Quelle panic.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
*  linux/kernel/panic.c
*
*  Copyright (C) 1991, 1992  Linus Torvalds
*/

/*
* This function is used through-out the kernel (including mm and fs)
* to indicate a major problem.
*/
#include <linux/debug_locks.h>
#include <linux/sched/debug.h>
#include <linux/interrupt.h>
#include <linux/kgdb.h>
#include <linux/kmsg_dump.h>
#include <linux/kallsyms.h>
#include <linux/notifier.h>
#include <linux/vt_kern.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/ftrace.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/kexec.h>
#include <linux/panic_notifier.h>
#include <linux/sched.h>
#include <linux/string_helpers.h>
#include <linux/sysrq.h>
#include <linux/init.h>
#include <linux/nmi.h>
#include <linux/console.h>
#include <linux/bug.h>
#include <linux/ratelimit.h>
#include <linux/debugfs.h>
#include <linux/sysfs.h>
#include <linux/context_tracking.h>
#include <linux/seq_buf.h>
#include <linux/sys_info.h>
#include <trace/events/error_report.h>
#include <asm/sections.h>

#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18

#ifdef CONFIG_SMP
/*
* Should we dump all CPUs backtraces in an oops event?
* Defaults to 0, can be changed via sysctl.
*/
static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
#else
#define sysctl_oops_all_cpu_backtrace 0
#endif /* CONFIG_SMP */

int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
static unsigned long tainted_mask =
IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
static int pause_on_oops;
static int pause_on_oops_flag;
static DEFINE_SPINLOCK(pause_on_oops_lock);
bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly;
unsigned long panic_on_taint;
bool panic_on_taint_nousertaint = false;
static unsigned int warn_limit __read_mostly;
static bool panic_console_replay;

bool panic_triggering_all_cpu_backtrace;

int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout);

unsigned long panic_print;

ATOMIC_NOTIFIER_HEAD(panic_notifier_list);

EXPORT_SYMBOL(panic_notifier_list);

#ifdef CONFIG_SYSCTL

/*
* Taint values can only be increased
* This means we can safely use a temporary.
*/
static int proc_taint(const struct ctl_table *table, int write,
          void *buffer, size_t *lenp, loff_t *ppos)
{
struct ctl_table t;
unsigned long tmptaint = get_taint();
int err;

if (write && !capable(CAP_SYS_ADMIN))
  return -EPERM;

t = *table;
t.data = &tmptaint;
err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
if (err < 0)
  return err;

if (write) {
  int i;

  /*
* If we are relying on panic_on_taint not producing
* false positives due to userspace input, bail out
* before setting the requested taint flags.
*/
  if (panic_on_taint_nousertaint && (tmptaint & panic_on_taint))
   return -EINVAL;

  /*
* Poor man's atomic or. Not worth adding a primitive
* to everyone's atomic.h for this
*/
  for (i = 0; i < TAINT_FLAGS_COUNT; i++)
   if ((1UL << i) & tmptaint)
    add_taint(i, LOCKDEP_STILL_OK);
}

return err;
}

static int sysctl_panic_print_handler(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
pr_info_once("Kernel: 'panic_print' sysctl interface will be obsoleted by both 'panic_sys_info' and 'panic_console_replay'\n");
return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}

static const struct ctl_table kern_panic_table[] = {
#ifdef CONFIG_SMP
{
  .procname       = "oops_all_cpu_backtrace",
  .data           = &sysctl_oops_all_cpu_backtrace,
  .maxlen         = sizeof(int),
  .mode           = 0644,
  .proc_handler   = proc_dointvec_minmax,
  .extra1         = SYSCTL_ZERO,
  .extra2         = SYSCTL_ONE,
},
#endif
{
  .procname = "tainted",
  .maxlen  = sizeof(long),
  .mode  = 0644,
  .proc_handler = proc_taint,
},
{
  .procname = "panic",
  .data  = &panic_timeout,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
{
  .procname = "panic_on_oops",
  .data  = &panic_on_oops,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
{
  .procname = "panic_print",
  .data  = &panic_print,
  .maxlen  = sizeof(unsigned long),
  .mode  = 0644,
  .proc_handler = sysctl_panic_print_handler,
},
{
  .procname = "panic_on_warn",
  .data  = &panic_on_warn,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = SYSCTL_ZERO,
  .extra2  = SYSCTL_ONE,
},
{
  .procname       = "warn_limit",
  .data           = &warn_limit,
  .maxlen         = sizeof(warn_limit),
  .mode           = 0644,
  .proc_handler   = proc_douintvec,
},
#if (defined(CONFIG_X86_32) || defined(CONFIG_PARISC)) && \
defined(CONFIG_DEBUG_STACKOVERFLOW)
{
  .procname = "panic_on_stackoverflow",
  .data  = &sysctl_panic_on_stackoverflow,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
#endif
{
  .procname = "panic_sys_info",
  .data  = &panic_print,
  .maxlen         = sizeof(panic_print),
  .mode  = 0644,
  .proc_handler = sysctl_sys_info_handler,
},
};

static __init int kernel_panic_sysctls_init(void)
{
register_sysctl_init("kernel", kern_panic_table);
return 0;
}
late_initcall(kernel_panic_sysctls_init);
#endif

/* The format is "panic_sys_info=tasks,mem,locks,ftrace,..." */
static int __init setup_panic_sys_info(char *buf)
{
/* There is no risk of race in kernel boot phase */
panic_print = sys_info_parse_param(buf);
return 1;
}
__setup("panic_sys_info=", setup_panic_sys_info);

static atomic_t warn_count = ATOMIC_INIT(0);

#ifdef CONFIG_SYSFS
static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
          char *page)
{
return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
}

static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);

static __init int kernel_panic_sysfs_init(void)
{
sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
return 0;
}
late_initcall(kernel_panic_sysfs_init);
#endif

static long no_blink(int state)
{
return 0;
}

/* Returns how long it waited in ms */
long (*panic_blink)(int state);
EXPORT_SYMBOL(panic_blink);

/*
* Stop ourself in panic -- architecture code may override this
*/
void __weak __noreturn panic_smp_self_stop(void)
{
while (1)
  cpu_relax();
}

/*
* Stop ourselves in NMI context if another CPU has already panicked. Arch code
* may override this to prepare for crash dumping, e.g. save regs info.
*/
void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs)
{
panic_smp_self_stop();
}

/*
* Stop other CPUs in panic.  Architecture dependent code may override this
* with more suitable version.  For example, if the architecture supports
* crash dump, it should save registers of each stopped CPU and disable
* per-CPU features such as virtualization extensions.
*/
void __weak crash_smp_send_stop(void)
{
static int cpus_stopped;

/*
* This function can be called twice in panic path, but obviously
* we execute this only once.
*/
if (cpus_stopped)
  return;

/*
* Note smp_send_stop is the usual smp shutdown function, which
* unfortunately means it may not be hardened to work in a panic
* situation.
*/
smp_send_stop();
cpus_stopped = 1;
}

atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);

/*
* A variant of panic() called from NMI context. We return if we've already
* panicked on this CPU. If another CPU already panicked, loop in
* nmi_panic_self_stop() which can provide architecture dependent code such
* as saving register state for crash dump.
*/
void nmi_panic(struct pt_regs *regs, const char *msg)
{
int old_cpu, this_cpu;

old_cpu = PANIC_CPU_INVALID;
this_cpu = raw_smp_processor_id();

/* atomic_try_cmpxchg updates old_cpu on failure */
if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
  panic("%s", msg);
else if (old_cpu != this_cpu)
  nmi_panic_self_stop(regs);
}
EXPORT_SYMBOL(nmi_panic);

void check_panic_on_warn(const char *origin)
{
unsigned int limit;

if (panic_on_warn)
  panic("%s: panic_on_warn set ...\n", origin);

limit = READ_ONCE(warn_limit);
if (atomic_inc_return(&warn_count) >= limit && limit)
  panic("%s: system warned too often (kernel.warn_limit is %d)",
        origin, limit);
}

/*
* Helper that triggers the NMI backtrace (if set in panic_print)
* and then performs the secondary CPUs shutdown - we cannot have
* the NMI backtrace after the CPUs are off!
*/
static void panic_other_cpus_shutdown(bool crash_kexec)
{
if (panic_print & SYS_INFO_ALL_CPU_BT) {
  /* Temporary allow non-panic CPUs to write their backtraces. */
  panic_triggering_all_cpu_backtrace = true;
  trigger_all_cpu_backtrace();
  panic_triggering_all_cpu_backtrace = false;
}

/*
* Note that smp_send_stop() is the usual SMP shutdown function,
* which unfortunately may not be hardened to work in a panic
* situation. If we want to do crash dump after notifier calls
* and kmsg_dump, we will need architecture dependent extra
* bits in addition to stopping other CPUs, hence we rely on
* crash_smp_send_stop() for that.
*/
if (!crash_kexec)
  smp_send_stop();
else
  crash_smp_send_stop();
}

/**
* vpanic - halt the system
* @fmt: The text string to print
* @args: Arguments for the format string
*
* Display a message, then perform cleanups. This function never returns.
*/
void vpanic(const char *fmt, va_list args)
{
static char buf[1024];
long i, i_next = 0, len;
int state = 0;
int old_cpu, this_cpu;
bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;

if (panic_on_warn) {
  /*
* This thread may hit another WARN() in the panic path.
* Resetting this prevents additional WARN() from panicking the
* system on this thread.  Other threads are blocked by the
* panic_mutex in panic().
*/
  panic_on_warn = 0;
}

/*
* Disable local interrupts. This will prevent panic_smp_self_stop
* from deadlocking the first cpu that invokes the panic, since
* there is nothing to prevent an interrupt handler (that runs
* after setting panic_cpu) from invoking panic() again.
*/
local_irq_disable();
preempt_disable_notrace();

/*
* It's possible to come here directly from a panic-assertion and
* not have preempt disabled. Some functions called from here want
* preempt to be disabled. No point enabling it later though...
*
* Only one CPU is allowed to execute the panic code from here. For
* multiple parallel invocations of panic, all other CPUs either
* stop themself or will wait until they are stopped by the 1st CPU
* with smp_send_stop().
*
* cmpxchg success means this is the 1st CPU which comes here,
* so go ahead.
* `old_cpu == this_cpu' means we came from nmi_panic() which sets
* panic_cpu to this CPU.  In this case, this is also the 1st CPU.
*/
old_cpu = PANIC_CPU_INVALID;
this_cpu = raw_smp_processor_id();

/* atomic_try_cmpxchg updates old_cpu on failure */
if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
  /* go ahead */
} else if (old_cpu != this_cpu)
  panic_smp_self_stop();

console_verbose();
bust_spinlocks(1);
len = vscnprintf(buf, sizeof(buf), fmt, args);

if (len && buf[len - 1] == '\n')
  buf[len - 1] = '\0';

pr_emerg("Kernel panic - not syncing: %s\n", buf);
#ifdef CONFIG_DEBUG_BUGVERBOSE
/*
* Avoid nested stack-dumping if a panic occurs during oops processing
*/
if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
  dump_stack();
#endif

/*
* If kgdb is enabled, give it a chance to run before we stop all
* the other CPUs or else we won't be able to debug processes left
* running on them.
*/
kgdb_panic(buf);

/*
* If we have crashed and we have a crash kernel loaded let it handle
* everything else.
* If we want to run this after calling panic_notifiers, pass
* the "crash_kexec_post_notifiers" option to the kernel.
*
* Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (!_crash_kexec_post_notifiers)
  __crash_kexec(NULL);

panic_other_cpus_shutdown(_crash_kexec_post_notifiers);

printk_legacy_allow_panic_sync();

/*
* Run any panic handlers, including those that might need to
* add information to the kmsg dump output.
*/
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);

sys_info(panic_print);

kmsg_dump_desc(KMSG_DUMP_PANIC, buf);

/*
* If you doubt kdump always works fine in any situation,
* "crash_kexec_post_notifiers" offers you a chance to run
* panic_notifiers and dumping kmsg before kdump.
* Note: since some panic_notifiers can make crashed kernel
* more unstable, it can increase risks of the kdump failure too.
*
* Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (_crash_kexec_post_notifiers)
  __crash_kexec(NULL);

console_unblank();

/*
* We may have ended up stopping the CPU holding the lock (in
* smp_send_stop()) while still having some valuable data in the console
* buffer.  Try to acquire the lock then release it regardless of the
* result.  The release will also print the buffers out.  Locks debug
* should be disabled to avoid reporting bad unlock balance when
* panic() is not being callled from OOPS.
*/
debug_locks_off();
console_flush_on_panic(CONSOLE_FLUSH_PENDING);

if ((panic_print & SYS_INFO_PANIC_CONSOLE_REPLAY) ||
  panic_console_replay)
  console_flush_on_panic(CONSOLE_REPLAY_ALL);

if (!panic_blink)
  panic_blink = no_blink;

if (panic_timeout > 0) {
  /*
* Delay timeout seconds before rebooting the machine.
* We can't use the "normal" timers since we just panicked.
*/
  pr_emerg("Rebooting in %d seconds..\n", panic_timeout);

  for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
   touch_nmi_watchdog();
   if (i >= i_next) {
    i += panic_blink(state ^= 1);
    i_next = i + 3600 / PANIC_BLINK_SPD;
   }
   mdelay(PANIC_TIMER_STEP);
  }
}
if (panic_timeout != 0) {
  /*
* This will not be a clean reboot, with everything
* shutting down.  But if there is a chance of
* rebooting the system it will be rebooted.
*/
  if (panic_reboot_mode != REBOOT_UNDEFINED)
   reboot_mode = panic_reboot_mode;
  emergency_restart();
}
#ifdef __sparc__
{
  extern int stop_a_enabled;
  /* Make sure the user can actually press Stop-A (L1-A) */
  stop_a_enabled = 1;
  pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
    "twice on console to return to the boot prom\n");
}
#endif
#if defined(CONFIG_S390)
disabled_wait();
#endif
pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);

/* Do not scroll important messages printed above */
suppress_printk = 1;

/*
* The final messages may not have been printed if in a context that
* defers printing (such as NMI) and irq_work is not available.
* Explicitly flush the kernel log buffer one last time.
*/
console_flush_on_panic(CONSOLE_FLUSH_PENDING);
nbcon_atomic_flush_unsafe();

local_irq_enable();
for (i = 0; ; i += PANIC_TIMER_STEP) {
  touch_softlockup_watchdog();
  if (i >= i_next) {
   i += panic_blink(state ^= 1);
   i_next = i + 3600 / PANIC_BLINK_SPD;
  }
  mdelay(PANIC_TIMER_STEP);
}
}
EXPORT_SYMBOL(vpanic);

/* Identical to vpanic(), except it takes variadic arguments instead of va_list */
void panic(const char *fmt, ...)
{
va_list args;

va_start(args, fmt);
vpanic(fmt, args);
va_end(args);
}
EXPORT_SYMBOL(panic);

#define TAINT_FLAG(taint, _c_true, _c_false, _module)   \
[ TAINT_##taint ] = {      \
  .c_true = _c_true, .c_false = _c_false,   \
  .module = _module,     \
  .desc = #taint,      \
}

/*
* TAINT_FORCED_RMMOD could be a per-module flag but the module
* is being removed anyway.
*/
const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
TAINT_FLAG(PROPRIETARY_MODULE,  'P', 'G', true),
TAINT_FLAG(FORCED_MODULE,  'F', ' ', true),
TAINT_FLAG(CPU_OUT_OF_SPEC,  'S', ' ', false),
TAINT_FLAG(FORCED_RMMOD,  'R', ' ', false),
TAINT_FLAG(MACHINE_CHECK,  'M', ' ', false),
TAINT_FLAG(BAD_PAGE,   'B', ' ', false),
TAINT_FLAG(USER,   'U', ' ', false),
TAINT_FLAG(DIE,    'D', ' ', false),
TAINT_FLAG(OVERRIDDEN_ACPI_TABLE, 'A', ' ', false),
TAINT_FLAG(WARN,   'W', ' ', false),
TAINT_FLAG(CRAP,   'C', ' ', true),
TAINT_FLAG(FIRMWARE_WORKAROUND,  'I', ' ', false),
TAINT_FLAG(OOT_MODULE,   'O', ' ', true),
TAINT_FLAG(UNSIGNED_MODULE,  'E', ' ', true),
TAINT_FLAG(SOFTLOCKUP,   'L', ' ', false),
TAINT_FLAG(LIVEPATCH,   'K', ' ', true),
TAINT_FLAG(AUX,    'X', ' ', true),
TAINT_FLAG(RANDSTRUCT,   'T', ' ', true),
TAINT_FLAG(TEST,   'N', ' ', true),
TAINT_FLAG(FWCTL,   'J', ' ', true),
};

#undef TAINT_FLAG

static void print_tainted_seq(struct seq_buf *s, bool verbose)
{
const char *sep = "";
int i;

if (!tainted_mask) {
  seq_buf_puts(s, "Not tainted");
  return;
}

seq_buf_printf(s, "Tainted: ");
for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
  const struct taint_flag *t = &taint_flags[i];
  bool is_set = test_bit(i, &tainted_mask);
  char c = is_set ? t->c_true : t->c_false;

  if (verbose) {
   if (is_set) {
    seq_buf_printf(s, "%s[%c]=%s", sep, c, t->desc);
    sep = ", ";
   }
  } else {
   seq_buf_putc(s, c);
  }
}
}

static const char *_print_tainted(bool verbose)
{
/* FIXME: what should the size be? */
static char buf[sizeof(taint_flags)];
struct seq_buf s;

BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);

seq_buf_init(&s, buf, sizeof(buf));

print_tainted_seq(&s, verbose);

return seq_buf_str(&s);
}

/**
* print_tainted - return a string to represent the kernel taint state.
*
* For individual taint flag meanings, see Documentation/admin-guide/sysctl/kernel.rst
*
* The string is overwritten by the next call to print_tainted(),
* but is always NULL terminated.
*/
const char *print_tainted(void)
{
return _print_tainted(false);
}

/**
* print_tainted_verbose - A more verbose version of print_tainted()
*/
const char *print_tainted_verbose(void)
{
return _print_tainted(true);
}

int test_taint(unsigned flag)
{
return test_bit(flag, &tainted_mask);
}
EXPORT_SYMBOL(test_taint);

unsigned long get_taint(void)
{
return tainted_mask;
}

/**
* add_taint: add a taint flag if not already set.
* @flag: one of the TAINT_* constants.
* @lockdep_ok: whether lock debugging is still OK.
*
* If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
* some notewortht-but-not-corrupting cases, it can be set to true.
*/
void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
{
if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
  pr_warn("Disabling lock debugging due to kernel taint\n");

set_bit(flag, &tainted_mask);

if (tainted_mask & panic_on_taint) {
  panic_on_taint = 0;
  panic("panic_on_taint set ...");
}
}
EXPORT_SYMBOL(add_taint);

static void spin_msec(int msecs)
{
int i;

for (i = 0; i < msecs; i++) {
  touch_nmi_watchdog();
  mdelay(1);
}
}

/*
* It just happens that oops_enter() and oops_exit() are identically
* implemented...
*/
static void do_oops_enter_exit(void)
{
unsigned long flags;
static int spin_counter;

if (!pause_on_oops)
  return;

spin_lock_irqsave(&pause_on_oops_lock, flags);
if (pause_on_oops_flag == 0) {
  /* This CPU may now print the oops message */
  pause_on_oops_flag = 1;
} else {
  /* We need to stall this CPU */
  if (!spin_counter) {
   /* This CPU gets to do the counting */
   spin_counter = pause_on_oops;
   do {
    spin_unlock(&pause_on_oops_lock);
    spin_msec(MSEC_PER_SEC);
    spin_lock(&pause_on_oops_lock);
   } while (--spin_counter);
   pause_on_oops_flag = 0;
  } else {
   /* This CPU waits for a different one */
   while (spin_counter) {
    spin_unlock(&pause_on_oops_lock);
    spin_msec(1);
    spin_lock(&pause_on_oops_lock);
   }
  }
}
spin_unlock_irqrestore(&pause_on_oops_lock, flags);
}

/*
* Return true if the calling CPU is allowed to print oops-related info.
* This is a bit racy..
*/
bool oops_may_print(void)
{
return pause_on_oops_flag == 0;
}

/*
* Called when the architecture enters its oops handler, before it prints
* anything.  If this is the first CPU to oops, and it's oopsing the first
* time then let it proceed.
*
* This is all enabled by the pause_on_oops kernel boot option.  We do all
* this to ensure that oopses don't scroll off the screen.  It has the
* side-effect of preventing later-oopsing CPUs from mucking up the display,
* too.
*
* It turns out that the CPU which is allowed to print ends up pausing for
* the right duration, whereas all the other CPUs pause for twice as long:
* once in oops_enter(), once in oops_exit().
*/
void oops_enter(void)
{
nbcon_cpu_emergency_enter();
tracing_off();
/* can't trust the integrity of the kernel anymore: */
debug_locks_off();
do_oops_enter_exit();

if (sysctl_oops_all_cpu_backtrace)
  trigger_all_cpu_backtrace();
}

static void print_oops_end_marker(void)
{
pr_warn("---[ end trace %016llx ]---\n", 0ULL);
}

/*
* Called when the architecture exits its oops handler, after printing
* everything.
*/
void oops_exit(void)
{
do_oops_enter_exit();
print_oops_end_marker();
nbcon_cpu_emergency_exit();
kmsg_dump(KMSG_DUMP_OOPS);
}

struct warn_args {
const char *fmt;
va_list args;
};

void __warn(const char *file, int line, void *caller, unsigned taint,
     struct pt_regs *regs, struct warn_args *args)
{
nbcon_cpu_emergency_enter();

disable_trace_on_warning();

if (file)
  pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
   raw_smp_processor_id(), current->pid, file, line,
   caller);
else
  pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
   raw_smp_processor_id(), current->pid, caller);

#pragma GCC diagnostic push
#ifndef __clang__
#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
#endif
if (args)
  vprintk(args->fmt, args->args);
#pragma GCC diagnostic pop

print_modules();

if (regs)
  show_regs(regs);

check_panic_on_warn("kernel");

if (!regs)
  dump_stack();

print_irqtrace_events(current);

print_oops_end_marker();
trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);

/* Just a warning, don't kill lockdep. */
add_taint(taint, LOCKDEP_STILL_OK);

nbcon_cpu_emergency_exit();
}

#ifdef CONFIG_BUG
#ifndef __WARN_FLAGS
void warn_slowpath_fmt(const char *file, int line, unsigned taint,
         const char *fmt, ...)
{
bool rcu = warn_rcu_enter();
struct warn_args args;

pr_warn(CUT_HERE);

if (!fmt) {
  __warn(file, line, __builtin_return_address(0), taint,
         NULL, NULL);
  warn_rcu_exit(rcu);
  return;
}

args.fmt = fmt;
va_start(args.args, fmt);
__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
va_end(args.args);
warn_rcu_exit(rcu);
}
EXPORT_SYMBOL(warn_slowpath_fmt);
#else
void __warn_printk(const char *fmt, ...)
{
bool rcu = warn_rcu_enter();
va_list args;

pr_warn(CUT_HERE);

va_start(args, fmt);
vprintk(fmt, args);
va_end(args);
warn_rcu_exit(rcu);
}
EXPORT_SYMBOL(__warn_printk);
#endif

/* Support resetting WARN*_ONCE state */

static int clear_warn_once_set(void *data, u64 val)
{
generic_bug_clear_once();
memset(__start_once, 0, __end_once - __start_once);
return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
    "%lld\n");

static __init int register_warn_debugfs(void)
{
/* Don't care about failure */
debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
       &clear_warn_once_fops);
return 0;
}

device_initcall(register_warn_debugfs);
#endif

#ifdef CONFIG_STACKPROTECTOR

/*
* Called when gcc's -fstack-protector feature is used, and
* gcc detects corruption of the on-stack canary value
*/
__visible noinstr void __stack_chk_fail(void)
{
unsigned long flags;

instrumentation_begin();
flags = user_access_save();

panic("stack-protector: Kernel stack is corrupted in: %pB",
  __builtin_return_address(0));

user_access_restore(flags);
instrumentation_end();
}
EXPORT_SYMBOL(__stack_chk_fail);

#endif

core_param(panic, panic_timeout, int, 0644);
core_param(panic_print, panic_print, ulong, 0644);
core_param(pause_on_oops, pause_on_oops, int, 0644);
core_param(panic_on_warn, panic_on_warn, int, 0644);
core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
core_param(panic_console_replay, panic_console_replay, bool, 0644);

static int __init oops_setup(char *s)
{
if (!s)
  return -EINVAL;
if (!strcmp(s, "panic"))
  panic_on_oops = 1;
return 0;
}
early_param("oops", oops_setup);

static int __init panic_on_taint_setup(char *s)
{
char *taint_str;

if (!s)
  return -EINVAL;

taint_str = strsep(&s, ",");
if (kstrtoul(taint_str, 16, &panic_on_taint))
  return -EINVAL;

/* make sure panic_on_taint doesn't hold out-of-range TAINT flags */
panic_on_taint &= TAINT_FLAGS_MAX;

if (!panic_on_taint)
  return -EINVAL;

if (s && !strcmp(s, "nousertaint"))
  panic_on_taint_nousertaint = true;

pr_info("panic_on_taint: bitmask=0x%lx nousertaint_mode=%s\n",
  panic_on_taint, str_enabled_disabled(panic_on_taint_nousertaint));

return 0;
}
early_param("panic_on_taint", panic_on_taint_setup);

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