1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #pragma once 30 31 #include <stdlib.h> 32 #include <limits.h> 33 #include "private/bionic_macros.h" 34 35 struct LinkerBlockAllocatorPage; 36 37 /* 38 * This class is a non-template version of the LinkerTypeAllocator 39 * It keeps code inside .cpp file by keeping the interface 40 * template-free. 41 * 42 * Please use LinkerTypeAllocator<type> where possible (everywhere). 43 */ 44 class LinkerBlockAllocator { 45 public: 46 explicit LinkerBlockAllocator(size_t block_size); 47 48 void* alloc(); 49 void free(void* block); 50 void protect_all(int prot); 51 52 private: 53 void create_new_page(); 54 LinkerBlockAllocatorPage* find_page(void* block); 55 56 size_t block_size_; 57 LinkerBlockAllocatorPage* page_list_; 58 void* free_block_list_; 59 60 DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator); 61 }; 62 63 /* 64 * A simple allocator for the dynamic linker. An allocator allocates instances 65 * of a single fixed-size type. Allocations are backed by page-sized private 66 * anonymous mmaps. 67 * 68 * The differences between this allocator and LinkerMemoryAllocator are: 69 * 1. This allocator manages space more efficiently. LinkerMemoryAllocator 70 * operates in power-of-two sized blocks up to 1k, when this implementation 71 * splits the page to aligned size of structure; For example for structures 72 * with size 513 this allocator will use 516 (520 for lp64) bytes of data 73 * where generalized implementation is going to use 1024 sized blocks. 74 * 75 * 2. This allocator does not munmap allocated memory, where LinkerMemoryAllocator does. 76 * 77 * 3. This allocator provides mprotect services to the user, where LinkerMemoryAllocator 78 * always treats it's memory as READ|WRITE. 79 */ 80 template<typename T> 81 class LinkerTypeAllocator { 82 public: LinkerTypeAllocator()83 LinkerTypeAllocator() : block_allocator_(sizeof(T)) {} alloc()84 T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); } free(T * t)85 void free(T* t) { block_allocator_.free(t); } protect_all(int prot)86 void protect_all(int prot) { block_allocator_.protect_all(prot); } 87 private: 88 LinkerBlockAllocator block_allocator_; 89 DISALLOW_COPY_AND_ASSIGN(LinkerTypeAllocator); 90 }; 91