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// SPDX-License-Identifier: GPL-2.0
#ifndef NOLIBC
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <syscall.h>
#include <sys/mount.h>
#include <sys/reboot.h>
#endif
/* from arch/x86/include/asm/setup.h */
#define COMMAND_LINE_SIZE 2048
/* from include/linux/kexex.h */
#define KEXEC_FILE_NO_INITRAMFS 0x00000004
#define KHO_FINILIZE "/debugfs/kho/out/finalize"
#define KERNEL_IMAGE "/kernel"
static int mount_filesystems(void)
{
if (mount("debugfs", "/debugfs", "debugfs", 0, NULL) < 0)
return -1;
return mount("proc", "/proc", "proc", 0, NULL);
}
static int kho_enable(void)
{
const char enable[] = "1";
int fd;
fd = open(KHO_FINILIZE, O_RDWR);
if (fd < 0)
return -1;
if (write(fd, enable, sizeof(enable)) != sizeof(enable))
return 1;
close(fd);
return 0;
}
static long kexec_file_load(int kernel_fd, int initrd_fd,
unsigned long cmdline_len, const char *cmdline,
unsigned long flags)
{
return syscall(__NR_kexec_file_load, kernel_fd, initrd_fd, cmdline_len,
cmdline, flags);
}
static int kexec_load(void)
{
char cmdline[COMMAND_LINE_SIZE];
ssize_t len;
int fd, err;
fd = open("/proc/cmdline", O_RDONLY);
if (fd < 0)
return -1;
len = read(fd, cmdline, sizeof(cmdline));
close(fd);
if (len < 0)
return -1;
/* replace \n with \0 */
cmdline[len - 1] = 0;
fd = open(KERNEL_IMAGE, O_RDONLY);
if (fd < 0)
return -1;
err = kexec_file_load(fd, -1, len, cmdline, KEXEC_FILE_NO_INITRAMFS);
close(fd);
return err ? : 0;
}
int main(int argc, char *argv[])
{
if (mount_filesystems())
goto err_reboot;
if (kho_enable())
goto err_reboot;
if (kexec_load())
goto err_reboot;
if (reboot(RB_KEXEC))
goto err_reboot;
return 0;
err_reboot:
reboot(RB_AUTOBOOT);
return -1;
}
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