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 * $FreeBSD: head/sys/boot/common/self_reloc.c 293724 2016-01-12 02:17:39Z smh $ 27 */ 28 29 #include <sys/types.h> 30 #include <elf.h> 31 #include <bootstrap.h> 32 #include <stddef.h> 33 34 #if defined(__aarch64__) 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(__x86_64__) 40 #define ElfW_Rel Elf64_Rel 41 #define ElfW_Dyn Elf64_Dyn 42 #define ELFW_R_TYPE ELF64_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(__x86_64__) 50 #define RELOC_TYPE_NONE R_X86_64_NONE 51 #define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE 52 #endif 53 54 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic); 55 56 /* 57 * A simple elf relocator. 58 */ 59 void 60 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic) 61 { 62 Elf_Word relsz, relent; 63 Elf_Addr *newaddr; 64 ElfW_Rel *rel = NULL; 65 ElfW_Dyn *dynp; 66 67 /* 68 * Find the relocation address, its size and the relocation entry. 69 */ 70 relsz = 0; 71 relent = 0; 72 for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) { 73 switch (dynp->d_tag) { 74 case DT_REL: 75 case DT_RELA: 76 rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr); 77 break; 78 case DT_RELSZ: 79 case DT_RELASZ: 80 relsz = dynp->d_un.d_val; 81 break; 82 case DT_RELENT: 83 case DT_RELAENT: 84 relent = dynp->d_un.d_val; 85 break; 86 default: 87 break; 88 } 89 } 90 91 /* 92 * Perform the actual relocation. 93 */ 94 for (; relsz > 0; relsz -= relent) { 95 switch (ELFW_R_TYPE(rel->r_info)) { 96 case RELOC_TYPE_NONE: 97 /* No relocation needs be performed. */ 98 break; 99 100 case RELOC_TYPE_RELATIVE: 101 /* Address relative to the base address. */ 102 newaddr = (Elf_Addr *)(rel->r_offset + baseaddr); 103 *newaddr += baseaddr; 104 /* Add the addend when the ABI uses them */ 105 #ifdef ELF_RELA 106 *newaddr += rel->r_addend; 107 #endif 108 break; 109 default: 110 /* XXX: do we need other relocations ? */ 111 break; 112 } 113 rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent); 114 } 115 } 116