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| Source at commit 296 created 12 years 10 months ago. By ifabio, add i386 folder | |
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| 1 | /*␊ |
| 2 | * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.␊ |
| 3 | *␊ |
| 4 | * @APPLE_LICENSE_HEADER_START@␊ |
| 5 | * ␊ |
| 6 | * This file contains Original Code and/or Modifications of Original Code␊ |
| 7 | * as defined in and that are subject to the Apple Public Source License␊ |
| 8 | * Version 2.0 (the 'License'). You may not use this file except in␊ |
| 9 | * compliance with the License. Please obtain a copy of the License at␊ |
| 10 | * http://www.opensource.apple.com/apsl/ and read it before using this␊ |
| 11 | * file.␊ |
| 12 | * ␊ |
| 13 | * The Original Code and all software distributed under the License are␊ |
| 14 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER␊ |
| 15 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,␊ |
| 16 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,␊ |
| 17 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.␊ |
| 18 | * Please see the License for the specific language governing rights and␊ |
| 19 | * limitations under the License.␊ |
| 20 | * ␊ |
| 21 | * @APPLE_LICENSE_HEADER_END@␊ |
| 22 | */␊ |
| 23 | /*␉$NetBSD: exec.h,v 1.6 1994/10/27 04:16:05 cgd Exp $␉*/␊ |
| 24 | ␊ |
| 25 | /*␊ |
| 26 | * Copyright (c) 1993 Christopher G. Demetriou␊ |
| 27 | * All rights reserved.␊ |
| 28 | *␊ |
| 29 | * Redistribution and use in source and binary forms, with or without␊ |
| 30 | * modification, are permitted provided that the following conditions␊ |
| 31 | * are met:␊ |
| 32 | * 1. Redistributions of source code must retain the above copyright␊ |
| 33 | * notice, this list of conditions and the following disclaimer.␊ |
| 34 | * 2. Redistributions in binary form must reproduce the above copyright␊ |
| 35 | * notice, this list of conditions and the following disclaimer in the␊ |
| 36 | * documentation and/or other materials provided with the distribution.␊ |
| 37 | * 3. The name of the author may not be used to endorse or promote products␊ |
| 38 | * derived from this software without specific prior written permission␊ |
| 39 | *␊ |
| 40 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR␊ |
| 41 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES␊ |
| 42 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.␊ |
| 43 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,␊ |
| 44 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT␊ |
| 45 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,␊ |
| 46 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY␊ |
| 47 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT␊ |
| 48 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF␊ |
| 49 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.␊ |
| 50 | */␊ |
| 51 | ␊ |
| 52 | #ifndef _MACHO_RELOC_H_␊ |
| 53 | #define _MACHO_RELOC_H_␊ |
| 54 | #include <stdint.h>␊ |
| 55 | ␊ |
| 56 | /*␊ |
| 57 | * Format of a relocation entry of a Mach-O file. Modified from the 4.3BSD␊ |
| 58 | * format. The modifications from the original format were changing the value␊ |
| 59 | * of the r_symbolnum field for "local" (r_extern == 0) relocation entries.␊ |
| 60 | * This modification is required to support symbols in an arbitrary number of␊ |
| 61 | * sections not just the three sections (text, data and bss) in a 4.3BSD file.␊ |
| 62 | * Also the last 4 bits have had the r_type tag added to them.␊ |
| 63 | */␊ |
| 64 | struct relocation_info {␊ |
| 65 | int32_t␉r_address;␉/* offset in the section to what is being␊ |
| 66 | ␉␉␉␉ relocated */␊ |
| 67 | uint32_t r_symbolnum:24,␉/* symbol index if r_extern == 1 or section␊ |
| 68 | ␉␉␉␉ ordinal if r_extern == 0 */␊ |
| 69 | ␉␉r_pcrel:1, ␉/* was relocated pc relative already */␊ |
| 70 | ␉␉r_length:2,␉/* 0=byte, 1=word, 2=long, 3=quad */␊ |
| 71 | ␉␉r_extern:1,␉/* does not include value of sym referenced */␊ |
| 72 | ␉␉r_type:4;␉/* if not 0, machine specific relocation type */␊ |
| 73 | };␊ |
| 74 | #define␉R_ABS␉0␉␉/* absolute relocation type for Mach-O files */␊ |
| 75 | ␊ |
| 76 | /*␊ |
| 77 | * The r_address is not really the address as it's name indicates but an offset.␊ |
| 78 | * In 4.3BSD a.out objects this offset is from the start of the "segment" for␊ |
| 79 | * which relocation entry is for (text or data). For Mach-O object files it is␊ |
| 80 | * also an offset but from the start of the "section" for which the relocation␊ |
| 81 | * entry is for. See comments in <mach-o/loader.h> about the r_address feild␊ |
| 82 | * in images for used with the dynamic linker.␊ |
| 83 | * ␊ |
| 84 | * In 4.3BSD a.out objects if r_extern is zero then r_symbolnum is an ordinal␊ |
| 85 | * for the segment the symbol being relocated is in. These ordinals are the␊ |
| 86 | * symbol types N_TEXT, N_DATA, N_BSS or N_ABS. In Mach-O object files these␊ |
| 87 | * ordinals refer to the sections in the object file in the order their section␊ |
| 88 | * structures appear in the headers of the object file they are in. The first␊ |
| 89 | * section has the ordinal 1, the second 2, and so on. This means that the␊ |
| 90 | * same ordinal in two different object files could refer to two different␊ |
| 91 | * sections. And further could have still different ordinals when combined␊ |
| 92 | * by the link-editor. The value R_ABS is used for relocation entries for␊ |
| 93 | * absolute symbols which need no further relocation.␊ |
| 94 | */␊ |
| 95 | ␊ |
| 96 | /*␊ |
| 97 | * For RISC machines some of the references are split across two instructions␊ |
| 98 | * and the instruction does not contain the complete value of the reference.␊ |
| 99 | * In these cases a second, or paired relocation entry, follows each of these␊ |
| 100 | * relocation entries, using a PAIR r_type, which contains the other part of the␊ |
| 101 | * reference not contained in the instruction. This other part is stored in the␊ |
| 102 | * pair's r_address field. The exact number of bits of the other part of the␊ |
| 103 | * reference store in the r_address field is dependent on the particular␊ |
| 104 | * relocation type for the particular architecture.␊ |
| 105 | */␊ |
| 106 | ␊ |
| 107 | /*␊ |
| 108 | * To make scattered loading by the link editor work correctly "local"␊ |
| 109 | * relocation entries can't be used when the item to be relocated is the value␊ |
| 110 | * of a symbol plus an offset (where the resulting expresion is outside the␊ |
| 111 | * block the link editor is moving, a blocks are divided at symbol addresses).␊ |
| 112 | * In this case. where the item is a symbol value plus offset, the link editor␊ |
| 113 | * needs to know more than just the section the symbol was defined. What is␊ |
| 114 | * needed is the actual value of the symbol without the offset so it can do the␊ |
| 115 | * relocation correctly based on where the value of the symbol got relocated to␊ |
| 116 | * not the value of the expression (with the offset added to the symbol value).␊ |
| 117 | * So for the NeXT 2.0 release no "local" relocation entries are ever used when␊ |
| 118 | * there is a non-zero offset added to a symbol. The "external" and "local"␊ |
| 119 | * relocation entries remain unchanged.␊ |
| 120 | *␊ |
| 121 | * The implemention is quite messy given the compatibility with the existing␊ |
| 122 | * relocation entry format. The ASSUMPTION is that a section will never be␊ |
| 123 | * bigger than 2**24 - 1 (0x00ffffff or 16,777,215) bytes. This assumption␊ |
| 124 | * allows the r_address (which is really an offset) to fit in 24 bits and high␊ |
| 125 | * bit of the r_address field in the relocation_info structure to indicate␊ |
| 126 | * it is really a scattered_relocation_info structure. Since these are only␊ |
| 127 | * used in places where "local" relocation entries are used and not where␊ |
| 128 | * "external" relocation entries are used the r_extern field has been removed.␊ |
| 129 | *␊ |
| 130 | * For scattered loading to work on a RISC machine where some of the references␊ |
| 131 | * are split across two instructions the link editor needs to be assured that␊ |
| 132 | * each reference has a unique 32 bit reference (that more than one reference is␊ |
| 133 | * NOT sharing the same high 16 bits for example) so it move each referenced␊ |
| 134 | * item independent of each other. Some compilers guarantees this but the␊ |
| 135 | * compilers don't so scattered loading can be done on those that do guarantee␊ |
| 136 | * this.␊ |
| 137 | */␊ |
| 138 | #if defined(__BIG_ENDIAN__) || defined(__LITTLE_ENDIAN__)␊ |
| 139 | /*␊ |
| 140 | * The reason for the ifdef's of __BIG_ENDIAN__ and __LITTLE_ENDIAN__ are that␊ |
| 141 | * when stattered relocation entries were added the mistake of using a mask␊ |
| 142 | * against a structure that is made up of bit fields was used. To make this␊ |
| 143 | * design work this structure must be laid out in memory the same way so the␊ |
| 144 | * mask can be applied can check the same bit each time (r_scattered).␊ |
| 145 | */␊ |
| 146 | #endif /* defined(__BIG_ENDIAN__) || defined(__LITTLE_ENDIAN__) */␊ |
| 147 | #define R_SCATTERED 0x80000000␉/* mask to be applied to the r_address field ␊ |
| 148 | ␉␉␉␉ of a relocation_info structure to tell that␊ |
| 149 | ␉␉␉␉ is is really a scattered_relocation_info␊ |
| 150 | ␉␉␉␉ stucture */␊ |
| 151 | struct scattered_relocation_info {␊ |
| 152 | #ifdef __BIG_ENDIAN__␊ |
| 153 | uint32_t␉r_scattered:1,␉/* 1=scattered, 0=non-scattered (see above) */␊ |
| 154 | ␉␉r_pcrel:1, ␉/* was relocated pc relative already */␊ |
| 155 | ␉␉r_length:2,␉/* 0=byte, 1=word, 2=long, 3=quad */␊ |
| 156 | ␉␉r_type:4,␉/* if not 0, machine specific relocation type */␊ |
| 157 | ␉␉r_address:24;␉/* offset in the section to what is being␊ |
| 158 | ␉␉␉␉ relocated */␊ |
| 159 | int32_t␉r_value;␉/* the value the item to be relocated is␊ |
| 160 | ␉␉␉␉ refering to (without any offset added) */␊ |
| 161 | #endif /* __BIG_ENDIAN__ */␊ |
| 162 | #ifdef __LITTLE_ENDIAN__␊ |
| 163 | uint32_t␊ |
| 164 | ␉␉r_address:24,␉/* offset in the section to what is being␊ |
| 165 | ␉␉␉␉ relocated */␊ |
| 166 | ␉␉r_type:4,␉/* if not 0, machine specific relocation type */␊ |
| 167 | ␉␉r_length:2,␉/* 0=byte, 1=word, 2=long, 3=quad */␊ |
| 168 | ␉␉r_pcrel:1, ␉/* was relocated pc relative already */␊ |
| 169 | ␉␉r_scattered:1;␉/* 1=scattered, 0=non-scattered (see above) */␊ |
| 170 | int32_t␉r_value;␉/* the value the item to be relocated is␊ |
| 171 | ␉␉␉␉ refering to (without any offset added) */␊ |
| 172 | #endif /* __LITTLE_ENDIAN__ */␊ |
| 173 | };␊ |
| 174 | ␊ |
| 175 | /*␊ |
| 176 | * Relocation types used in a generic implementation. Relocation entries for␊ |
| 177 | * normal things use the generic relocation as discribed above and their r_type␊ |
| 178 | * is GENERIC_RELOC_VANILLA (a value of zero).␊ |
| 179 | *␊ |
| 180 | * Another type of generic relocation, GENERIC_RELOC_SECTDIFF, is to support␊ |
| 181 | * the difference of two symbols defined in different sections. That is the␊ |
| 182 | * expression "symbol1 - symbol2 + constant" is a relocatable expression when␊ |
| 183 | * both symbols are defined in some section. For this type of relocation the␊ |
| 184 | * both relocations entries are scattered relocation entries. The value of␊ |
| 185 | * symbol1 is stored in the first relocation entry's r_value field and the␊ |
| 186 | * value of symbol2 is stored in the pair's r_value field.␊ |
| 187 | *␊ |
| 188 | * A special case for a prebound lazy pointer is needed to beable to set the␊ |
| 189 | * value of the lazy pointer back to its non-prebound state. This is done␊ |
| 190 | * using the GENERIC_RELOC_PB_LA_PTR r_type. This is a scattered relocation␊ |
| 191 | * entry where the r_value feild is the value of the lazy pointer not prebound.␊ |
| 192 | */␊ |
| 193 | enum reloc_type_generic␊ |
| 194 | {␊ |
| 195 | GENERIC_RELOC_VANILLA,␉/* generic relocation as discribed above */␊ |
| 196 | GENERIC_RELOC_PAIR,␉␉/* Only follows a GENERIC_RELOC_SECTDIFF */␊ |
| 197 | GENERIC_RELOC_SECTDIFF,␊ |
| 198 | GENERIC_RELOC_PB_LA_PTR,␉/* prebound lazy pointer */␊ |
| 199 | GENERIC_RELOC_LOCAL_SECTDIFF,␊ |
| 200 | GENERIC_RELOC_TLV␉␉/* thread local variables */␊ |
| 201 | };␊ |
| 202 | ␊ |
| 203 | #endif /* _MACHO_RELOC_H_ */␊ |
| 204 | |
