88 lines
3.5 KiB
C
88 lines
3.5 KiB
C
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// Copyright 2019 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_PROFILER_UNWINDER_H_
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#define BASE_PROFILER_UNWINDER_H_
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#include <vector>
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#include "base/macros.h"
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#include "base/profiler/frame.h"
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#include "base/profiler/module_cache.h"
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#include "base/profiler/register_context.h"
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namespace base {
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// The result of attempting to unwind stack frames.
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enum class UnwindResult {
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// The end of the stack was reached successfully.
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COMPLETED,
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// The walk reached a frame that it doesn't know how to unwind, but might be
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// unwindable by the other native/aux unwinder.
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UNRECOGNIZED_FRAME,
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// The walk was aborted and is not resumable.
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ABORTED,
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};
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// Unwinder provides an interface for stack frame unwinder implementations for
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// use with the StackSamplingProfiler. The profiler is expected to call
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// CanUnwind() to determine if the Unwinder thinks it can unwind from the frame
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// represented by the context values, then TryUnwind() to attempt the
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// unwind.
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class Unwinder {
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public:
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virtual ~Unwinder() = default;
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// Invoked to allow the unwinder to add any modules it recognizes to the
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// ModuleCache.
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virtual void AddInitialModules(ModuleCache* module_cache) {}
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// Invoked at the time the stack is captured. IMPORTANT NOTE: this function is
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// invoked while the target thread is suspended. To avoid deadlock it must not
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// invoke any non-reentrant code that is also invoked by the target thread. In
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// particular, it may not perform any heap allocation or deallocation,
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// including indirectly via use of DCHECK/CHECK or other logging statements.
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virtual void OnStackCapture() {}
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// Allows the unwinder to update ModuleCache with any modules it's responsible
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// for. Invoked for each sample between OnStackCapture() and the initial
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// invocations of CanUnwindFrom()/TryUnwind().
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virtual void UpdateModules(ModuleCache* module_cache) {}
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// Returns true if the unwinder recognizes the code referenced by
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// |current_frame| as code from which it should be able to unwind. When
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// multiple unwinders are in use, each should return true for a disjoint set
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// of frames. Note that if the unwinder returns true it may still legitmately
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// fail to unwind; e.g. in the case of a native unwind for a function that
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// doesn't have unwind information.
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virtual bool CanUnwindFrom(const Frame& current_frame) const = 0;
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// Attempts to unwind the frame represented by the context values.
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// Walks the native frames on the stack pointed to by the stack pointer in
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// |thread_context|, appending the frames to |stack|. When invoked
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// stack->back() contains the frame corresponding to the state in
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// |thread_context|.
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// Precondition: RegisterContextStackPointer(thread_context) is less than
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// |stack_top|.
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// Postcondition: If the implementation returns UNRECOGNIZED_FRAME, indicating
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// that it successfully unwound, RegisterContextStackPointer(thread_context)
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// is greater than the previous value and less than |stack_top|.
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virtual UnwindResult TryUnwind(RegisterContext* thread_context,
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uintptr_t stack_top,
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ModuleCache* module_cache,
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std::vector<Frame>* stack) const = 0;
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Unwinder(const Unwinder&) = delete;
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Unwinder& operator=(const Unwinder&) = delete;
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protected:
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Unwinder() = default;
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};
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} // namespace base
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#endif // BASE_PROFILER_UNWINDER_H_
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