[ELF] Add ability to boot ELF images generated by wraplinux and mkelfImage
Delete ELF as a generic image type. The method for invoking an ELF-based image (as well as any tables that must be set up to allow it to boot) will always depend on the specific architecture. core/elf.c now only provides the elf_load() function, to avoid duplicating functionality between ELF-based image types. Add arch/i386/image/elfboot.c, to handle the generic case of 32-bit x86 ELF images. We don't currently set up any multiboot tables, ELF notes, etc. This seems to be sufficient for loading kernels generated using both wraplinux and coreboot's mkelfImage. Note that while Etherboot 5.4 allowed ELF images to return, we don't. There is no callback mechanism for the loaded image to shut down gPXE, which means that we have to shut down before invoking the image. This means that we lose device state, protection against being trampled on, etc. It is not safe to continue afterwards.
This commit is contained in:
Michael Brown
parent
fe3162ab1c
commit
77a5cc6b13
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/*
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* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <errno.h>
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#include <elf.h>
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#include <gpxe/image.h>
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#include <gpxe/elf.h>
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#include <gpxe/features.h>
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#include <gpxe/init.h>
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/**
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* @file
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*
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* ELF bootable image
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*
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*/
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FEATURE ( FEATURE_IMAGE, "ELF", DHCP_EB_FEATURE_ELF, 1 );
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struct image_type elfboot_image_type __image_type ( PROBE_NORMAL );
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/**
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* Execute ELF image
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*
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* @v image ELF image
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* @ret rc Return status code
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*/
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static int elfboot_exec ( struct image *image ) {
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physaddr_t entry = image->priv.phys;
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/* An ELF image has no callback interface, so we need to shut
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* down before invoking it.
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*/
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shutdown();
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/* Jump to OS with flat physical addressing */
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__asm__ __volatile__ ( PHYS_CODE ( "call *%%edi\n\t" )
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: : "D" ( entry )
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: "eax", "ebx", "ecx", "edx", "esi", "ebp",
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"memory" );
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DBGC ( image, "ELF %p returned\n", image );
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/* It isn't safe to continue after calling shutdown() */
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while ( 1 ) {}
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return -ECANCELED; /* -EIMPOSSIBLE, anyone? */
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}
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/**
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* Load ELF image into memory
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*
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* @v image ELF file
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* @ret rc Return status code
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*/
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static int elfboot_load ( struct image *image ) {
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Elf32_Ehdr ehdr;
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static const uint8_t e_ident[] = {
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[EI_MAG0] = ELFMAG0,
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[EI_MAG1] = ELFMAG1,
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[EI_MAG2] = ELFMAG2,
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[EI_MAG3] = ELFMAG3,
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[EI_CLASS] = ELFCLASS32,
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[EI_DATA] = ELFDATA2LSB,
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[EI_VERSION] = EV_CURRENT,
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};
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int rc;
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/* Read ELF header */
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copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
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if ( memcmp ( ehdr.e_ident, e_ident, sizeof ( e_ident ) ) != 0 ) {
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DBG ( "Invalid ELF identifier\n" );
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return -ENOEXEC;
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}
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/* This is an ELF image, valid or otherwise */
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if ( ! image->type )
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image->type = &elfboot_image_type;
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/* Load the image using core ELF support */
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if ( ( rc = elf_load ( image ) ) != 0 ) {
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DBGC ( image, "ELF %p could not load: %s\n",
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image, strerror ( rc ) );
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return rc;
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}
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return 0;
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}
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/** ELF image type */
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struct image_type elfboot_image_type __image_type ( PROBE_NORMAL ) = {
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.name = "ELF",
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.load = elfboot_load,
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.exec = elfboot_exec,
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};
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@ -20,6 +20,7 @@
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#define ERRFILE_multiboot ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00030000 )
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#define ERRFILE_nbi ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00040000 )
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#define ERRFILE_pxe_image ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00050000 )
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#define ERRFILE_elfboot ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00060000 )
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#define ERRFILE_undi ( ERRFILE_ARCH | ERRFILE_NET | 0x00000000 )
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#define ERRFILE_undiload ( ERRFILE_ARCH | ERRFILE_NET | 0x00010000 )
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@ -121,8 +121,7 @@
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*
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*/
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#undef IMAGE_NBI /* NBI image support */
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#undef IMAGE_ELF64 /* ELF64 image support */
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#undef IMAGE_ELF /* ELF image support */
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#define IMAGE_ELF /* ELF image support */
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#undef IMAGE_FREEBSD /* FreeBSD kernel image support */
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#define IMAGE_MULTIBOOT /* MultiBoot image support */
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#undef IMAGE_AOUT /* a.out image support */
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@ -131,11 +131,8 @@ REQUIRE_OBJECT ( nmb );
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#ifdef IMAGE_NBI
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REQUIRE_OBJECT ( nbi );
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#endif
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#ifdef IMAGE_ELF64
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REQUIRE_OBJECT ( elf64 );
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#endif
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#ifdef IMAGE_ELF
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REQUIRE_OBJECT ( elf );
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REQUIRE_OBJECT ( elfboot );
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#endif
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#ifdef IMAGE_FREEBSD
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REQUIRE_OBJECT ( freebsd );
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@ -21,6 +21,9 @@
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*
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* ELF image format
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*
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* A "pure" ELF image is not a bootable image. There are various
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* bootable formats based upon ELF (e.g. Multiboot), which share
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* common ELF-related functionality.
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*/
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#include <errno.h>
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@ -30,22 +33,10 @@
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#include <gpxe/image.h>
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#include <gpxe/elf.h>
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struct image_type elf_image_type __image_type ( PROBE_NORMAL );
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typedef Elf32_Ehdr Elf_Ehdr;
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typedef Elf32_Phdr Elf_Phdr;
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typedef Elf32_Off Elf_Off;
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/**
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* Execute ELF image
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*
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* @v image ELF file
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* @ret rc Return status code
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*/
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static int elf_exec ( struct image *image __unused ) {
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return -ENOTSUP;
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}
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/**
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* Load ELF segment into memory
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*
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@ -112,6 +103,9 @@ int elf_load ( struct image *image ) {
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unsigned int phnum;
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int rc;
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/* Image type must already have been set by caller */
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assert ( image->type != NULL );
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/* Read ELF header */
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copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
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if ( memcmp ( &ehdr.e_ident[EI_MAG0], ELFMAG, SELFMAG ) != 0 ) {
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@ -119,10 +113,6 @@ int elf_load ( struct image *image ) {
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return -ENOEXEC;
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}
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/* This is an ELF image, valid or otherwise */
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if ( ! image->type )
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image->type = &elf_image_type;
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/* Read ELF program headers */
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for ( phoff = ehdr.e_phoff , phnum = ehdr.e_phnum ; phnum ;
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phoff += ehdr.e_phentsize, phnum-- ) {
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@ -141,10 +131,3 @@ int elf_load ( struct image *image ) {
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return 0;
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}
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/** ELF image type */
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struct image_type elf_image_type __image_type ( PROBE_NORMAL ) = {
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.name = "ELF",
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.load = elf_load,
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.exec = elf_exec,
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};
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@ -43,6 +43,7 @@
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#define DHCP_EB_FEATURE_MULTIBOOT 0x19 /**< Multiboot format */
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#define DHCP_EB_FEATURE_NBI 0x20 /**< NBI format */
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#define DHCP_EB_FEATURE_PXE 0x21 /**< PXE format */
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#define DHCP_EB_FEATURE_ELF 0x22 /**< ELF format */
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/** @} */
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