1 /* 2 * Copyright (C) 2008 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 #include "space_bitmap-inl.h" 18 19 #include "android-base/stringprintf.h" 20 21 #include "art_field-inl.h" 22 #include "dex/dex_file-inl.h" 23 #include "mem_map.h" 24 #include "mirror/class-inl.h" 25 #include "mirror/object-inl.h" 26 #include "mirror/object_array.h" 27 28 namespace art { 29 namespace gc { 30 namespace accounting { 31 32 using android::base::StringPrintf; 33 34 template<size_t kAlignment> 35 size_t SpaceBitmap<kAlignment>::ComputeBitmapSize(uint64_t capacity) { 36 // Number of space (heap) bytes covered by one bitmap word. 37 // (Word size in bytes = `sizeof(intptr_t)`, which is expected to be 38 // 4 on a 32-bit architecture and 8 on a 64-bit one.) 39 const uint64_t kBytesCoveredPerWord = kAlignment * kBitsPerIntPtrT; 40 // Calculate the number of words required to cover a space (heap) 41 // having a size of `capacity` bytes. 42 return (RoundUp(capacity, kBytesCoveredPerWord) / kBytesCoveredPerWord) * sizeof(intptr_t); 43 } 44 45 template<size_t kAlignment> 46 size_t SpaceBitmap<kAlignment>::ComputeHeapSize(uint64_t bitmap_bytes) { 47 return bitmap_bytes * kBitsPerByte * kAlignment; 48 } 49 50 template<size_t kAlignment> 51 SpaceBitmap<kAlignment>* SpaceBitmap<kAlignment>::CreateFromMemMap( 52 const std::string& name, MemMap* mem_map, uint8_t* heap_begin, size_t heap_capacity) { 53 CHECK(mem_map != nullptr); 54 uintptr_t* bitmap_begin = reinterpret_cast<uintptr_t*>(mem_map->Begin()); 55 const size_t bitmap_size = ComputeBitmapSize(heap_capacity); 56 return new SpaceBitmap(name, mem_map, bitmap_begin, bitmap_size, heap_begin, heap_capacity); 57 } 58 59 template<size_t kAlignment> 60 SpaceBitmap<kAlignment>::SpaceBitmap(const std::string& name, 61 MemMap* mem_map, 62 uintptr_t* bitmap_begin, 63 size_t bitmap_size, 64 const void* heap_begin, 65 size_t heap_capacity) 66 : mem_map_(mem_map), 67 bitmap_begin_(reinterpret_cast<Atomic<uintptr_t>*>(bitmap_begin)), 68 bitmap_size_(bitmap_size), 69 heap_begin_(reinterpret_cast<uintptr_t>(heap_begin)), 70 heap_limit_(reinterpret_cast<uintptr_t>(heap_begin) + heap_capacity), 71 name_(name) { 72 CHECK(bitmap_begin_ != nullptr); 73 CHECK_NE(bitmap_size, 0U); 74 } 75 76 template<size_t kAlignment> 77 SpaceBitmap<kAlignment>::~SpaceBitmap() {} 78 79 template<size_t kAlignment> 80 SpaceBitmap<kAlignment>* SpaceBitmap<kAlignment>::Create( 81 const std::string& name, uint8_t* heap_begin, size_t heap_capacity) { 82 // Round up since `heap_capacity` is not necessarily a multiple of `kAlignment * kBitsPerIntPtrT` 83 // (we represent one word as an `intptr_t`). 84 const size_t bitmap_size = ComputeBitmapSize(heap_capacity); 85 std::string error_msg; 86 std::unique_ptr<MemMap> mem_map(MemMap::MapAnonymous(name.c_str(), nullptr, bitmap_size, 87 PROT_READ | PROT_WRITE, false, false, 88 &error_msg)); 89 if (UNLIKELY(mem_map.get() == nullptr)) { 90 LOG(ERROR) << "Failed to allocate bitmap " << name << ": " << error_msg; 91 return nullptr; 92 } 93 return CreateFromMemMap(name, mem_map.release(), heap_begin, heap_capacity); 94 } 95 96 template<size_t kAlignment> 97 void SpaceBitmap<kAlignment>::SetHeapLimit(uintptr_t new_end) { 98 DCHECK_ALIGNED(new_end, kBitsPerIntPtrT * kAlignment); 99 size_t new_size = OffsetToIndex(new_end - heap_begin_) * sizeof(intptr_t); 100 if (new_size < bitmap_size_) { 101 bitmap_size_ = new_size; 102 } 103 heap_limit_ = new_end; 104 // Not sure if doing this trim is necessary, since nothing past the end of the heap capacity 105 // should be marked. 106 } 107 108 template<size_t kAlignment> 109 std::string SpaceBitmap<kAlignment>::Dump() const { 110 return StringPrintf("%s: %p-%p", name_.c_str(), reinterpret_cast<void*>(HeapBegin()), 111 reinterpret_cast<void*>(HeapLimit())); 112 } 113 114 template<size_t kAlignment> 115 void SpaceBitmap<kAlignment>::Clear() { 116 if (bitmap_begin_ != nullptr) { 117 mem_map_->MadviseDontNeedAndZero(); 118 } 119 } 120 121 template<size_t kAlignment> 122 void SpaceBitmap<kAlignment>::ClearRange(const mirror::Object* begin, const mirror::Object* end) { 123 uintptr_t begin_offset = reinterpret_cast<uintptr_t>(begin) - heap_begin_; 124 uintptr_t end_offset = reinterpret_cast<uintptr_t>(end) - heap_begin_; 125 // Align begin and end to bitmap word boundaries. 126 while (begin_offset < end_offset && OffsetBitIndex(begin_offset) != 0) { 127 Clear(reinterpret_cast<mirror::Object*>(heap_begin_ + begin_offset)); 128 begin_offset += kAlignment; 129 } 130 while (begin_offset < end_offset && OffsetBitIndex(end_offset) != 0) { 131 end_offset -= kAlignment; 132 Clear(reinterpret_cast<mirror::Object*>(heap_begin_ + end_offset)); 133 } 134 // Bitmap word boundaries. 135 const uintptr_t start_index = OffsetToIndex(begin_offset); 136 const uintptr_t end_index = OffsetToIndex(end_offset); 137 ZeroAndReleasePages(reinterpret_cast<uint8_t*>(&bitmap_begin_[start_index]), 138 (end_index - start_index) * sizeof(*bitmap_begin_)); 139 } 140 141 template<size_t kAlignment> 142 void SpaceBitmap<kAlignment>::CopyFrom(SpaceBitmap* source_bitmap) { 143 DCHECK_EQ(Size(), source_bitmap->Size()); 144 const size_t count = source_bitmap->Size() / sizeof(intptr_t); 145 Atomic<uintptr_t>* const src = source_bitmap->Begin(); 146 Atomic<uintptr_t>* const dest = Begin(); 147 for (size_t i = 0; i < count; ++i) { 148 dest[i].StoreRelaxed(src[i].LoadRelaxed()); 149 } 150 } 151 152 template<size_t kAlignment> 153 void SpaceBitmap<kAlignment>::SweepWalk(const SpaceBitmap<kAlignment>& live_bitmap, 154 const SpaceBitmap<kAlignment>& mark_bitmap, 155 uintptr_t sweep_begin, uintptr_t sweep_end, 156 SpaceBitmap::SweepCallback* callback, void* arg) { 157 CHECK(live_bitmap.bitmap_begin_ != nullptr); 158 CHECK(mark_bitmap.bitmap_begin_ != nullptr); 159 CHECK_EQ(live_bitmap.heap_begin_, mark_bitmap.heap_begin_); 160 CHECK_EQ(live_bitmap.bitmap_size_, mark_bitmap.bitmap_size_); 161 CHECK(callback != nullptr); 162 CHECK_LE(sweep_begin, sweep_end); 163 CHECK_GE(sweep_begin, live_bitmap.heap_begin_); 164 165 if (sweep_end <= sweep_begin) { 166 return; 167 } 168 169 // TODO: rewrite the callbacks to accept a std::vector<mirror::Object*> rather than a mirror::Object**? 170 constexpr size_t buffer_size = sizeof(intptr_t) * kBitsPerIntPtrT; 171 #ifdef __LP64__ 172 // Heap-allocate for smaller stack frame. 173 std::unique_ptr<mirror::Object*[]> pointer_buf_ptr(new mirror::Object*[buffer_size]); 174 mirror::Object** pointer_buf = pointer_buf_ptr.get(); 175 #else 176 // Stack-allocate buffer as it's small enough. 177 mirror::Object* pointer_buf[buffer_size]; 178 #endif 179 mirror::Object** pb = &pointer_buf[0]; 180 181 size_t start = OffsetToIndex(sweep_begin - live_bitmap.heap_begin_); 182 size_t end = OffsetToIndex(sweep_end - live_bitmap.heap_begin_ - 1); 183 CHECK_LT(end, live_bitmap.Size() / sizeof(intptr_t)); 184 Atomic<uintptr_t>* live = live_bitmap.bitmap_begin_; 185 Atomic<uintptr_t>* mark = mark_bitmap.bitmap_begin_; 186 for (size_t i = start; i <= end; i++) { 187 uintptr_t garbage = live[i].LoadRelaxed() & ~mark[i].LoadRelaxed(); 188 if (UNLIKELY(garbage != 0)) { 189 uintptr_t ptr_base = IndexToOffset(i) + live_bitmap.heap_begin_; 190 do { 191 const size_t shift = CTZ(garbage); 192 garbage ^= (static_cast<uintptr_t>(1)) << shift; 193 *pb++ = reinterpret_cast<mirror::Object*>(ptr_base + shift * kAlignment); 194 } while (garbage != 0); 195 // Make sure that there are always enough slots available for an 196 // entire word of one bits. 197 if (pb >= &pointer_buf[buffer_size - kBitsPerIntPtrT]) { 198 (*callback)(pb - &pointer_buf[0], &pointer_buf[0], arg); 199 pb = &pointer_buf[0]; 200 } 201 } 202 } 203 if (pb > &pointer_buf[0]) { 204 (*callback)(pb - &pointer_buf[0], &pointer_buf[0], arg); 205 } 206 } 207 208 template class SpaceBitmap<kObjectAlignment>; 209 template class SpaceBitmap<kPageSize>; 210 211 } // namespace accounting 212 } // namespace gc 213 } // namespace art 214
