// SPDX-License-Identifier: GPL-2.0

  #include <linux/unistd.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/minix_fs.h>

  #include <linux/romfs_fs.h>
  #include <linux/initrd.h>
  #include <linux/sched.h>

  #include <linux/freezer.h>

  #include <linux/kmod.h>

  #include <uapi/linux/mount.h>

  
  #include "do_mounts.h"
  
  unsigned long initrd_start, initrd_end;
  int initrd_below_start_ok;
  unsigned int real_root_dev;	/* do_proc_dointvec cannot handle kdev_t */

  static int __initdata mount_initrd = 1;

  phys_addr_t phys_initrd_start __initdata;
  unsigned long phys_initrd_size __initdata;

  static int __init no_initrd(char *str)
  {
  	mount_initrd = 0;
  	return 1;
  }
  
  __setup("noinitrd", no_initrd);

  static int __init early_initrdmem(char *p)

  {
  	phys_addr_t start;
  	unsigned long size;
  	char *endp;
  
  	start = memparse(p, &endp);
  	if (*endp == ',') {
  		size = memparse(endp + 1, NULL);
  
  		phys_initrd_start = start;
  		phys_initrd_size = size;
  	}
  	return 0;
  }

  early_param("initrdmem", early_initrdmem);

  static int __init early_initrd(char *p)
  {
  	return early_initrdmem(p);
  }

  early_param("initrd", early_initrd);

  static int __init init_linuxrc(struct subprocess_info *info, struct cred *new)

  {

  	ksys_unshare(CLONE_FS | CLONE_FILES);

  	console_on_rootfs();

  	/* move initrd over / and chdir/chroot in initrd root */

  	init_chdir("/root");

  	init_mount(".", "/", NULL, MS_MOVE, NULL);

  	init_chroot(".");

  	ksys_setsid();

  	return 0;

  }
  
  static void __init handle_initrd(void)
  {

  	struct subprocess_info *info;

  	static char *argv[] = { "linuxrc", NULL, };
  	extern char *envp_init[];

  	int error;

  	pr_warn("using deprecated initrd support, will be removed in 2021.
  ");

  	real_root_dev = new_encode_dev(ROOT_DEV);

  	create_dev("/dev/root.old", Root_RAM0);

  	/* mount initrd on rootfs' /root */
  	mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);

  	init_mkdir("/old", 0700);

  	init_chdir("/old");

  	/*
  	 * In case that a resume from disk is carried out by linuxrc or one of
  	 * its children, we need to tell the freezer not to wait for us.
  	 */
  	current->flags |= PF_FREEZER_SKIP;

  	info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  					 GFP_KERNEL, init_linuxrc, NULL, NULL);
  	if (!info)
  		return;
  	call_usermodehelper_exec(info, UMH_WAIT_PROC);

  
  	current->flags &= ~PF_FREEZER_SKIP;

  
  	/* move initrd to rootfs' /old */

  	init_mount("..", ".", NULL, MS_MOVE, NULL);

  	/* switch root and cwd back to / of rootfs */

  	init_chroot("..");

  
  	if (new_decode_dev(real_root_dev) == Root_RAM0) {

  		init_chdir("/old");

  		return;
  	}

  	init_chdir("/");

  	ROOT_DEV = new_decode_dev(real_root_dev);
  	mount_root();
  
  	printk(KERN_NOTICE "Trying to move old root to /initrd ... ");

  	error = init_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);

  	if (!error)
  		printk("okay
  ");
  	else {

  		if (error == -ENOENT)
  			printk("/initrd does not exist. Ignored.
  ");
  		else
  			printk("failed
  ");

  		printk(KERN_NOTICE "Unmounting old root
  ");

  		init_umount("/old", MNT_DETACH);

  	}
  }

  bool __init initrd_load(void)

  {
  	if (mount_initrd) {

  		create_dev("/dev/ram", Root_RAM0);

  		/*
  		 * Load the initrd data into /dev/ram0. Execute it as initrd
  		 * unless /dev/ram0 is supposed to be our actual root device,
  		 * in that case the ram disk is just set up here, and gets
  		 * mounted in the normal path.
  		 */
  		if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {

  			init_unlink("/initrd.image");

  			handle_initrd();

  			return true;

  		}
  	}

  	init_unlink("/initrd.image");

  	return false;

  }