diff options
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/image/elf.c')
| -rw-r--r-- | contrib/syslinux-4.02/gpxe/src/image/elf.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/image/elf.c b/contrib/syslinux-4.02/gpxe/src/image/elf.c new file mode 100644 index 0000000..a0ec065 --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/image/elf.c @@ -0,0 +1,162 @@ +/* + * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** + * @file + * + * ELF image format + * + * A "pure" ELF image is not a bootable image. There are various + * bootable formats based upon ELF (e.g. Multiboot), which share + * common ELF-related functionality. + */ + +#include <errno.h> +#include <elf.h> +#include <gpxe/uaccess.h> +#include <gpxe/segment.h> +#include <gpxe/image.h> +#include <gpxe/elf.h> + +typedef Elf32_Ehdr Elf_Ehdr; +typedef Elf32_Phdr Elf_Phdr; +typedef Elf32_Off Elf_Off; + +/** + * Load ELF segment into memory + * + * @v image ELF file + * @v phdr ELF program header + * @v ehdr ELF executable header + * @ret rc Return status code + */ +static int elf_load_segment ( struct image *image, Elf_Phdr *phdr, + Elf_Ehdr *ehdr ) { + physaddr_t dest; + userptr_t buffer; + unsigned long e_offset; + int rc; + + /* Do nothing for non-PT_LOAD segments */ + if ( phdr->p_type != PT_LOAD ) + return 0; + + /* Check segment lies within image */ + if ( ( phdr->p_offset + phdr->p_filesz ) > image->len ) { + DBGC ( image, "ELF %p segment outside image\n", image ); + return -ENOEXEC; + } + + /* Find start address: use physical address for preference, + * fall back to virtual address if no physical address + * supplied. + */ + dest = phdr->p_paddr; + if ( ! dest ) + dest = phdr->p_vaddr; + if ( ! dest ) { + DBGC ( image, "ELF %p segment loads to physical address 0\n", + image ); + return -ENOEXEC; + } + buffer = phys_to_user ( dest ); + + DBGC ( image, "ELF %p loading segment [%x,%x) to [%x,%x,%x)\n", image, + phdr->p_offset, ( phdr->p_offset + phdr->p_filesz ), + phdr->p_paddr, ( phdr->p_paddr + phdr->p_filesz ), + ( phdr->p_paddr + phdr->p_memsz ) ); + + /* Verify and prepare segment */ + if ( ( rc = prep_segment ( buffer, phdr->p_filesz, + phdr->p_memsz ) ) != 0 ) { + DBGC ( image, "ELF %p could not prepare segment: %s\n", + image, strerror ( rc ) ); + return rc; + } + + /* Copy image to segment */ + memcpy_user ( buffer, 0, image->data, phdr->p_offset, phdr->p_filesz ); + + /* Set execution address, if it lies within this segment */ + if ( ( e_offset = ( ehdr->e_entry - dest ) ) < phdr->p_filesz ) { + image->priv.phys = ehdr->e_entry; + DBGC ( image, "ELF %p found physical entry point at %lx\n", + image, image->priv.phys ); + } else if ( ( e_offset = ( ehdr->e_entry - phdr->p_vaddr ) ) + < phdr->p_filesz ) { + if ( ! image->priv.phys ) { + image->priv.phys = ( dest + e_offset ); + DBGC ( image, "ELF %p found virtual entry point at %lx" + " (virt %lx)\n", image, image->priv.phys, + ( ( unsigned long ) ehdr->e_entry ) ); + } + } + + return 0; +} + +/** + * Load ELF image into memory + * + * @v image ELF file + * @ret rc Return status code + */ +int elf_load ( struct image *image ) { + Elf_Ehdr ehdr; + Elf_Phdr phdr; + Elf_Off phoff; + unsigned int phnum; + int rc; + + /* Image type must already have been set by caller */ + assert ( image->type != NULL ); + + /* Read ELF header */ + copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) ); + if ( memcmp ( &ehdr.e_ident[EI_MAG0], ELFMAG, SELFMAG ) != 0 ) { + DBGC ( image, "ELF %p has invalid signature\n", image ); + return -ENOEXEC; + } + + /* Invalidate execution address */ + image->priv.phys = 0; + + /* Read ELF program headers */ + for ( phoff = ehdr.e_phoff , phnum = ehdr.e_phnum ; phnum ; + phoff += ehdr.e_phentsize, phnum-- ) { + if ( phoff > image->len ) { + DBGC ( image, "ELF %p program header %d outside " + "image\n", image, phnum ); + return -ENOEXEC; + } + copy_from_user ( &phdr, image->data, phoff, sizeof ( phdr ) ); + if ( ( rc = elf_load_segment ( image, &phdr, &ehdr ) ) != 0 ) + return rc; + } + + /* Check for a valid execution address */ + if ( ! image->priv.phys ) { + DBGC ( image, "ELF %p entry point %lx outside image\n", + image, ( ( unsigned long ) ehdr.e_entry ) ); + return -ENOEXEC; + } + + return 0; +} |