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 <linux/seq_buf.h> 39 #include <trace/events/error_report.h> 40 #include <asm/sections.h> 41 42 #define PANIC_TIMER_STEP 100 43 #define PANIC_BLINK_SPD 18 44 45 #ifdef CONFIG_SMP 46 /* 47 * Should we dump all CPUs backtraces in an oops event? 48 * Defaults to 0, can be changed via sysctl. 49 */ 50 static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; 51 #else 52 #define sysctl_oops_all_cpu_backtrace 0 53 #endif /* CONFIG_SMP */ 54 55 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; 56 static unsigned long tainted_mask = 57 IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0; 58 static int pause_on_oops; 59 static int pause_on_oops_flag; 60 static DEFINE_SPINLOCK(pause_on_oops_lock); 61 bool crash_kexec_post_notifiers; 62 int panic_on_warn __read_mostly; 63 unsigned long panic_on_taint; 64 bool panic_on_taint_nousertaint = false; 65 static unsigned int warn_limit __read_mostly; 66 67 bool panic_triggering_all_cpu_backtrace; 68 69 int panic_timeout = CONFIG_PANIC_TIMEOUT; 70 EXPORT_SYMBOL_GPL(panic_timeout); 71 72 #define PANIC_PRINT_TASK_INFO 0x00000001 73 #define PANIC_PRINT_MEM_INFO 0x00000002 74 #define PANIC_PRINT_TIMER_INFO 0x00000004 75 #define PANIC_PRINT_LOCK_INFO 0x00000008 76 #define PANIC_PRINT_FTRACE_INFO 0x00000010 77 #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 78 #define PANIC_PRINT_ALL_CPU_BT 0x00000040 79 #define PANIC_PRINT_BLOCKED_TASKS 0x00000080 80 unsigned long panic_print; 81 82 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 83 84 EXPORT_SYMBOL(panic_notifier_list); 85 86 #ifdef CONFIG_SYSCTL 87 static const struct ctl_table kern_panic_table[] = { 88 #ifdef CONFIG_SMP 89 { 90 .procname = "oops_all_cpu_backtrace", 91 .data = &sysctl_oops_all_cpu_backtrace, 92 .maxlen = sizeof(int), 93 .mode = 0644, 94 .proc_handler = proc_dointvec_minmax, 95 .extra1 = SYSCTL_ZERO, 96 .extra2 = SYSCTL_ONE, 97 }, 98 #endif 99 { 100 .procname = "panic", 101 .data = &panic_timeout, 102 .maxlen = sizeof(int), 103 .mode = 0644, 104 .proc_handler = proc_dointvec, 105 }, 106 { 107 .procname = "panic_on_oops", 108 .data = &panic_on_oops, 109 .maxlen = sizeof(int), 110 .mode = 0644, 111 .proc_handler = proc_dointvec, 112 }, 113 { 114 .procname = "panic_print", 115 .data = &panic_print, 116 .maxlen = sizeof(unsigned long), 117 .mode = 0644, 118 .proc_handler = proc_doulongvec_minmax, 119 }, 120 { 121 .procname = "panic_on_warn", 122 .data = &panic_on_warn, 123 .maxlen = sizeof(int), 124 .mode = 0644, 125 .proc_handler = proc_dointvec_minmax, 126 .extra1 = SYSCTL_ZERO, 127 .extra2 = SYSCTL_ONE, 128 }, 129 { 130 .procname = "warn_limit", 131 .data = &warn_limit, 132 .maxlen = sizeof(warn_limit), 133 .mode = 0644, 134 .proc_handler = proc_douintvec, 135 }, 136 }; 137 138 static __init int kernel_panic_sysctls_init(void) 139 { 140 register_sysctl_init("kernel", kern_panic_table); 141 return 0; 142 } 143 late_initcall(kernel_panic_sysctls_init); 144 #endif 145 146 static atomic_t warn_count = ATOMIC_INIT(0); 147 148 #ifdef CONFIG_SYSFS 149 static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, 150 char *page) 151 { 152 return sysfs_emit(page, "%d\n", atomic_read(&warn_count)); 153 } 154 155 static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); 156 157 static __init int kernel_panic_sysfs_init(void) 158 { 159 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL); 160 return 0; 161 } 162 late_initcall(kernel_panic_sysfs_init); 163 #endif 164 165 static long no_blink(int state) 166 { 167 return 0; 168 } 169 170 /* Returns how long it waited in ms */ 171 long (*panic_blink)(int state); 172 EXPORT_SYMBOL(panic_blink); 173 174 /* 175 * Stop ourself in panic -- architecture code may override this 176 */ 177 void __weak __noreturn panic_smp_self_stop(void) 178 { 179 while (1) 180 cpu_relax(); 181 } 182 183 /* 184 * Stop ourselves in NMI context if another CPU has already panicked. Arch code 185 * may override this to prepare for crash dumping, e.g. save regs info. 186 */ 187 void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs) 188 { 189 panic_smp_self_stop(); 190 } 191 192 /* 193 * Stop other CPUs in panic. Architecture dependent code may override this 194 * with more suitable version. For example, if the architecture supports 195 * crash dump, it should save registers of each stopped CPU and disable 196 * per-CPU features such as virtualization extensions. 197 */ 198 void __weak crash_smp_send_stop(void) 199 { 200 static int cpus_stopped; 201 202 /* 203 * This function can be called twice in panic path, but obviously 204 * we execute this only once. 205 */ 206 if (cpus_stopped) 207 return; 208 209 /* 210 * Note smp_send_stop is the usual smp shutdown function, which 211 * unfortunately means it may not be hardened to work in a panic 212 * situation. 213 */ 214 smp_send_stop(); 215 cpus_stopped = 1; 216 } 217 218 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); 219 220 /* 221 * A variant of panic() called from NMI context. We return if we've already 222 * panicked on this CPU. If another CPU already panicked, loop in 223 * nmi_panic_self_stop() which can provide architecture dependent code such 224 * as saving register state for crash dump. 225 */ 226 void nmi_panic(struct pt_regs *regs, const char *msg) 227 { 228 int old_cpu, this_cpu; 229 230 old_cpu = PANIC_CPU_INVALID; 231 this_cpu = raw_smp_processor_id(); 232 233 /* atomic_try_cmpxchg updates old_cpu on failure */ 234 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) 235 panic("%s", msg); 236 else if (old_cpu != this_cpu) 237 nmi_panic_self_stop(regs); 238 } 239 EXPORT_SYMBOL(nmi_panic); 240 241 static void panic_print_sys_info(bool console_flush) 242 { 243 if (console_flush) { 244 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) 245 console_flush_on_panic(CONSOLE_REPLAY_ALL); 246 return; 247 } 248 249 if (panic_print & PANIC_PRINT_TASK_INFO) 250 show_state(); 251 252 if (panic_print & PANIC_PRINT_MEM_INFO) 253 show_mem(); 254 255 if (panic_print & PANIC_PRINT_TIMER_INFO) 256 sysrq_timer_list_show(); 257 258 if (panic_print & PANIC_PRINT_LOCK_INFO) 259 debug_show_all_locks(); 260 261 if (panic_print & PANIC_PRINT_FTRACE_INFO) 262 ftrace_dump(DUMP_ALL); 263 264 if (panic_print & PANIC_PRINT_BLOCKED_TASKS) 265 show_state_filter(TASK_UNINTERRUPTIBLE); 266 } 267 268 void check_panic_on_warn(const char *origin) 269 { 270 unsigned int limit; 271 272 if (panic_on_warn) 273 panic("%s: panic_on_warn set ...\n", origin); 274 275 limit = READ_ONCE(warn_limit); 276 if (atomic_inc_return(&warn_count) >= limit && limit) 277 panic("%s: system warned too often (kernel.warn_limit is %d)", 278 origin, limit); 279 } 280 281 /* 282 * Helper that triggers the NMI backtrace (if set in panic_print) 283 * and then performs the secondary CPUs shutdown - we cannot have 284 * the NMI backtrace after the CPUs are off! 285 */ 286 static void panic_other_cpus_shutdown(bool crash_kexec) 287 { 288 if (panic_print & PANIC_PRINT_ALL_CPU_BT) { 289 /* Temporary allow non-panic CPUs to write their backtraces. */ 290 panic_triggering_all_cpu_backtrace = true; 291 trigger_all_cpu_backtrace(); 292 panic_triggering_all_cpu_backtrace = false; 293 } 294 295 /* 296 * Note that smp_send_stop() is the usual SMP shutdown function, 297 * which unfortunately may not be hardened to work in a panic 298 * situation. If we want to do crash dump after notifier calls 299 * and kmsg_dump, we will need architecture dependent extra 300 * bits in addition to stopping other CPUs, hence we rely on 301 * crash_smp_send_stop() for that. 302 */ 303 if (!crash_kexec) 304 smp_send_stop(); 305 else 306 crash_smp_send_stop(); 307 } 308 309 /** 310 * vpanic - halt the system 311 * @fmt: The text string to print 312 * @args: Arguments for the format string 313 * 314 * Display a message, then perform cleanups. This function never returns. 315 */ 316 void vpanic(const char *fmt, va_list args) 317 { 318 static char buf[1024]; 319 long i, i_next = 0, len; 320 int state = 0; 321 int old_cpu, this_cpu; 322 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; 323 324 if (panic_on_warn) { 325 /* 326 * This thread may hit another WARN() in the panic path. 327 * Resetting this prevents additional WARN() from panicking the 328 * system on this thread. Other threads are blocked by the 329 * panic_mutex in panic(). 330 */ 331 panic_on_warn = 0; 332 } 333 334 /* 335 * Disable local interrupts. This will prevent panic_smp_self_stop 336 * from deadlocking the first cpu that invokes the panic, since 337 * there is nothing to prevent an interrupt handler (that runs 338 * after setting panic_cpu) from invoking panic() again. 339 */ 340 local_irq_disable(); 341 preempt_disable_notrace(); 342 343 /* 344 * It's possible to come here directly from a panic-assertion and 345 * not have preempt disabled. Some functions called from here want 346 * preempt to be disabled. No point enabling it later though... 347 * 348 * Only one CPU is allowed to execute the panic code from here. For 349 * multiple parallel invocations of panic, all other CPUs either 350 * stop themself or will wait until they are stopped by the 1st CPU 351 * with smp_send_stop(). 352 * 353 * cmpxchg success means this is the 1st CPU which comes here, 354 * so go ahead. 355 * `old_cpu == this_cpu' means we came from nmi_panic() which sets 356 * panic_cpu to this CPU. In this case, this is also the 1st CPU. 357 */ 358 old_cpu = PANIC_CPU_INVALID; 359 this_cpu = raw_smp_processor_id(); 360 361 /* atomic_try_cmpxchg updates old_cpu on failure */ 362 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { 363 /* go ahead */ 364 } else if (old_cpu != this_cpu) 365 panic_smp_self_stop(); 366 367 console_verbose(); 368 bust_spinlocks(1); 369 len = vscnprintf(buf, sizeof(buf), fmt, args); 370 371 if (len && buf[len - 1] == '\n') 372 buf[len - 1] = '\0'; 373 374 pr_emerg("Kernel panic - not syncing: %s\n", buf); 375 #ifdef CONFIG_DEBUG_BUGVERBOSE 376 /* 377 * Avoid nested stack-dumping if a panic occurs during oops processing 378 */ 379 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 380 dump_stack(); 381 #endif 382 383 /* 384 * If kgdb is enabled, give it a chance to run before we stop all 385 * the other CPUs or else we won't be able to debug processes left 386 * running on them. 387 */ 388 kgdb_panic(buf); 389 390 /* 391 * If we have crashed and we have a crash kernel loaded let it handle 392 * everything else. 393 * If we want to run this after calling panic_notifiers, pass 394 * the "crash_kexec_post_notifiers" option to the kernel. 395 * 396 * Bypass the panic_cpu check and call __crash_kexec directly. 397 */ 398 if (!_crash_kexec_post_notifiers) 399 __crash_kexec(NULL); 400 401 panic_other_cpus_shutdown(_crash_kexec_post_notifiers); 402 403 printk_legacy_allow_panic_sync(); 404 405 /* 406 * Run any panic handlers, including those that might need to 407 * add information to the kmsg dump output. 408 */ 409 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 410 411 panic_print_sys_info(false); 412 413 kmsg_dump_desc(KMSG_DUMP_PANIC, buf); 414 415 /* 416 * If you doubt kdump always works fine in any situation, 417 * "crash_kexec_post_notifiers" offers you a chance to run 418 * panic_notifiers and dumping kmsg before kdump. 419 * Note: since some panic_notifiers can make crashed kernel 420 * more unstable, it can increase risks of the kdump failure too. 421 * 422 * Bypass the panic_cpu check and call __crash_kexec directly. 423 */ 424 if (_crash_kexec_post_notifiers) 425 __crash_kexec(NULL); 426 427 console_unblank(); 428 429 /* 430 * We may have ended up stopping the CPU holding the lock (in 431 * smp_send_stop()) while still having some valuable data in the console 432 * buffer. Try to acquire the lock then release it regardless of the 433 * result. The release will also print the buffers out. Locks debug 434 * should be disabled to avoid reporting bad unlock balance when 435 * panic() is not being callled from OOPS. 436 */ 437 debug_locks_off(); 438 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 439 440 panic_print_sys_info(true); 441 442 if (!panic_blink) 443 panic_blink = no_blink; 444 445 if (panic_timeout > 0) { 446 /* 447 * Delay timeout seconds before rebooting the machine. 448 * We can't use the "normal" timers since we just panicked. 449 */ 450 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 451 452 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 453 touch_nmi_watchdog(); 454 if (i >= i_next) { 455 i += panic_blink(state ^= 1); 456 i_next = i + 3600 / PANIC_BLINK_SPD; 457 } 458 mdelay(PANIC_TIMER_STEP); 459 } 460 } 461 if (panic_timeout != 0) { 462 /* 463 * This will not be a clean reboot, with everything 464 * shutting down. But if there is a chance of 465 * rebooting the system it will be rebooted. 466 */ 467 if (panic_reboot_mode != REBOOT_UNDEFINED) 468 reboot_mode = panic_reboot_mode; 469 emergency_restart(); 470 } 471 #ifdef __sparc__ 472 { 473 extern int stop_a_enabled; 474 /* Make sure the user can actually press Stop-A (L1-A) */ 475 stop_a_enabled = 1; 476 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 477 "twice on console to return to the boot prom\n"); 478 } 479 #endif 480 #if defined(CONFIG_S390) 481 disabled_wait(); 482 #endif 483 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 484 485 /* Do not scroll important messages printed above */ 486 suppress_printk = 1; 487 488 /* 489 * The final messages may not have been printed if in a context that 490 * defers printing (such as NMI) and irq_work is not available. 491 * Explicitly flush the kernel log buffer one last time. 492 */ 493 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 494 nbcon_atomic_flush_unsafe(); 495 496 local_irq_enable(); 497 for (i = 0; ; i += PANIC_TIMER_STEP) { 498 touch_softlockup_watchdog(); 499 if (i >= i_next) { 500 i += panic_blink(state ^= 1); 501 i_next = i + 3600 / PANIC_BLINK_SPD; 502 } 503 mdelay(PANIC_TIMER_STEP); 504 } 505 } 506 EXPORT_SYMBOL(vpanic); 507 508 /* Identical to vpanic(), except it takes variadic arguments instead of va_list */ 509 void panic(const char *fmt, ...) 510 { 511 va_list args; 512 513 va_start(args, fmt); 514 vpanic(fmt, args); 515 va_end(args); 516 } 517 EXPORT_SYMBOL(panic); 518 519 #define TAINT_FLAG(taint, _c_true, _c_false, _module) \ 520 [ TAINT_##taint ] = { \ 521 .c_true = _c_true, .c_false = _c_false, \ 522 .module = _module, \ 523 .desc = #taint, \ 524 } 525 526 /* 527 * TAINT_FORCED_RMMOD could be a per-module flag but the module 528 * is being removed anyway. 529 */ 530 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { 531 TAINT_FLAG(PROPRIETARY_MODULE, 'P', 'G', true), 532 TAINT_FLAG(FORCED_MODULE, 'F', ' ', true), 533 TAINT_FLAG(CPU_OUT_OF_SPEC, 'S', ' ', false), 534 TAINT_FLAG(FORCED_RMMOD, 'R', ' ', false), 535 TAINT_FLAG(MACHINE_CHECK, 'M', ' ', false), 536 TAINT_FLAG(BAD_PAGE, 'B', ' ', false), 537 TAINT_FLAG(USER, 'U', ' ', false), 538 TAINT_FLAG(DIE, 'D', ' ', false), 539 TAINT_FLAG(OVERRIDDEN_ACPI_TABLE, 'A', ' ', false), 540 TAINT_FLAG(WARN, 'W', ' ', false), 541 TAINT_FLAG(CRAP, 'C', ' ', true), 542 TAINT_FLAG(FIRMWARE_WORKAROUND, 'I', ' ', false), 543 TAINT_FLAG(OOT_MODULE, 'O', ' ', true), 544 TAINT_FLAG(UNSIGNED_MODULE, 'E', ' ', true), 545 TAINT_FLAG(SOFTLOCKUP, 'L', ' ', false), 546 TAINT_FLAG(LIVEPATCH, 'K', ' ', true), 547 TAINT_FLAG(AUX, 'X', ' ', true), 548 TAINT_FLAG(RANDSTRUCT, 'T', ' ', true), 549 TAINT_FLAG(TEST, 'N', ' ', true), 550 TAINT_FLAG(FWCTL, 'J', ' ', true), 551 }; 552 553 #undef TAINT_FLAG 554 555 static void print_tainted_seq(struct seq_buf *s, bool verbose) 556 { 557 const char *sep = ""; 558 int i; 559 560 if (!tainted_mask) { 561 seq_buf_puts(s, "Not tainted"); 562 return; 563 } 564 565 seq_buf_printf(s, "Tainted: "); 566 for (i = 0; i < TAINT_FLAGS_COUNT; i++) { 567 const struct taint_flag *t = &taint_flags[i]; 568 bool is_set = test_bit(i, &tainted_mask); 569 char c = is_set ? t->c_true : t->c_false; 570 571 if (verbose) { 572 if (is_set) { 573 seq_buf_printf(s, "%s[%c]=%s", sep, c, t->desc); 574 sep = ", "; 575 } 576 } else { 577 seq_buf_putc(s, c); 578 } 579 } 580 } 581 582 static const char *_print_tainted(bool verbose) 583 { 584 /* FIXME: what should the size be? */ 585 static char buf[sizeof(taint_flags)]; 586 struct seq_buf s; 587 588 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); 589 590 seq_buf_init(&s, buf, sizeof(buf)); 591 592 print_tainted_seq(&s, verbose); 593 594 return seq_buf_str(&s); 595 } 596 597 /** 598 * print_tainted - return a string to represent the kernel taint state. 599 * 600 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst 601 * 602 * The string is overwritten by the next call to print_tainted(), 603 * but is always NULL terminated. 604 */ 605 const char *print_tainted(void) 606 { 607 return _print_tainted(false); 608 } 609 610 /** 611 * print_tainted_verbose - A more verbose version of print_tainted() 612 */ 613 const char *print_tainted_verbose(void) 614 { 615 return _print_tainted(true); 616 } 617 618 int test_taint(unsigned flag) 619 { 620 return test_bit(flag, &tainted_mask); 621 } 622 EXPORT_SYMBOL(test_taint); 623 624 unsigned long get_taint(void) 625 { 626 return tainted_mask; 627 } 628 629 /** 630 * add_taint: add a taint flag if not already set. 631 * @flag: one of the TAINT_* constants. 632 * @lockdep_ok: whether lock debugging is still OK. 633 * 634 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 635 * some notewortht-but-not-corrupting cases, it can be set to true. 636 */ 637 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 638 { 639 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 640 pr_warn("Disabling lock debugging due to kernel taint\n"); 641 642 set_bit(flag, &tainted_mask); 643 644 if (tainted_mask & panic_on_taint) { 645 panic_on_taint = 0; 646 panic("panic_on_taint set ..."); 647 } 648 } 649 EXPORT_SYMBOL(add_taint); 650 651 static void spin_msec(int msecs) 652 { 653 int i; 654 655 for (i = 0; i < msecs; i++) { 656 touch_nmi_watchdog(); 657 mdelay(1); 658 } 659 } 660 661 /* 662 * It just happens that oops_enter() and oops_exit() are identically 663 * implemented... 664 */ 665 static void do_oops_enter_exit(void) 666 { 667 unsigned long flags; 668 static int spin_counter; 669 670 if (!pause_on_oops) 671 return; 672 673 spin_lock_irqsave(&pause_on_oops_lock, flags); 674 if (pause_on_oops_flag == 0) { 675 /* This CPU may now print the oops message */ 676 pause_on_oops_flag = 1; 677 } else { 678 /* We need to stall this CPU */ 679 if (!spin_counter) { 680 /* This CPU gets to do the counting */ 681 spin_counter = pause_on_oops; 682 do { 683 spin_unlock(&pause_on_oops_lock); 684 spin_msec(MSEC_PER_SEC); 685 spin_lock(&pause_on_oops_lock); 686 } while (--spin_counter); 687 pause_on_oops_flag = 0; 688 } else { 689 /* This CPU waits for a different one */ 690 while (spin_counter) { 691 spin_unlock(&pause_on_oops_lock); 692 spin_msec(1); 693 spin_lock(&pause_on_oops_lock); 694 } 695 } 696 } 697 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 698 } 699 700 /* 701 * Return true if the calling CPU is allowed to print oops-related info. 702 * This is a bit racy.. 703 */ 704 bool oops_may_print(void) 705 { 706 return pause_on_oops_flag == 0; 707 } 708 709 /* 710 * Called when the architecture enters its oops handler, before it prints 711 * anything. If this is the first CPU to oops, and it's oopsing the first 712 * time then let it proceed. 713 * 714 * This is all enabled by the pause_on_oops kernel boot option. We do all 715 * this to ensure that oopses don't scroll off the screen. It has the 716 * side-effect of preventing later-oopsing CPUs from mucking up the display, 717 * too. 718 * 719 * It turns out that the CPU which is allowed to print ends up pausing for 720 * the right duration, whereas all the other CPUs pause for twice as long: 721 * once in oops_enter(), once in oops_exit(). 722 */ 723 void oops_enter(void) 724 { 725 nbcon_cpu_emergency_enter(); 726 tracing_off(); 727 /* can't trust the integrity of the kernel anymore: */ 728 debug_locks_off(); 729 do_oops_enter_exit(); 730 731 if (sysctl_oops_all_cpu_backtrace) 732 trigger_all_cpu_backtrace(); 733 } 734 735 static void print_oops_end_marker(void) 736 { 737 pr_warn("---[ end trace %016llx ]---\n", 0ULL); 738 } 739 740 /* 741 * Called when the architecture exits its oops handler, after printing 742 * everything. 743 */ 744 void oops_exit(void) 745 { 746 do_oops_enter_exit(); 747 print_oops_end_marker(); 748 nbcon_cpu_emergency_exit(); 749 kmsg_dump(KMSG_DUMP_OOPS); 750 } 751 752 struct warn_args { 753 const char *fmt; 754 va_list args; 755 }; 756 757 void __warn(const char *file, int line, void *caller, unsigned taint, 758 struct pt_regs *regs, struct warn_args *args) 759 { 760 nbcon_cpu_emergency_enter(); 761 762 disable_trace_on_warning(); 763 764 if (file) 765 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", 766 raw_smp_processor_id(), current->pid, file, line, 767 caller); 768 else 769 pr_warn("WARNING: CPU: %d PID: %d at %pS\n", 770 raw_smp_processor_id(), current->pid, caller); 771 772 #pragma GCC diagnostic push 773 #ifndef __clang__ 774 #pragma GCC diagnostic ignored "-Wsuggest-attribute=format" 775 #endif 776 if (args) 777 vprintk(args->fmt, args->args); 778 #pragma GCC diagnostic pop 779 780 print_modules(); 781 782 if (regs) 783 show_regs(regs); 784 785 check_panic_on_warn("kernel"); 786 787 if (!regs) 788 dump_stack(); 789 790 print_irqtrace_events(current); 791 792 print_oops_end_marker(); 793 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); 794 795 /* Just a warning, don't kill lockdep. */ 796 add_taint(taint, LOCKDEP_STILL_OK); 797 798 nbcon_cpu_emergency_exit(); 799 } 800 801 #ifdef CONFIG_BUG 802 #ifndef __WARN_FLAGS 803 void warn_slowpath_fmt(const char *file, int line, unsigned taint, 804 const char *fmt, ...) 805 { 806 bool rcu = warn_rcu_enter(); 807 struct warn_args args; 808 809 pr_warn(CUT_HERE); 810 811 if (!fmt) { 812 __warn(file, line, __builtin_return_address(0), taint, 813 NULL, NULL); 814 warn_rcu_exit(rcu); 815 return; 816 } 817 818 args.fmt = fmt; 819 va_start(args.args, fmt); 820 __warn(file, line, __builtin_return_address(0), taint, NULL, &args); 821 va_end(args.args); 822 warn_rcu_exit(rcu); 823 } 824 EXPORT_SYMBOL(warn_slowpath_fmt); 825 #else 826 void __warn_printk(const char *fmt, ...) 827 { 828 bool rcu = warn_rcu_enter(); 829 va_list args; 830 831 pr_warn(CUT_HERE); 832 833 va_start(args, fmt); 834 vprintk(fmt, args); 835 va_end(args); 836 warn_rcu_exit(rcu); 837 } 838 EXPORT_SYMBOL(__warn_printk); 839 #endif 840 841 /* Support resetting WARN*_ONCE state */ 842 843 static int clear_warn_once_set(void *data, u64 val) 844 { 845 generic_bug_clear_once(); 846 memset(__start_once, 0, __end_once - __start_once); 847 return 0; 848 } 849 850 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, 851 "%lld\n"); 852 853 static __init int register_warn_debugfs(void) 854 { 855 /* Don't care about failure */ 856 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL, 857 &clear_warn_once_fops); 858 return 0; 859 } 860 861 device_initcall(register_warn_debugfs); 862 #endif 863 864 #ifdef CONFIG_STACKPROTECTOR 865 866 /* 867 * Called when gcc's -fstack-protector feature is used, and 868 * gcc detects corruption of the on-stack canary value 869 */ 870 __visible noinstr void __stack_chk_fail(void) 871 { 872 unsigned long flags; 873 874 instrumentation_begin(); 875 flags = user_access_save(); 876 877 panic("stack-protector: Kernel stack is corrupted in: %pB", 878 __builtin_return_address(0)); 879 880 user_access_restore(flags); 881 instrumentation_end(); 882 } 883 EXPORT_SYMBOL(__stack_chk_fail); 884 885 #endif 886 887 core_param(panic, panic_timeout, int, 0644); 888 core_param(panic_print, panic_print, ulong, 0644); 889 core_param(pause_on_oops, pause_on_oops, int, 0644); 890 core_param(panic_on_warn, panic_on_warn, int, 0644); 891 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); 892 893 static int __init oops_setup(char *s) 894 { 895 if (!s) 896 return -EINVAL; 897 if (!strcmp(s, "panic")) 898 panic_on_oops = 1; 899 return 0; 900 } 901 early_param("oops", oops_setup); 902 903 static int __init panic_on_taint_setup(char *s) 904 { 905 char *taint_str; 906 907 if (!s) 908 return -EINVAL; 909 910 taint_str = strsep(&s, ","); 911 if (kstrtoul(taint_str, 16, &panic_on_taint)) 912 return -EINVAL; 913 914 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ 915 panic_on_taint &= TAINT_FLAGS_MAX; 916 917 if (!panic_on_taint) 918 return -EINVAL; 919 920 if (s && !strcmp(s, "nousertaint")) 921 panic_on_taint_nousertaint = true; 922 923 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", 924 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); 925 926 return 0; 927 } 928 early_param("panic_on_taint", panic_on_taint_setup); 929