root/base/debug/profiler.cc

DEFINITIONS

1. StartProfiling
2. StopProfiling
3. FlushProfiling
4. BeingProfiled
5. RestartProfilingAfterFork
6. StartProfiling
7. StopProfiling
8. FlushProfiling
9. BeingProfiled
10. RestartProfilingAfterFork
11. IsBinaryInstrumented
12. GetProfilerReturnAddrResolutionFunc
13. GetProfilerDynamicFunctionEntryHookFunc
14. GetProfilerAddDynamicSymbolFunc
15. GetProfilerMoveDynamicSymbolFunc
16. IsBinaryInstrumented
17. FindResolutionFunctionInImports
18. FindFunctionInImports
19. GetProfilerReturnAddrResolutionFunc
20. GetProfilerDynamicFunctionEntryHookFunc
21. GetProfilerAddDynamicSymbolFunc
22. GetProfilerMoveDynamicSymbolFunc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/debug/profiler.h"

#include <string>

#include "base/process/process_handle.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"

#if defined(OS_WIN)
#include "base/win/pe_image.h"
#endif  // defined(OS_WIN)

// TODO(peria): Enable profiling on Windows.
#if defined(ENABLE_PROFILING) && !defined(NO_TCMALLOC) && !defined(OS_WIN)
#include "third_party/tcmalloc/chromium/src/gperftools/profiler.h"
#endif

namespace base {
namespace debug {

// TODO(peria): Enable profiling on Windows.
#if defined(ENABLE_PROFILING) && !defined(NO_TCMALLOC) && !defined(OS_WIN)

static int profile_count = 0;

void StartProfiling(const std::string& name) {
  ++profile_count;
  std::string full_name(name);
  std::string pid = StringPrintf("%d", GetCurrentProcId());
  std::string count = StringPrintf("%d", profile_count);
  ReplaceSubstringsAfterOffset(&full_name, 0, "{pid}", pid);
  ReplaceSubstringsAfterOffset(&full_name, 0, "{count}", count);
  ProfilerStart(full_name.c_str());
}

void StopProfiling() {
  ProfilerFlush();
  ProfilerStop();
}

void FlushProfiling() {
  ProfilerFlush();
}

bool BeingProfiled() {
  return ProfilingIsEnabledForAllThreads();
}

void RestartProfilingAfterFork() {
  ProfilerRegisterThread();
}

#else

void StartProfiling(const std::string& name) {
}

void StopProfiling() {
}

void FlushProfiling() {
}

bool BeingProfiled() {
  return false;
}

void RestartProfilingAfterFork() {
}

#endif

#if !defined(OS_WIN)

bool IsBinaryInstrumented() {
  return false;
}

ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc() {
  return NULL;
}

DynamicFunctionEntryHook GetProfilerDynamicFunctionEntryHookFunc() {
  return NULL;
}

AddDynamicSymbol GetProfilerAddDynamicSymbolFunc() {
  return NULL;
}

MoveDynamicSymbol GetProfilerMoveDynamicSymbolFunc() {
  return NULL;
}

#else  // defined(OS_WIN)

// http://blogs.msdn.com/oldnewthing/archive/2004/10/25/247180.aspx
extern "C" IMAGE_DOS_HEADER __ImageBase;

bool IsBinaryInstrumented() {
  enum InstrumentationCheckState {
    UNINITIALIZED,
    INSTRUMENTED_IMAGE,
    NON_INSTRUMENTED_IMAGE,
  };

  static InstrumentationCheckState state = UNINITIALIZED;

  if (state == UNINITIALIZED) {
    HMODULE this_module = reinterpret_cast<HMODULE>(&__ImageBase);
    base::win::PEImage image(this_module);

    // Check to be sure our image is structured as we'd expect.
    DCHECK(image.VerifyMagic());

    // Syzygy-instrumented binaries contain a PE image section named ".thunks",
    // and all Syzygy-modified binaries contain the ".syzygy" image section.
    // This is a very fast check, as it only looks at the image header.
    if ((image.GetImageSectionHeaderByName(".thunks") != NULL) &&
        (image.GetImageSectionHeaderByName(".syzygy") != NULL)) {
      state = INSTRUMENTED_IMAGE;
    } else {
      state = NON_INSTRUMENTED_IMAGE;
    }
  }
  DCHECK(state != UNINITIALIZED);

  return state == INSTRUMENTED_IMAGE;
}

namespace {

struct FunctionSearchContext {
  const char* name;
  FARPROC function;
};

// Callback function to PEImage::EnumImportChunks.
bool FindResolutionFunctionInImports(
    const base::win::PEImage &image, const char* module_name,
    PIMAGE_THUNK_DATA unused_name_table, PIMAGE_THUNK_DATA import_address_table,
    PVOID cookie) {
  FunctionSearchContext* context =
      reinterpret_cast<FunctionSearchContext*>(cookie);

  DCHECK_NE(static_cast<FunctionSearchContext*>(NULL), context);
  DCHECK_EQ(static_cast<FARPROC>(NULL), context->function);

  // Our import address table contains pointers to the functions we import
  // at this point. Let's retrieve the first such function and use it to
  // find the module this import was resolved to by the loader.
  const wchar_t* function_in_module =
      reinterpret_cast<const wchar_t*>(import_address_table->u1.Function);

  // Retrieve the module by a function in the module.
  const DWORD kFlags = GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
                       GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT;
  HMODULE module = NULL;
  if (!::GetModuleHandleEx(kFlags, function_in_module, &module)) {
    // This can happen if someone IAT patches us to a thunk.
    return true;
  }

  // See whether this module exports the function we're looking for.
  FARPROC exported_func = ::GetProcAddress(module, context->name);
  if (exported_func != NULL) {
    // We found it, return the function and terminate the enumeration.
    context->function = exported_func;
    return false;
  }

  // Keep going.
  return true;
}

template <typename FunctionType>
FunctionType FindFunctionInImports(const char* function_name) {
  if (!IsBinaryInstrumented())
    return NULL;

  HMODULE this_module = reinterpret_cast<HMODULE>(&__ImageBase);
  base::win::PEImage image(this_module);

  FunctionSearchContext ctx = { function_name, NULL };
  image.EnumImportChunks(FindResolutionFunctionInImports, &ctx);

  return reinterpret_cast<FunctionType>(ctx.function);
}

}  // namespace

ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc() {
  return FindFunctionInImports<ReturnAddressLocationResolver>(
      "ResolveReturnAddressLocation");
}

DynamicFunctionEntryHook GetProfilerDynamicFunctionEntryHookFunc() {
  return FindFunctionInImports<DynamicFunctionEntryHook>(
      "OnDynamicFunctionEntry");
}

AddDynamicSymbol GetProfilerAddDynamicSymbolFunc() {
  return FindFunctionInImports<AddDynamicSymbol>(
      "AddDynamicSymbol");
}

MoveDynamicSymbol GetProfilerMoveDynamicSymbolFunc() {
  return FindFunctionInImports<MoveDynamicSymbol>(
      "MoveDynamicSymbol");
}

#endif  // defined(OS_WIN)

}  // namespace debug
}  // namespace base