mirror of
https://git.suyu.dev/suyu/suyu.git
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151 lines
4.6 KiB
C++
151 lines
4.6 KiB
C++
// Copyright 2017 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <vector>
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#include "common/common_funcs.h"
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#include "common/logging/log.h"
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#include "common/swap.h"
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#include "core/loader/linker.h"
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#include "core/memory.h"
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namespace Loader {
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enum class RelocationType : u32 { ABS64 = 257, GLOB_DAT = 1025, JUMP_SLOT = 1026, RELATIVE = 1027 };
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enum DynamicType : u32 {
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DT_NULL = 0,
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DT_PLTRELSZ = 2,
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DT_STRTAB = 5,
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DT_SYMTAB = 6,
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DT_RELA = 7,
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DT_RELASZ = 8,
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DT_STRSZ = 10,
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DT_JMPREL = 23,
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};
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struct Elf64_Rela {
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u64_le offset;
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RelocationType type;
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u32_le symbol;
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s64_le addend;
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};
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static_assert(sizeof(Elf64_Rela) == 0x18, "Elf64_Rela has incorrect size.");
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struct Elf64_Dyn {
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u64_le tag;
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u64_le value;
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};
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static_assert(sizeof(Elf64_Dyn) == 0x10, "Elf64_Dyn has incorrect size.");
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struct Elf64_Sym {
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u32_le name;
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INSERT_PADDING_BYTES(0x2);
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u16_le shndx;
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u64_le value;
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u64_le size;
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};
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static_assert(sizeof(Elf64_Sym) == 0x18, "Elf64_Sym has incorrect size.");
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void Linker::WriteRelocations(std::vector<u8>& program_image,
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const std::vector<Symbol>& symbols, u64 relocation_offset,
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u64 size, bool is_jump_relocation, VAddr load_base) {
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for (u64 i = 0; i < size; i += sizeof(Elf64_Rela)) {
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Elf64_Rela rela;
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std::memcpy(&rela, &program_image[relocation_offset + i], sizeof(Elf64_Rela));
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const Symbol& symbol = symbols[rela.symbol];
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switch (rela.type) {
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case RelocationType::RELATIVE: {
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const u64 value = load_base + rela.addend;
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if (!symbol.name.empty()) {
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exports[symbol.name] = value;
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}
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std::memcpy(&program_image[rela.offset], &value, sizeof(u64));
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break;
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}
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case RelocationType::JUMP_SLOT:
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case RelocationType::GLOB_DAT:
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if (!symbol.value) {
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imports[symbol.name] = {rela.offset + load_base, 0};
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} else {
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exports[symbol.name] = symbol.value;
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std::memcpy(&program_image[rela.offset], &symbol.value, sizeof(u64));
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}
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break;
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case RelocationType::ABS64:
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if (!symbol.value) {
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imports[symbol.name] = {rela.offset + load_base, rela.addend};
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} else {
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const u64 value = symbol.value + rela.addend;
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exports[symbol.name] = value;
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std::memcpy(&program_image[rela.offset], &value, sizeof(u64));
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}
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break;
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default:
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LOG_CRITICAL(Loader, "Unknown relocation type: %d", rela.type);
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break;
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}
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}
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}
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void Linker::Relocate(std::vector<u8>& program_image, u32 dynamic_section_offset,
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VAddr load_base) {
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std::map<u64, u64> dynamic;
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while (dynamic_section_offset < program_image.size()) {
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Elf64_Dyn dyn;
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std::memcpy(&dyn, &program_image[dynamic_section_offset], sizeof(Elf64_Dyn));
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dynamic_section_offset += sizeof(Elf64_Dyn);
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if (dyn.tag == DT_NULL) {
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break;
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}
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dynamic[dyn.tag] = dyn.value;
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}
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u64 offset = dynamic[DT_SYMTAB];
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std::vector<Symbol> symbols;
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while (offset < program_image.size()) {
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Elf64_Sym sym;
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std::memcpy(&sym, &program_image[offset], sizeof(Elf64_Sym));
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offset += sizeof(Elf64_Sym);
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if (sym.name >= dynamic[DT_STRSZ]) {
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break;
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}
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std::string name = reinterpret_cast<char*>(&program_image[dynamic[DT_STRTAB] + sym.name]);
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if (sym.value) {
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exports[name] = load_base + sym.value;
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symbols.emplace_back(std::move(name), load_base + sym.value);
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} else {
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symbols.emplace_back(std::move(name), 0);
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}
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}
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if (dynamic.find(DT_RELA) != dynamic.end()) {
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WriteRelocations(program_image, symbols, dynamic[DT_RELA], dynamic[DT_RELASZ], false,
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load_base);
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}
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if (dynamic.find(DT_JMPREL) != dynamic.end()) {
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WriteRelocations(program_image, symbols, dynamic[DT_JMPREL], dynamic[DT_PLTRELSZ], true,
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load_base);
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}
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}
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void Linker::ResolveImports() {
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// Resolve imports
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for (const auto& import : imports) {
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const auto& search = exports.find(import.first);
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if (search != exports.end()) {
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Memory::Write64(import.second.ea, search->second + import.second.addend);
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}
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else {
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LOG_ERROR(Loader, "Unresolved import: %s", import.first.c_str());
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}
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}
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}
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} // namespace Loader
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