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