yuzu/src/core/loader/elf.cpp

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// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
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#include <cstring>
#include <memory>
#include <string>
#include "common/common_funcs.h"
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#include "common/common_types.h"
#include "common/file_util.h"
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#include "common/logging/log.h"
#include "core/hle/kernel/code_set.h"
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#include "core/hle/kernel/process.h"
#include "core/hle/kernel/vm_manager.h"
#include "core/loader/elf.h"
#include "core/memory.h"
////////////////////////////////////////////////////////////////////////////////////////////////////
// ELF Header Constants
// File type
enum ElfType {
ET_NONE = 0,
ET_REL = 1,
ET_EXEC = 2,
ET_DYN = 3,
ET_CORE = 4,
ET_LOPROC = 0xFF00,
ET_HIPROC = 0xFFFF,
};
// Machine/Architecture
enum ElfMachine {
EM_NONE = 0,
EM_M32 = 1,
EM_SPARC = 2,
EM_386 = 3,
EM_68K = 4,
EM_88K = 5,
EM_860 = 7,
EM_MIPS = 8
};
// File version
#define EV_NONE 0
#define EV_CURRENT 1
// Identification index
#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_VERSION 6
#define EI_PAD 7
#define EI_NIDENT 16
// Sections constants
// Section types
#define SHT_NULL 0
#define SHT_PROGBITS 1
#define SHT_SYMTAB 2
#define SHT_STRTAB 3
#define SHT_RELA 4
#define SHT_HASH 5
#define SHT_DYNAMIC 6
#define SHT_NOTE 7
#define SHT_NOBITS 8
#define SHT_REL 9
#define SHT_SHLIB 10
#define SHT_DYNSYM 11
#define SHT_LOPROC 0x70000000
#define SHT_HIPROC 0x7FFFFFFF
#define SHT_LOUSER 0x80000000
#define SHT_HIUSER 0xFFFFFFFF
// Section flags
enum ElfSectionFlags {
SHF_WRITE = 0x1,
SHF_ALLOC = 0x2,
SHF_EXECINSTR = 0x4,
SHF_MASKPROC = 0xF0000000,
};
// Segment types
#define PT_NULL 0
#define PT_LOAD 1
#define PT_DYNAMIC 2
#define PT_INTERP 3
#define PT_NOTE 4
#define PT_SHLIB 5
#define PT_PHDR 6
#define PT_LOPROC 0x70000000
#define PT_HIPROC 0x7FFFFFFF
// Segment flags
#define PF_X 0x1
#define PF_W 0x2
#define PF_R 0x4
#define PF_MASKPROC 0xF0000000
typedef unsigned int Elf32_Addr;
typedef unsigned short Elf32_Half;
typedef unsigned int Elf32_Off;
typedef signed int Elf32_Sword;
typedef unsigned int Elf32_Word;
////////////////////////////////////////////////////////////////////////////////////////////////////
// ELF file header
struct Elf32_Ehdr {
unsigned char e_ident[EI_NIDENT];
Elf32_Half e_type;
Elf32_Half e_machine;
Elf32_Word e_version;
Elf32_Addr e_entry;
Elf32_Off e_phoff;
Elf32_Off e_shoff;
Elf32_Word e_flags;
Elf32_Half e_ehsize;
Elf32_Half e_phentsize;
Elf32_Half e_phnum;
Elf32_Half e_shentsize;
Elf32_Half e_shnum;
Elf32_Half e_shstrndx;
};
// Section header
struct Elf32_Shdr {
Elf32_Word sh_name;
Elf32_Word sh_type;
Elf32_Word sh_flags;
Elf32_Addr sh_addr;
Elf32_Off sh_offset;
Elf32_Word sh_size;
Elf32_Word sh_link;
Elf32_Word sh_info;
Elf32_Word sh_addralign;
Elf32_Word sh_entsize;
};
// Segment header
struct Elf32_Phdr {
Elf32_Word p_type;
Elf32_Off p_offset;
Elf32_Addr p_vaddr;
Elf32_Addr p_paddr;
Elf32_Word p_filesz;
Elf32_Word p_memsz;
Elf32_Word p_flags;
Elf32_Word p_align;
};
// Symbol table entry
struct Elf32_Sym {
Elf32_Word st_name;
Elf32_Addr st_value;
Elf32_Word st_size;
unsigned char st_info;
unsigned char st_other;
Elf32_Half st_shndx;
};
// Relocation entries
struct Elf32_Rel {
Elf32_Addr r_offset;
Elf32_Word r_info;
};
////////////////////////////////////////////////////////////////////////////////////////////////////
// ElfReader class
typedef int SectionID;
class ElfReader {
private:
char* base;
u32* base32;
Elf32_Ehdr* header;
Elf32_Phdr* segments;
Elf32_Shdr* sections;
u32* sectionAddrs;
bool relocate;
VAddr entryPoint;
public:
explicit ElfReader(void* ptr);
u32 Read32(int off) const {
return base32[off >> 2];
}
// Quick accessors
ElfType GetType() const {
return (ElfType)(header->e_type);
}
ElfMachine GetMachine() const {
return (ElfMachine)(header->e_machine);
}
VAddr GetEntryPoint() const {
return entryPoint;
}
u32 GetFlags() const {
return (u32)(header->e_flags);
}
Kernel::CodeSet LoadInto(VAddr vaddr);
int GetNumSegments() const {
return (int)(header->e_phnum);
}
int GetNumSections() const {
return (int)(header->e_shnum);
}
const u8* GetPtr(int offset) const {
return (u8*)base + offset;
}
const char* GetSectionName(int section) const;
const u8* GetSectionDataPtr(int section) const {
if (section < 0 || section >= header->e_shnum)
return nullptr;
if (sections[section].sh_type != SHT_NOBITS)
return GetPtr(sections[section].sh_offset);
else
return nullptr;
}
bool IsCodeSection(int section) const {
return sections[section].sh_type == SHT_PROGBITS;
}
const u8* GetSegmentPtr(int segment) {
return GetPtr(segments[segment].p_offset);
}
u32 GetSectionAddr(SectionID section) const {
return sectionAddrs[section];
}
unsigned int GetSectionSize(SectionID section) const {
return sections[section].sh_size;
}
SectionID GetSectionByName(const char* name, int firstSection = 0) const; //-1 for not found
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bool DidRelocate() const {
return relocate;
}
};
ElfReader::ElfReader(void* ptr) {
base = (char*)ptr;
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base32 = (u32*)ptr;
header = (Elf32_Ehdr*)ptr;
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segments = (Elf32_Phdr*)(base + header->e_phoff);
sections = (Elf32_Shdr*)(base + header->e_shoff);
entryPoint = header->e_entry;
}
const char* ElfReader::GetSectionName(int section) const {
if (sections[section].sh_type == SHT_NULL)
return nullptr;
int name_offset = sections[section].sh_name;
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const char* ptr = reinterpret_cast<const char*>(GetSectionDataPtr(header->e_shstrndx));
if (ptr)
return ptr + name_offset;
return nullptr;
}
Kernel::CodeSet ElfReader::LoadInto(VAddr vaddr) {
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LOG_DEBUG(Loader, "String section: {}", header->e_shstrndx);
// Should we relocate?
relocate = (header->e_type != ET_EXEC);
if (relocate) {
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LOG_DEBUG(Loader, "Relocatable module");
entryPoint += vaddr;
} else {
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LOG_DEBUG(Loader, "Prerelocated executable");
}
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LOG_DEBUG(Loader, "{} segments:", header->e_phnum);
// First pass : Get the bits into RAM
const VAddr base_addr = relocate ? vaddr : 0;
u64 total_image_size = 0;
for (unsigned int i = 0; i < header->e_phnum; ++i) {
const Elf32_Phdr* p = &segments[i];
if (p->p_type == PT_LOAD) {
total_image_size += (p->p_memsz + 0xFFF) & ~0xFFF;
}
}
std::vector<u8> program_image(total_image_size);
std::size_t current_image_position = 0;
Kernel::CodeSet codeset;
for (unsigned int i = 0; i < header->e_phnum; ++i) {
const Elf32_Phdr* p = &segments[i];
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LOG_DEBUG(Loader, "Type: {} Vaddr: {:08X} Filesz: {:08X} Memsz: {:08X} ", p->p_type,
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p->p_vaddr, p->p_filesz, p->p_memsz);
if (p->p_type == PT_LOAD) {
Kernel::CodeSet::Segment* codeset_segment;
u32 permission_flags = p->p_flags & (PF_R | PF_W | PF_X);
if (permission_flags == (PF_R | PF_X)) {
codeset_segment = &codeset.CodeSegment();
} else if (permission_flags == (PF_R)) {
codeset_segment = &codeset.RODataSegment();
} else if (permission_flags == (PF_R | PF_W)) {
codeset_segment = &codeset.DataSegment();
} else {
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LOG_ERROR(Loader, "Unexpected ELF PT_LOAD segment id {} with flags {:X}", i,
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p->p_flags);
continue;
}
if (codeset_segment->size != 0) {
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LOG_ERROR(Loader,
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"ELF has more than one segment of the same type. Skipping extra "
"segment (id {})",
i);
continue;
}
const VAddr segment_addr = base_addr + p->p_vaddr;
const u32 aligned_size = (p->p_memsz + 0xFFF) & ~0xFFF;
codeset_segment->offset = current_image_position;
codeset_segment->addr = segment_addr;
codeset_segment->size = aligned_size;
memcpy(&program_image[current_image_position], GetSegmentPtr(i), p->p_filesz);
current_image_position += aligned_size;
}
}
codeset.entrypoint = base_addr + header->e_entry;
codeset.memory = std::make_shared<std::vector<u8>>(std::move(program_image));
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LOG_DEBUG(Loader, "Done loading.");
return codeset;
}
SectionID ElfReader::GetSectionByName(const char* name, int firstSection) const {
for (int i = firstSection; i < header->e_shnum; i++) {
const char* secname = GetSectionName(i);
if (secname != nullptr && strcmp(name, secname) == 0)
return i;
}
return -1;
}
////////////////////////////////////////////////////////////////////////////////////////////////////
// Loader namespace
namespace Loader {
AppLoader_ELF::AppLoader_ELF(FileSys::VirtualFile file) : AppLoader(std::move(file)) {}
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FileType AppLoader_ELF::IdentifyType(const FileSys::VirtualFile& file) {
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static constexpr u16 ELF_MACHINE_ARM{0x28};
u32 magic = 0;
if (4 != file->ReadObject(&magic))
return FileType::Error;
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u16 machine = 0;
if (2 != file->ReadObject(&machine, 18))
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return FileType::Error;
if (Common::MakeMagic('\x7f', 'E', 'L', 'F') == magic && ELF_MACHINE_ARM == machine)
return FileType::ELF;
return FileType::Error;
}
ResultStatus AppLoader_ELF::Load(Kernel::Process& process) {
if (is_loaded)
return ResultStatus::ErrorAlreadyLoaded;
std::vector<u8> buffer = file->ReadAllBytes();
if (buffer.size() != file->GetSize())
return ResultStatus::ErrorIncorrectELFFileSize;
const VAddr base_address = process.VMManager().GetCodeRegionBaseAddress();
ElfReader elf_reader(&buffer[0]);
Kernel::CodeSet codeset = elf_reader.LoadInto(base_address);
const VAddr entry_point = codeset.entrypoint;
process.LoadModule(std::move(codeset), entry_point);
process.Run(entry_point, 48, Memory::DEFAULT_STACK_SIZE);
is_loaded = true;
return ResultStatus::Success;
}
} // namespace Loader