08cf949855
For a 32-bit userspace, `struct LinkedListEntry` takes 8 bytes for storing the two pointers, a default block allocator size alignment of 16-bytes would waste 50% of memory. By changing the alignment to size of a pointer, it saves >1MB memory postboot on wembley device. Bug: http://b/206889551 Test: bionic-unit-tests Change-Id: Ie92399c9bb3971f631396ee09bbbfd7eb17dc1a7
98 lines
3.5 KiB
C++
98 lines
3.5 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#pragma once
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#include <stdlib.h>
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#include <limits.h>
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#include <android-base/macros.h>
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static constexpr size_t kBlockSizeAlign = sizeof(void*);
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static constexpr size_t kBlockSizeMin = sizeof(void*) * 2;
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struct LinkerBlockAllocatorPage;
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/*
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* This class is a non-template version of the LinkerTypeAllocator
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* It keeps code inside .cpp file by keeping the interface
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* template-free.
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*
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* Please use LinkerTypeAllocator<type> where possible (everywhere).
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*/
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class LinkerBlockAllocator {
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public:
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explicit LinkerBlockAllocator(size_t block_size);
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void* alloc();
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void free(void* block);
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void protect_all(int prot);
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// Purge all pages if all previously allocated blocks have been freed.
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void purge();
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private:
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void create_new_page();
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LinkerBlockAllocatorPage* find_page(void* block);
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size_t block_size_;
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LinkerBlockAllocatorPage* page_list_;
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void* free_block_list_;
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size_t allocated_;
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DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator);
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};
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/*
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* A simple allocator for the dynamic linker. An allocator allocates instances
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* of a single fixed-size type. Allocations are backed by page-sized private
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* anonymous mmaps.
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*
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* The differences between this allocator and BionicAllocator are:
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* 1. This allocator manages space more efficiently. BionicAllocator operates in
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* power-of-two sized blocks up to 1k, when this implementation splits the
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* page to aligned size of structure; For example for structures with size
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* 513 this allocator will use 516 (520 for lp64) bytes of data where
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* generalized implementation is going to use 1024 sized blocks.
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*
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* 2. This allocator does not munmap allocated memory, where BionicAllocator does.
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*
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* 3. This allocator provides mprotect services to the user, where BionicAllocator
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* always treats its memory as READ|WRITE.
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*/
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template<typename T>
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class LinkerTypeAllocator {
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public:
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LinkerTypeAllocator() : block_allocator_(sizeof(T)) {}
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T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); }
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void free(T* t) { block_allocator_.free(t); }
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void protect_all(int prot) { block_allocator_.protect_all(prot); }
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private:
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LinkerBlockAllocator block_allocator_;
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DISALLOW_COPY_AND_ASSIGN(LinkerTypeAllocator);
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};
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