| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "read_elf.h" |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <algorithm> |
| #include <base/file.h> |
| #include <base/logging.h> |
| |
| #pragma clang diagnostic push |
| #pragma clang diagnostic ignored "-Wunused-parameter" |
| |
| #include <llvm/ADT/StringRef.h> |
| #include <llvm/Object/Binary.h> |
| #include <llvm/Object/ELFObjectFile.h> |
| #include <llvm/Object/ObjectFile.h> |
| |
| #pragma clang diagnostic pop |
| |
| #include <elf.h> |
| |
| #include "utils.h" |
| |
| static bool GetBuildIdFromNoteSection(const char* section, size_t section_size, BuildId* build_id) { |
| const char* p = section; |
| const char* end = p + section_size; |
| while (p < end) { |
| CHECK_LE(p + 12, end); |
| size_t namesz = *reinterpret_cast<const uint32_t*>(p); |
| p += 4; |
| size_t descsz = *reinterpret_cast<const uint32_t*>(p); |
| p += 4; |
| uint32_t type = *reinterpret_cast<const uint32_t*>(p); |
| p += 4; |
| namesz = ALIGN(namesz, 4); |
| descsz = ALIGN(descsz, 4); |
| CHECK_LE(p + namesz + descsz, end); |
| if ((type == NT_GNU_BUILD_ID) && (strcmp(p, ELF_NOTE_GNU) == 0)) { |
| std::fill(build_id->begin(), build_id->end(), 0); |
| memcpy(build_id->data(), p + namesz, std::min(build_id->size(), descsz)); |
| return true; |
| } |
| p += namesz + descsz; |
| } |
| return false; |
| } |
| |
| bool GetBuildIdFromNoteFile(const std::string& filename, BuildId* build_id) { |
| std::string content; |
| if (!android::base::ReadFileToString(filename, &content)) { |
| LOG(DEBUG) << "can't read note file " << filename; |
| return false; |
| } |
| if (GetBuildIdFromNoteSection(content.c_str(), content.size(), build_id) == false) { |
| LOG(DEBUG) << "can't read build_id from note file " << filename; |
| return false; |
| } |
| return true; |
| } |
| |
| template <class ELFT> |
| bool GetBuildIdFromELFFile(const llvm::object::ELFFile<ELFT>* elf, BuildId* build_id) { |
| for (auto section_iterator = elf->begin_sections(); section_iterator != elf->end_sections(); |
| ++section_iterator) { |
| if (section_iterator->sh_type == SHT_NOTE) { |
| auto contents = elf->getSectionContents(&*section_iterator); |
| if (contents.getError()) { |
| LOG(DEBUG) << "read note section error"; |
| continue; |
| } |
| if (GetBuildIdFromNoteSection(reinterpret_cast<const char*>(contents->data()), |
| contents->size(), build_id)) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| bool GetBuildIdFromElfFile(const std::string& filename, BuildId* build_id) { |
| auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename)); |
| if (owning_binary.getError()) { |
| PLOG(DEBUG) << "can't open file " << filename; |
| return false; |
| } |
| bool result = false; |
| llvm::object::Binary* binary = owning_binary.get().getBinary(); |
| if (auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary)) { |
| if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) { |
| result = GetBuildIdFromELFFile(elf->getELFFile(), build_id); |
| } else if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) { |
| result = GetBuildIdFromELFFile(elf->getELFFile(), build_id); |
| } else { |
| PLOG(DEBUG) << "unknown elf format in file " << filename; |
| } |
| } |
| if (!result) { |
| PLOG(DEBUG) << "can't read build_id from file " << filename; |
| } |
| return result; |
| } |
| template <class ELFT> |
| bool ParseSymbolsFromELFFile(const llvm::object::ELFFile<ELFT>* elf, |
| std::function<void(const ElfFileSymbol&)> callback) { |
| bool is_arm = (elf->getHeader()->e_machine == EM_ARM); |
| auto begin = elf->begin_symbols(); |
| auto end = elf->end_symbols(); |
| if (begin == end) { |
| begin = elf->begin_dynamic_symbols(); |
| end = elf->end_dynamic_symbols(); |
| } |
| for (; begin != end; ++begin) { |
| auto& elf_symbol = *begin; |
| |
| ElfFileSymbol symbol; |
| memset(&symbol, '\0', sizeof(symbol)); |
| |
| auto shdr = elf->getSection(&elf_symbol); |
| if (shdr == nullptr) { |
| continue; |
| } |
| auto section_name = elf->getSectionName(shdr); |
| if (section_name.getError() || section_name.get().empty()) { |
| continue; |
| } |
| if (section_name.get() == ".text") { |
| symbol.is_in_text_section = true; |
| } |
| |
| auto symbol_name = elf->getSymbolName(begin); |
| if (symbol_name.getError()) { |
| continue; |
| } |
| symbol.name = symbol_name.get(); |
| if (symbol.name.empty()) { |
| continue; |
| } |
| |
| symbol.start_in_file = elf_symbol.st_value - shdr->sh_addr + shdr->sh_offset; |
| if ((symbol.start_in_file & 1) != 0 && is_arm) { |
| // Arm sets bit 0 to mark it as thumb code, remove the flag. |
| symbol.start_in_file &= ~1; |
| } |
| symbol.len = elf_symbol.st_size; |
| int type = elf_symbol.getType(); |
| if (type == STT_FUNC) { |
| symbol.is_func = true; |
| } else if (type == STT_NOTYPE) { |
| if (symbol.is_in_text_section) { |
| symbol.is_label = true; |
| |
| // Arm has meaningless labels like $t, $d, $x, exclude them. |
| if (is_arm) { |
| size_t test_pos = (symbol.name.find(linker_prefix) == 0) ? linker_prefix.size() : 0; |
| if (test_pos + 2 == symbol.name.size() && symbol.name[test_pos] == '$') { |
| symbol.is_label = false; |
| } |
| } |
| } |
| } |
| |
| callback(symbol); |
| } |
| return true; |
| } |
| |
| bool ParseSymbolsFromElfFile(const std::string& filename, |
| std::function<void(const ElfFileSymbol&)> callback) { |
| auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename)); |
| if (owning_binary.getError()) { |
| PLOG(DEBUG) << "can't open file '" << filename << "'"; |
| return false; |
| } |
| bool result = false; |
| llvm::object::Binary* binary = owning_binary.get().getBinary(); |
| if (auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary)) { |
| if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) { |
| result = ParseSymbolsFromELFFile(elf->getELFFile(), callback); |
| } else if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) { |
| result = ParseSymbolsFromELFFile(elf->getELFFile(), callback); |
| } else { |
| PLOG(DEBUG) << "unknown elf format in file" << filename; |
| } |
| } |
| if (!result) { |
| PLOG(DEBUG) << "can't parse symbols from file " << filename; |
| } |
| return result; |
| } |