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