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