root/arch/um/kernel/reboot.c
// SPDX-License-Identifier: GPL-2.0
/* 
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/sched/mm.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/oom.h>
#include <linux/reboot.h>
#include <kern_util.h>
#include <os.h>
#include <skas.h>

void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

static void kill_off_processes(void)
{
        struct task_struct *p;
        int pid;

        read_lock(&tasklist_lock);
        for_each_process(p) {
                struct task_struct *t;

                t = find_lock_task_mm(p);
                if (!t)
                        continue;
                pid = t->mm->context.id.pid;
                task_unlock(t);
                os_kill_ptraced_process(pid, 1);
        }
        read_unlock(&tasklist_lock);
}

void uml_cleanup(void)
{
        kmalloc_ok = 0;
        do_uml_exitcalls();
        kill_off_processes();
}

void machine_restart(char * __unused)
{
        uml_cleanup();
        reboot_skas();
}

void machine_power_off(void)
{
        uml_cleanup();
        halt_skas();
}

void machine_halt(void)
{
        machine_power_off();
}

static int sys_power_off_handler(struct sys_off_data *data)
{
        machine_power_off();
        return 0;
}

static int register_power_off(void)
{
        register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
                                 SYS_OFF_PRIO_DEFAULT,
                                 sys_power_off_handler, NULL);
        return 0;
}
__initcall(register_power_off);