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 __noreturn 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 __noreturn 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, this_cpu; 196 197 old_cpu = PANIC_CPU_INVALID; 198 this_cpu = raw_smp_processor_id(); 199 200 /* atomic_try_cmpxchg updates old_cpu on failure */ 201 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) 202 panic("%s", msg); 203 else if (old_cpu != this_cpu) 204 nmi_panic_self_stop(regs); 205 } 206 EXPORT_SYMBOL(nmi_panic); 207 208 static void panic_print_sys_info(bool console_flush) 209 { 210 if (console_flush) { 211 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) 212 console_flush_on_panic(CONSOLE_REPLAY_ALL); 213 return; 214 } 215 216 if (panic_print & PANIC_PRINT_TASK_INFO) 217 show_state(); 218 219 if (panic_print & PANIC_PRINT_MEM_INFO) 220 show_mem(); 221 222 if (panic_print & PANIC_PRINT_TIMER_INFO) 223 sysrq_timer_list_show(); 224 225 if (panic_print & PANIC_PRINT_LOCK_INFO) 226 debug_show_all_locks(); 227 228 if (panic_print & PANIC_PRINT_FTRACE_INFO) 229 ftrace_dump(DUMP_ALL); 230 } 231 232 void check_panic_on_warn(const char *origin) 233 { 234 unsigned int limit; 235 236 if (panic_on_warn) 237 panic("%s: panic_on_warn set ...\n", origin); 238 239 limit = READ_ONCE(warn_limit); 240 if (atomic_inc_return(&warn_count) >= limit && limit) 241 panic("%s: system warned too often (kernel.warn_limit is %d)", 242 origin, limit); 243 } 244 245 /* 246 * Helper that triggers the NMI backtrace (if set in panic_print) 247 * and then performs the secondary CPUs shutdown - we cannot have 248 * the NMI backtrace after the CPUs are off! 249 */ 250 static void panic_other_cpus_shutdown(bool crash_kexec) 251 { 252 if (panic_print & PANIC_PRINT_ALL_CPU_BT) 253 trigger_all_cpu_backtrace(); 254 255 /* 256 * Note that smp_send_stop() is the usual SMP shutdown function, 257 * which unfortunately may not be hardened to work in a panic 258 * situation. If we want to do crash dump after notifier calls 259 * and kmsg_dump, we will need architecture dependent extra 260 * bits in addition to stopping other CPUs, hence we rely on 261 * crash_smp_send_stop() for that. 262 */ 263 if (!crash_kexec) 264 smp_send_stop(); 265 else 266 crash_smp_send_stop(); 267 } 268 269 /** 270 * panic - halt the system 271 * @fmt: The text string to print 272 * 273 * Display a message, then perform cleanups. 274 * 275 * This function never returns. 276 */ 277 void panic(const char *fmt, ...) 278 { 279 static char buf[1024]; 280 va_list args; 281 long i, i_next = 0, len; 282 int state = 0; 283 int old_cpu, this_cpu; 284 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; 285 286 if (panic_on_warn) { 287 /* 288 * This thread may hit another WARN() in the panic path. 289 * Resetting this prevents additional WARN() from panicking the 290 * system on this thread. Other threads are blocked by the 291 * panic_mutex in panic(). 292 */ 293 panic_on_warn = 0; 294 } 295 296 /* 297 * Disable local interrupts. This will prevent panic_smp_self_stop 298 * from deadlocking the first cpu that invokes the panic, since 299 * there is nothing to prevent an interrupt handler (that runs 300 * after setting panic_cpu) from invoking panic() again. 301 */ 302 local_irq_disable(); 303 preempt_disable_notrace(); 304 305 /* 306 * It's possible to come here directly from a panic-assertion and 307 * not have preempt disabled. Some functions called from here want 308 * preempt to be disabled. No point enabling it later though... 309 * 310 * Only one CPU is allowed to execute the panic code from here. For 311 * multiple parallel invocations of panic, all other CPUs either 312 * stop themself or will wait until they are stopped by the 1st CPU 313 * with smp_send_stop(). 314 * 315 * cmpxchg success means this is the 1st CPU which comes here, 316 * so go ahead. 317 * `old_cpu == this_cpu' means we came from nmi_panic() which sets 318 * panic_cpu to this CPU. In this case, this is also the 1st CPU. 319 */ 320 old_cpu = PANIC_CPU_INVALID; 321 this_cpu = raw_smp_processor_id(); 322 323 /* atomic_try_cmpxchg updates old_cpu on failure */ 324 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { 325 /* go ahead */ 326 } else if (old_cpu != this_cpu) 327 panic_smp_self_stop(); 328 329 console_verbose(); 330 bust_spinlocks(1); 331 va_start(args, fmt); 332 len = vscnprintf(buf, sizeof(buf), fmt, args); 333 va_end(args); 334 335 if (len && buf[len - 1] == '\n') 336 buf[len - 1] = '\0'; 337 338 pr_emerg("Kernel panic - not syncing: %s\n", buf); 339 #ifdef CONFIG_DEBUG_BUGVERBOSE 340 /* 341 * Avoid nested stack-dumping if a panic occurs during oops processing 342 */ 343 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 344 dump_stack(); 345 #endif 346 347 /* 348 * If kgdb is enabled, give it a chance to run before we stop all 349 * the other CPUs or else we won't be able to debug processes left 350 * running on them. 351 */ 352 kgdb_panic(buf); 353 354 /* 355 * If we have crashed and we have a crash kernel loaded let it handle 356 * everything else. 357 * If we want to run this after calling panic_notifiers, pass 358 * the "crash_kexec_post_notifiers" option to the kernel. 359 * 360 * Bypass the panic_cpu check and call __crash_kexec directly. 361 */ 362 if (!_crash_kexec_post_notifiers) 363 __crash_kexec(NULL); 364 365 panic_other_cpus_shutdown(_crash_kexec_post_notifiers); 366 367 /* 368 * Run any panic handlers, including those that might need to 369 * add information to the kmsg dump output. 370 */ 371 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 372 373 panic_print_sys_info(false); 374 375 kmsg_dump(KMSG_DUMP_PANIC); 376 377 /* 378 * If you doubt kdump always works fine in any situation, 379 * "crash_kexec_post_notifiers" offers you a chance to run 380 * panic_notifiers and dumping kmsg before kdump. 381 * Note: since some panic_notifiers can make crashed kernel 382 * more unstable, it can increase risks of the kdump failure too. 383 * 384 * Bypass the panic_cpu check and call __crash_kexec directly. 385 */ 386 if (_crash_kexec_post_notifiers) 387 __crash_kexec(NULL); 388 389 console_unblank(); 390 391 /* 392 * We may have ended up stopping the CPU holding the lock (in 393 * smp_send_stop()) while still having some valuable data in the console 394 * buffer. Try to acquire the lock then release it regardless of the 395 * result. The release will also print the buffers out. Locks debug 396 * should be disabled to avoid reporting bad unlock balance when 397 * panic() is not being callled from OOPS. 398 */ 399 debug_locks_off(); 400 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 401 402 panic_print_sys_info(true); 403 404 if (!panic_blink) 405 panic_blink = no_blink; 406 407 if (panic_timeout > 0) { 408 /* 409 * Delay timeout seconds before rebooting the machine. 410 * We can't use the "normal" timers since we just panicked. 411 */ 412 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 413 414 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 415 touch_nmi_watchdog(); 416 if (i >= i_next) { 417 i += panic_blink(state ^= 1); 418 i_next = i + 3600 / PANIC_BLINK_SPD; 419 } 420 mdelay(PANIC_TIMER_STEP); 421 } 422 } 423 if (panic_timeout != 0) { 424 /* 425 * This will not be a clean reboot, with everything 426 * shutting down. But if there is a chance of 427 * rebooting the system it will be rebooted. 428 */ 429 if (panic_reboot_mode != REBOOT_UNDEFINED) 430 reboot_mode = panic_reboot_mode; 431 emergency_restart(); 432 } 433 #ifdef __sparc__ 434 { 435 extern int stop_a_enabled; 436 /* Make sure the user can actually press Stop-A (L1-A) */ 437 stop_a_enabled = 1; 438 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 439 "twice on console to return to the boot prom\n"); 440 } 441 #endif 442 #if defined(CONFIG_S390) 443 disabled_wait(); 444 #endif 445 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 446 447 /* Do not scroll important messages printed above */ 448 suppress_printk = 1; 449 local_irq_enable(); 450 for (i = 0; ; i += PANIC_TIMER_STEP) { 451 touch_softlockup_watchdog(); 452 if (i >= i_next) { 453 i += panic_blink(state ^= 1); 454 i_next = i + 3600 / PANIC_BLINK_SPD; 455 } 456 mdelay(PANIC_TIMER_STEP); 457 } 458 } 459 460 EXPORT_SYMBOL(panic); 461 462 /* 463 * TAINT_FORCED_RMMOD could be a per-module flag but the module 464 * is being removed anyway. 465 */ 466 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { 467 [ TAINT_PROPRIETARY_MODULE ] = { 'P', 'G', true }, 468 [ TAINT_FORCED_MODULE ] = { 'F', ' ', true }, 469 [ TAINT_CPU_OUT_OF_SPEC ] = { 'S', ' ', false }, 470 [ TAINT_FORCED_RMMOD ] = { 'R', ' ', false }, 471 [ TAINT_MACHINE_CHECK ] = { 'M', ' ', false }, 472 [ TAINT_BAD_PAGE ] = { 'B', ' ', false }, 473 [ TAINT_USER ] = { 'U', ' ', false }, 474 [ TAINT_DIE ] = { 'D', ' ', false }, 475 [ TAINT_OVERRIDDEN_ACPI_TABLE ] = { 'A', ' ', false }, 476 [ TAINT_WARN ] = { 'W', ' ', false }, 477 [ TAINT_CRAP ] = { 'C', ' ', true }, 478 [ TAINT_FIRMWARE_WORKAROUND ] = { 'I', ' ', false }, 479 [ TAINT_OOT_MODULE ] = { 'O', ' ', true }, 480 [ TAINT_UNSIGNED_MODULE ] = { 'E', ' ', true }, 481 [ TAINT_SOFTLOCKUP ] = { 'L', ' ', false }, 482 [ TAINT_LIVEPATCH ] = { 'K', ' ', true }, 483 [ TAINT_AUX ] = { 'X', ' ', true }, 484 [ TAINT_RANDSTRUCT ] = { 'T', ' ', true }, 485 [ TAINT_TEST ] = { 'N', ' ', true }, 486 }; 487 488 /** 489 * print_tainted - return a string to represent the kernel taint state. 490 * 491 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst 492 * 493 * The string is overwritten by the next call to print_tainted(), 494 * but is always NULL terminated. 495 */ 496 const char *print_tainted(void) 497 { 498 static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")]; 499 500 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); 501 502 if (tainted_mask) { 503 char *s; 504 int i; 505 506 s = buf + sprintf(buf, "Tainted: "); 507 for (i = 0; i < TAINT_FLAGS_COUNT; i++) { 508 const struct taint_flag *t = &taint_flags[i]; 509 *s++ = test_bit(i, &tainted_mask) ? 510 t->c_true : t->c_false; 511 } 512 *s = 0; 513 } else 514 snprintf(buf, sizeof(buf), "Not tainted"); 515 516 return buf; 517 } 518 519 int test_taint(unsigned flag) 520 { 521 return test_bit(flag, &tainted_mask); 522 } 523 EXPORT_SYMBOL(test_taint); 524 525 unsigned long get_taint(void) 526 { 527 return tainted_mask; 528 } 529 530 /** 531 * add_taint: add a taint flag if not already set. 532 * @flag: one of the TAINT_* constants. 533 * @lockdep_ok: whether lock debugging is still OK. 534 * 535 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 536 * some notewortht-but-not-corrupting cases, it can be set to true. 537 */ 538 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 539 { 540 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 541 pr_warn("Disabling lock debugging due to kernel taint\n"); 542 543 set_bit(flag, &tainted_mask); 544 545 if (tainted_mask & panic_on_taint) { 546 panic_on_taint = 0; 547 panic("panic_on_taint set ..."); 548 } 549 } 550 EXPORT_SYMBOL(add_taint); 551 552 static void spin_msec(int msecs) 553 { 554 int i; 555 556 for (i = 0; i < msecs; i++) { 557 touch_nmi_watchdog(); 558 mdelay(1); 559 } 560 } 561 562 /* 563 * It just happens that oops_enter() and oops_exit() are identically 564 * implemented... 565 */ 566 static void do_oops_enter_exit(void) 567 { 568 unsigned long flags; 569 static int spin_counter; 570 571 if (!pause_on_oops) 572 return; 573 574 spin_lock_irqsave(&pause_on_oops_lock, flags); 575 if (pause_on_oops_flag == 0) { 576 /* This CPU may now print the oops message */ 577 pause_on_oops_flag = 1; 578 } else { 579 /* We need to stall this CPU */ 580 if (!spin_counter) { 581 /* This CPU gets to do the counting */ 582 spin_counter = pause_on_oops; 583 do { 584 spin_unlock(&pause_on_oops_lock); 585 spin_msec(MSEC_PER_SEC); 586 spin_lock(&pause_on_oops_lock); 587 } while (--spin_counter); 588 pause_on_oops_flag = 0; 589 } else { 590 /* This CPU waits for a different one */ 591 while (spin_counter) { 592 spin_unlock(&pause_on_oops_lock); 593 spin_msec(1); 594 spin_lock(&pause_on_oops_lock); 595 } 596 } 597 } 598 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 599 } 600 601 /* 602 * Return true if the calling CPU is allowed to print oops-related info. 603 * This is a bit racy.. 604 */ 605 bool oops_may_print(void) 606 { 607 return pause_on_oops_flag == 0; 608 } 609 610 /* 611 * Called when the architecture enters its oops handler, before it prints 612 * anything. If this is the first CPU to oops, and it's oopsing the first 613 * time then let it proceed. 614 * 615 * This is all enabled by the pause_on_oops kernel boot option. We do all 616 * this to ensure that oopses don't scroll off the screen. It has the 617 * side-effect of preventing later-oopsing CPUs from mucking up the display, 618 * too. 619 * 620 * It turns out that the CPU which is allowed to print ends up pausing for 621 * the right duration, whereas all the other CPUs pause for twice as long: 622 * once in oops_enter(), once in oops_exit(). 623 */ 624 void oops_enter(void) 625 { 626 tracing_off(); 627 /* can't trust the integrity of the kernel anymore: */ 628 debug_locks_off(); 629 do_oops_enter_exit(); 630 631 if (sysctl_oops_all_cpu_backtrace) 632 trigger_all_cpu_backtrace(); 633 } 634 635 static void print_oops_end_marker(void) 636 { 637 pr_warn("---[ end trace %016llx ]---\n", 0ULL); 638 } 639 640 /* 641 * Called when the architecture exits its oops handler, after printing 642 * everything. 643 */ 644 void oops_exit(void) 645 { 646 do_oops_enter_exit(); 647 print_oops_end_marker(); 648 kmsg_dump(KMSG_DUMP_OOPS); 649 } 650 651 struct warn_args { 652 const char *fmt; 653 va_list args; 654 }; 655 656 void __warn(const char *file, int line, void *caller, unsigned taint, 657 struct pt_regs *regs, struct warn_args *args) 658 { 659 disable_trace_on_warning(); 660 661 if (file) 662 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", 663 raw_smp_processor_id(), current->pid, file, line, 664 caller); 665 else 666 pr_warn("WARNING: CPU: %d PID: %d at %pS\n", 667 raw_smp_processor_id(), current->pid, caller); 668 669 if (args) 670 vprintk(args->fmt, args->args); 671 672 print_modules(); 673 674 if (regs) 675 show_regs(regs); 676 677 check_panic_on_warn("kernel"); 678 679 if (!regs) 680 dump_stack(); 681 682 print_irqtrace_events(current); 683 684 print_oops_end_marker(); 685 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); 686 687 /* Just a warning, don't kill lockdep. */ 688 add_taint(taint, LOCKDEP_STILL_OK); 689 } 690 691 #ifdef CONFIG_BUG 692 #ifndef __WARN_FLAGS 693 void warn_slowpath_fmt(const char *file, int line, unsigned taint, 694 const char *fmt, ...) 695 { 696 bool rcu = warn_rcu_enter(); 697 struct warn_args args; 698 699 pr_warn(CUT_HERE); 700 701 if (!fmt) { 702 __warn(file, line, __builtin_return_address(0), taint, 703 NULL, NULL); 704 warn_rcu_exit(rcu); 705 return; 706 } 707 708 args.fmt = fmt; 709 va_start(args.args, fmt); 710 __warn(file, line, __builtin_return_address(0), taint, NULL, &args); 711 va_end(args.args); 712 warn_rcu_exit(rcu); 713 } 714 EXPORT_SYMBOL(warn_slowpath_fmt); 715 #else 716 void __warn_printk(const char *fmt, ...) 717 { 718 bool rcu = warn_rcu_enter(); 719 va_list args; 720 721 pr_warn(CUT_HERE); 722 723 va_start(args, fmt); 724 vprintk(fmt, args); 725 va_end(args); 726 warn_rcu_exit(rcu); 727 } 728 EXPORT_SYMBOL(__warn_printk); 729 #endif 730 731 /* Support resetting WARN*_ONCE state */ 732 733 static int clear_warn_once_set(void *data, u64 val) 734 { 735 generic_bug_clear_once(); 736 memset(__start_once, 0, __end_once - __start_once); 737 return 0; 738 } 739 740 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, 741 "%lld\n"); 742 743 static __init int register_warn_debugfs(void) 744 { 745 /* Don't care about failure */ 746 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL, 747 &clear_warn_once_fops); 748 return 0; 749 } 750 751 device_initcall(register_warn_debugfs); 752 #endif 753 754 #ifdef CONFIG_STACKPROTECTOR 755 756 /* 757 * Called when gcc's -fstack-protector feature is used, and 758 * gcc detects corruption of the on-stack canary value 759 */ 760 __visible noinstr void __stack_chk_fail(void) 761 { 762 instrumentation_begin(); 763 panic("stack-protector: Kernel stack is corrupted in: %pB", 764 __builtin_return_address(0)); 765 instrumentation_end(); 766 } 767 EXPORT_SYMBOL(__stack_chk_fail); 768 769 #endif 770 771 core_param(panic, panic_timeout, int, 0644); 772 core_param(panic_print, panic_print, ulong, 0644); 773 core_param(pause_on_oops, pause_on_oops, int, 0644); 774 core_param(panic_on_warn, panic_on_warn, int, 0644); 775 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); 776 777 static int __init oops_setup(char *s) 778 { 779 if (!s) 780 return -EINVAL; 781 if (!strcmp(s, "panic")) 782 panic_on_oops = 1; 783 return 0; 784 } 785 early_param("oops", oops_setup); 786 787 static int __init panic_on_taint_setup(char *s) 788 { 789 char *taint_str; 790 791 if (!s) 792 return -EINVAL; 793 794 taint_str = strsep(&s, ","); 795 if (kstrtoul(taint_str, 16, &panic_on_taint)) 796 return -EINVAL; 797 798 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ 799 panic_on_taint &= TAINT_FLAGS_MAX; 800 801 if (!panic_on_taint) 802 return -EINVAL; 803 804 if (s && !strcmp(s, "nousertaint")) 805 panic_on_taint_nousertaint = true; 806 807 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", 808 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); 809 810 return 0; 811 } 812 early_param("panic_on_taint", panic_on_taint_setup); 813