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// 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/sched.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 <asm/sections.h>
#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18
int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
static unsigned long tainted_mask =
IS_ENABLED(CONFIG_GCC_PLUGIN_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;
int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout);
#define PANIC_PRINT_TASK_INFO 0x00000001
#define PANIC_PRINT_MEM_INFO 0x00000002
#define PANIC_PRINT_TIMER_INFO 0x00000004
#define PANIC_PRINT_LOCK_INFO 0x00000008
#define PANIC_PRINT_FTRACE_INFO 0x00000010
#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
unsigned long panic_print;
ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
EXPORT_SYMBOL(panic_notifier_list);
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 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 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, cpu;
cpu = raw_smp_processor_id();
old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
if (old_cpu == PANIC_CPU_INVALID)
panic("%s", msg);
else if (old_cpu != cpu)
nmi_panic_self_stop(regs);
}
EXPORT_SYMBOL(nmi_panic);
static void panic_print_sys_info(void)
{
if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
console_flush_on_panic(CONSOLE_REPLAY_ALL);
if (panic_print & PANIC_PRINT_TASK_INFO)
show_state();
if (panic_print & PANIC_PRINT_MEM_INFO)
show_mem(0, NULL);
if (panic_print & PANIC_PRINT_TIMER_INFO)
sysrq_timer_list_show();
if (panic_print & PANIC_PRINT_LOCK_INFO)
debug_show_all_locks();
if (panic_print & PANIC_PRINT_FTRACE_INFO)
ftrace_dump(DUMP_ALL);
}
/**
* panic - halt the system
* @fmt: The text string to print
*
* Display a message, then perform cleanups.
*
* This function never returns.
*/
void panic(const char *fmt, ...)
{
static char buf[1024];
va_list args;
long i, i_next = 0, len;
int state = 0;
int old_cpu, this_cpu;
bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
/*
* 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();
/*
* 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().
*
* `old_cpu == PANIC_CPU_INVALID' 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.
*/
this_cpu = raw_smp_processor_id();
old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
panic_smp_self_stop();
console_verbose();
bust_spinlocks(1);
va_start(args, fmt);
len = vscnprintf(buf, sizeof(buf), fmt, args);
va_end(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) {
printk_safe_flush_on_panic();
__crash_kexec(NULL);
/*
* 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();
} else {
/*
* If we want to do crash dump after notifier calls and
* kmsg_dump, we will need architecture dependent extra
* works in addition to stopping other CPUs.
*/
crash_smp_send_stop();
}
/*
* 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);
/* Call flush even twice. It tries harder with a single online CPU */
printk_safe_flush_on_panic();
kmsg_dump(KMSG_DUMP_PANIC);
/*
* 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);
#ifdef CONFIG_VT
unblank_screen();
#endif
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);
panic_print_sys_info();
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);
}
}
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