blob: 7a2e597ae0db500262a7eb70711050cacceb3f17 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
// Copyright (c) 2020 Johannes Stoelp
#pragma once
#include <stdint.h>
/// ----------
/// ELF Header
/// ----------
// Index into `ident`.
#define EI_MAG0 0
#define EI_MAG1 1
#define EI_MAG2 2
#define EI_MAG3 3
#define EI_CLASS 4
#define EI_DATA 5
#define EI_OSABI 7
// indent[EI_CLASS]
#define ELFCLASS32 1
#define ELFCLASS64 2
// indent[EI_CLASS]
#define ELFDATA2LSB 1
#define ELFDATA2MSB 2
// indent[EI_OSABI]
#define ELFOSABI_SYSV 0
// Objec file `type`.
#define ET_NONE 0
#define ET_DYN 3
typedef struct {
uint8_t ident[16]; // ELF identification.
uint16_t type; // Object file type.
uint16_t machine; // Machine type.
uint32_t version; // Object file version.
uint64_t entry; // Entrypoint address.
uint64_t phoff; // Program header file offset.
uint64_t shoff; // Section header file offset.
uint32_t flags; // Processor specific flags.
uint16_t ehsize; // ELF header size.
uint16_t phentsize; // Program header entry size.
uint16_t phnum; // Number of program header entries.
uint16_t shentsize; // Section header entry size.
uint16_t shnum; // Number of section header entries.
uint16_t shstrndx; // Section name string table index.
} Elf64Ehdr;
/// --------------
/// Program Header
/// --------------
#define PT_NULL 0 /* ignored */
#define PT_LOAD 1 /* Mark loadable segment (allowed p_memsz > p_filesz). */
#define PT_DYNAMIC 2 /* Location of .dynamic section */
#define PT_INTERP 3 /* Location of .interp section */
#define PT_NOTE 4 /* Location of auxiliary information */
#define PT_SHLIB 5 /* Reserved, but unspecified semantic */
#define PT_PHDR 6 /* Location & size of program headers itself */
#define PT_GNU_EH_FRAME 0x6474e550 /* [x86-64] stack unwinding tables */
#define PT_LOPROC 0x70000000
#define PT_HIPROC 0x7fffffff
#define PF_X 0x1 /* Phdr flag eXecute flag bitmask */
#define PF_W 0x2 /* Phdr flag Write flag bitmask */
#define PF_R 0x4 /* Phdr flag Read flag bitmask */
typedef struct {
uint32_t type; // Segment kind.
uint32_t flags; // Flags describing Segment attributes like R, W, X.
uint64_t offset; // Offset into the file where the Segment starts.
uint64_t vaddr; // Virtual address of first byte of Segment in memory.
uint64_t paddr; // Physical address, ignored in our case.
uint64_t filesz; // Number of bytes of the Segment in the file image.
uint64_t memsz; // Number of bytes of the segement in memory.
uint64_t align;
} Elf64Phdr;
/// ---------------
/// Dynamic Section
/// ---------------
#define DT_NULL 0 /* [ignored] Marks end of dynamic section */
#define DT_NEEDED 1 /* [val] Name of needed library */
#define DT_PLTRELSZ 2 /* [val] Size in bytes of PLT relocs */
#define DT_PLTGOT 3 /* [ptr] Processor defined value */
#define DT_HASH 4 /* [ptr] Address of symbol hash table */
#define DT_STRTAB 5 /* [ptr] Address of string table */
#define DT_SYMTAB 6 /* [ptr] Address of symbol table */
#define DT_RELA 7 /* [ptr] Address of Rela relocs */
#define DT_RELASZ 8 /* [val] Total size of Rela relocs */
#define DT_RELAENT 9 /* [val] Size of one Rela reloc */
#define DT_STRSZ 10 /* [val] Size of string table */
#define DT_SYMENT 11 /* [val] Size of one symbol table entry */
#define DT_INIT 12 /* [ptr] Address of init function */
#define DT_FINI 13 /* [ptr] Address of termination function */
#define DT_SONAME 14 /* [val] Name of shared object */
#define DT_RPATH 15 /* [val] Library search path (deprecated) */
#define DT_SYMBOLIC 16 /* [ignored] Start symbol search here */
#define DT_REL 17 /* [ptr] Address of Rel relocs */
#define DT_RELSZ 18 /* [val] Total size of Rel relocs */
#define DT_RELENT 19 /* [val] Size of one Rel reloc */
#define DT_PLTREL 20 /* [val] Type of reloc in PLT */
#define DT_DEBUG 21 /* [ptr] For debugging; unspecified */
#define DT_TEXTREL 22 /* [ignored] Reloc might modify .text */
#define DT_JMPREL 23 /* [ptr] Address of PLT relocs */
#define DT_BIND_NOW 24 /* [ignored] Process relocations of object */
#define DT_INIT_ARRAY 25 /* [ptr] Address of array of initialization functions */
#define DT_FINI_ARRAY 26 /* [ptr] Address of array of termination functions */
#define DT_INIT_ARRAYSZ 27 /* [val] Size in bytes of the initialization array */
#define DT_FINI_ARRAYSZ 28 /* [val] Size in bytes of the termination array */
#define DT_MAX_CNT 29
typedef struct {
uint64_t tag;
union {
uint64_t val;
void* ptr;
};
} Elf64Dyn;
/// ------------
/// Symbol Entry
/// ------------
typedef struct {
uint32_t name; // Symbol name (index into string table).
uint8_t info; // Symbol Binding bits[7..4] + Symbol Type bits[3..0].
uint8_t other; // Reserved.
uint16_t shndx; // Section table index.
uint64_t value; //
uint64_t size; //
} Elf64Sym;
#define ELF64_ST_BIND(i) ((i) >> 4)
#define ELF64_ST_TYPE(i) ((i)&0xf)
// Symbold Bindings.
#define STB_GLOBAL 1 /* Global symbol, visible to all object files. */
#define STB_WEAK 2 /* Global scope, but with lower precedence than global symbols. */
// Symbol Types.
#define STT_NOTYPE 0 /* No type. */
#define STT_OBJECT 1 /* Data Object. */
#define STT_FUNC 2 /* Function entry point. */
// Special Section Indicies.
#define SHN_UNDEF 0 /* Undefined section. */
#define SHN_ABS 0xff1 /* Indicates an absolute value. */
/// -----------------
/// Relocations Entry
/// -----------------
typedef struct {
uint64_t offset; // Virtual address of the storage unit affected by the relocation.
uint64_t info; // Symbol table index + relocation type.
} Elf64Rel;
typedef struct {
uint64_t offset; // Virtual address of the storage unit affected by the relocation.
uint64_t info; // Symbol table index + relocation type.
int64_t addend; // Constant value used to compute the relocation value.
} Elf64Rela;
#define ELF64_R_SYM(i) ((i) >> 32)
#define ELF64_R_TYPE(i) ((i)&0xffffffffL)
// x86_64 relocation types.
#define R_X86_64_64 1 /* Absolute 64bit address, address affected by relocation: `base + offset` */
#define R_X86_64_COPY 5 /* Copy content from sym addr to relocation address: `base + offset` */
#define R_X86_64_GLOB_DAT 6 /* Address affected by relocation: `base + offset` */
#define R_X86_64_JUMP_SLOT 7 /* Address affected by relocation: `base + offset` */
#define R_X86_64_RELATIVE 8 /* Relative address *`base + offset` = `base + addend` */
|
