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 88 /* 89 * Taint values can only be increased 90 * This means we can safely use a temporary. 91 */ 92 static int proc_taint(const struct ctl_table *table, int write, 93 void *buffer, size_t *lenp, loff_t *ppos) 94 { 95 struct ctl_table t; 96 unsigned long tmptaint = get_taint(); 97 int err; 98 99 if (write && !capable(CAP_SYS_ADMIN)) 100 return -EPERM; 101 102 t = *table; 103 t.data = &tmptaint; 104 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); 105 if (err < 0) 106 return err; 107 108 if (write) { 109 int i; 110 111 /* 112 * If we are relying on panic_on_taint not producing 113 * false positives due to userspace input, bail out 114 * before setting the requested taint flags. 115 */ 116 if (panic_on_taint_nousertaint && (tmptaint & panic_on_taint)) 117 return -EINVAL; 118 119 /* 120 * Poor man's atomic or. Not worth adding a primitive 121 * to everyone's atomic.h for this 122 */ 123 for (i = 0; i < TAINT_FLAGS_COUNT; i++) 124 if ((1UL << i) & tmptaint) 125 add_taint(i, LOCKDEP_STILL_OK); 126 } 127 128 return err; 129 } 130 131 static const struct ctl_table kern_panic_table[] = { 132 #ifdef CONFIG_SMP 133 { 134 .procname = "oops_all_cpu_backtrace", 135 .data = &sysctl_oops_all_cpu_backtrace, 136 .maxlen = sizeof(int), 137 .mode = 0644, 138 .proc_handler = proc_dointvec_minmax, 139 .extra1 = SYSCTL_ZERO, 140 .extra2 = SYSCTL_ONE, 141 }, 142 #endif 143 { 144 .procname = "tainted", 145 .maxlen = sizeof(long), 146 .mode = 0644, 147 .proc_handler = proc_taint, 148 }, 149 { 150 .procname = "panic", 151 .data = &panic_timeout, 152 .maxlen = sizeof(int), 153 .mode = 0644, 154 .proc_handler = proc_dointvec, 155 }, 156 { 157 .procname = "panic_on_oops", 158 .data = &panic_on_oops, 159 .maxlen = sizeof(int), 160 .mode = 0644, 161 .proc_handler = proc_dointvec, 162 }, 163 { 164 .procname = "panic_print", 165 .data = &panic_print, 166 .maxlen = sizeof(unsigned long), 167 .mode = 0644, 168 .proc_handler = proc_doulongvec_minmax, 169 }, 170 { 171 .procname = "panic_on_warn", 172 .data = &panic_on_warn, 173 .maxlen = sizeof(int), 174 .mode = 0644, 175 .proc_handler = proc_dointvec_minmax, 176 .extra1 = SYSCTL_ZERO, 177 .extra2 = SYSCTL_ONE, 178 }, 179 { 180 .procname = "warn_limit", 181 .data = &warn_limit, 182 .maxlen = sizeof(warn_limit), 183 .mode = 0644, 184 .proc_handler = proc_douintvec, 185 }, 186 #if (defined(CONFIG_X86_32) || defined(CONFIG_PARISC)) && \ 187 defined(CONFIG_DEBUG_STACKOVERFLOW) 188 { 189 .procname = "panic_on_stackoverflow", 190 .data = &sysctl_panic_on_stackoverflow, 191 .maxlen = sizeof(int), 192 .mode = 0644, 193 .proc_handler = proc_dointvec, 194 }, 195 #endif 196 }; 197 198 static __init int kernel_panic_sysctls_init(void) 199 { 200 register_sysctl_init("kernel", kern_panic_table); 201 return 0; 202 } 203 late_initcall(kernel_panic_sysctls_init); 204 #endif 205 206 static atomic_t warn_count = ATOMIC_INIT(0); 207 208 #ifdef CONFIG_SYSFS 209 static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, 210 char *page) 211 { 212 return sysfs_emit(page, "%d\n", atomic_read(&warn_count)); 213 } 214 215 static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); 216 217 static __init int kernel_panic_sysfs_init(void) 218 { 219 sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL); 220 return 0; 221 } 222 late_initcall(kernel_panic_sysfs_init); 223 #endif 224 225 static long no_blink(int state) 226 { 227 return 0; 228 } 229 230 /* Returns how long it waited in ms */ 231 long (*panic_blink)(int state); 232 EXPORT_SYMBOL(panic_blink); 233 234 /* 235 * Stop ourself in panic -- architecture code may override this 236 */ 237 void __weak __noreturn panic_smp_self_stop(void) 238 { 239 while (1) 240 cpu_relax(); 241 } 242 243 /* 244 * Stop ourselves in NMI context if another CPU has already panicked. Arch code 245 * may override this to prepare for crash dumping, e.g. save regs info. 246 */ 247 void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs) 248 { 249 panic_smp_self_stop(); 250 } 251 252 /* 253 * Stop other CPUs in panic. Architecture dependent code may override this 254 * with more suitable version. For example, if the architecture supports 255 * crash dump, it should save registers of each stopped CPU and disable 256 * per-CPU features such as virtualization extensions. 257 */ 258 void __weak crash_smp_send_stop(void) 259 { 260 static int cpus_stopped; 261 262 /* 263 * This function can be called twice in panic path, but obviously 264 * we execute this only once. 265 */ 266 if (cpus_stopped) 267 return; 268 269 /* 270 * Note smp_send_stop is the usual smp shutdown function, which 271 * unfortunately means it may not be hardened to work in a panic 272 * situation. 273 */ 274 smp_send_stop(); 275 cpus_stopped = 1; 276 } 277 278 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); 279 280 /* 281 * A variant of panic() called from NMI context. We return if we've already 282 * panicked on this CPU. If another CPU already panicked, loop in 283 * nmi_panic_self_stop() which can provide architecture dependent code such 284 * as saving register state for crash dump. 285 */ 286 void nmi_panic(struct pt_regs *regs, const char *msg) 287 { 288 int old_cpu, this_cpu; 289 290 old_cpu = PANIC_CPU_INVALID; 291 this_cpu = raw_smp_processor_id(); 292 293 /* atomic_try_cmpxchg updates old_cpu on failure */ 294 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) 295 panic("%s", msg); 296 else if (old_cpu != this_cpu) 297 nmi_panic_self_stop(regs); 298 } 299 EXPORT_SYMBOL(nmi_panic); 300 301 static void panic_print_sys_info(bool console_flush) 302 { 303 if (console_flush) { 304 if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) 305 console_flush_on_panic(CONSOLE_REPLAY_ALL); 306 return; 307 } 308 309 if (panic_print & PANIC_PRINT_TASK_INFO) 310 show_state(); 311 312 if (panic_print & PANIC_PRINT_MEM_INFO) 313 show_mem(); 314 315 if (panic_print & PANIC_PRINT_TIMER_INFO) 316 sysrq_timer_list_show(); 317 318 if (panic_print & PANIC_PRINT_LOCK_INFO) 319 debug_show_all_locks(); 320 321 if (panic_print & PANIC_PRINT_FTRACE_INFO) 322 ftrace_dump(DUMP_ALL); 323 324 if (panic_print & PANIC_PRINT_BLOCKED_TASKS) 325 show_state_filter(TASK_UNINTERRUPTIBLE); 326 } 327 328 void check_panic_on_warn(const char *origin) 329 { 330 unsigned int limit; 331 332 if (panic_on_warn) 333 panic("%s: panic_on_warn set ...\n", origin); 334 335 limit = READ_ONCE(warn_limit); 336 if (atomic_inc_return(&warn_count) >= limit && limit) 337 panic("%s: system warned too often (kernel.warn_limit is %d)", 338 origin, limit); 339 } 340 341 /* 342 * Helper that triggers the NMI backtrace (if set in panic_print) 343 * and then performs the secondary CPUs shutdown - we cannot have 344 * the NMI backtrace after the CPUs are off! 345 */ 346 static void panic_other_cpus_shutdown(bool crash_kexec) 347 { 348 if (panic_print & PANIC_PRINT_ALL_CPU_BT) { 349 /* Temporary allow non-panic CPUs to write their backtraces. */ 350 panic_triggering_all_cpu_backtrace = true; 351 trigger_all_cpu_backtrace(); 352 panic_triggering_all_cpu_backtrace = false; 353 } 354 355 /* 356 * Note that smp_send_stop() is the usual SMP shutdown function, 357 * which unfortunately may not be hardened to work in a panic 358 * situation. If we want to do crash dump after notifier calls 359 * and kmsg_dump, we will need architecture dependent extra 360 * bits in addition to stopping other CPUs, hence we rely on 361 * crash_smp_send_stop() for that. 362 */ 363 if (!crash_kexec) 364 smp_send_stop(); 365 else 366 crash_smp_send_stop(); 367 } 368 369 /** 370 * vpanic - halt the system 371 * @fmt: The text string to print 372 * @args: Arguments for the format string 373 * 374 * Display a message, then perform cleanups. This function never returns. 375 */ 376 void vpanic(const char *fmt, va_list args) 377 { 378 static char buf[1024]; 379 long i, i_next = 0, len; 380 int state = 0; 381 int old_cpu, this_cpu; 382 bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; 383 384 if (panic_on_warn) { 385 /* 386 * This thread may hit another WARN() in the panic path. 387 * Resetting this prevents additional WARN() from panicking the 388 * system on this thread. Other threads are blocked by the 389 * panic_mutex in panic(). 390 */ 391 panic_on_warn = 0; 392 } 393 394 /* 395 * Disable local interrupts. This will prevent panic_smp_self_stop 396 * from deadlocking the first cpu that invokes the panic, since 397 * there is nothing to prevent an interrupt handler (that runs 398 * after setting panic_cpu) from invoking panic() again. 399 */ 400 local_irq_disable(); 401 preempt_disable_notrace(); 402 403 /* 404 * It's possible to come here directly from a panic-assertion and 405 * not have preempt disabled. Some functions called from here want 406 * preempt to be disabled. No point enabling it later though... 407 * 408 * Only one CPU is allowed to execute the panic code from here. For 409 * multiple parallel invocations of panic, all other CPUs either 410 * stop themself or will wait until they are stopped by the 1st CPU 411 * with smp_send_stop(). 412 * 413 * cmpxchg success means this is the 1st CPU which comes here, 414 * so go ahead. 415 * `old_cpu == this_cpu' means we came from nmi_panic() which sets 416 * panic_cpu to this CPU. In this case, this is also the 1st CPU. 417 */ 418 old_cpu = PANIC_CPU_INVALID; 419 this_cpu = raw_smp_processor_id(); 420 421 /* atomic_try_cmpxchg updates old_cpu on failure */ 422 if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { 423 /* go ahead */ 424 } else if (old_cpu != this_cpu) 425 panic_smp_self_stop(); 426 427 console_verbose(); 428 bust_spinlocks(1); 429 len = vscnprintf(buf, sizeof(buf), fmt, args); 430 431 if (len && buf[len - 1] == '\n') 432 buf[len - 1] = '\0'; 433 434 pr_emerg("Kernel panic - not syncing: %s\n", buf); 435 #ifdef CONFIG_DEBUG_BUGVERBOSE 436 /* 437 * Avoid nested stack-dumping if a panic occurs during oops processing 438 */ 439 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 440 dump_stack(); 441 #endif 442 443 /* 444 * If kgdb is enabled, give it a chance to run before we stop all 445 * the other CPUs or else we won't be able to debug processes left 446 * running on them. 447 */ 448 kgdb_panic(buf); 449 450 /* 451 * If we have crashed and we have a crash kernel loaded let it handle 452 * everything else. 453 * If we want to run this after calling panic_notifiers, pass 454 * the "crash_kexec_post_notifiers" option to the kernel. 455 * 456 * Bypass the panic_cpu check and call __crash_kexec directly. 457 */ 458 if (!_crash_kexec_post_notifiers) 459 __crash_kexec(NULL); 460 461 panic_other_cpus_shutdown(_crash_kexec_post_notifiers); 462 463 printk_legacy_allow_panic_sync(); 464 465 /* 466 * Run any panic handlers, including those that might need to 467 * add information to the kmsg dump output. 468 */ 469 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 470 471 panic_print_sys_info(false); 472 473 kmsg_dump_desc(KMSG_DUMP_PANIC, buf); 474 475 /* 476 * If you doubt kdump always works fine in any situation, 477 * "crash_kexec_post_notifiers" offers you a chance to run 478 * panic_notifiers and dumping kmsg before kdump. 479 * Note: since some panic_notifiers can make crashed kernel 480 * more unstable, it can increase risks of the kdump failure too. 481 * 482 * Bypass the panic_cpu check and call __crash_kexec directly. 483 */ 484 if (_crash_kexec_post_notifiers) 485 __crash_kexec(NULL); 486 487 console_unblank(); 488 489 /* 490 * We may have ended up stopping the CPU holding the lock (in 491 * smp_send_stop()) while still having some valuable data in the console 492 * buffer. Try to acquire the lock then release it regardless of the 493 * result. The release will also print the buffers out. Locks debug 494 * should be disabled to avoid reporting bad unlock balance when 495 * panic() is not being callled from OOPS. 496 */ 497 debug_locks_off(); 498 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 499 500 panic_print_sys_info(true); 501 502 if (!panic_blink) 503 panic_blink = no_blink; 504 505 if (panic_timeout > 0) { 506 /* 507 * Delay timeout seconds before rebooting the machine. 508 * We can't use the "normal" timers since we just panicked. 509 */ 510 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 511 512 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 513 touch_nmi_watchdog(); 514 if (i >= i_next) { 515 i += panic_blink(state ^= 1); 516 i_next = i + 3600 / PANIC_BLINK_SPD; 517 } 518 mdelay(PANIC_TIMER_STEP); 519 } 520 } 521 if (panic_timeout != 0) { 522 /* 523 * This will not be a clean reboot, with everything 524 * shutting down. But if there is a chance of 525 * rebooting the system it will be rebooted. 526 */ 527 if (panic_reboot_mode != REBOOT_UNDEFINED) 528 reboot_mode = panic_reboot_mode; 529 emergency_restart(); 530 } 531 #ifdef __sparc__ 532 { 533 extern int stop_a_enabled; 534 /* Make sure the user can actually press Stop-A (L1-A) */ 535 stop_a_enabled = 1; 536 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 537 "twice on console to return to the boot prom\n"); 538 } 539 #endif 540 #if defined(CONFIG_S390) 541 disabled_wait(); 542 #endif 543 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 544 545 /* Do not scroll important messages printed above */ 546 suppress_printk = 1; 547 548 /* 549 * The final messages may not have been printed if in a context that 550 * defers printing (such as NMI) and irq_work is not available. 551 * Explicitly flush the kernel log buffer one last time. 552 */ 553 console_flush_on_panic(CONSOLE_FLUSH_PENDING); 554 nbcon_atomic_flush_unsafe(); 555 556 local_irq_enable(); 557 for (i = 0; ; i += PANIC_TIMER_STEP) { 558 touch_softlockup_watchdog(); 559 if (i >= i_next) { 560 i += panic_blink(state ^= 1); 561 i_next = i + 3600 / PANIC_BLINK_SPD; 562 } 563 mdelay(PANIC_TIMER_STEP); 564 } 565 } 566 EXPORT_SYMBOL(vpanic); 567 568 /* Identical to vpanic(), except it takes variadic arguments instead of va_list */ 569 void panic(const char *fmt, ...) 570 { 571 va_list args; 572 573 va_start(args, fmt); 574 vpanic(fmt, args); 575 va_end(args); 576 } 577 EXPORT_SYMBOL(panic); 578 579 #define TAINT_FLAG(taint, _c_true, _c_false, _module) \ 580 [ TAINT_##taint ] = { \ 581 .c_true = _c_true, .c_false = _c_false, \ 582 .module = _module, \ 583 .desc = #taint, \ 584 } 585 586 /* 587 * TAINT_FORCED_RMMOD could be a per-module flag but the module 588 * is being removed anyway. 589 */ 590 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = { 591 TAINT_FLAG(PROPRIETARY_MODULE, 'P', 'G', true), 592 TAINT_FLAG(FORCED_MODULE, 'F', ' ', true), 593 TAINT_FLAG(CPU_OUT_OF_SPEC, 'S', ' ', false), 594 TAINT_FLAG(FORCED_RMMOD, 'R', ' ', false), 595 TAINT_FLAG(MACHINE_CHECK, 'M', ' ', false), 596 TAINT_FLAG(BAD_PAGE, 'B', ' ', false), 597 TAINT_FLAG(USER, 'U', ' ', false), 598 TAINT_FLAG(DIE, 'D', ' ', false), 599 TAINT_FLAG(OVERRIDDEN_ACPI_TABLE, 'A', ' ', false), 600 TAINT_FLAG(WARN, 'W', ' ', false), 601 TAINT_FLAG(CRAP, 'C', ' ', true), 602 TAINT_FLAG(FIRMWARE_WORKAROUND, 'I', ' ', false), 603 TAINT_FLAG(OOT_MODULE, 'O', ' ', true), 604 TAINT_FLAG(UNSIGNED_MODULE, 'E', ' ', true), 605 TAINT_FLAG(SOFTLOCKUP, 'L', ' ', false), 606 TAINT_FLAG(LIVEPATCH, 'K', ' ', true), 607 TAINT_FLAG(AUX, 'X', ' ', true), 608 TAINT_FLAG(RANDSTRUCT, 'T', ' ', true), 609 TAINT_FLAG(TEST, 'N', ' ', true), 610 TAINT_FLAG(FWCTL, 'J', ' ', true), 611 }; 612 613 #undef TAINT_FLAG 614 615 static void print_tainted_seq(struct seq_buf *s, bool verbose) 616 { 617 const char *sep = ""; 618 int i; 619 620 if (!tainted_mask) { 621 seq_buf_puts(s, "Not tainted"); 622 return; 623 } 624 625 seq_buf_printf(s, "Tainted: "); 626 for (i = 0; i < TAINT_FLAGS_COUNT; i++) { 627 const struct taint_flag *t = &taint_flags[i]; 628 bool is_set = test_bit(i, &tainted_mask); 629 char c = is_set ? t->c_true : t->c_false; 630 631 if (verbose) { 632 if (is_set) { 633 seq_buf_printf(s, "%s[%c]=%s", sep, c, t->desc); 634 sep = ", "; 635 } 636 } else { 637 seq_buf_putc(s, c); 638 } 639 } 640 } 641 642 static const char *_print_tainted(bool verbose) 643 { 644 /* FIXME: what should the size be? */ 645 static char buf[sizeof(taint_flags)]; 646 struct seq_buf s; 647 648 BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT); 649 650 seq_buf_init(&s, buf, sizeof(buf)); 651 652 print_tainted_seq(&s, verbose); 653 654 return seq_buf_str(&s); 655 } 656 657 /** 658 * print_tainted - return a string to represent the kernel taint state. 659 * 660 * For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst 661 * 662 * The string is overwritten by the next call to print_tainted(), 663 * but is always NULL terminated. 664 */ 665 const char *print_tainted(void) 666 { 667 return _print_tainted(false); 668 } 669 670 /** 671 * print_tainted_verbose - A more verbose version of print_tainted() 672 */ 673 const char *print_tainted_verbose(void) 674 { 675 return _print_tainted(true); 676 } 677 678 int test_taint(unsigned flag) 679 { 680 return test_bit(flag, &tainted_mask); 681 } 682 EXPORT_SYMBOL(test_taint); 683 684 unsigned long get_taint(void) 685 { 686 return tainted_mask; 687 } 688 689 /** 690 * add_taint: add a taint flag if not already set. 691 * @flag: one of the TAINT_* constants. 692 * @lockdep_ok: whether lock debugging is still OK. 693 * 694 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 695 * some notewortht-but-not-corrupting cases, it can be set to true. 696 */ 697 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 698 { 699 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 700 pr_warn("Disabling lock debugging due to kernel taint\n"); 701 702 set_bit(flag, &tainted_mask); 703 704 if (tainted_mask & panic_on_taint) { 705 panic_on_taint = 0; 706 panic("panic_on_taint set ..."); 707 } 708 } 709 EXPORT_SYMBOL(add_taint); 710 711 static void spin_msec(int msecs) 712 { 713 int i; 714 715 for (i = 0; i < msecs; i++) { 716 touch_nmi_watchdog(); 717 mdelay(1); 718 } 719 } 720 721 /* 722 * It just happens that oops_enter() and oops_exit() are identically 723 * implemented... 724 */ 725 static void do_oops_enter_exit(void) 726 { 727 unsigned long flags; 728 static int spin_counter; 729 730 if (!pause_on_oops) 731 return; 732 733 spin_lock_irqsave(&pause_on_oops_lock, flags); 734 if (pause_on_oops_flag == 0) { 735 /* This CPU may now print the oops message */ 736 pause_on_oops_flag = 1; 737 } else { 738 /* We need to stall this CPU */ 739 if (!spin_counter) { 740 /* This CPU gets to do the counting */ 741 spin_counter = pause_on_oops; 742 do { 743 spin_unlock(&pause_on_oops_lock); 744 spin_msec(MSEC_PER_SEC); 745 spin_lock(&pause_on_oops_lock); 746 } while (--spin_counter); 747 pause_on_oops_flag = 0; 748 } else { 749 /* This CPU waits for a different one */ 750 while (spin_counter) { 751 spin_unlock(&pause_on_oops_lock); 752 spin_msec(1); 753 spin_lock(&pause_on_oops_lock); 754 } 755 } 756 } 757 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 758 } 759 760 /* 761 * Return true if the calling CPU is allowed to print oops-related info. 762 * This is a bit racy.. 763 */ 764 bool oops_may_print(void) 765 { 766 return pause_on_oops_flag == 0; 767 } 768 769 /* 770 * Called when the architecture enters its oops handler, before it prints 771 * anything. If this is the first CPU to oops, and it's oopsing the first 772 * time then let it proceed. 773 * 774 * This is all enabled by the pause_on_oops kernel boot option. We do all 775 * this to ensure that oopses don't scroll off the screen. It has the 776 * side-effect of preventing later-oopsing CPUs from mucking up the display, 777 * too. 778 * 779 * It turns out that the CPU which is allowed to print ends up pausing for 780 * the right duration, whereas all the other CPUs pause for twice as long: 781 * once in oops_enter(), once in oops_exit(). 782 */ 783 void oops_enter(void) 784 { 785 nbcon_cpu_emergency_enter(); 786 tracing_off(); 787 /* can't trust the integrity of the kernel anymore: */ 788 debug_locks_off(); 789 do_oops_enter_exit(); 790 791 if (sysctl_oops_all_cpu_backtrace) 792 trigger_all_cpu_backtrace(); 793 } 794 795 static void print_oops_end_marker(void) 796 { 797 pr_warn("---[ end trace %016llx ]---\n", 0ULL); 798 } 799 800 /* 801 * Called when the architecture exits its oops handler, after printing 802 * everything. 803 */ 804 void oops_exit(void) 805 { 806 do_oops_enter_exit(); 807 print_oops_end_marker(); 808 nbcon_cpu_emergency_exit(); 809 kmsg_dump(KMSG_DUMP_OOPS); 810 } 811 812 struct warn_args { 813 const char *fmt; 814 va_list args; 815 }; 816 817 void __warn(const char *file, int line, void *caller, unsigned taint, 818 struct pt_regs *regs, struct warn_args *args) 819 { 820 nbcon_cpu_emergency_enter(); 821 822 disable_trace_on_warning(); 823 824 if (file) 825 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", 826 raw_smp_processor_id(), current->pid, file, line, 827 caller); 828 else 829 pr_warn("WARNING: CPU: %d PID: %d at %pS\n", 830 raw_smp_processor_id(), current->pid, caller); 831 832 #pragma GCC diagnostic push 833 #ifndef __clang__ 834 #pragma GCC diagnostic ignored "-Wsuggest-attribute=format" 835 #endif 836 if (args) 837 vprintk(args->fmt, args->args); 838 #pragma GCC diagnostic pop 839 840 print_modules(); 841 842 if (regs) 843 show_regs(regs); 844 845 check_panic_on_warn("kernel"); 846 847 if (!regs) 848 dump_stack(); 849 850 print_irqtrace_events(current); 851 852 print_oops_end_marker(); 853 trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); 854 855 /* Just a warning, don't kill lockdep. */ 856 add_taint(taint, LOCKDEP_STILL_OK); 857 858 nbcon_cpu_emergency_exit(); 859 } 860 861 #ifdef CONFIG_BUG 862 #ifndef __WARN_FLAGS 863 void warn_slowpath_fmt(const char *file, int line, unsigned taint, 864 const char *fmt, ...) 865 { 866 bool rcu = warn_rcu_enter(); 867 struct warn_args args; 868 869 pr_warn(CUT_HERE); 870 871 if (!fmt) { 872 __warn(file, line, __builtin_return_address(0), taint, 873 NULL, NULL); 874 warn_rcu_exit(rcu); 875 return; 876 } 877 878 args.fmt = fmt; 879 va_start(args.args, fmt); 880 __warn(file, line, __builtin_return_address(0), taint, NULL, &args); 881 va_end(args.args); 882 warn_rcu_exit(rcu); 883 } 884 EXPORT_SYMBOL(warn_slowpath_fmt); 885 #else 886 void __warn_printk(const char *fmt, ...) 887 { 888 bool rcu = warn_rcu_enter(); 889 va_list args; 890 891 pr_warn(CUT_HERE); 892 893 va_start(args, fmt); 894 vprintk(fmt, args); 895 va_end(args); 896 warn_rcu_exit(rcu); 897 } 898 EXPORT_SYMBOL(__warn_printk); 899 #endif 900 901 /* Support resetting WARN*_ONCE state */ 902 903 static int clear_warn_once_set(void *data, u64 val) 904 { 905 generic_bug_clear_once(); 906 memset(__start_once, 0, __end_once - __start_once); 907 return 0; 908 } 909 910 DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set, 911 "%lld\n"); 912 913 static __init int register_warn_debugfs(void) 914 { 915 /* Don't care about failure */ 916 debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL, 917 &clear_warn_once_fops); 918 return 0; 919 } 920 921 device_initcall(register_warn_debugfs); 922 #endif 923 924 #ifdef CONFIG_STACKPROTECTOR 925 926 /* 927 * Called when gcc's -fstack-protector feature is used, and 928 * gcc detects corruption of the on-stack canary value 929 */ 930 __visible noinstr void __stack_chk_fail(void) 931 { 932 unsigned long flags; 933 934 instrumentation_begin(); 935 flags = user_access_save(); 936 937 panic("stack-protector: Kernel stack is corrupted in: %pB", 938 __builtin_return_address(0)); 939 940 user_access_restore(flags); 941 instrumentation_end(); 942 } 943 EXPORT_SYMBOL(__stack_chk_fail); 944 945 #endif 946 947 core_param(panic, panic_timeout, int, 0644); 948 core_param(panic_print, panic_print, ulong, 0644); 949 core_param(pause_on_oops, pause_on_oops, int, 0644); 950 core_param(panic_on_warn, panic_on_warn, int, 0644); 951 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); 952 953 static int __init oops_setup(char *s) 954 { 955 if (!s) 956 return -EINVAL; 957 if (!strcmp(s, "panic")) 958 panic_on_oops = 1; 959 return 0; 960 } 961 early_param("oops", oops_setup); 962 963 static int __init panic_on_taint_setup(char *s) 964 { 965 char *taint_str; 966 967 if (!s) 968 return -EINVAL; 969 970 taint_str = strsep(&s, ","); 971 if (kstrtoul(taint_str, 16, &panic_on_taint)) 972 return -EINVAL; 973 974 /* make sure panic_on_taint doesn't hold out-of-range TAINT flags */ 975 panic_on_taint &= TAINT_FLAGS_MAX; 976 977 if (!panic_on_taint) 978 return -EINVAL; 979 980 if (s && !strcmp(s, "nousertaint")) 981 panic_on_taint_nousertaint = true; 982 983 pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n", 984 panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint)); 985 986 return 0; 987 } 988 early_param("panic_on_taint", panic_on_taint_setup); 989