1 /*
2  * Copyright (C) 2015 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 #ifndef __LINKER_ALLOCATOR_H
30 #define __LINKER_ALLOCATOR_H
31 
32 #include <stdlib.h>
33 #include <sys/cdefs.h>
34 #include <sys/mman.h>
35 #include <stddef.h>
36 #include <unistd.h>
37 
38 #include <vector>
39 
40 #include "private/bionic_prctl.h"
41 #include "private/libc_logging.h"
42 
43 const uint32_t kSmallObjectMaxSizeLog2 = 10;
44 const uint32_t kSmallObjectMinSizeLog2 = 4;
45 const uint32_t kSmallObjectAllocatorsCount = kSmallObjectMaxSizeLog2 - kSmallObjectMinSizeLog2 + 1;
46 
47 class LinkerSmallObjectAllocator;
48 
49 // This structure is placed at the beginning of each addressable page
50 // and has all information we need to find the corresponding memory allocator.
51 struct page_info {
52   char signature[4];
53   uint32_t type;
54   union {
55     // we use allocated_size for large objects allocator
56     size_t allocated_size;
57     // and allocator_addr for small ones.
58     LinkerSmallObjectAllocator* allocator_addr;
59   };
60 } __attribute__((aligned(16)));
61 
62 struct small_object_page_record {
63   void* page_addr;
64   size_t free_blocks_cnt;
65   size_t allocated_blocks_cnt;
66 };
67 
68 // for lower_bound...
69 bool operator<(const small_object_page_record& one, const small_object_page_record& two);
70 
71 struct small_object_block_record {
72   small_object_block_record* next;
73   size_t free_blocks_cnt;
74 };
75 
76 // This is implementation for std::vector allocator
77 template <typename T>
78 class linker_vector_allocator {
79  public:
80   typedef T value_type;
81   typedef T* pointer;
82   typedef const T* const_pointer;
83   typedef T& reference;
84   typedef const T& const_reference;
85   typedef size_t size_type;
86   typedef ptrdiff_t difference_type;
87 
88   T* allocate(size_t n, const T* hint = nullptr) {
89     size_t size = n * sizeof(T);
90     void* ptr = mmap(const_cast<T*>(hint), size,
91         PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
92     if (ptr == MAP_FAILED) {
93       // Spec says we need to throw std::bad_alloc here but because our
94       // code does not support exception handling anyways - we are going to abort.
95       __libc_fatal("mmap failed");
96     }
97 
98     prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, "linker_alloc_vector");
99 
100     return reinterpret_cast<T*>(ptr);
101   }
102 
deallocate(T * ptr,size_t n)103   void deallocate(T* ptr, size_t n) {
104     munmap(ptr, n * sizeof(T));
105   }
106 };
107 
108 typedef
109     std::vector<small_object_page_record, linker_vector_allocator<small_object_page_record>>
110     linker_vector_t;
111 
112 
113 class LinkerSmallObjectAllocator {
114  public:
115   LinkerSmallObjectAllocator(uint32_t type, size_t block_size);
116   void* alloc();
117   void free(void* ptr);
118 
get_block_size()119   size_t get_block_size() const { return block_size_; }
120  private:
121   void alloc_page();
122   void free_page(linker_vector_t::iterator page_record);
123   linker_vector_t::iterator find_page_record(void* ptr);
124   void create_page_record(void* page_addr, size_t free_blocks_cnt);
125 
126   uint32_t type_;
127   size_t block_size_;
128 
129   size_t free_pages_cnt_;
130   small_object_block_record* free_blocks_list_;
131 
132   // sorted vector of page records
133   linker_vector_t page_records_;
134 };
135 
136 class LinkerMemoryAllocator {
137  public:
LinkerMemoryAllocator()138   constexpr LinkerMemoryAllocator() : allocators_(nullptr), allocators_buf_() {}
139   void* alloc(size_t size);
140 
141   // Note that this implementation of realloc never shrinks allocation
142   void* realloc(void* ptr, size_t size);
143   void free(void* ptr);
144  private:
145   void* alloc_mmap(size_t size);
146   page_info* get_page_info(void* ptr);
147   LinkerSmallObjectAllocator* get_small_object_allocator(uint32_t type);
148   void initialize_allocators();
149 
150   LinkerSmallObjectAllocator* allocators_;
151   uint8_t allocators_buf_[sizeof(LinkerSmallObjectAllocator)*kSmallObjectAllocatorsCount];
152 };
153 
154 
155 #endif  /* __LINKER_ALLOCATOR_H */
156