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_TASK_INFO) 216 show_state(); 217 218 if (panic_print & PANIC_PRINT_MEM_INFO) 219 show_mem(0, NULL); 220 221 if (panic_print & PANIC_PRINT_TIMER_INFO) 222 sysrq_timer_list_show(); 223 224 if (panic_print & PANIC_PRINT_LOCK_INFO) 225 debug_show_all_locks(); 226 227 if (panic_print & PANIC_PRINT_FTRACE_INFO) 228 ftrace_dump(DUMP_ALL); 229 } 230 231 void check_panic_on_warn(const char *origin) 232 { 233 unsigned int limit; 234 235 if (panic_on_warn) 236 panic("%s: panic_on_warn set ...\n", origin); 237 238 limit = READ_ONCE(warn_limit); 239 if (atomic_inc_return(&warn_count) >= limit && limit) 240 panic("%s: system warned too often (kernel.warn_limit is %d)", 241 origin, limit); 242 } 243 244 /* 245 * Helper that triggers the NMI backtrace (if set in panic_print) 246 * and then performs the secondary CPUs shutdown - we cannot have 247 * the NMI backtrace after the CPUs are off! 248 */ 249 static void panic_other_cpus_shutdown(bool crash_kexec) 250 { 251 if (panic_print & PANIC_PRINT_ALL_CPU_BT) 252 trigger_all_cpu_backtrace(); 253 254 /* 255 * Note that smp_send_stop() is the usual SMP shutdown function, 256 * which unfortunately may not be hardened to work in a panic 257 * situation. If we want to do crash dump after notifier calls 258 * and kmsg_dump, we will need architecture dependent extra 259 * bits in addition to stopping other CPUs, hence we rely on 260 * crash_smp_send_stop() for that. 261 */ 262 if (!crash_kexec) 263 smp_send_stop(); 264 else 265 crash_smp_send_stop(); 266 } 267 268 /** 269 * panic - halt the system 270 * @fmt: The text string to print 271 * 272 * Display a message, then perform cleanups. 273 * 274 * This function never returns. 275 */ 276 void panic(const char *fmt, ...) 277 { 278 static char buf[1024]; 279 va_list args; 280 long i, i_next = 0, len; 281 int state = 0; 282 int old_cpu, this_cpu; 283 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; 284 285 if (panic_on_warn) { 286 /* 287 * This thread may hit another WARN() in the panic path. 288 * Resetting this prevents additional WARN() from panicking the 289 * system on this thread. Other threads are blocked by the 290 * panic_mutex in panic(). 291 */ 292 panic_on_warn = 0; 293 } 294 295 /* 296 * Disable local interrupts. This will prevent panic_smp_self_stop 297 * from deadlocking the first cpu that invokes the panic, since 298 * there is nothing to prevent an interrupt handler (that runs 299 * after setting panic_cpu) from invoking panic() again. 300 */ 301 local_irq_disable(); 302 preempt_disable_notrace(); 303 304 /* 305 * It's possible to come here directly from a panic-assertion and 306 * not have preempt disabled. Some functions called from here want 307 * preempt to be disabled. No point enabling it later though... 308 * 309 * Only one CPU is allowed to execute the panic code from here. For 310 * multiple parallel invocations of panic, all other CPUs either 311 * stop themself or will wait until they are stopped by the 1st CPU 312 * with smp_send_stop(). 313 * 314 * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which 315 * comes here, so go ahead. 316 * `old_cpu == this_cpu' means we came from nmi_panic() which sets 317 * panic_cpu to this CPU. In this case, this is also the 1st CPU. 318 */ 319 this_cpu = raw_smp_processor_id(); 320 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); 321 322 if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu) 323 panic_smp_self_stop(); 324 325 console_verbose(); 326 bust_spinlocks(1); 327 va_start(args, fmt); 328 len = vscnprintf(buf, sizeof(buf), fmt, args); 329 va_end(args); 330 331 if (len && buf[len - 1] == '\n') 332 buf[len - 1] = '\0'; 333 334 pr_emerg("Kernel panic - not syncing: %s\n", buf); 335 #ifdef CONFIG_DEBUG_BUGVERBOSE 336 /* 337 * Avoid nested stack-dumping if a panic occurs during oops processing 338 */ 339 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 340 dump_stack(); 341 #endif 342 343 /* 344 * If kgdb is enabled, give it a chance to run before we stop all 345 * the other CPUs or else we won't be able to debug processes left 346 * running on them. 347 */ 348 kgdb_panic(buf); 349 350 /* 351 * If we have crashed and we have a crash kernel loaded let it handle 352 * everything else. 353 * If we want to run this after calling panic_notifiers, pass 354 * the "crash_kexec_post_notifiers" option to the kernel. 355 * 356 * Bypass the panic_cpu check and call __crash_kexec directly. 357 */ 358 if (!_crash_kexec_post_notifiers) 359 __crash_kexec(NULL); 360 361 panic_other_cpus_shutdown(_crash_kexec_post_notifiers); 362 363 /* 364 * Run any panic handlers, including those that might need to 365 * add information to the kmsg dump output. 366 */ 367 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 368 369 panic_print_sys_info(false); 370 371 kmsg_dump(KMSG_DUMP_PANIC); 372 373 /* 374 * If you doubt kdump always works fine in any situation, 375 * "crash_kexec_post_notifiers" offers you a chance to run 376 * panic_notifiers and dumping kmsg before kdump. 377 * Note: since some panic_notifiers can make crashed kernel 378 * more unstable, it can increase risks of the kdump failure too. 379 * 380 * Bypass the panic_cpu check and call __crash_kexec directly. 381 */ 382 if (_crash_kexec_post_notifiers) 383 __crash_kexec(NULL); 384 385 console_unblank(); 386 387 /* 388 * We may have ended up stopping the CPU holding the lock (in 389 * smp_send_stop()) while still having some valuable data in the console 390 * buffer. Try to acquire the lock then release it regardless of the 391 * result. The release will also print the buffers out. Locks debug 392 * should be disabled to avoid reporting bad unlock balance when 393 * panic() is not being callled from OOPS. 394 */ 395 debug_locks_off(); 396 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 397 398 panic_print_sys_info(true); 399 400 if (!panic_blink) 401 panic_blink = no_blink; 402 403 if (panic_timeout > 0) { 404 /* 405 * Delay timeout seconds before rebooting the machine. 406 * We can't use the "normal" timers since we just panicked. 407 */ 408 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 409 410 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 411 touch_nmi_watchdog(); 412 if (i >= i_next) { 413 i += panic_blink(state ^= 1); 414 i_next = i + 3600 / PANIC_BLINK_SPD; 415 } 416 mdelay(PANIC_TIMER_STEP); 417 } 418 } 419 if (panic_timeout != 0) { 420 /* 421 * This will not be a clean reboot, with everything 422 * shutting down. But if there is a chance of 423 * rebooting the system it will be rebooted. 424 */ 425 if (panic_reboot_mode != REBOOT_UNDEFINED) 426 reboot_mode = panic_reboot_mode; 427 emergency_restart(); 428 } 429 #ifdef __sparc__ 430 { 431 extern int stop_a_enabled; 432 /* Make sure the user can actually press Stop-A (L1-A) */ 433 stop_a_enabled = 1; 434 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 435 "twice on console to return to the boot prom\n"); 436 } 437 #endif 438 #if defined(CONFIG_S390) 439 disabled_wait(); 440 #endif 441 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 442 443 /* Do not scroll important messages printed above */ 444 suppress_printk = 1; 445 local_irq_enable(); 446 for (i = 0; ; i += PANIC_TIMER_STEP) { 447 touch_softlockup_watchdog(); 448 if (i >= i_next) { 449 i += panic_blink(state ^= 1); 450 i_next = i + 3600 / PANIC_BLINK_SPD; 451 } 452 mdelay(PANIC_TIMER_STEP); 453 } 454 } 455 456 EXPORT_SYMBOL(panic); 457 458 /* 459 * TAINT_FORCED_RMMOD could be a per-module flag but the module 460 * is being removed anyway. 461 */ 462 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { 463 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true }, 464 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true }, 465 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false }, 466 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false }, 467 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false }, 468 [ TAINT_BAD_PAGE ] = { 'B', ' ', false }, 469 [ TAINT_USER ] = { 'U', ' ', false }, 470 [ TAINT_DIE ] = { 'D', ' ', false }, 471 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false }, 472 [ TAINT_WARN ] = { 'W', ' ', false }, 473 [ TAINT_CRAP ] = { 'C', ' ', true }, 474 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false }, 475 [ TAINT_OOT_MODULE ] = { 'O', ' ', true }, 476 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true }, 477 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false }, 478 [ TAINT_LIVEPATCH ] = { 'K', ' ', true }, 479 [ TAINT_AUX ] = { 'X', ' ', true }, 480 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true }, 481 [ TAINT_TEST ] = { 'N', ' ', true }, 482 }; 483 484 /** 485 * print_tainted - return a string to represent the kernel taint state. 486 * 487 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst 488 * 489 * The string is overwritten by the next call to print_tainted(), 490 * but is always NULL terminated. 491 */ 492 const char *print_tainted(void) 493 { 494 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")]; 495 496 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); 497 498 if (tainted_mask) { 499 char *s; 500 int i; 501 502 s = buf + sprintf(buf, "Tainted: "); 503 for (i = 0; i < TAINT_FLAGS_COUNT; i++) { 504 const struct taint_flag *t = &taint_flags[i]; 505 *s++ = test_bit(i, &tainted_mask) ? 506 t->c_true : t->c_false; 507 } 508 *s = 0; 509 } else 510 snprintf(buf, sizeof(buf), "Not tainted"); 511 512 return buf; 513 } 514 515 int test_taint(unsigned flag) 516 { 517 return test_bit(flag, &tainted_mask); 518 } 519 EXPORT_SYMBOL(test_taint); 520 521 unsigned long get_taint(void) 522 { 523 return tainted_mask; 524 } 525 526 /** 527 * add_taint: add a taint flag if not already set. 528 * @flag: one of the TAINT_* constants. 529 * @lockdep_ok: whether lock debugging is still OK. 530 * 531 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 532 * some notewortht-but-not-corrupting cases, it can be set to true. 533 */ 534 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 535 { 536 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 537 pr_warn("Disabling lock debugging due to kernel taint\n"); 538 539 set_bit(flag, &tainted_mask); 540 541 if (tainted_mask & panic_on_taint) { 542 panic_on_taint = 0; 543 panic("panic_on_taint set ..."); 544 } 545 } 546 EXPORT_SYMBOL(add_taint); 547 548 static void spin_msec(int msecs) 549 { 550 int i; 551 552 for (i = 0; i < msecs; i++) { 553 touch_nmi_watchdog(); 554 mdelay(1); 555 } 556 } 557 558 /* 559 * It just happens that oops_enter() and oops_exit() are identically 560 * implemented... 561 */ 562 static void do_oops_enter_exit(void) 563 { 564 unsigned long flags; 565 static int spin_counter; 566 567 if (!pause_on_oops) 568 return; 569 570 spin_lock_irqsave(&pause_on_oops_lock, flags); 571 if (pause_on_oops_flag == 0) { 572 /* This CPU may now print the oops message */ 573 pause_on_oops_flag = 1; 574 } else { 575 /* We need to stall this CPU */ 576 if (!spin_counter) { 577 /* This CPU gets to do the counting */ 578 spin_counter = pause_on_oops; 579 do { 580 spin_unlock(&pause_on_oops_lock); 581 spin_msec(MSEC_PER_SEC); 582 spin_lock(&pause_on_oops_lock); 583 } while (--spin_counter); 584 pause_on_oops_flag = 0; 585 } else { 586 /* This CPU waits for a different one */ 587 while (spin_counter) { 588 spin_unlock(&pause_on_oops_lock); 589 spin_msec(1); 590 spin_lock(&pause_on_oops_lock); 591 } 592 } 593 } 594 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 595 } 596 597 /* 598 * Return true if the calling CPU is allowed to print oops-related info. 599 * This is a bit racy.. 600 */ 601 bool oops_may_print(void) 602 { 603 return pause_on_oops_flag == 0; 604 } 605 606 /* 607 * Called when the architecture enters its oops handler, before it prints 608 * anything. If this is the first CPU to oops, and it's oopsing the first 609 * time then let it proceed. 610 * 611 * This is all enabled by the pause_on_oops kernel boot option. We do all 612 * this to ensure that oopses don't scroll off the screen. It has the 613 * side-effect of preventing later-oopsing CPUs from mucking up the display, 614 * too. 615 * 616 * It turns out that the CPU which is allowed to print ends up pausing for 617 * the right duration, whereas all the other CPUs pause for twice as long: 618 * once in oops_enter(), once in oops_exit(). 619 */ 620 void oops_enter(void) 621 { 622 tracing_off(); 623 /* can't trust the integrity of the kernel anymore: */ 624 debug_locks_off(); 625 do_oops_enter_exit(); 626 627 if (sysctl_oops_all_cpu_backtrace) 628 trigger_all_cpu_backtrace(); 629 } 630 631 static void print_oops_end_marker(void) 632 { 633 pr_warn("---[ end trace %016llx ]---\n", 0ULL); 634 } 635 636 /* 637 * Called when the architecture exits its oops handler, after printing 638 * everything. 639 */ 640 void oops_exit(void) 641 { 642 do_oops_enter_exit(); 643 print_oops_end_marker(); 644 kmsg_dump(KMSG_DUMP_OOPS); 645 } 646 647 struct warn_args { 648 const char *fmt; 649 va_list args; 650 }; 651 652 void __warn(const char *file, int line, void *caller, unsigned taint, 653 struct pt_regs *regs, struct warn_args *args) 654 { 655 disable_trace_on_warning(); 656 657 if (file) 658 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", 659 raw_smp_processor_id(), current->pid, file, line, 660 caller); 661 else 662 pr_warn("WARNING: CPU: %d PID: %d at %pS\n", 663 raw_smp_processor_id(), current->pid, caller); 664 665 if (args) 666 vprintk(args->fmt, args->args); 667 668 print_modules(); 669 670 if (regs) 671 show_regs(regs); 672 673 check_panic_on_warn("kernel"); 674 675 if (!regs) 676 dump_stack(); 677 678 print_irqtrace_events(current); 679 680 print_oops_end_marker(); 681 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); 682 683 /* Just a warning, don't kill lockdep. */ 684 add_taint(taint, LOCKDEP_STILL_OK); 685 } 686 687 #ifndef __WARN_FLAGS 688 void warn_slowpath_fmt(const char *file, int line, unsigned taint, 689 const char *fmt, ...) 690 { 691 bool rcu = warn_rcu_enter(); 692 struct warn_args args; 693 694 pr_warn(CUT_HERE); 695 696 if (!fmt) { 697 __warn(file, line, __builtin_return_address(0), taint, 698 NULL, NULL); 699 return; 700 } 701 702 args.fmt = fmt; 703 va_start(args.args, fmt); 704 __warn(file, line, __builtin_return_address(0), taint, NULL, &args); 705 va_end(args.args); 706 warn_rcu_exit(rcu); 707 } 708 EXPORT_SYMBOL(warn_slowpath_fmt); 709 #else 710 void __warn_printk(const char *fmt, ...) 711 { 712 bool rcu = warn_rcu_enter(); 713 va_list args; 714 715 pr_warn(CUT_HERE); 716 717 va_start(args, fmt); 718 vprintk(fmt, args); 719 va_end(args); 720 warn_rcu_exit(rcu); 721 } 722 EXPORT_SYMBOL(__warn_printk); 723 #endif 724 725 #ifdef CONFIG_BUG 726 727 /* Support resetting WARN*_ONCE state */ 728 729 static int clear_warn_once_set(void *data, u64 val) 730 { 731 generic_bug_clear_once(); 732 memset(__start_once, 0, __end_once - __start_once); 733 return 0; 734 } 735 736 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, 737 "%lld\n"); 738 739 static __init int register_warn_debugfs(void) 740 { 741 /* Don't care about failure */ 742 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL, 743 &clear_warn_once_fops); 744 return 0; 745 } 746 747 device_initcall(register_warn_debugfs); 748 #endif 749 750 #ifdef CONFIG_STACKPROTECTOR 751 752 /* 753 * Called when gcc's -fstack-protector feature is used, and 754 * gcc detects corruption of the on-stack canary value 755 */ 756 __visible noinstr void __stack_chk_fail(void) 757 { 758 instrumentation_begin(); 759 panic("stack-protector: Kernel stack is corrupted in: %pB", 760 __builtin_return_address(0)); 761 instrumentation_end(); 762 } 763 EXPORT_SYMBOL(__stack_chk_fail); 764 765 #endif 766 767 core_param(panic, panic_timeout, int, 0644); 768 core_param(panic_print, panic_print, ulong, 0644); 769 core_param(pause_on_oops, pause_on_oops, int, 0644); 770 core_param(panic_on_warn, panic_on_warn, int, 0644); 771 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); 772 773 static int __init oops_setup(char *s) 774 { 775 if (!s) 776 return -EINVAL; 777 if (!strcmp(s, "panic")) 778 panic_on_oops = 1; 779 return 0; 780 } 781 early_param("oops", oops_setup); 782 783 static int __init panic_on_taint_setup(char *s) 784 { 785 char *taint_str; 786 787 if (!s) 788 return -EINVAL; 789 790 taint_str = strsep(&s, ","); 791 if (kstrtoul(taint_str, 16, &panic_on_taint)) 792 return -EINVAL; 793 794 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ 795 panic_on_taint &= TAINT_FLAGS_MAX; 796 797 if (!panic_on_taint) 798 return -EINVAL; 799 800 if (s && !strcmp(s, "nousertaint")) 801 panic_on_taint_nousertaint = true; 802 803 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", 804 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); 805 806 return 0; 807 } 808 early_param("panic_on_taint", panic_on_taint_setup); 809