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//===-- NativeProcessELF.cpp ---------------------------------- -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "NativeProcessELF.h"
#include "lldb/Utility/DataExtractor.h"
namespace lldb_private {
llvm::Optional<uint64_t>
NativeProcessELF::GetAuxValue(enum AuxVector::EntryType type) {
if (m_aux_vector == nullptr) {
auto buffer_or_error = GetAuxvData();
if (!buffer_or_error)
return llvm::None;
DataExtractor auxv_data(buffer_or_error.get()->getBufferStart(),
buffer_or_error.get()->getBufferSize(),
GetByteOrder(), GetAddressByteSize());
m_aux_vector = llvm::make_unique<AuxVector>(auxv_data);
}
return m_aux_vector->GetAuxValue(type);
}
lldb::addr_t NativeProcessELF::GetSharedLibraryInfoAddress() {
if (!m_shared_library_info_addr.hasValue()) {
if (GetAddressByteSize() == 8)
m_shared_library_info_addr =
GetELFImageInfoAddress<llvm::ELF::Elf64_Ehdr, llvm::ELF::Elf64_Phdr,
llvm::ELF::Elf64_Dyn>();
else
m_shared_library_info_addr =
GetELFImageInfoAddress<llvm::ELF::Elf32_Ehdr, llvm::ELF::Elf32_Phdr,
llvm::ELF::Elf32_Dyn>();
}
return m_shared_library_info_addr.getValue();
}
template <typename ELF_EHDR, typename ELF_PHDR, typename ELF_DYN>
lldb::addr_t NativeProcessELF::GetELFImageInfoAddress() {
llvm::Optional<uint64_t> maybe_phdr_addr =
GetAuxValue(AuxVector::AUXV_AT_PHDR);
llvm::Optional<uint64_t> maybe_phdr_entry_size =
GetAuxValue(AuxVector::AUXV_AT_PHENT);
llvm::Optional<uint64_t> maybe_phdr_num_entries =
GetAuxValue(AuxVector::AUXV_AT_PHNUM);
if (!maybe_phdr_addr || !maybe_phdr_entry_size || !maybe_phdr_num_entries)
return LLDB_INVALID_ADDRESS;
lldb::addr_t phdr_addr = *maybe_phdr_addr;
size_t phdr_entry_size = *maybe_phdr_entry_size;
size_t phdr_num_entries = *maybe_phdr_num_entries;
// Find the PT_DYNAMIC segment (.dynamic section) in the program header and
// what the load bias by calculating the difference of the program header
// load address and its virtual address.
lldb::offset_t load_bias;
bool found_load_bias = false;
lldb::addr_t dynamic_section_addr = 0;
uint64_t dynamic_section_size = 0;
bool found_dynamic_section = false;
ELF_PHDR phdr_entry;
for (size_t i = 0; i < phdr_num_entries; i++) {
size_t bytes_read;
auto error = ReadMemory(phdr_addr + i * phdr_entry_size, &phdr_entry,
sizeof(phdr_entry), bytes_read);
if (!error.Success())
return LLDB_INVALID_ADDRESS;
if (phdr_entry.p_type == llvm::ELF::PT_PHDR) {
load_bias = phdr_addr - phdr_entry.p_vaddr;
found_load_bias = true;
}
if (phdr_entry.p_type == llvm::ELF::PT_DYNAMIC) {
dynamic_section_addr = phdr_entry.p_vaddr;
dynamic_section_size = phdr_entry.p_memsz;
found_dynamic_section = true;
}
}
if (!found_load_bias || !found_dynamic_section)
return LLDB_INVALID_ADDRESS;
// Find the DT_DEBUG entry in the .dynamic section
dynamic_section_addr += load_bias;
ELF_DYN dynamic_entry;
size_t dynamic_num_entries = dynamic_section_size / sizeof(dynamic_entry);
for (size_t i = 0; i < dynamic_num_entries; i++) {
size_t bytes_read;
auto error = ReadMemory(dynamic_section_addr + i * sizeof(dynamic_entry),
&dynamic_entry, sizeof(dynamic_entry), bytes_read);
if (!error.Success())
return LLDB_INVALID_ADDRESS;
// Return the &DT_DEBUG->d_ptr which points to r_debug which contains the
// link_map.
if (dynamic_entry.d_tag == llvm::ELF::DT_DEBUG) {
return dynamic_section_addr + i * sizeof(dynamic_entry) +
sizeof(dynamic_entry.d_tag);
}
}
return LLDB_INVALID_ADDRESS;
}
} // namespace lldb_private
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