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
|
// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <vector>
#include "common/common_funcs.h"
#include "common/logging/log.h"
#include "common/swap.h"
#include "core/loader/linker.h"
#include "core/memory.h"
namespace Loader {
enum class RelocationType : u32 { ABS64 = 257, GLOB_DAT = 1025, JUMP_SLOT = 1026, RELATIVE = 1027 };
enum DynamicType : u32 {
DT_NULL = 0,
DT_PLTRELSZ = 2,
DT_STRTAB = 5,
DT_SYMTAB = 6,
DT_RELA = 7,
DT_RELASZ = 8,
DT_STRSZ = 10,
DT_JMPREL = 23,
};
struct Elf64_Rela {
u64_le offset;
RelocationType type;
u32_le symbol;
s64_le addend;
};
static_assert(sizeof(Elf64_Rela) == 0x18, "Elf64_Rela has incorrect size.");
struct Elf64_Dyn {
u64_le tag;
u64_le value;
};
static_assert(sizeof(Elf64_Dyn) == 0x10, "Elf64_Dyn has incorrect size.");
struct Elf64_Sym {
u32_le name;
INSERT_PADDING_BYTES(0x2);
u16_le shndx;
u64_le value;
u64_le size;
};
static_assert(sizeof(Elf64_Sym) == 0x18, "Elf64_Sym has incorrect size.");
void Linker::WriteRelocations(std::vector<u8>& program_image, const std::vector<Symbol>& symbols,
u64 relocation_offset, u64 size, bool is_jump_relocation,
VAddr load_base) {
for (u64 i = 0; i < size; i += sizeof(Elf64_Rela)) {
Elf64_Rela rela;
std::memcpy(&rela, &program_image[relocation_offset + i], sizeof(Elf64_Rela));
const Symbol& symbol = symbols[rela.symbol];
switch (rela.type) {
case RelocationType::RELATIVE: {
const u64 value = load_base + rela.addend;
if (!symbol.name.empty()) {
exports[symbol.name] = value;
}
std::memcpy(&program_image[rela.offset], &value, sizeof(u64));
break;
}
case RelocationType::JUMP_SLOT:
case RelocationType::GLOB_DAT:
if (!symbol.value) {
imports[symbol.name] = {rela.offset + load_base, 0};
} else {
exports[symbol.name] = symbol.value;
std::memcpy(&program_image[rela.offset], &symbol.value, sizeof(u64));
}
break;
case RelocationType::ABS64:
if (!symbol.value) {
imports[symbol.name] = {rela.offset + load_base, rela.addend};
} else {
const u64 value = symbol.value + rela.addend;
exports[symbol.name] = value;
std::memcpy(&program_image[rela.offset], &value, sizeof(u64));
}
break;
default:
NGLOG_CRITICAL(Loader, "Unknown relocation type: {}", static_cast<int>(rela.type));
break;
}
}
}
void Linker::Relocate(std::vector<u8>& program_image, u32 dynamic_section_offset, VAddr load_base) {
std::map<u64, u64> dynamic;
while (dynamic_section_offset < program_image.size()) {
Elf64_Dyn dyn;
std::memcpy(&dyn, &program_image[dynamic_section_offset], sizeof(Elf64_Dyn));
dynamic_section_offset += sizeof(Elf64_Dyn);
if (dyn.tag == DT_NULL) {
break;
}
dynamic[dyn.tag] = dyn.value;
}
u64 offset = dynamic[DT_SYMTAB];
std::vector<Symbol> symbols;
while (offset < program_image.size()) {
Elf64_Sym sym;
std::memcpy(&sym, &program_image[offset], sizeof(Elf64_Sym));
offset += sizeof(Elf64_Sym);
if (sym.name >= dynamic[DT_STRSZ]) {
break;
}
std::string name = reinterpret_cast<char*>(&program_image[dynamic[DT_STRTAB] + sym.name]);
if (sym.value) {
exports[name] = load_base + sym.value;
symbols.emplace_back(std::move(name), load_base + sym.value);
} else {
symbols.emplace_back(std::move(name), 0);
}
}
if (dynamic.find(DT_RELA) != dynamic.end()) {
WriteRelocations(program_image, symbols, dynamic[DT_RELA], dynamic[DT_RELASZ], false,
load_base);
}
if (dynamic.find(DT_JMPREL) != dynamic.end()) {
WriteRelocations(program_image, symbols, dynamic[DT_JMPREL], dynamic[DT_PLTRELSZ], true,
load_base);
}
}
void Linker::ResolveImports() {
// Resolve imports
for (const auto& import : imports) {
const auto& search = exports.find(import.first);
if (search != exports.end()) {
Memory::Write64(import.second.ea, search->second + import.second.addend);
} else {
NGLOG_ERROR(Loader, "Unresolved import: {}", import.first);
}
}
}
} // namespace Loader
|
