simpleperf/dso.cpp

/*
 * 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/file.h>
#include <android-base/logging.h>
#include <android-base/strings.h>

#include "environment.h"
#include "read_apk.h"
#include "read_dex_file.h"
#include "read_elf.h"
#include "utils.h"

namespace simpleperf_dso_impl {

void DebugElfFileFinder::Reset() {
  vdso_64bit_.clear();
  vdso_32bit_.clear();
  symfs_dir_.clear();
  build_id_to_file_map_.clear();
}

bool DebugElfFileFinder::SetSymFsDir(const std::string& symfs_dir) {
  std::string dirname = symfs_dir;
  if (!dirname.empty()) {
    if (dirname.back() != '/') {
      dirname.push_back('/');
    }
    if (!IsDir(symfs_dir)) {
      LOG(ERROR) << "Invalid symfs_dir '" << symfs_dir << "'";
      return false;
    }
  }
  symfs_dir_ = dirname;
  build_id_to_file_map_.clear();
  std::string build_id_list_file = symfs_dir_ + "build_id_list";
  std::string build_id_list;
  if (android::base::ReadFileToString(build_id_list_file, &build_id_list)) {
    for (auto& line : android::base::Split(build_id_list, "\n")) {
      std::vector<std::string> items = android::base::Split(line, "=");
      if (items.size() == 2u) {
        build_id_to_file_map_[items[0]] = items[1];
      }
    }
  }
  return true;
}

void DebugElfFileFinder::SetVdsoFile(const std::string& vdso_file, bool is_64bit) {
  if (is_64bit) {
    vdso_64bit_ = vdso_file;
  } else {
    vdso_32bit_ = vdso_file;
  }
}

std::string DebugElfFileFinder::FindDebugFile(const std::string& dso_path, bool force_64bit,
                                              BuildId& build_id) {
  if (dso_path == "[vdso]") {
    if (force_64bit && !vdso_64bit_.empty()) {
      return vdso_64bit_;
    } else if (!force_64bit && !vdso_32bit_.empty()) {
      return vdso_32bit_;
    }
  } else if (!symfs_dir_.empty()) {
    if (!build_id.IsEmpty() || GetBuildIdFromDsoPath(dso_path, &build_id)) {
      std::string result;
      auto check_path = [&](const std::string& path) {
        BuildId debug_build_id;
        if (GetBuildIdFromDsoPath(path, &debug_build_id) && debug_build_id == build_id) {
          result = path;
          return true;
        }
        return false;
      };

      // 1. Try build_id_to_file_map.
      auto it = build_id_to_file_map_.find(build_id.ToString());
      if (it != build_id_to_file_map_.end()) {
        if (check_path(symfs_dir_ + it->second)) {
          return result;
        }
      }
      // 2. Try concatenating symfs_dir and dso_path.
      if (check_path(symfs_dir_ + dso_path)) {
        return result;
      }
      // 3. Try concatenating /usr/lib/debug and dso_path.
      // Linux host can store debug shared libraries in /usr/lib/debug.
      if (check_path("/usr/lib/debug" + dso_path)) {
        return result;
      }
    }
  }
  return dso_path;
}
}  // namespace simpleperf_dso_imp

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),
      dump_id_(UINT_MAX) {
}

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::vmlinux_;
std::string Dso::kallsyms_;
bool Dso::read_kernel_symbols_from_proc_;
std::unordered_map<std::string, BuildId> Dso::build_id_map_;
size_t Dso::dso_count_;
uint32_t Dso::g_dump_id_;
simpleperf_dso_impl::DebugElfFileFinder Dso::debug_elf_file_finder_;

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) {
  return debug_elf_file_finder_.SetSymFsDir(symfs_dir);
}

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);
}

void Dso::SetVdsoFile(const std::string& vdso_file, bool is_64bit) {
  debug_elf_file_finder_.SetVdsoFile(vdso_file, is_64bit);
}

BuildId Dso::FindExpectedBuildIdForPath(const std::string& path) {
  auto it = build_id_map_.find(path);
  if (it != build_id_map_.end()) {
    return it->second;
  }
  return BuildId();
}

BuildId Dso::GetExpectedBuildId() {
  return FindExpectedBuildIdForPath(path_);
}

Dso::Dso(DsoType type, const std::string& path, const std::string& debug_file_path)
    : type_(type),
      path_(path),
      debug_file_path_(debug_file_path),
      is_loaded_(false),
      dump_id_(UINT_MAX),
      symbol_dump_id_(0),
      symbol_warning_loglevel_(android::base::WARNING) {
  size_t pos = path.find_last_of("/\\");
  if (pos != std::string::npos) {
    file_name_ = path.substr(pos + 1);
  } else {
    file_name_ = path;
  }
  dso_count_++;
}

Dso::~Dso() {
  if (--dso_count_ == 0) {
    // Clean up global variables when no longer used.
    symbol_name_allocator.Clear();
    demangle_ = true;
    vmlinux_.clear();
    kallsyms_.clear();
    read_kernel_symbols_from_proc_ = false;
    build_id_map_.clear();
    g_dump_id_ = 0;
    debug_elf_file_finder_.Reset();
  }
}

uint32_t Dso::CreateDumpId() {
  CHECK(!HasDumpId());
  return dump_id_ = g_dump_id_++;
}

uint32_t Dso::CreateSymbolDumpId(const Symbol* symbol) {
  CHECK(!symbol->HasDumpId());
  symbol->dump_id_ = symbol_dump_id_++;
  return symbol->dump_id_;
}

const Symbol* Dso::FindSymbol(uint64_t vaddr_in_dso) {
  if (!is_loaded_) {
    Load();
  }
  auto it = std::upper_bound(symbols_.begin(), symbols_.end(),
                             Symbol("", vaddr_in_dso, 0),
                             Symbol::CompareValueByAddr);
  if (it != symbols_.begin()) {
    --it;
    if (it->addr <= vaddr_in_dso && (it->addr + it->len > vaddr_in_dso)) {
      return &*it;
    }
  }
  if (!unknown_symbols_.empty()) {
    auto it = unknown_symbols_.find(vaddr_in_dso);
    if (it != unknown_symbols_.end()) {
      return &it->second;
    }
  }
  return nullptr;
}

void Dso::SetSymbols(std::vector<Symbol>* symbols) {
  symbols_ = std::move(*symbols);
  symbols->clear();
}

void Dso::AddUnknownSymbol(uint64_t vaddr_in_dso, const std::string& name) {
  unknown_symbols_.insert(std::make_pair(vaddr_in_dso, Symbol(name, vaddr_in_dso, 1)));
}

void Dso::Load() {
  is_loaded_ = true;
  std::vector<Symbol> symbols = LoadSymbols();
  if (symbols_.empty()) {
    symbols_ = std::move(symbols);
  } else {
    std::vector<Symbol> merged_symbols;
    std::set_union(symbols_.begin(), symbols_.end(), symbols.begin(), symbols.end(),
                   std::back_inserter(merged_symbols), Symbol::CompareValueByAddr);
    symbols_ = std::move(merged_symbols);
  }
}

static void ReportReadElfSymbolResult(ElfStatus result, const std::string& path,
    const std::string& debug_file_path,
    android::base::LogSeverity warning_loglevel = android::base::WARNING) {
  if (result == ElfStatus::NO_ERROR) {
    LOG(VERBOSE) << "Read symbols from " << debug_file_path << " successfully";
  } else if (result == ElfStatus::NO_SYMBOL_TABLE) {
    if (path == "[vdso]") {
      // Vdso only contains dynamic symbol table, and we can't change that.
      return;
    }
    // Lacking symbol table isn't considered as an error but worth reporting.
    LOG(warning_loglevel) << debug_file_path << " doesn't contain symbol table";
  } else {
    LOG(warning_loglevel) << "failed to read symbols from " << debug_file_path << ": " << result;
  }
}

static void SortAndFixSymbols(std::vector<Symbol>& symbols) {
  std::sort(symbols.begin(), symbols.end(), Symbol::CompareValueByAddr);
  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;
  }
}

class ElfDso : public Dso {
 public:
  ElfDso(const std::string& path, const std::string& debug_file_path)
      : Dso(DSO_ELF_FILE, path, debug_file_path),
        min_vaddr_(std::numeric_limits<uint64_t>::max()) {}

  uint64_t MinVirtualAddress() override {
    if (min_vaddr_ == std::numeric_limits<uint64_t>::max()) {
      min_vaddr_ = 0;
      if (type_ == DSO_ELF_FILE) {
        BuildId build_id = GetExpectedBuildId();

        uint64_t addr;
        ElfStatus result = ReadMinExecutableVirtualAddressFromElfFile(
            GetDebugFilePath(), build_id, &addr);
        if (result != ElfStatus::NO_ERROR) {
          LOG(WARNING) << "failed to read min virtual address of "
                       << GetDebugFilePath() << ": " << result;
        } else {
          min_vaddr_ = addr;
        }
      }
    }
    return min_vaddr_;
  }

  void SetMinVirtualAddress(uint64_t min_vaddr) override {
    min_vaddr_ = min_vaddr;
  }

 protected:
  std::vector<Symbol> LoadSymbols() override {
    std::vector<Symbol> symbols;
    BuildId build_id = GetExpectedBuildId();
    auto symbol_callback = [&](const ElfFileSymbol& symbol) {
      if (symbol.is_func || (symbol.is_label && symbol.is_in_text_section)) {
        symbols.emplace_back(symbol.name, symbol.vaddr, symbol.len);
      }
    };
    ElfStatus status;
    std::tuple<bool, std::string, std::string> tuple = SplitUrlInApk(debug_file_path_);
    if (std::get<0>(tuple)) {
      status = ParseSymbolsFromApkFile(std::get<1>(tuple), std::get<2>(tuple), build_id,
                                       symbol_callback);
    } else {
      status = ParseSymbolsFromElfFile(debug_file_path_, build_id, symbol_callback);
    }
    ReportReadElfSymbolResult(status, path_, debug_file_path_,
                              symbols_.empty() ? android::base::WARNING : android::base::DEBUG);
    SortAndFixSymbols(symbols);
    return symbols;
  }

 private:
  uint64_t min_vaddr_;
};

class KernelDso : public Dso {
 public:
  KernelDso(const std::string& path, const std::string& debug_file_path)
      : Dso(DSO_KERNEL, path, debug_file_path) {}

 protected:
  std::vector<Symbol> LoadSymbols() override {
    std::vector<Symbol> symbols;
    BuildId build_id = GetExpectedBuildId();
    if (!vmlinux_.empty()) {
      auto symbol_callback = [&](const ElfFileSymbol& symbol) {
        if (symbol.is_func) {
          symbols.emplace_back(symbol.name, symbol.vaddr, symbol.len);
        }
      };
      ElfStatus status = ParseSymbolsFromElfFile(vmlinux_, build_id, symbol_callback);
      ReportReadElfSymbolResult(status, path_, vmlinux_);
    } else if (!kallsyms_.empty()) {
      symbols = ReadSymbolsFromKallsyms(kallsyms_);
    } else if (read_kernel_symbols_from_proc_ || !build_id.IsEmpty()) {
      // Try /proc/kallsyms only when asked to do so, or when build id matches.
      // Otherwise, it is likely to use /proc/kallsyms on host for perf.data recorded on device.
      bool can_read_kallsyms = true;
      if (!build_id.IsEmpty()) {
        BuildId real_build_id;
        if (!GetKernelBuildId(&real_build_id) || build_id != real_build_id) {
          LOG(DEBUG) << "failed to read symbols from /proc/kallsyms: Build id mismatch";
          can_read_kallsyms = false;
        }
      }
      if (can_read_kallsyms) {
        std::string kallsyms;
        if (!android::base::ReadFileToString("/proc/kallsyms", &kallsyms)) {
          LOG(DEBUG) << "failed to read /proc/kallsyms";
        } else {
          symbols = ReadSymbolsFromKallsyms(kallsyms);
        }
      }
    }
    SortAndFixSymbols(symbols);
    if (!symbols.empty()) {
      symbols.back().len = std::numeric_limits<uint64_t>::max() - symbols.back().addr;
    }
    return symbols;
  }

 private:
  std::vector<Symbol> ReadSymbolsFromKallsyms(std::string& kallsyms) {
    std::vector<Symbol> symbols;
    auto symbol_callback = [&](const KernelSymbol& symbol) {
      if (strchr("TtWw", symbol.type) && symbol.addr != 0u) {
        symbols.emplace_back(symbol.name, symbol.addr, 0);
      }
      return false;
    };
    ProcessKernelSymbols(kallsyms, symbol_callback);
    if (symbols.empty()) {
      LOG(WARNING) << "Symbol addresses in /proc/kallsyms on device are all zero. "
                      "`echo 0 >/proc/sys/kernel/kptr_restrict` if possible.";
    }
    return symbols;
  }
};

class KernelModuleDso : public Dso {
 public:
  KernelModuleDso(const std::string& path, const std::string& debug_file_path)
      : Dso(DSO_KERNEL_MODULE, path, debug_file_path) {}

 protected:
  std::vector<Symbol> LoadSymbols() override {
    std::vector<Symbol> symbols;
    BuildId build_id = GetExpectedBuildId();
    auto symbol_callback = [&](const ElfFileSymbol& symbol) {
      if (symbol.is_func || symbol.is_in_text_section) {
        symbols.emplace_back(symbol.name, symbol.vaddr, symbol.len);
      }
    };
    ElfStatus status = ParseSymbolsFromElfFile(debug_file_path_, build_id, symbol_callback);
    ReportReadElfSymbolResult(status, path_, debug_file_path_,
                              symbols_.empty() ? android::base::WARNING : android::base::DEBUG);
    SortAndFixSymbols(symbols);
    return symbols;
  }
};

std::unique_ptr<Dso> Dso::CreateDso(DsoType dso_type, const std::string& dso_path,
                                    bool force_64bit) {
  switch (dso_type) {
    case DSO_ELF_FILE: {
      BuildId build_id = FindExpectedBuildIdForPath(dso_path);
      return std::unique_ptr<Dso>(new ElfDso(dso_path,
          debug_elf_file_finder_.FindDebugFile(dso_path, force_64bit, build_id)));
    }
    case DSO_KERNEL:
      return std::unique_ptr<Dso>(new KernelDso(dso_path, dso_path));
    case DSO_KERNEL_MODULE:
      return std::unique_ptr<Dso>(new KernelModuleDso(dso_path, dso_path));
    case DSO_DEX_FILE:
      return std::unique_ptr<Dso>(new DexFileDso(dso_path, dso_path));
    default:
      LOG(FATAL) << "Unexpected dso_type " << static_cast<int>(dso_type);
  }
  return nullptr;
}

std::vector<Symbol> DexFileDso::LoadSymbols() {
  std::vector<Symbol> symbols;
  std::vector<DexFileSymbol> dex_file_symbols;
  if (!ReadSymbolsFromDexFile(debug_file_path_, dex_file_offsets_, &dex_file_symbols)) {
    android::base::LogSeverity level = symbols_.empty() ? android::base::WARNING
                                                        : android::base::DEBUG;
    LOG(level) << "Failed to read symbols from " << debug_file_path_;
    return symbols;
  }
  LOG(VERBOSE) << "Read symbols from " << debug_file_path_ << " successfully";
  for (auto& symbol : dex_file_symbols) {
    symbols.emplace_back(symbol.name, symbol.offset, symbol.len);
  }
  SortAndFixSymbols(symbols);
  return symbols;
}

const char* DsoTypeToString(DsoType dso_type) {
  switch (dso_type) {
    case DSO_KERNEL:
      return "dso_kernel";
    case DSO_KERNEL_MODULE:
      return "dso_kernel_module";
    case DSO_ELF_FILE:
      return "dso_elf_file";
    case DSO_DEX_FILE:
      return "dso_dex_file";
    default:
      return "unknown";
  }
}

bool GetBuildIdFromDsoPath(const std::string& dso_path, BuildId* build_id) {
  auto tuple = SplitUrlInApk(dso_path);
  ElfStatus result;
  if (std::get<0>(tuple)) {
    result = GetBuildIdFromApkFile(std::get<1>(tuple), std::get<2>(tuple), build_id);
  } else {
    result = GetBuildIdFromElfFile(dso_path, build_id);
  }
  return result == ElfStatus::NO_ERROR;
}