1/* $OpenBSD: self_reloc.c,v 1.3 2018/10/20 11:59:07 kettenis Exp $ */ 2/*- 3 * Copyright (c) 2008-2010 Rui Paulo <rpaulo@FreeBSD.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/param.h> 29#include <machine/reloc.h> 30 31#if defined(__aarch64__) || defined(__amd64__) 32#define ELFSIZE 64 33#define ElfW_Rel Elf64_Rela 34#define ElfW_Dyn Elf64_Dyn 35#define ELFW_R_TYPE ELF64_R_TYPE 36#define ELF_RELA 37#elif defined(__arm__) || defined(__i386__) 38#define ELFSIZE 32 39#define ElfW_Rel Elf32_Rel 40#define ElfW_Dyn Elf32_Dyn 41#define ELFW_R_TYPE ELF32_R_TYPE 42#else 43#error architecture not supported 44#endif 45 46#include <sys/exec_elf.h> 47 48#if defined(__aarch64__) 49#define RELOC_TYPE_NONE R_AARCH64_NONE 50#define RELOC_TYPE_RELATIVE R_AARCH64_RELATIVE 51#elif defined(__amd64__) 52#define RELOC_TYPE_NONE R_X86_64_NONE 53#define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE 54#elif defined(__arm__) 55#define RELOC_TYPE_NONE R_ARM_NONE 56#define RELOC_TYPE_RELATIVE R_ARM_RELATIVE 57#elif defined(__i386__) 58#define RELOC_TYPE_NONE R_386_NONE 59#define RELOC_TYPE_RELATIVE R_386_RELATIVE 60#endif 61 62/* 63 * A simple elf relocator. 64 */ 65void 66self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic) 67{ 68 Elf_Word relsz, relent; 69 Elf_Addr *newaddr; 70 ElfW_Rel *rel = NULL; 71 ElfW_Dyn *dynp; 72 73 /* 74 * Find the relocation address, its size and the relocation entry. 75 */ 76 relsz = 0; 77 relent = 0; 78 for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) { 79 switch (dynp->d_tag) { 80 case DT_REL: 81 case DT_RELA: 82 rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr); 83 break; 84 case DT_RELSZ: 85 case DT_RELASZ: 86 relsz = dynp->d_un.d_val; 87 break; 88 case DT_RELENT: 89 case DT_RELAENT: 90 relent = dynp->d_un.d_val; 91 break; 92 default: 93 break; 94 } 95 } 96 97 /* 98 * Perform the actual relocation. We rely on the object having been 99 * linked at 0, so that the difference between the load and link 100 * address is the same as the load address. 101 */ 102 for (; relsz > 0; relsz -= relent) { 103 switch (ELFW_R_TYPE(rel->r_info)) { 104 case RELOC_TYPE_NONE: 105 /* No relocation needs be performed. */ 106 break; 107 108 case RELOC_TYPE_RELATIVE: 109 newaddr = (Elf_Addr *)(rel->r_offset + baseaddr); 110#ifdef ELF_RELA 111 /* Addend relative to the base address. */ 112 *newaddr = baseaddr + rel->r_addend; 113#else 114 /* Address relative to the base address. */ 115 *newaddr += baseaddr; 116#endif 117 break; 118 default: 119 /* XXX: do we need other relocations ? */ 120 break; 121 } 122 rel = (ElfW_Rel *) ((caddr_t) rel + relent); 123 } 124} 125