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/types.h> 28 #include <elf.h> 29 #include <bootstrap.h> 30 31 #if defined(__aarch64__) || defined(__amd64__) || defined(__riscv) 32 #define ElfW_Rel Elf64_Rela 33 #define ElfW_Dyn Elf64_Dyn 34 #define ELFW_R_TYPE ELF64_R_TYPE 35 #define ELF_RELA 36 #elif defined(__arm__) || defined(__i386__) 37 #define ElfW_Rel Elf32_Rel 38 #define ElfW_Dyn Elf32_Dyn 39 #define ELFW_R_TYPE ELF32_R_TYPE 40 #else 41 #error architecture not supported 42 #endif 43 #if defined(__aarch64__) 44 #define RELOC_TYPE_NONE R_AARCH64_NONE 45 #define RELOC_TYPE_RELATIVE R_AARCH64_RELATIVE 46 #elif defined(__amd64__) 47 #define RELOC_TYPE_NONE R_X86_64_NONE 48 #define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE 49 #elif defined(__arm__) 50 #define RELOC_TYPE_NONE R_ARM_NONE 51 #define RELOC_TYPE_RELATIVE R_ARM_RELATIVE 52 #elif defined(__i386__) 53 #define RELOC_TYPE_NONE R_386_NONE 54 #define RELOC_TYPE_RELATIVE R_386_RELATIVE 55 #elif defined(__riscv) 56 #define RELOC_TYPE_NONE R_RISCV_NONE 57 #define RELOC_TYPE_RELATIVE R_RISCV_RELATIVE 58 #endif 59 60 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic); 61 62 /* 63 * A simple elf relocator. 64 */ 65 void 66 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic) 67 { 68 Elf_Word relsz, relent; 69 Elf_Addr *newaddr; 70 ElfW_Rel *rel; 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 *)(void *)((caddr_t) rel + relent); 123 } 124 } 125