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Annotation of qemu/roms/ipxe/src/image/elf.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (C) 2007 Michael Brown <[email protected]>.
        !             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: /**
        !            22:  * @file
        !            23:  *
        !            24:  * ELF image format
        !            25:  *
        !            26:  * A "pure" ELF image is not a bootable image.  There are various
        !            27:  * bootable formats based upon ELF (e.g. Multiboot), which share
        !            28:  * common ELF-related functionality.
        !            29:  */
        !            30: 
        !            31: #include <errno.h>
        !            32: #include <elf.h>
        !            33: #include <ipxe/uaccess.h>
        !            34: #include <ipxe/segment.h>
        !            35: #include <ipxe/image.h>
        !            36: #include <ipxe/elf.h>
        !            37: 
        !            38: typedef Elf32_Ehdr     Elf_Ehdr;
        !            39: typedef Elf32_Phdr     Elf_Phdr;
        !            40: typedef Elf32_Off      Elf_Off;
        !            41: 
        !            42: /**
        !            43:  * Load ELF segment into memory
        !            44:  *
        !            45:  * @v image            ELF file
        !            46:  * @v phdr             ELF program header
        !            47:  * @v ehdr             ELF executable header
        !            48:  * @ret entry          Entry point, if found
        !            49:  * @ret rc             Return status code
        !            50:  */
        !            51: static int elf_load_segment ( struct image *image, Elf_Phdr *phdr,
        !            52:                              Elf_Ehdr *ehdr, physaddr_t *entry ) {
        !            53:        physaddr_t dest;
        !            54:        userptr_t buffer;
        !            55:        unsigned long e_offset;
        !            56:        int rc;
        !            57: 
        !            58:        /* Do nothing for non-PT_LOAD segments */
        !            59:        if ( phdr->p_type != PT_LOAD )
        !            60:                return 0;
        !            61: 
        !            62:        /* Check segment lies within image */
        !            63:        if ( ( phdr->p_offset + phdr->p_filesz ) > image->len ) {
        !            64:                DBGC ( image, "ELF %p segment outside image\n", image );
        !            65:                return -ENOEXEC;
        !            66:        }
        !            67: 
        !            68:        /* Find start address: use physical address for preference,
        !            69:         * fall back to virtual address if no physical address
        !            70:         * supplied.
        !            71:         */
        !            72:        dest = phdr->p_paddr;
        !            73:        if ( ! dest )
        !            74:                dest = phdr->p_vaddr;
        !            75:        if ( ! dest ) {
        !            76:                DBGC ( image, "ELF %p segment loads to physical address 0\n",
        !            77:                       image );
        !            78:                return -ENOEXEC;
        !            79:        }
        !            80:        buffer = phys_to_user ( dest );
        !            81: 
        !            82:        DBGC ( image, "ELF %p loading segment [%x,%x) to [%x,%x,%x)\n", image,
        !            83:               phdr->p_offset, ( phdr->p_offset + phdr->p_filesz ),
        !            84:               phdr->p_paddr, ( phdr->p_paddr + phdr->p_filesz ),
        !            85:               ( phdr->p_paddr + phdr->p_memsz ) );
        !            86: 
        !            87:        /* Verify and prepare segment */
        !            88:        if ( ( rc = prep_segment ( buffer, phdr->p_filesz,
        !            89:                                   phdr->p_memsz ) ) != 0 ) {
        !            90:                DBGC ( image, "ELF %p could not prepare segment: %s\n",
        !            91:                       image, strerror ( rc ) );
        !            92:                return rc;
        !            93:        }
        !            94: 
        !            95:        /* Copy image to segment */
        !            96:        memcpy_user ( buffer, 0, image->data, phdr->p_offset, phdr->p_filesz );
        !            97: 
        !            98:        /* Set execution address, if it lies within this segment */
        !            99:        if ( ( e_offset = ( ehdr->e_entry - dest ) ) < phdr->p_filesz ) {
        !           100:                *entry = ehdr->e_entry;
        !           101:                DBGC ( image, "ELF %p found physical entry point at %lx\n",
        !           102:                       image, *entry );
        !           103:        } else if ( ( e_offset = ( ehdr->e_entry - phdr->p_vaddr ) )
        !           104:                    < phdr->p_filesz ) {
        !           105:                if ( ! *entry ) {
        !           106:                        *entry = ( dest + e_offset );
        !           107:                        DBGC ( image, "ELF %p found virtual entry point at %lx"
        !           108:                               " (virt %lx)\n", image, *entry,
        !           109:                               ( ( unsigned long ) ehdr->e_entry ) );
        !           110:                }
        !           111:        }
        !           112: 
        !           113:        return 0;
        !           114: }
        !           115: 
        !           116: /**
        !           117:  * Load ELF image into memory
        !           118:  *
        !           119:  * @v image            ELF file
        !           120:  * @ret entry          Entry point
        !           121:  * @ret rc             Return status code
        !           122:  */
        !           123: int elf_load ( struct image *image, physaddr_t *entry ) {
        !           124:        Elf_Ehdr ehdr;
        !           125:        Elf_Phdr phdr;
        !           126:        Elf_Off phoff;
        !           127:        unsigned int phnum;
        !           128:        int rc;
        !           129: 
        !           130:        /* Read ELF header */
        !           131:        copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
        !           132:        if ( memcmp ( &ehdr.e_ident[EI_MAG0], ELFMAG, SELFMAG ) != 0 ) {
        !           133:                DBGC ( image, "ELF %p has invalid signature\n", image );
        !           134:                return -ENOEXEC;
        !           135:        }
        !           136: 
        !           137:        /* Invalidate entry point */
        !           138:        *entry = 0;
        !           139: 
        !           140:        /* Read ELF program headers */
        !           141:        for ( phoff = ehdr.e_phoff , phnum = ehdr.e_phnum ; phnum ;
        !           142:              phoff += ehdr.e_phentsize, phnum-- ) {
        !           143:                if ( phoff > image->len ) {
        !           144:                        DBGC ( image, "ELF %p program header %d outside "
        !           145:                               "image\n", image, phnum );
        !           146:                        return -ENOEXEC;
        !           147:                }
        !           148:                copy_from_user ( &phdr, image->data, phoff, sizeof ( phdr ) );
        !           149:                if ( ( rc = elf_load_segment ( image, &phdr, &ehdr,
        !           150:                                               entry ) ) != 0 ) {
        !           151:                        return rc;
        !           152:                }
        !           153:        }
        !           154: 
        !           155:        /* Check for a valid execution address */
        !           156:        if ( ! *entry ) {
        !           157:                DBGC ( image, "ELF %p entry point %lx outside image\n",
        !           158:                       image, ( ( unsigned long ) ehdr.e_entry ) );
        !           159:                return -ENOEXEC;
        !           160:        }
        !           161: 
        !           162:        return 0;
        !           163: }

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