1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef __LINKER_BLOCK_ALLOCATOR_H 18 #define __LINKER_BLOCK_ALLOCATOR_H 19 20 #include <stdlib.h> 21 #include <limits.h> 22 #include "private/bionic_macros.h" 23 24 struct LinkerBlockAllocatorPage; 25 26 /* 27 * This class is a non-template version of the LinkerTypeAllocator 28 * It keeps code inside .cpp file by keeping the interface 29 * template-free. 30 * 31 * Please use LinkerTypeAllocator<type> where possible (everywhere). 32 */ 33 class LinkerBlockAllocator { 34 public: 35 explicit LinkerBlockAllocator(size_t block_size); 36 37 void* alloc(); 38 void free(void* block); 39 void protect_all(int prot); 40 41 private: 42 void create_new_page(); 43 LinkerBlockAllocatorPage* find_page(void* block); 44 45 size_t block_size_; 46 LinkerBlockAllocatorPage* page_list_; 47 void* free_block_list_; 48 49 DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator); 50 }; 51 52 /* 53 * A simple allocator for the dynamic linker. An allocator allocates instances 54 * of a single fixed-size type. Allocations are backed by page-sized private 55 * anonymous mmaps. 56 * 57 * The differences between this allocator and LinkerMemoryAllocator are: 58 * 1. This allocator manages space more efficiently. LinkerMemoryAllocator 59 * operates in power-of-two sized blocks up to 1k, when this implementation 60 * splits the page to aligned size of structure; For example for structures 61 * with size 513 this allocator will use 516 (520 for lp64) bytes of data 62 * where generalized implementation is going to use 1024 sized blocks. 63 * 64 * 2. This allocator does not munmap allocated memory, where LinkerMemoryAllocator does. 65 * 66 * 3. This allocator provides mprotect services to the user, where LinkerMemoryAllocator 67 * always treats it's memory as READ|WRITE. 68 */ 69 template<typename T> 70 class LinkerTypeAllocator { 71 public: LinkerTypeAllocator()72 LinkerTypeAllocator() : block_allocator_(sizeof(T)) {} alloc()73 T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); } free(T * t)74 void free(T* t) { block_allocator_.free(t); } protect_all(int prot)75 void protect_all(int prot) { block_allocator_.protect_all(prot); } 76 private: 77 LinkerBlockAllocator block_allocator_; 78 DISALLOW_COPY_AND_ASSIGN(LinkerTypeAllocator); 79 }; 80 81 #endif // __LINKER_BLOCK_ALLOCATOR_H 82