76 lines
2.5 KiB
C
76 lines
2.5 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_ANDROID_REACHED_ADDRESSES_BITSET_H_
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#define BASE_ANDROID_REACHED_ADDRESSES_BITSET_H_
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#include <atomic>
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#include <vector>
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#include "base/base_export.h"
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namespace base {
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template <typename T>
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class NoDestructor;
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namespace android {
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// ReachedAddressesBitset is a set that stores addresses for the
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// ReachedCodeProfiler in compact form. Its main features are lock-free
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// thread-safety and fast adding of elements.
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//
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// The addresses are kept with |kBytesGranularity| to save the storage space.
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//
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// Once insterted, elements cannot be erased from the set.
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//
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// All methods can be called from any thread.
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class BASE_EXPORT ReachedAddressesBitset {
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public:
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// Returns an instance of ReachedAddressesBitset having enough storage space
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// to keep all addresses from the .text section.
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// Returns nullptr if SUPPORTS_CODE_ORDERING isn't defined.
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// This instance is stored in the .bss section of the binary, meaning that it
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// doesn't incur the binary size overhead and it doesn't increase the resident
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// memory footprint when not used.
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static ReachedAddressesBitset* GetTextBitset();
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// Inserts |address| into the bitset iff |address| lies in the range between
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// |start_address_| and |end_address_|.
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void RecordAddress(uintptr_t address);
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// Returns a list of recorded addresses in the form of offsets from
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// |start_address_|.
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std::vector<uint32_t> GetReachedOffsets() const;
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private:
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friend class ReachedAddressesBitsetTest;
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friend class NoDestructor<ReachedAddressesBitset>;
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// Represents the number of bytes that are mapped into the same bit in the
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// bitset.
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static constexpr size_t kBytesGranularity = 4;
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// Constructs a ReachedAddressesBitset on top of an external storage of
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// |storage_size| pointed by |storage_ptr|. This external storage must outlive
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// the constructed bitset instance. The size of storage must be large enough
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// to fit all addresses in the range between |start_address| and
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// |end_address|.
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ReachedAddressesBitset(uintptr_t start_address,
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uintptr_t end_address,
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std::atomic<uint32_t>* storage_ptr,
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size_t storage_size);
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size_t NumberOfReachableElements() const;
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uintptr_t start_address_;
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uintptr_t end_address_;
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std::atomic<uint32_t>* reached_;
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};
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} // namespace android
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} // namespace base
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#endif // BASE_ANDROID_REACHED_ADDRESSES_BITSET_H_
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