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