linux/init/do_mounts_initrd.c
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   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/unistd.h>
   3#include <linux/kernel.h>
   4#include <linux/fs.h>
   5#include <linux/minix_fs.h>
   6#include <linux/romfs_fs.h>
   7#include <linux/initrd.h>
   8#include <linux/sched.h>
   9#include <linux/freezer.h>
  10#include <linux/kmod.h>
  11
  12#include "do_mounts.h"
  13
  14unsigned long initrd_start, initrd_end;
  15int initrd_below_start_ok;
  16unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  17static int __initdata mount_initrd = 1;
  18
  19static int __init no_initrd(char *str)
  20{
  21        mount_initrd = 0;
  22        return 1;
  23}
  24
  25__setup("noinitrd", no_initrd);
  26
  27static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  28{
  29        ksys_unshare(CLONE_FS | CLONE_FILES);
  30        /* stdin/stdout/stderr for /linuxrc */
  31        ksys_open("/dev/console", O_RDWR, 0);
  32        ksys_dup(0);
  33        ksys_dup(0);
  34        /* move initrd over / and chdir/chroot in initrd root */
  35        ksys_chdir("/root");
  36        ksys_mount(".", "/", NULL, MS_MOVE, NULL);
  37        ksys_chroot(".");
  38        ksys_setsid();
  39        return 0;
  40}
  41
  42static void __init handle_initrd(void)
  43{
  44        struct subprocess_info *info;
  45        static char *argv[] = { "linuxrc", NULL, };
  46        extern char *envp_init[];
  47        int error;
  48
  49        real_root_dev = new_encode_dev(ROOT_DEV);
  50        create_dev("/dev/root.old", Root_RAM0);
  51        /* mount initrd on rootfs' /root */
  52        mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  53        ksys_mkdir("/old", 0700);
  54        ksys_chdir("/old");
  55
  56        /* try loading default modules from initrd */
  57        load_default_modules();
  58
  59        /*
  60         * In case that a resume from disk is carried out by linuxrc or one of
  61         * its children, we need to tell the freezer not to wait for us.
  62         */
  63        current->flags |= PF_FREEZER_SKIP;
  64
  65        info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  66                                         GFP_KERNEL, init_linuxrc, NULL, NULL);
  67        if (!info)
  68                return;
  69        call_usermodehelper_exec(info, UMH_WAIT_PROC);
  70
  71        current->flags &= ~PF_FREEZER_SKIP;
  72
  73        /* move initrd to rootfs' /old */
  74        ksys_mount("..", ".", NULL, MS_MOVE, NULL);
  75        /* switch root and cwd back to / of rootfs */
  76        ksys_chroot("..");
  77
  78        if (new_decode_dev(real_root_dev) == Root_RAM0) {
  79                ksys_chdir("/old");
  80                return;
  81        }
  82
  83        ksys_chdir("/");
  84        ROOT_DEV = new_decode_dev(real_root_dev);
  85        mount_root();
  86
  87        printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  88        error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  89        if (!error)
  90                printk("okay\n");
  91        else {
  92                int fd = ksys_open("/dev/root.old", O_RDWR, 0);
  93                if (error == -ENOENT)
  94                        printk("/initrd does not exist. Ignored.\n");
  95                else
  96                        printk("failed\n");
  97                printk(KERN_NOTICE "Unmounting old root\n");
  98                ksys_umount("/old", MNT_DETACH);
  99                printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 100                if (fd < 0) {
 101                        error = fd;
 102                } else {
 103                        error = ksys_ioctl(fd, BLKFLSBUF, 0);
 104                        ksys_close(fd);
 105                }
 106                printk(!error ? "okay\n" : "failed\n");
 107        }
 108}
 109
 110bool __init initrd_load(void)
 111{
 112        if (mount_initrd) {
 113                create_dev("/dev/ram", Root_RAM0);
 114                /*
 115                 * Load the initrd data into /dev/ram0. Execute it as initrd
 116                 * unless /dev/ram0 is supposed to be our actual root device,
 117                 * in that case the ram disk is just set up here, and gets
 118                 * mounted in the normal path.
 119                 */
 120                if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 121                        ksys_unlink("/initrd.image");
 122                        handle_initrd();
 123                        return true;
 124                }
 125        }
 126        ksys_unlink("/initrd.image");
 127        return false;
 128}
 129