i < msecs; i++) { 545 touch_nmi_watchdog(); 546 mdelay(1); 547 } 548 } 549 550 /* 551 * It just happens that oops_enter() and oops_exit() are identically 552 * implemented... 553 */ 554 static void do_oops_enter_exit(void) 555 { 556 unsigned long flags; 557 static int spin_counter; 558 559 if (!pause_on_oops) 560 return; 561 562 spin_lock_irqsave(&pause_on_oops_lock, flags); 563 if (pause_on_oops_flag == 0) { 564 /* This CPU may now print the oops message */ 565 pause_on_oops_flag = 1; 566 } else { 567 /* We need to stall this CPU */ 568 if (!spin_counter) { 569 /* This CPU gets to do the counting */ 570 spin_counter = pause_on_oops; 571 do { 572 spin_unlock(&pause_on_oops_lock); 573 spin_msec(MSEC_PER_SEC); 574 spin_lock(&pause_on_oops_lock); 575 } while (--spin_counter); 576 pause_on_oops_flag = 0; 577 } else { 578 /* This CPU waits for a different one */ 579 while (spin_counter) { 580 spin_unlock(&pause_on_oops_lock); 581 spin_msec(1); 582 spin_lock(&pause_on_oops_lock); 583 } 584 } 585 } 586 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 587 } 588 589 /* 590 * Return true if the calling CPU is allowed to print oops-related info. 591 * This is a bit racy.. 592 */ 593 bool oops_may_print(void) 594 { 595 return pause_on_oops_flag == 0; 596 } 597 598 /* 599 * Called when the architecture enters its oops handler, before it prints 600 * anything. If this is the first CPU to oops, and it's oopsing the first 601 * time then let it proceed. 602 * 603 * This is all enabled by the pause_on_oops kernel boot option. We do all 604 * this to ensure that oopses don't scroll off the screen. It has the 605 * side-effect of preventing later-oopsing CPUs from mucking up the display, 606 * too. 607 * 608 * It turns out that the CPU which is allowed to print ends up pausing for 609 * the right duration, whereas all the other CPUs pause for twice as long: 610 * once in oops_enter(), once in oops_exit(). 611 */ 612 void oops_enter(void) 613 { 614 tracing_off(); 615 /* can't trust the integrity of the kernel anymore: */ 616 debug_locks_off(); 617 do_oops_enter_exit(); 618 619 if (sysctl_oops_all_cpu_backtrace) 620 trigger_all_cpu_backtrace(); 621 } 622 623 static void print_oops_end_marker(void) 624 { 625 pr_warn("---[ end trace %016llx ]---\n", 0ULL); 626 } 627 628 /* 629 * Called when the architecture exits its oops handler, after printing 630 * everything. 631 */ 632 void oops_exit(void) 633 { 634 do_oops_enter_exit(); 635 print_oops_end_marker(); 636 kmsg_dump(KMSG_DUMP_OOPS); 637 } 638 639 struct warn_args { 640 const char *fmt; 641 va_list args; 642 }; 643 644 void __warn(const char *file, int line, void *caller, unsigned taint, 645 struct pt_regs *regs, struct warn_args *args) 646 { 647 disable_trace_on_warning(); 648 649 if (file) 650 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", 651 raw_smp_processor_id(), current->pid, file, line, 652 caller); 653 else 654 pr_warn("WARNING: CPU: %d PID: %d at %pS\n", 655 raw_smp_processor_id(), current->pid, caller); 656 657 if (args) 658 vprintk(args->fmt, args->args); 659 660 print_modules(); 661 662 if (regs) 663 show_regs(regs); 664 665 check_panic_on_warn("kernel"); 666 667 if (!regs) 668 dump_stack(); 669 670 print_irqtrace_events(current); 671 672 print_oops_end_marker(); 673 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); 674 675 /* Just a warning, don't kill lockdep. */ 676 add_taint(taint, LOCKDEP_STILL_OK); 677 } 678 679 #ifndef __WARN_FLAGS 680 void warn_slowpath_fmt(const char *file, int line, unsigned taint, 681 const char *fmt, ...) 682 { 683 bool rcu = warn_rcu_enter(); 684 struct warn_args args; 685 686 pr_warn(CUT_HERE); 687 688 if (!fmt) { 689 __warn(file, line, __builtin_return_address(0), taint, 690 NULL, NULL); 691 return; 692 } 693 694 args.fmt = fmt; 695 va_start(args.args, fmt); 696 __warn(file, line, __builtin_return_address(0), taint, NULL, &args); 697 va_end(args.args); 698 warn_rcu_exit(rcu); 699 } 700 EXPORT_SYMBOL(warn_slowpath_fmt); 701 #else 702 void __warn_printk(const char *fmt, ...) 703 { 704 bool rcu = warn_rcu_enter(); 705 va_list args; 706 707 pr_warn(CUT_HERE); 708 709 va_start(args, fmt); 710 vprintk(fmt, args); 711 va_end(args); 712 warn_rcu_exit(rcu); 713 } 714 EXPORT_SYMBOL(__warn_printk); 715 #endif 716 717 #ifdef CONFIG_BUG 718 719 /* Support resetting WARN*_ONCE state */ 720 721 static int clear_warn_once_set(void *data, u64 val) 722 { 723 generic_bug_clear_once(); 724 memset(__start_once, 0, __end_once - __start_once); 725 return 0; 726 } 727 728 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, 729 "%lld\n"); 730 731 static __init int register_warn_debugfs(void) 732 { 733 /* Don't care about failure */ 734 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL, 735 &clear_warn_once_fops); 736 return 0; 737 } 738 739 device_initcall(register_warn_debugfs); 740 #endif 741 742 #ifdef CONFIG_STACKPROTECTOR 743 744 /* 745 * Called when gcc's -fstack-protector feature is used, and 746 * gcc detects corruption of the on-stack canary value 747 */ 748 __visible noinstr void __stack_chk_fail(void) 749 { 750 instrumentation_begin(); 751 panic("stack-protector: Kernel stack is corrupted in: %pB", 752 __builtin_return_address(0)); 753 instrumentation_end(); 754 } 755 EXPORT_SYMBOL(__stack_chk_fail); 756 757 #endif 758 759 core_param(panic, panic_timeout, int, 0644); 760 core_param(panic_print, panic_print, ulong, 0644); 761 core_param(pause_on_oops, pause_on_oops, int, 0644); 762 core_param(panic_on_warn, panic_on_warn, int, 0644); 763 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); 764 765 static int __init oops_setup(char *s) 766 { 767 if (!s) 768 return -EINVAL; 769 if (!strcmp(s, "panic")) 770 panic_on_oops = 1; 771 return 0; 772 } 773 early_param("oops", oops_setup); 774 775 static int __init panic_on_taint_setup(char *s) 776 { 777 char *taint_str; 778 779 if (!s) 780 return -EINVAL; 781 782 taint_str = strsep(&s, ","); 783 if (kstrtoul(taint_str, 16, &panic_on_taint)) 784 return -EINVAL; 785 786 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ 787 panic_on_taint &= TAINT_FLAGS_MAX; 788 789 if (!panic_on_taint) 790 return -EINVAL; 791 792 if (s && !strcmp(s, "nousertaint")) 793 panic_on_taint_nousertaint = true; 794 795 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", 796 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); 797 798 return 0; 799 } 800 early_param("panic_on_taint", panic_on_taint_setup); 801