| /* |
| * 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 "dso.h" |
| |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include <algorithm> |
| #include <limits> |
| #include <vector> |
| |
| #include <android-base/logging.h> |
| |
| #include "environment.h" |
| #include "read_apk.h" |
| #include "read_elf.h" |
| #include "utils.h" |
| |
| static OneTimeFreeAllocator symbol_name_allocator; |
| |
| Symbol::Symbol(const std::string& name, uint64_t addr, uint64_t len) |
| : addr(addr), |
| len(len), |
| name_(symbol_name_allocator.AllocateString(name)), |
| demangled_name_(nullptr) { |
| } |
| |
| const char* Symbol::DemangledName() const { |
| if (demangled_name_ == nullptr) { |
| const std::string s = Dso::Demangle(name_); |
| if (s == name_) { |
| demangled_name_ = name_; |
| } else { |
| demangled_name_ = symbol_name_allocator.AllocateString(s); |
| } |
| } |
| return demangled_name_; |
| } |
| |
| bool Dso::demangle_ = true; |
| std::string Dso::symfs_dir_; |
| std::string Dso::vmlinux_; |
| std::unordered_map<std::string, BuildId> Dso::build_id_map_; |
| size_t Dso::dso_count_; |
| |
| void Dso::SetDemangle(bool demangle) { |
| demangle_ = demangle; |
| } |
| |
| extern "C" char* __cxa_demangle(const char* mangled_name, char* buf, size_t* n, int* status); |
| |
| std::string Dso::Demangle(const std::string& name) { |
| if (!demangle_) { |
| return name; |
| } |
| int status; |
| bool is_linker_symbol = (name.find(linker_prefix) == 0); |
| const char* mangled_str = name.c_str(); |
| if (is_linker_symbol) { |
| mangled_str += linker_prefix.size(); |
| } |
| std::string result = name; |
| char* demangled_name = __cxa_demangle(mangled_str, nullptr, nullptr, &status); |
| if (status == 0) { |
| if (is_linker_symbol) { |
| result = std::string("[linker]") + demangled_name; |
| } else { |
| result = demangled_name; |
| } |
| free(demangled_name); |
| } else if (is_linker_symbol) { |
| result = std::string("[linker]") + mangled_str; |
| } |
| return result; |
| } |
| |
| bool Dso::SetSymFsDir(const std::string& symfs_dir) { |
| std::string dirname = symfs_dir; |
| if (!dirname.empty()) { |
| if (dirname.back() != '/') { |
| dirname.push_back('/'); |
| } |
| std::vector<std::string> files; |
| std::vector<std::string> subdirs; |
| GetEntriesInDir(symfs_dir, &files, &subdirs); |
| if (files.empty() && subdirs.empty()) { |
| LOG(ERROR) << "Invalid symfs_dir '" << symfs_dir << "'"; |
| return false; |
| } |
| } |
| symfs_dir_ = dirname; |
| return true; |
| } |
| |
| void Dso::SetVmlinux(const std::string& vmlinux) { |
| vmlinux_ = vmlinux; |
| } |
| |
| void Dso::SetBuildIds(const std::vector<std::pair<std::string, BuildId>>& build_ids) { |
| std::unordered_map<std::string, BuildId> map; |
| for (auto& pair : build_ids) { |
| LOG(DEBUG) << "build_id_map: " << pair.first << ", " << pair.second.ToString(); |
| map.insert(pair); |
| } |
| build_id_map_ = std::move(map); |
| } |
| |
| BuildId Dso::GetExpectedBuildId(const std::string& filename) { |
| auto it = build_id_map_.find(filename); |
| if (it != build_id_map_.end()) { |
| return it->second; |
| } |
| return BuildId(); |
| } |
| |
| std::unique_ptr<Dso> Dso::CreateDso(DsoType dso_type, const std::string& dso_path) { |
| std::string path = dso_path; |
| if (dso_type == DSO_KERNEL) { |
| path = "[kernel.kallsyms]"; |
| } |
| return std::unique_ptr<Dso>(new Dso(dso_type, path)); |
| } |
| |
| Dso::Dso(DsoType type, const std::string& path) |
| : type_(type), path_(path), min_vaddr_(std::numeric_limits<uint64_t>::max()), is_loaded_(false) { |
| dso_count_++; |
| } |
| |
| Dso::~Dso() { |
| if (--dso_count_ == 0) { |
| symbol_name_allocator.Clear(); |
| } |
| } |
| |
| struct SymbolComparator { |
| bool operator()(const Symbol& symbol1, const Symbol& symbol2) { |
| return symbol1.addr < symbol2.addr; |
| } |
| }; |
| |
| std::string Dso::GetAccessiblePath() const { |
| return symfs_dir_ + path_; |
| } |
| |
| const Symbol* Dso::FindSymbol(uint64_t vaddr_in_dso) { |
| if (!is_loaded_) { |
| is_loaded_ = true; |
| if (!Load()) { |
| LOG(DEBUG) << "failed to load dso: " << path_; |
| return nullptr; |
| } |
| } |
| |
| auto it = std::upper_bound(symbols_.begin(), symbols_.end(), Symbol("", vaddr_in_dso, 0), |
| SymbolComparator()); |
| if (it != symbols_.begin()) { |
| --it; |
| if (it->addr <= vaddr_in_dso && it->addr + it->len > vaddr_in_dso) { |
| return &*it; |
| } |
| } |
| return nullptr; |
| } |
| |
| uint64_t Dso::MinVirtualAddress() { |
| if (min_vaddr_ == std::numeric_limits<uint64_t>::max()) { |
| min_vaddr_ = 0; |
| if (type_ == DSO_ELF_FILE) { |
| BuildId build_id = GetExpectedBuildId(GetAccessiblePath()); |
| |
| uint64_t addr; |
| if (ReadMinExecutableVirtualAddressFromElfFile(GetAccessiblePath(), build_id, &addr)) { |
| min_vaddr_ = addr; |
| } |
| } |
| } |
| return min_vaddr_; |
| } |
| |
| bool Dso::Load() { |
| bool result = false; |
| switch (type_) { |
| case DSO_KERNEL: |
| result = LoadKernel(); |
| break; |
| case DSO_KERNEL_MODULE: |
| result = LoadKernelModule(); |
| break; |
| case DSO_ELF_FILE: { |
| if (std::get<0>(SplitUrlInApk(path_))) { |
| result = LoadEmbeddedElfFile(); |
| } else { |
| result = LoadElfFile(); |
| } |
| break; |
| } |
| } |
| if (result) { |
| std::sort(symbols_.begin(), symbols_.end(), SymbolComparator()); |
| FixupSymbolLength(); |
| } |
| return result; |
| } |
| |
| static bool IsKernelFunctionSymbol(const KernelSymbol& symbol) { |
| return (symbol.type == 'T' || symbol.type == 't' || symbol.type == 'W' || symbol.type == 'w'); |
| } |
| |
| bool Dso::KernelSymbolCallback(const KernelSymbol& kernel_symbol, Dso* dso) { |
| if (IsKernelFunctionSymbol(kernel_symbol)) { |
| dso->InsertSymbol(Symbol(kernel_symbol.name, kernel_symbol.addr, 0)); |
| } |
| return false; |
| } |
| |
| void Dso::VmlinuxSymbolCallback(const ElfFileSymbol& elf_symbol, Dso* dso) { |
| if (elf_symbol.is_func) { |
| dso->InsertSymbol(Symbol(elf_symbol.name, elf_symbol.vaddr, elf_symbol.len)); |
| } |
| } |
| |
| bool Dso::LoadKernel() { |
| BuildId build_id = GetExpectedBuildId(DEFAULT_KERNEL_FILENAME_FOR_BUILD_ID); |
| if (!vmlinux_.empty()) { |
| ParseSymbolsFromElfFile(vmlinux_, build_id, |
| std::bind(VmlinuxSymbolCallback, std::placeholders::_1, this)); |
| } else { |
| if (!build_id.IsEmpty()) { |
| BuildId real_build_id; |
| GetKernelBuildId(&real_build_id); |
| bool match = (build_id == real_build_id); |
| LOG(DEBUG) << "check kernel build id (" << (match ? "match" : "mismatch") << "): expected " |
| << build_id.ToString() << ", real " << real_build_id.ToString(); |
| if (!match) { |
| return false; |
| } |
| } |
| |
| ProcessKernelSymbols("/proc/kallsyms", |
| std::bind(&KernelSymbolCallback, std::placeholders::_1, this)); |
| bool allZero = true; |
| for (auto& symbol : symbols_) { |
| if (symbol.addr != 0) { |
| allZero = false; |
| break; |
| } |
| } |
| if (allZero) { |
| LOG(WARNING) << "Symbol addresses in /proc/kallsyms are all zero. Check " |
| "/proc/sys/kernel/kptr_restrict if possible."; |
| symbols_.clear(); |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| void Dso::ElfFileSymbolCallback(const ElfFileSymbol& elf_symbol, Dso* dso, |
| bool (*filter)(const ElfFileSymbol&)) { |
| if (filter(elf_symbol)) { |
| dso->InsertSymbol(Symbol(elf_symbol.name, elf_symbol.vaddr, elf_symbol.len)); |
| } |
| } |
| |
| static bool SymbolFilterForKernelModule(const ElfFileSymbol& elf_symbol) { |
| // TODO: Parse symbol outside of .text section. |
| return (elf_symbol.is_func && elf_symbol.is_in_text_section); |
| } |
| |
| bool Dso::LoadKernelModule() { |
| BuildId build_id = GetExpectedBuildId(path_); |
| ParseSymbolsFromElfFile( |
| symfs_dir_ + path_, build_id, |
| std::bind(ElfFileSymbolCallback, std::placeholders::_1, this, SymbolFilterForKernelModule)); |
| return true; |
| } |
| |
| static bool SymbolFilterForDso(const ElfFileSymbol& elf_symbol) { |
| return elf_symbol.is_func || (elf_symbol.is_label && elf_symbol.is_in_text_section); |
| } |
| |
| bool Dso::LoadElfFile() { |
| bool loaded = false; |
| BuildId build_id = GetExpectedBuildId(GetAccessiblePath()); |
| |
| if (symfs_dir_.empty()) { |
| // Linux host can store debug shared libraries in /usr/lib/debug. |
| loaded = ParseSymbolsFromElfFile( |
| "/usr/lib/debug" + path_, build_id, |
| std::bind(ElfFileSymbolCallback, std::placeholders::_1, this, SymbolFilterForDso)); |
| } |
| if (!loaded) { |
| loaded = ParseSymbolsFromElfFile( |
| GetAccessiblePath(), build_id, |
| std::bind(ElfFileSymbolCallback, std::placeholders::_1, this, SymbolFilterForDso)); |
| } |
| return loaded; |
| } |
| |
| bool Dso::LoadEmbeddedElfFile() { |
| std::string path = GetAccessiblePath(); |
| BuildId build_id = GetExpectedBuildId(path); |
| auto tuple = SplitUrlInApk(path); |
| CHECK(std::get<0>(tuple)); |
| return ParseSymbolsFromApkFile(std::get<1>(tuple), std::get<2>(tuple), build_id, |
| std::bind(ElfFileSymbolCallback, std::placeholders::_1, |
| this, SymbolFilterForDso)); |
| } |
| |
| void Dso::InsertSymbol(const Symbol& symbol) { |
| symbols_.push_back(symbol); |
| } |
| |
| void Dso::FixupSymbolLength() { |
| Symbol* prev_symbol = nullptr; |
| for (auto& symbol : symbols_) { |
| if (prev_symbol != nullptr && prev_symbol->len == 0) { |
| prev_symbol->len = symbol.addr - prev_symbol->addr; |
| } |
| prev_symbol = &symbol; |
| } |
| if (prev_symbol != nullptr && prev_symbol->len == 0) { |
| prev_symbol->len = std::numeric_limits<unsigned long long>::max() - prev_symbol->addr; |
| } |
| } |