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citra/src/core/loader/elf.cpp
Lioncash 661f7bbcfd core: Make converting constructors explicit where applicable 
Avoids unwanted implicit conversions. Thankfully, given the large amount
of cleanup in past PRs, only this tiny amount is left over to cover.
2018-07-30 08:21:13 +08:00

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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.
#include <cstring>
#include <memory>
#include <string>
#include "common/common_types.h"
#include "common/file_util.h"
#include "common/logging/log.h"
#include "core/hle/kernel/process.h"
#include "core/hle/kernel/resource_limit.h"
#include "core/loader/elf.h"
#include "core/memory.h"
using Kernel::CodeSet;
using Kernel::SharedPtr;
////////////////////////////////////////////////////////////////////////////////////////////////////
// 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;
u32 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);
}
u32 GetEntryPoint() const {
return entryPoint;
}
u32 GetFlags() const {
return (u32)(header->e_flags);
}
SharedPtr<CodeSet> LoadInto(u32 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
bool DidRelocate() const {
return relocate;
}
};
ElfReader::ElfReader(void* ptr) {
base = (char*)ptr;
base32 = (u32*)ptr;
header = (Elf32_Ehdr*)ptr;
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;
const char* ptr = reinterpret_cast<const char*>(GetSectionDataPtr(header->e_shstrndx));
if (ptr)
return ptr + name_offset;
return nullptr;
}
SharedPtr<CodeSet> ElfReader::LoadInto(u32 vaddr) {
LOG_DEBUG(Loader, "String section: {}", header->e_shstrndx);
// Should we relocate?
relocate = (header->e_type != ET_EXEC);
if (relocate) {
LOG_DEBUG(Loader, "Relocatable module");
entryPoint += vaddr;
} else {
LOG_DEBUG(Loader, "Prerelocated executable");
}
LOG_DEBUG(Loader, "{} segments:", header->e_phnum);
// First pass : Get the bits into RAM
u32 base_addr = relocate ? vaddr : 0;
u32 total_image_size = 0;
for (unsigned int i = 0; i < header->e_phnum; ++i) {
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);
size_t current_image_position = 0;
SharedPtr<CodeSet> codeset = CodeSet::Create("", 0);
for (unsigned int i = 0; i < header->e_phnum; ++i) {
Elf32_Phdr* p = &segments[i];
LOG_DEBUG(Loader, "Type: {} Vaddr: {:08X} Filesz: {:08X} Memsz: {:08X} ", p->p_type,
p->p_vaddr, p->p_filesz, p->p_memsz);
if (p->p_type == PT_LOAD) {
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->code;
} else if (permission_flags == (PF_R)) {
codeset_segment = &codeset->rodata;
} else if (permission_flags == (PF_R | PF_W)) {
codeset_segment = &codeset->data;
} else {
LOG_ERROR(Loader, "Unexpected ELF PT_LOAD segment id {} with flags {:X}", i,
p->p_flags);
continue;
}
if (codeset_segment->size != 0) {
LOG_ERROR(Loader,
"ELF has more than one segment of the same type. Skipping extra "
"segment (id {})",
i);
continue;
}
u32 segment_addr = base_addr + p->p_vaddr;
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));
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 {
FileType AppLoader_ELF::IdentifyType(FileUtil::IOFile& file) {
u32 magic;
file.Seek(0, SEEK_SET);
if (1 != file.ReadArray<u32>(&magic, 1))
return FileType::Error;
if (MakeMagic('\x7f', 'E', 'L', 'F') == magic)
return FileType::ELF;
return FileType::Error;
}
ResultStatus AppLoader_ELF::Load(Kernel::SharedPtr<Kernel::Process>& process) {
if (is_loaded)
return ResultStatus::ErrorAlreadyLoaded;
if (!file.IsOpen())
return ResultStatus::Error;
// Reset read pointer in case this file has been read before.
file.Seek(0, SEEK_SET);
size_t size = file.GetSize();
std::unique_ptr<u8[]> buffer(new u8[size]);
if (file.ReadBytes(&buffer[0], size) != size)
return ResultStatus::Error;
ElfReader elf_reader(&buffer[0]);
SharedPtr<CodeSet> codeset = elf_reader.LoadInto(Memory::PROCESS_IMAGE_VADDR);
codeset->name = filename;
process = Kernel::Process::Create(std::move(codeset));
process->svc_access_mask.set();
process->address_mappings = default_address_mappings;
// Attach the default resource limit (APPLICATION) to the process
process->resource_limit =
Kernel::ResourceLimit::GetForCategory(Kernel::ResourceLimitCategory::APPLICATION);
process->Run(48, Kernel::DEFAULT_STACK_SIZE);
is_loaded = true;
return ResultStatus::Success;
}
} // namespace Loader
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