| // Copyright 2014 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Declares LargeBlockHeap, a heap that directly grabs pages of memory from the |
| // OS and redzones blocks with entire pages. This is only intended for use with |
| // sufficiently large allocations (hence the name) where the redzone overhead |
| // can be amortized. |
| // |
| // SyzyASan overhead is roughly 45% overall, with 25% coming from memory |
| // allocation overhead (20 + 16 = 36 bytes of overhead for average allocation |
| // sizes of 144 bytes in Chrome). If we wish to maintain a similar overhead |
| // then allocations being fed into the large block heap should be at least |
| // 32KB in size. Ideally the large allocation heap should not be leaned on too |
| // heavily as it can cause significant memory fragmentation. |
| |
| #ifndef SYZYGY_AGENT_ASAN_HEAPS_LARGE_BLOCK_HEAP_H_ |
| #define SYZYGY_AGENT_ASAN_HEAPS_LARGE_BLOCK_HEAP_H_ |
| |
| #include <unordered_set> |
| |
| #include "syzygy/agent/asan/allocators.h" |
| #include "syzygy/agent/asan/heap.h" |
| #include "syzygy/agent/asan/memory_notifier.h" |
| #include "syzygy/common/recursive_lock.h" |
| |
| namespace agent { |
| namespace asan { |
| namespace heaps { |
| |
| class LargeBlockHeap : public BlockHeapInterface { |
| public: |
| // Constructor. |
| // @param internal_heap The heap to use for making internal allocations. |
| explicit LargeBlockHeap(HeapInterface* internal_heap); |
| |
| // Virtual destructor. |
| virtual ~LargeBlockHeap() { } |
| |
| // @name HeapInterface implementation. |
| // @{ |
| virtual uint32 GetHeapFeatures() const; |
| virtual void* Allocate(size_t bytes); |
| virtual bool Free(void* alloc); |
| virtual bool IsAllocated(void* alloc); |
| virtual size_t GetAllocationSize(void* alloc); |
| virtual void Lock(); |
| virtual void Unlock(); |
| // @} |
| |
| // @name BlockHeapInterface implementation. |
| // @{ |
| virtual void* AllocateBlock(size_t size, |
| size_t min_left_redzone_size, |
| size_t min_right_redzone_size, |
| BlockLayout* layout); |
| virtual bool FreeBlock(const BlockInfo& block_info); |
| // @} |
| |
| // @returns the number of active allocations in this heap. |
| size_t size() const { return allocs_.size(); } |
| |
| protected: |
| // The collection of allocations that has been made through this allocator. |
| // It is expected that a small number of allocations will be made, so keeping |
| // track of these explicitly is fine for now. |
| typedef std::unordered_set< |
| void*, |
| std::hash<void*>, |
| std::equal_to<void*>, |
| HeapAllocator<void*>> AllocationSet; |
| AllocationSet allocs_; // Under lock_. |
| |
| // The global lock for this allocator. |
| common::RecursiveLock lock_; |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(LargeBlockHeap); |
| }; |
| |
| } // namespace heaps |
| } // namespace asan |
| } // namespace agent |
| |
| #endif // SYZYGY_AGENT_ASAN_HEAPS_LARGE_BLOCK_HEAP_H_ |