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 __FBSDID("$FreeBSD$"); 29 30 #include <sys/types.h> 31 #include <elf.h> 32 #include <bootstrap.h> 33 34 #if defined(__aarch64__) || defined(__amd64__) || defined(__riscv) 35 #define ElfW_Rel Elf64_Rela 36 #define ElfW_Dyn Elf64_Dyn 37 #define ELFW_R_TYPE ELF64_R_TYPE 38 #define ELF_RELA 39 #elif defined(__arm__) || defined(__i386__) 40 #define ElfW_Rel Elf32_Rel 41 #define ElfW_Dyn Elf32_Dyn 42 #define ELFW_R_TYPE ELF32_R_TYPE 43 #else 44 #error architecture not supported 45 #endif 46 #if defined(__aarch64__) 47 #define RELOC_TYPE_NONE R_AARCH64_NONE 48 #define RELOC_TYPE_RELATIVE R_AARCH64_RELATIVE 49 #elif defined(__amd64__) 50 #define RELOC_TYPE_NONE R_X86_64_NONE 51 #define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE 52 #elif defined(__arm__) 53 #define RELOC_TYPE_NONE R_ARM_NONE 54 #define RELOC_TYPE_RELATIVE R_ARM_RELATIVE 55 #elif defined(__i386__) 56 #define RELOC_TYPE_NONE R_386_NONE 57 #define RELOC_TYPE_RELATIVE R_386_RELATIVE 58 #elif defined(__riscv) 59 #define RELOC_TYPE_NONE R_RISCV_NONE 60 #define RELOC_TYPE_RELATIVE R_RISCV_RELATIVE 61 #endif 62 63 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic); 64 65 /* 66 * A simple elf relocator. 67 */ 68 void 69 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic) 70 { 71 Elf_Word relsz, relent; 72 Elf_Addr *newaddr; 73 ElfW_Rel *rel; 74 ElfW_Dyn *dynp; 75 76 /* 77 * Find the relocation address, its size and the relocation entry. 78 */ 79 relsz = 0; 80 relent = 0; 81 for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) { 82 switch (dynp->d_tag) { 83 case DT_REL: 84 case DT_RELA: 85 rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr); 86 break; 87 case DT_RELSZ: 88 case DT_RELASZ: 89 relsz = dynp->d_un.d_val; 90 break; 91 case DT_RELENT: 92 case DT_RELAENT: 93 relent = dynp->d_un.d_val; 94 break; 95 default: 96 break; 97 } 98 } 99 100 /* 101 * Perform the actual relocation. We rely on the object having been 102 * linked at 0, so that the difference between the load and link 103 * address is the same as the load address. 104 */ 105 for (; relsz > 0; relsz -= relent) { 106 switch (ELFW_R_TYPE(rel->r_info)) { 107 case RELOC_TYPE_NONE: 108 /* No relocation needs be performed. */ 109 break; 110 111 case RELOC_TYPE_RELATIVE: 112 newaddr = (Elf_Addr *)(rel->r_offset + baseaddr); 113 #ifdef ELF_RELA 114 /* Addend relative to the base address. */ 115 *newaddr = baseaddr + rel->r_addend; 116 #else 117 /* Address relative to the base address. */ 118 *newaddr += baseaddr; 119 #endif 120 break; 121 default: 122 /* XXX: do we need other relocations ? */ 123 break; 124 } 125 rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent); 126 } 127 } 128