src/arch/i386/image/elfboot.c

   1 /*
   2  * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <errno.h>
  22 #include <elf.h>
  23 #include <gpxe/image.h>
  24 #include <gpxe/elf.h>
  25 #include <gpxe/features.h>
  26 #include <gpxe/init.h>
  27
  28 /**
  29  * @file
  30  *
  31  * ELF bootable image
  32  *
  33  */
  34
  35 FEATURE ( FEATURE_IMAGE, "ELF", DHCP_EB_FEATURE_ELF, 1 );
  36
  37 struct image_type elfboot_image_type __image_type ( PROBE_NORMAL );
  38
  39 /**
  40  * Execute ELF image
  41  *
  42  * @v image             ELF image
  43  * @ret rc              Return status code
  44  */
  45 static int elfboot_exec ( struct image *image ) {
  46         physaddr_t entry = image->priv.phys;
  47
  48         /* An ELF image has no callback interface, so we need to shut
  49          * down before invoking it.
  50          */
  51         shutdown ( SHUTDOWN_BOOT );
  52
  53         /* Jump to OS with flat physical addressing */
  54         DBGC ( image, "ELF %p starting execution at %lx\n", image, entry );
  55         __asm__ __volatile__ ( PHYS_CODE ( "call *%%edi\n\t" )
  56                                : : "D" ( entry )
  57                                : "eax", "ebx", "ecx", "edx", "esi", "ebp",
  58                                  "memory" );
  59
  60         DBGC ( image, "ELF %p returned\n", image );
  61
  62         /* It isn't safe to continue after calling shutdown() */
  63         while ( 1 ) {}
  64
  65         return -ECANCELED;  /* -EIMPOSSIBLE, anyone? */
  66 }
  67
  68 /**
  69  * Load ELF image into memory
  70  *
  71  * @v image             ELF file
  72  * @ret rc              Return status code
  73  */
  74 static int elfboot_load ( struct image *image ) {
  75         Elf32_Ehdr ehdr;
  76         static const uint8_t e_ident[] = {
  77                 [EI_MAG0]       = ELFMAG0,
  78                 [EI_MAG1]       = ELFMAG1,
  79                 [EI_MAG2]       = ELFMAG2,
  80                 [EI_MAG3]       = ELFMAG3,
  81                 [EI_CLASS]      = ELFCLASS32,
  82                 [EI_DATA]       = ELFDATA2LSB,
  83                 [EI_VERSION]    = EV_CURRENT,
  84         };
  85         int rc;
  86
  87         /* Read ELF header */
  88         copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
  89         if ( memcmp ( ehdr.e_ident, e_ident, sizeof ( e_ident ) ) != 0 ) {
  90                 DBG ( "Invalid ELF identifier\n" );
  91                 return -ENOEXEC;
  92         }
  93
  94         /* This is an ELF image, valid or otherwise */
  95         if ( ! image->type )
  96                 image->type = &elfboot_image_type;
  97
  98         /* Load the image using core ELF support */
  99         if ( ( rc = elf_load ( image ) ) != 0 ) {
 100                 DBGC ( image, "ELF %p could not load: %s\n",
 101                        image, strerror ( rc ) );
 102                 return rc;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /** ELF image type */
 109 struct image_type elfboot_image_type __image_type ( PROBE_NORMAL ) = {
 110         .name = "ELF",
 111         .load = elfboot_load,
 112         .exec = elfboot_exec,
 113 };