// 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. #ifndef BASE_DEBUG_PROFILER_H_ #define BASE_DEBUG_PROFILER_H_ #include #include #include "base/base_export.h" // The Profiler functions allow usage of the underlying sampling based // profiler. If the application has not been built with the necessary // flags (-DENABLE_PROFILING and not -DNO_TCMALLOC) then these functions // are noops. namespace base { namespace debug { // Start profiling with the supplied name. // {pid} will be replaced by the process' pid and {count} will be replaced // by the count of the profile run (starts at 1 with each process). BASE_EXPORT void StartProfiling(const std::string& name); // Stop profiling and write out data. BASE_EXPORT void StopProfiling(); // Force data to be written to file. BASE_EXPORT void FlushProfiling(); // Returns true if process is being profiled. BASE_EXPORT bool BeingProfiled(); // Reset profiling after a fork, which disables timers. BASE_EXPORT void RestartProfilingAfterFork(); // Returns true iff this executable supports profiling. BASE_EXPORT bool IsProfilingSupported(); // There's a class of profilers that use "return address swizzling" to get a // hook on function exits. This class of profilers uses some form of entry hook, // like e.g. binary instrumentation, or a compiler flag, that calls a hook each // time a function is invoked. The hook then switches the return address on the // stack for the address of an exit hook function, and pushes the original // return address to a shadow stack of some type. When in due course the CPU // executes a return to the exit hook, the exit hook will do whatever work it // does on function exit, then arrange to return to the original return address. // This class of profiler does not play well with programs that look at the // return address, as does e.g. V8. V8 uses the return address to certain // runtime functions to find the JIT code that called it, and from there finds // the V8 data structures associated to the JS function involved. // A return address resolution function is used to fix this. It allows such // programs to resolve a location on stack where a return address originally // resided, to the shadow stack location where the profiler stashed it. typedef uintptr_t (*ReturnAddressLocationResolver)( uintptr_t return_addr_location); typedef void (*AddDynamicSymbol)(const void* address, size_t length, const char* name, size_t name_len); typedef void (*MoveDynamicSymbol)(const void* address, const void* new_address); // If this binary is instrumented and the instrumentation supplies a function // for each of those purposes, find and return the function in question. // Otherwise returns NULL. BASE_EXPORT ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc(); BASE_EXPORT AddDynamicSymbol GetProfilerAddDynamicSymbolFunc(); BASE_EXPORT MoveDynamicSymbol GetProfilerMoveDynamicSymbolFunc(); } // namespace debug } // namespace base #endif // BASE_DEBUG_PROFILER_H_