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https://github.com/RGBCube/serenity
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Move ELFLoader code into Kernel/.
This commit is contained in:
Andreas Kling
parent
ac7a60225e
commit
44036f32bc
10 changed files with 5 additions and 27 deletions
219
Kernel/ELFLoader.cpp
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219
Kernel/ELFLoader.cpp
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#include "ELFLoader.h"
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#include <AK/kstdio.h>
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//#define ELFLOADER_DEBUG
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//#define SUPPORT_RELOCATIONS
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ELFLoader::ELFLoader(const byte* buffer)
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: m_image(buffer)
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{
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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.is_valid())
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return false;
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if (!layout())
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return false;
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#ifdef SUPPORT_RELOCATIONS
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if (!perform_relocations())
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return false;
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#endif
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return true;
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}
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bool 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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bool failed = false;
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m_image.for_each_program_header([&] (const ELFImage::ProgramHeader& program_header) {
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if (program_header.type() != PT_LOAD)
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return;
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#ifdef ELFLOADER_DEBUG
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kprintf("PH: L%x %u r:%u w:%u\n", program_header.laddr().get(), program_header.size_in_memory(), program_header.is_readable(), program_header.is_writable());
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#endif
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if (program_header.is_writable()) {
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allocate_section(program_header.laddr(), program_header.size_in_memory(), program_header.alignment(), program_header.is_readable(), program_header.is_writable());
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} else {
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map_section(program_header.laddr(), program_header.size_in_memory(), program_header.alignment(), program_header.offset(), program_header.is_readable(), program_header.is_writable());
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}
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});
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m_image.for_each_section_of_type(SHT_PROGBITS, [] (const ELFImage::Section& section) {
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#ifdef ELFLOADER_DEBUG
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kprintf("ELFLoader: Copying progbits section: %s\n", section.name());
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#endif
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if (!section.size())
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return true;
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char* ptr = (char*)section.address();
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if (!ptr) {
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#ifdef ELFLOADER_DEBUG
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kprintf("ELFLoader: ignoring section '%s' with null address\n", section.name());
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#endif
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return true;
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}
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// If this section isn't writable, it's already mmapped.
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if (section.is_writable())
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memcpy(ptr, section.raw_data(), section.size());
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#ifdef SUPPORT_RELOCATIONS
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m_sections.set(section.name(), move(ptr));
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#endif
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return true;
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});
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m_image.for_each_section_of_type(SHT_NOBITS, [&failed] (const ELFImage::Section& section) {
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#ifdef ELFLOADER_DEBUG
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kprintf("ELFLoader: Copying nobits section: %s\n", section.name());
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#endif
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if (!section.size())
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return true;
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char* ptr = (char*)section.address();
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if (!ptr) {
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kprintf("ELFLoader: failed to allocate section '%s'\n", section.name());
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failed = true;
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return false;
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}
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memset(ptr, 0, section.size());
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#ifdef SUPPORT_RELOCATIONS
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m_sections.set(section.name(), move(ptr));
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#endif
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return true;
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});
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return !failed;
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}
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#ifdef SUPPORT_RELOCATIONS
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void* ELFLoader::lookup(const ELFImage::Symbol& symbol)
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{
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if (symbol.section().is_undefined())
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return symbol_ptr(symbol.name());
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return area_for_section(symbol.section()) + symbol.value();
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}
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#endif
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#ifdef SUPPORT_RELOCATIONS
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char* ELFLoader::area_for_section(const ELFImage::Section& section)
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{
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return area_for_section_name(section.name());
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}
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char* ELFLoader::area_for_section_name(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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#endif
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#ifdef SUPPORT_RELOCATIONS
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bool ELFLoader::perform_relocations()
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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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bool failed = false;
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m_image.for_each_section_of_type(SHT_PROGBITS, [this, &failed] (const ELFImage::Section& section) -> bool {
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auto& relocations = section.relocations();
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if (relocations.is_undefined())
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return true;
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relocations.for_each_relocation([this, section, &failed] (const ELFImage::Relocation& relocation) {
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auto symbol = relocation.symbol();
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auto& patch_ptr = *reinterpret_cast<ptrdiff_t*>(area_for_section(section) + relocation.offset());
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switch (relocation.type()) {
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case R_386_PC32: {
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char* target_ptr = (char*)lookup(symbol);
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if (!target_ptr) {
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kprintf("ELFLoader: unresolved symbol '%s'\n", symbol.name());
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failed = true;
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return false;
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}
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ptrdiff_t relativeOffset = (char*)target_ptr - ((char*)&patch_ptr + 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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target_ptr,
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relativeOffset
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);
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#endif
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patch_ptr = 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* target_ptr = area_for_section(symbol.section()) + symbol.value();
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patch_ptr += (ptrdiff_t)target_ptr;
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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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return true;
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});
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return !failed;
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});
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return !failed;
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}
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#endif
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char* ELFLoader::symbol_ptr(const char* name)
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{
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char* found_ptr = nullptr;
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m_image.for_each_symbol([&] (const ELFImage::Symbol symbol) {
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if (symbol.type() != STT_FUNC)
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return true;
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if (strcmp(symbol.name(), name))
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return true;
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if (m_image.is_executable())
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found_ptr = (char*)symbol.value();
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#ifdef SUPPORT_RELOCATIONS
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else if (m_image.is_relocatable())
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found_ptr = area_for_section(symbol.section()) + symbol.value();
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#endif
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else
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ASSERT_NOT_REACHED();
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return false;
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});
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return found_ptr;
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}
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bool ELFLoader::allocate_section(LinearAddress laddr, size_t size, size_t alignment, bool is_readable, bool is_writable)
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{
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ASSERT(alloc_section_hook);
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char namebuf[16];
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ksprintf(namebuf, "elf-alloc-%s%s", is_readable ? "r" : "", is_writable ? "w" : "");
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return alloc_section_hook(laddr, size, alignment, is_readable, is_writable, namebuf);
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}
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bool ELFLoader::map_section(LinearAddress laddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable)
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{
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ASSERT(alloc_section_hook);
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char namebuf[16];
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ksprintf(namebuf, "elf-map-%s%s", is_readable ? "r" : "", is_writable ? "w" : "");
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return map_section_hook(laddr, size, alignment, offset_in_image, is_readable, is_writable, namebuf);
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}
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