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#include "ELFLoader.h"
#include <AK/Demangle.h>
#include <AK/QuickSort.h>
#include <AK/kstdio.h>
#ifdef KERNEL
#include <Kernel/VM/MemoryManager.h>
#endif
//#define ELFLOADER_DEBUG
ELFLoader::ELFLoader(const u8* buffer, size_t size)
: m_image(buffer, size)
{
}
ELFLoader::~ELFLoader()
{
}
bool ELFLoader::load()
{
#ifdef ELFLOADER_DEBUG
m_image.dump();
#endif
if (!m_image.is_valid())
return false;
if (!layout())
return false;
return true;
}
bool ELFLoader::layout()
{
bool failed = false;
m_image.for_each_program_header([&](const ELFImage::ProgramHeader& program_header) {
if (program_header.type() == PT_TLS) {
#ifdef KERNEL
auto* tls_image = tls_section_hook(program_header.size_in_memory(), program_header.alignment());
if (!tls_image) {
failed = true;
return;
}
if (!m_image.is_within_image(program_header.raw_data(), program_header.size_in_image())) {
dbg() << "Shenanigans! ELF PT_TLS header sneaks outside of executable.";
failed = true;
return;
}
memcpy(tls_image, program_header.raw_data(), program_header.size_in_image());
#endif
return;
}
if (program_header.type() != PT_LOAD)
return;
#ifdef ELFLOADER_DEBUG
kprintf("PH: V%p %u r:%u w:%u\n", program_header.vaddr().get(), program_header.size_in_memory(), program_header.is_readable(), program_header.is_writable());
#endif
#ifdef KERNEL
if (program_header.is_writable()) {
auto* allocated_section = alloc_section_hook(
program_header.vaddr(),
program_header.size_in_memory(),
program_header.alignment(),
program_header.is_readable(),
program_header.is_writable(),
String::format("elf-alloc-%s%s", program_header.is_readable() ? "r" : "", program_header.is_writable() ? "w" : ""));
if (!allocated_section) {
failed = true;
return;
}
if (!m_image.is_within_image(program_header.raw_data(), program_header.size_in_image())) {
dbg() << "Shenanigans! Writable ELF PT_LOAD header sneaks outside of executable.";
failed = true;
return;
}
memcpy(program_header.vaddr().as_ptr(), program_header.raw_data(), program_header.size_in_image());
} else {
auto* mapped_section = map_section_hook(
program_header.vaddr(),
program_header.size_in_memory(),
program_header.alignment(),
program_header.offset(),
program_header.is_readable(),
program_header.is_writable(),
program_header.is_executable(),
String::format("elf-map-%s%s%s", program_header.is_readable() ? "r" : "", program_header.is_writable() ? "w" : "", program_header.is_executable() ? "x" : ""));
if (!mapped_section) {
failed = true;
}
}
#endif
});
return !failed;
}
char* ELFLoader::symbol_ptr(const char* name)
{
char* found_ptr = nullptr;
m_image.for_each_symbol([&](const ELFImage::Symbol symbol) {
if (symbol.type() != STT_FUNC)
return IterationDecision::Continue;
if (strcmp(symbol.name(), name))
return IterationDecision::Continue;
if (m_image.is_executable())
found_ptr = (char*)(size_t)symbol.value();
else
ASSERT_NOT_REACHED();
return IterationDecision::Break;
});
return found_ptr;
}
String ELFLoader::symbolicate(u32 address, u32* out_offset) const
{
SortedSymbol* sorted_symbols = nullptr;
#ifdef KERNEL
if (!m_sorted_symbols_region) {
m_sorted_symbols_region = MM.allocate_kernel_region(PAGE_ROUND_UP(m_image.symbol_count() * sizeof(SortedSymbol)), "Sorted symbols", Region::Access::Read | Region::Access::Write);
sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
size_t index = 0;
m_image.for_each_symbol([&](auto& symbol) {
sorted_symbols[index++] = { symbol.value(), symbol.name() };
return IterationDecision::Continue;
});
quick_sort(sorted_symbols, sorted_symbols + m_image.symbol_count(), [](auto& a, auto& b) {
return a.address < b.address;
});
} else {
sorted_symbols = (SortedSymbol*)m_sorted_symbols_region->vaddr().as_ptr();
}
#else
if (m_sorted_symbols.is_empty()) {
m_sorted_symbols.ensure_capacity(m_image.symbol_count());
m_image.for_each_symbol([this](auto& symbol) {
m_sorted_symbols.append({ symbol.value(), symbol.name() });
return IterationDecision::Continue;
});
quick_sort(m_sorted_symbols.begin(), m_sorted_symbols.end(), [](auto& a, auto& b) {
return a.address < b.address;
});
}
sorted_symbols = m_sorted_symbols.data();
#endif
for (size_t i = 0; i < m_image.symbol_count(); ++i) {
if (sorted_symbols[i].address > address) {
if (i == 0)
return "!!";
auto& symbol = sorted_symbols[i - 1];
if (out_offset) {
*out_offset = address - symbol.address;
return demangle(symbol.name);
}
return String::format("%s +%u", demangle(symbol.name).characters(), address - symbol.address);
}
}
return "??";
}
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