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133 lines
3.8 KiB
C++
133 lines
3.8 KiB
C++
#include "ELFLoader.h"
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#include <AK/kstdio.h>
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//#define ELFLOADER_DEBUG
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#ifdef SERENITY
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ELFLoader::ELFLoader(ExecSpace& execSpace, ByteBuffer&& file)
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#else
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ELFLoader::ELFLoader(ExecSpace& execSpace, MappedFile&& file)
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#endif
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: m_execSpace(execSpace)
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{
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m_image = make<ELFImage>(move(file));
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}
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ELFLoader::~ELFLoader()
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{
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}
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bool ELFLoader::load()
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{
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#ifdef ELFLOADER_DEBUG
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m_image->dump();
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#endif
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if (!m_image->isValid())
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return false;
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layout();
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exportSymbols();
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performRelocations();
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return true;
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}
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void ELFLoader::layout()
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{
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#ifdef ELFLOADER_DEBUG
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kprintf("[ELFLoader] Layout\n");
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#endif
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m_image->forEachSectionOfType(SHT_PROGBITS, [this] (const ELFImage::Section& section) {
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#ifdef ELFLOADER_DEBUG
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kprintf("[ELFLoader] Allocating progbits section: %s\n", section.name());
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#endif
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char* ptr = m_execSpace.allocateArea(section.name(), section.size());
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memcpy(ptr, section.rawData(), section.size());
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m_sections.set(section.name(), move(ptr));
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});
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}
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void* ELFLoader::lookup(const ELFImage::Symbol& symbol)
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{
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if (symbol.section().isUndefined())
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return m_execSpace.symbolPtr(symbol.name());
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return areaForSection(symbol.section()) + symbol.value();
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}
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char* ELFLoader::areaForSection(const ELFImage::Section& section)
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{
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return areaForSectionName(section.name());
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}
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char* ELFLoader::areaForSectionName(const char* name)
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{
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if (auto it = m_sections.find(name); it != m_sections.end())
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return (*it).value;
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ASSERT_NOT_REACHED();
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return nullptr;
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}
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void ELFLoader::performRelocations()
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{
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#ifdef ELFLOADER_DEBUG
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kprintf("[ELFLoader] Performing relocations\n");
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#endif
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m_image->forEachSectionOfType(SHT_PROGBITS, [this] (const ELFImage::Section& section) {
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auto& relocations = section.relocations();
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if (relocations.isUndefined())
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return;
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relocations.forEachRelocation([this, section] (const ELFImage::Relocation& relocation) {
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auto symbol = relocation.symbol();
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auto& patchPtr = *reinterpret_cast<ptrdiff_t*>(areaForSection(section) + relocation.offset());
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switch (relocation.type()) {
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case R_386_PC32: {
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char* targetPtr = (char*)lookup(symbol);
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ptrdiff_t relativeOffset = (char*)targetPtr - ((char*)&patchPtr + 4);
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#ifdef ELFLOADER_DEBUG
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kprintf("[ELFLoader] Relocate PC32: offset=%x, symbol=%u(%s) value=%x target=%p, offset=%d\n",
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relocation.offset(),
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symbol.index(),
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symbol.name(),
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symbol.value(),
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targetPtr,
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relativeOffset
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);
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#endif
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patchPtr = relativeOffset;
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break;
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}
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case R_386_32: {
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#ifdef ELFLOADER_DEBUG
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kprintf("[ELFLoader] Relocate Abs32: symbol=%u(%s), value=%x, section=%s\n",
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symbol.index(),
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symbol.name(),
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symbol.value(),
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symbol.section().name()
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);
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#endif
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char* targetPtr = areaForSection(symbol.section()) + symbol.value();
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patchPtr += (ptrdiff_t)targetPtr;
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break;
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}
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default:
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ASSERT_NOT_REACHED();
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break;
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}
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});
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});
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}
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void ELFLoader::exportSymbols()
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{
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m_image->forEachSymbol([&] (const ELFImage::Symbol symbol) {
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#ifdef ELFLOADER_DEBUG
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kprintf("symbol: %u, type=%u, name=%s, section=%u\n", symbol.index(), symbol.type(), symbol.name(), symbol.sectionIndex());
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#endif
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if (symbol.type() == STT_FUNC)
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m_execSpace.addSymbol(symbol.name(), areaForSection(symbol.section()) + symbol.value(), symbol.size());
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// FIXME: What about other symbol types?
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});
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}
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