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Commit e7ba4cc2 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Add Symbols parsing. 

Bug: 23762183

Test: New unit tests pass.
Change-Id: Ib67fee879120b5e82889076a0f7221dc429ac140
parent 3f220aaa

libunwindstack/Android.bp

+2 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ cc_defaults { 
        "Log.cpp",

        "Regs.cpp",

        "Memory.cpp",

        "Symbols.cpp",

    ],



    shared_libs: [
@@ -102,6 +103,7 @@ cc_defaults { 
        "tests/MemoryRangeTest.cpp",

        "tests/MemoryRemoteTest.cpp",

        "tests/RegsTest.cpp",

        "tests/SymbolsTest.cpp",

    ],



    cflags: [

libunwindstack/Symbols.cpp

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Original line number Diff line number Diff line 
/*

 * Copyright (C) 2017 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 <assert.h>

#include <elf.h>

#include <stdint.h>



#include <string>



#include "Memory.h"

#include "Symbols.h"



Symbols::Symbols(uint64_t offset, uint64_t size, uint64_t entry_size, uint64_t str_offset,

                 uint64_t str_size)

    : cur_offset_(offset),

      offset_(offset),

      end_(offset + size),

      entry_size_(entry_size),

      str_offset_(str_offset),

      str_end_(str_offset_ + str_size) {}



const Symbols::Info* Symbols::GetInfoFromCache(uint64_t addr) {

  // Binary search the table.

  size_t first = 0;

  size_t last = symbols_.size();

  while (first < last) {

    size_t current = first + (last - first) / 2;

    const Info* info = &symbols_[current];

    if (addr < info->start_offset) {

      last = current;

    } else if (addr < info->end_offset) {

      return info;

    } else {

      first = current + 1;

    }

  }

  return nullptr;

}



template <typename SymType>

bool Symbols::GetName(uint64_t addr, uint64_t load_bias, Memory* elf_memory, std::string* name,

                      uint64_t* func_offset) {

  addr += load_bias;



  if (symbols_.size() != 0) {

    const Info* info = GetInfoFromCache(addr);

    if (info) {

      assert(addr >= info->start_offset && addr <= info->end_offset);

      *func_offset = addr - info->start_offset;

      return elf_memory->ReadString(info->str_offset, name, str_end_ - info->str_offset);

    }

  }



  bool symbol_added = false;

  bool return_value = false;

  while (cur_offset_ + entry_size_ <= end_) {

    SymType entry;

    if (!elf_memory->Read(cur_offset_, &entry, sizeof(entry))) {

      // Stop all processing, something looks like it is corrupted.

      cur_offset_ = UINT64_MAX;

      return false;

    }

    cur_offset_ += entry_size_;



    if (entry.st_shndx != SHN_UNDEF && ELF32_ST_TYPE(entry.st_info) == STT_FUNC) {

      // Treat st_value as virtual address.

      uint64_t start_offset = entry.st_value;

      if (entry.st_shndx != SHN_ABS) {

        start_offset += load_bias;

      }

      uint64_t end_offset = start_offset + entry.st_size;



      // Cache the value.

      symbols_.emplace_back(start_offset, end_offset, str_offset_ + entry.st_name);

      symbol_added = true;



      if (addr >= start_offset && addr < end_offset) {

        *func_offset = addr - start_offset;

        uint64_t offset = str_offset_ + entry.st_name;

        if (offset < str_end_) {

          return_value = elf_memory->ReadString(offset, name, str_end_ - offset);

        }

        break;

      }

    }

  }



  if (symbol_added) {

    std::sort(symbols_.begin(), symbols_.end(),

              [](const Info& a, const Info& b) { return a.start_offset < b.start_offset; });

  }

  return return_value;

}



// Instantiate all of the needed template functions.

template bool Symbols::GetName<Elf32_Sym>(uint64_t, uint64_t, Memory*, std::string*, uint64_t*);

template bool Symbols::GetName<Elf64_Sym>(uint64_t, uint64_t, Memory*, std::string*, uint64_t*);

libunwindstack/Symbols.h

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Original line number Diff line number Diff line 
/*

 * Copyright (C) 2016 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.

 */



#ifndef _LIBUNWINDSTACK_SYMBOLS_H

#define _LIBUNWINDSTACK_SYMBOLS_H



#include <stdint.h>



#include <string>

#include <vector>



// Forward declaration.

class Memory;



class Symbols {

  struct Info {

    Info(uint64_t start_offset, uint64_t end_offset, uint64_t str_offset)

        : start_offset(start_offset), end_offset(end_offset), str_offset(str_offset) {}

    uint64_t start_offset;

    uint64_t end_offset;

    uint64_t str_offset;

  };



 public:

  Symbols(uint64_t offset, uint64_t size, uint64_t entry_size, uint64_t str_offset,

          uint64_t str_size);

  virtual ~Symbols() = default;



  const Info* GetInfoFromCache(uint64_t addr);



  template <typename SymType>

  bool GetName(uint64_t addr, uint64_t load_bias, Memory* elf_memory, std::string* name,

               uint64_t* func_offset);



  void ClearCache() {

    symbols_.clear();

    cur_offset_ = offset_;

  }



 private:

  uint64_t cur_offset_;

  uint64_t offset_;

  uint64_t end_;

  uint64_t entry_size_;

  uint64_t str_offset_;

  uint64_t str_end_;



  std::vector<Info> symbols_;

};



#endif  // _LIBUNWINDSTACK_SYMBOLS_H

libunwindstack/tests/SymbolsTest.cpp

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Original line number Diff line number Diff line 
/*

 * Copyright (C) 2016 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 <elf.h>

#include <errno.h>

#include <signal.h>

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include <sys/mman.h>

#include <sys/ptrace.h>

#include <sys/types.h>

#include <time.h>

#include <unistd.h>



#include <vector>



#include <android-base/file.h>

#include <android-base/test_utils.h>

#include <gtest/gtest.h>



#include "Memory.h"

#include "MemoryFake.h"

#include "Symbols.h"



template <typename TypeParam>

class SymbolsTest : public ::testing::Test {

 protected:

  void SetUp() override { memory_.Clear(); }



  void InitSym(TypeParam* sym, uint32_t st_value, uint32_t st_size, uint32_t st_name) {

    memset(sym, 0, sizeof(*sym));

    sym->st_info = STT_FUNC;

    sym->st_value = st_value;

    sym->st_size = st_size;

    sym->st_name = st_name;

    sym->st_shndx = SHN_COMMON;

  }



  MemoryFake memory_;

};

TYPED_TEST_CASE_P(SymbolsTest);



TYPED_TEST_P(SymbolsTest, function_bounds_check) {

  Symbols symbols(0x1000, sizeof(TypeParam), sizeof(TypeParam), 0x2000, 0x100);



  TypeParam sym;

  this->InitSym(&sym, 0x5000, 0x10, 0x40);

  uint64_t offset = 0x1000;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));



  std::string fake_name("fake_function");

  this->memory_.SetMemory(0x2040, fake_name.c_str(), fake_name.size() + 1);



  std::string name;

  uint64_t func_offset;

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("fake_function", name);

  ASSERT_EQ(0U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x500f, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("fake_function", name);

  ASSERT_EQ(0xfU, func_offset);



  // Check one before and one after the function.

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x4fff, 0, &this->memory_, &name, &func_offset));

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x5010, 0, &this->memory_, &name, &func_offset));

}



TYPED_TEST_P(SymbolsTest, no_symbol) {

  Symbols symbols(0x1000, sizeof(TypeParam), sizeof(TypeParam), 0x2000, 0x100);



  TypeParam sym;

  this->InitSym(&sym, 0x5000, 0x10, 0x40);

  uint64_t offset = 0x1000;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));



  std::string fake_name("fake_function");

  this->memory_.SetMemory(0x2040, fake_name.c_str(), fake_name.size() + 1);



  // First verify that we can get the name.

  std::string name;

  uint64_t func_offset;

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("fake_function", name);

  ASSERT_EQ(0U, func_offset);



  // Now modify the info field so it's no longer a function.

  sym.st_info = 0;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  // Clear the cache to force the symbol data to be re-read.

  symbols.ClearCache();

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));



  // Set the function back, and set the shndx to UNDEF.

  sym.st_info = STT_FUNC;

  sym.st_shndx = SHN_UNDEF;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  // Clear the cache to force the symbol data to be re-read.

  symbols.ClearCache();

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));

}



TYPED_TEST_P(SymbolsTest, multiple_entries) {

  Symbols symbols(0x1000, sizeof(TypeParam) * 3, sizeof(TypeParam), 0x2000, 0x500);



  TypeParam sym;

  uint64_t offset = 0x1000;

  std::string fake_name;



  this->InitSym(&sym, 0x5000, 0x10, 0x40);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_one";

  this->memory_.SetMemory(0x2040, fake_name.c_str(), fake_name.size() + 1);

  offset += sizeof(sym);



  this->InitSym(&sym, 0x3004, 0x200, 0x100);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_two";

  this->memory_.SetMemory(0x2100, fake_name.c_str(), fake_name.size() + 1);

  offset += sizeof(sym);



  this->InitSym(&sym, 0xa010, 0x20, 0x230);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_three";

  this->memory_.SetMemory(0x2230, fake_name.c_str(), fake_name.size() + 1);



  std::string name;

  uint64_t func_offset;

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x3005, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_two", name);

  ASSERT_EQ(1U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5004, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_one", name);

  ASSERT_EQ(4U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0xa011, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_three", name);

  ASSERT_EQ(1U, func_offset);



  // Reget some of the others to verify getting one function name doesn't

  // affect any of the next calls.

  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5008, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_one", name);

  ASSERT_EQ(8U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x3008, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_two", name);

  ASSERT_EQ(4U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0xa01a, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_three", name);

  ASSERT_EQ(0xaU, func_offset);

}



TYPED_TEST_P(SymbolsTest, multiple_entries_nonstandard_size) {

  uint64_t entry_size = sizeof(TypeParam) + 5;

  Symbols symbols(0x1000, entry_size * 3, entry_size, 0x2000, 0x500);



  TypeParam sym;

  uint64_t offset = 0x1000;

  std::string fake_name;



  this->InitSym(&sym, 0x5000, 0x10, 0x40);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_one";

  this->memory_.SetMemory(0x2040, fake_name.c_str(), fake_name.size() + 1);

  offset += entry_size;



  this->InitSym(&sym, 0x3004, 0x200, 0x100);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_two";

  this->memory_.SetMemory(0x2100, fake_name.c_str(), fake_name.size() + 1);

  offset += entry_size;



  this->InitSym(&sym, 0xa010, 0x20, 0x230);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  fake_name = "function_three";

  this->memory_.SetMemory(0x2230, fake_name.c_str(), fake_name.size() + 1);



  std::string name;

  uint64_t func_offset;

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x3005, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_two", name);

  ASSERT_EQ(1U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5004, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_one", name);

  ASSERT_EQ(4U, func_offset);



  name.clear();

  ASSERT_TRUE(symbols.GetName<TypeParam>(0xa011, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function_three", name);

  ASSERT_EQ(1U, func_offset);

}



TYPED_TEST_P(SymbolsTest, load_bias) {

  Symbols symbols(0x1000, sizeof(TypeParam), sizeof(TypeParam), 0x2000, 0x100);



  TypeParam sym;

  this->InitSym(&sym, 0x5000, 0x10, 0x40);

  uint64_t offset = 0x1000;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));



  std::string fake_name("fake_function");

  this->memory_.SetMemory(0x2040, fake_name.c_str(), fake_name.size() + 1);



  // Set a non-zero load_bias that should be a valid function offset.

  std::string name;

  uint64_t func_offset;

  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5004, 0x1000, &this->memory_, &name, &func_offset));

  ASSERT_EQ("fake_function", name);

  ASSERT_EQ(4U, func_offset);



  // Set a flag that should cause the load_bias to be ignored.

  sym.st_shndx = SHN_ABS;

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  // Clear the cache to force the symbol data to be re-read.

  symbols.ClearCache();

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x5004, 0x1000, &this->memory_, &name, &func_offset));

}



TYPED_TEST_P(SymbolsTest, symtab_value_out_of_bounds) {

  Symbols symbols_end_at_100(0x1000, sizeof(TypeParam) * 2, sizeof(TypeParam), 0x2000, 0x100);

  Symbols symbols_end_at_200(0x1000, sizeof(TypeParam) * 2, sizeof(TypeParam), 0x2000, 0x200);



  TypeParam sym;

  uint64_t offset = 0x1000;



  this->InitSym(&sym, 0x5000, 0x10, 0xfb);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  offset += sizeof(sym);



  this->InitSym(&sym, 0x3000, 0x10, 0x100);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));



  // Put the name across the end of the tab.

  std::string fake_name("fake_function");

  this->memory_.SetMemory(0x20fb, fake_name.c_str(), fake_name.size() + 1);



  std::string name;

  uint64_t func_offset;

  // Verify that we can get the function name properly for both entries.

  ASSERT_TRUE(symbols_end_at_200.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("fake_function", name);

  ASSERT_EQ(0U, func_offset);

  ASSERT_TRUE(symbols_end_at_200.GetName<TypeParam>(0x3000, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("function", name);

  ASSERT_EQ(0U, func_offset);



  // Now use the symbol table that ends at 0x100.

  ASSERT_FALSE(

      symbols_end_at_100.GetName<TypeParam>(0x5000, 0, &this->memory_, &name, &func_offset));

  ASSERT_FALSE(

      symbols_end_at_100.GetName<TypeParam>(0x3000, 0, &this->memory_, &name, &func_offset));

}



// Verify the entire func table is cached.

TYPED_TEST_P(SymbolsTest, symtab_read_cached) {

  Symbols symbols(0x1000, 3 * sizeof(TypeParam), sizeof(TypeParam), 0xa000, 0x1000);



  TypeParam sym;

  uint64_t offset = 0x1000;



  // Make sure that these entries are not in ascending order.

  this->InitSym(&sym, 0x5000, 0x10, 0x100);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  offset += sizeof(sym);



  this->InitSym(&sym, 0x2000, 0x300, 0x200);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  offset += sizeof(sym);



  this->InitSym(&sym, 0x1000, 0x100, 0x300);

  this->memory_.SetMemory(offset, &sym, sizeof(sym));

  offset += sizeof(sym);



  // Do call that should cache all of the entries (except the string data).

  std::string name;

  uint64_t func_offset;

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x6000, 0, &this->memory_, &name, &func_offset));

  this->memory_.Clear();

  ASSERT_FALSE(symbols.GetName<TypeParam>(0x6000, 0, &this->memory_, &name, &func_offset));



  // Clear the memory and only put the symbol data string data in memory.

  this->memory_.Clear();



  std::string fake_name;

  fake_name = "first_entry";

  this->memory_.SetMemory(0xa100, fake_name.c_str(), fake_name.size() + 1);

  fake_name = "second_entry";

  this->memory_.SetMemory(0xa200, fake_name.c_str(), fake_name.size() + 1);

  fake_name = "third_entry";

  this->memory_.SetMemory(0xa300, fake_name.c_str(), fake_name.size() + 1);



  ASSERT_TRUE(symbols.GetName<TypeParam>(0x5001, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("first_entry", name);

  ASSERT_EQ(1U, func_offset);



  ASSERT_TRUE(symbols.GetName<TypeParam>(0x2002, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("second_entry", name);

  ASSERT_EQ(2U, func_offset);



  ASSERT_TRUE(symbols.GetName<TypeParam>(0x1003, 0, &this->memory_, &name, &func_offset));

  ASSERT_EQ("third_entry", name);

  ASSERT_EQ(3U, func_offset);

}



REGISTER_TYPED_TEST_CASE_P(SymbolsTest, function_bounds_check, no_symbol, multiple_entries,

                           multiple_entries_nonstandard_size, load_bias, symtab_value_out_of_bounds,

                           symtab_read_cached);



typedef ::testing::Types<Elf32_Sym, Elf64_Sym> SymbolsTestTypes;

INSTANTIATE_TYPED_TEST_CASE_P(, SymbolsTest, SymbolsTestTypes);