michael@0: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_DEBUG_PROFILER_H
michael@0: #define BASE_DEBUG_PROFILER_H
michael@0: 
michael@0: #include <string>
michael@0: 
michael@0: #include "base/base_export.h"
michael@0: #include "base/basictypes.h"
michael@0: 
michael@0: // The Profiler functions allow usage of the underlying sampling based
michael@0: // profiler. If the application has not been built with the necessary
michael@0: // flags (-DENABLE_PROFILING and not -DNO_TCMALLOC) then these functions
michael@0: // are noops.
michael@0: namespace base {
michael@0: namespace debug {
michael@0: 
michael@0: // Start profiling with the supplied name.
michael@0: // {pid} will be replaced by the process' pid and {count} will be replaced
michael@0: // by the count of the profile run (starts at 1 with each process).
michael@0: BASE_EXPORT void StartProfiling(const std::string& name);
michael@0: 
michael@0: // Stop profiling and write out data.
michael@0: BASE_EXPORT void StopProfiling();
michael@0: 
michael@0: // Force data to be written to file.
michael@0: BASE_EXPORT void FlushProfiling();
michael@0: 
michael@0: // Returns true if process is being profiled.
michael@0: BASE_EXPORT bool BeingProfiled();
michael@0: 
michael@0: // Reset profiling after a fork, which disables timers.
michael@0: BASE_EXPORT void RestartProfilingAfterFork();
michael@0: 
michael@0: // Returns true iff this executable is instrumented with the Syzygy profiler.
michael@0: BASE_EXPORT bool IsBinaryInstrumented();
michael@0: 
michael@0: // There's a class of profilers that use "return address swizzling" to get a
michael@0: // hook on function exits. This class of profilers uses some form of entry hook,
michael@0: // like e.g. binary instrumentation, or a compiler flag, that calls a hook each
michael@0: // time a function is invoked. The hook then switches the return address on the
michael@0: // stack for the address of an exit hook function, and pushes the original
michael@0: // return address to a shadow stack of some type. When in due course the CPU
michael@0: // executes a return to the exit hook, the exit hook will do whatever work it
michael@0: // does on function exit, then arrange to return to the original return address.
michael@0: // This class of profiler does not play well with programs that look at the
michael@0: // return address, as does e.g. V8. V8 uses the return address to certain
michael@0: // runtime functions to find the JIT code that called it, and from there finds
michael@0: // the V8 data structures associated to the JS function involved.
michael@0: // A return address resolution function is used to fix this. It allows such
michael@0: // programs to resolve a location on stack where a return address originally
michael@0: // resided, to the shadow stack location where the profiler stashed it.
michael@0: typedef uintptr_t (*ReturnAddressLocationResolver)(
michael@0:     uintptr_t return_addr_location);
michael@0: 
michael@0: // This type declaration must match V8's FunctionEntryHook.
michael@0: typedef void (*DynamicFunctionEntryHook)(uintptr_t function,
michael@0:                                          uintptr_t return_addr_location);
michael@0: 
michael@0: // The functions below here are to support profiling V8-generated code.
michael@0: // V8 has provisions for generating a call to an entry hook for newly generated
michael@0: // JIT code, and it can push symbol information on code generation and advise
michael@0: // when the garbage collector moves code. The functions declarations below here
michael@0: // make glue between V8's facilities and a profiler.
michael@0: 
michael@0: // This type declaration must match V8's FunctionEntryHook.
michael@0: typedef void (*DynamicFunctionEntryHook)(uintptr_t function,
michael@0:                                          uintptr_t return_addr_location);
michael@0: 
michael@0: typedef void (*AddDynamicSymbol)(const void* address,
michael@0:                                  size_t length,
michael@0:                                  const char* name,
michael@0:                                  size_t name_len);
michael@0: typedef void (*MoveDynamicSymbol)(const void* address, const void* new_address);
michael@0: 
michael@0: 
michael@0: // If this binary is instrumented and the instrumentation supplies a function
michael@0: // for each of those purposes, find and return the function in question.
michael@0: // Otherwise returns NULL.
michael@0: BASE_EXPORT ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc();
michael@0: BASE_EXPORT DynamicFunctionEntryHook GetProfilerDynamicFunctionEntryHookFunc();
michael@0: BASE_EXPORT AddDynamicSymbol GetProfilerAddDynamicSymbolFunc();
michael@0: BASE_EXPORT MoveDynamicSymbol GetProfilerMoveDynamicSymbolFunc();
michael@0: 
michael@0: }  // namespace debug
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // BASE_DEBUG_DEBUGGER_H