Colin Cross | bcb4ed3 | 2016-01-14 15:35:40 -0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2016 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 | // Header page: |
| 18 | // |
| 19 | // For minimum allocation size (8 bytes), bitmap can store used allocations for |
| 20 | // up to 4032*8*8=258048, which is 256KiB minus the header page |
| 21 | |
| 22 | #include <assert.h> |
| 23 | #include <stdlib.h> |
| 24 | |
| 25 | #include <sys/cdefs.h> |
| 26 | #include <sys/mman.h> |
| 27 | |
| 28 | #include <cmath> |
| 29 | #include <cstddef> |
| 30 | #include <cstdint> |
| 31 | #include <memory> |
| 32 | #include <mutex> |
| 33 | |
| 34 | #include "android-base/macros.h" |
| 35 | |
| 36 | #include "anon_vma_naming.h" |
| 37 | #include "Allocator.h" |
| 38 | #include "LinkedList.h" |
| 39 | |
| 40 | // runtime interfaces used: |
| 41 | // abort |
| 42 | // assert - fprintf + mmap |
| 43 | // mmap |
| 44 | // munmap |
| 45 | // prctl |
| 46 | |
| 47 | constexpr size_t const_log2(size_t n, size_t p = 0) { |
| 48 | return (n <= 1) ? p : const_log2(n / 2, p + 1); |
| 49 | } |
| 50 | |
| 51 | constexpr unsigned int div_round_up(unsigned int x, unsigned int y) { |
| 52 | return (x + y - 1) / y; |
| 53 | } |
| 54 | |
| 55 | #define ARRAY_SIZE(x) (sizeof(x)/sizeof((x)[0])) |
| 56 | |
| 57 | static constexpr size_t kPageSize = 4096; |
| 58 | static constexpr size_t kChunkSize = 256 * 1024; |
| 59 | static constexpr size_t kUsableChunkSize = kChunkSize - kPageSize; |
| 60 | static constexpr size_t kMaxBucketAllocationSize = kChunkSize / 4; |
| 61 | static constexpr size_t kMinBucketAllocationSize = 8; |
| 62 | static constexpr unsigned int kNumBuckets = const_log2(kMaxBucketAllocationSize) |
| 63 | - const_log2(kMinBucketAllocationSize) + 1; |
| 64 | static constexpr unsigned int kUsablePagesPerChunk = kUsableChunkSize |
| 65 | / kPageSize; |
| 66 | |
| 67 | std::atomic<int> heap_count; |
| 68 | |
| 69 | class Chunk; |
| 70 | |
| 71 | class HeapImpl { |
| 72 | public: |
| 73 | HeapImpl(); |
| 74 | ~HeapImpl(); |
| 75 | void* operator new(std::size_t count) noexcept; |
| 76 | void operator delete(void* ptr); |
| 77 | |
| 78 | void* Alloc(size_t size); |
| 79 | void Free(void* ptr); |
| 80 | bool Empty(); |
| 81 | |
| 82 | void MoveToFullList(Chunk* chunk, int bucket_); |
| 83 | void MoveToFreeList(Chunk* chunk, int bucket_); |
| 84 | |
| 85 | private: |
| 86 | DISALLOW_COPY_AND_ASSIGN(HeapImpl); |
| 87 | |
| 88 | LinkedList<Chunk*> free_chunks_[kNumBuckets]; |
| 89 | LinkedList<Chunk*> full_chunks_[kNumBuckets]; |
| 90 | |
| 91 | void MoveToList(Chunk* chunk, LinkedList<Chunk*>* head); |
| 92 | void* MapAlloc(size_t size); |
| 93 | void MapFree(void* ptr); |
| 94 | void* AllocLocked(size_t size); |
| 95 | void FreeLocked(void* ptr); |
| 96 | |
| 97 | struct MapAllocation { |
| 98 | void *ptr; |
| 99 | size_t size; |
| 100 | MapAllocation* next; |
| 101 | }; |
| 102 | MapAllocation* map_allocation_list_; |
| 103 | std::mutex m_; |
| 104 | }; |
| 105 | |
| 106 | // Integer log 2, rounds down |
| 107 | static inline unsigned int log2(size_t n) { |
| 108 | return 8 * sizeof(unsigned long long) - __builtin_clzll(n) - 1; |
| 109 | } |
| 110 | |
| 111 | static inline unsigned int size_to_bucket(size_t size) { |
| 112 | if (size < kMinBucketAllocationSize) |
| 113 | return kMinBucketAllocationSize; |
| 114 | return log2(size - 1) + 1 - const_log2(kMinBucketAllocationSize); |
| 115 | } |
| 116 | |
| 117 | static inline size_t bucket_to_size(unsigned int bucket) { |
| 118 | return kMinBucketAllocationSize << bucket; |
| 119 | } |
| 120 | |
| 121 | static void* MapAligned(size_t size, size_t align) { |
| 122 | const int prot = PROT_READ | PROT_WRITE; |
| 123 | const int flags = MAP_ANONYMOUS | MAP_PRIVATE; |
| 124 | |
| 125 | size = (size + kPageSize - 1) & ~(kPageSize - 1); |
| 126 | |
| 127 | // Over-allocate enough to align |
| 128 | size_t map_size = size + align - kPageSize; |
| 129 | if (map_size < size) { |
| 130 | return nullptr; |
| 131 | } |
| 132 | |
| 133 | void* ptr = mmap(NULL, map_size, prot, flags, -1, 0); |
| 134 | if (ptr == MAP_FAILED) { |
| 135 | return nullptr; |
| 136 | } |
| 137 | |
| 138 | size_t aligned_size = map_size; |
| 139 | void* aligned_ptr = ptr; |
| 140 | |
| 141 | std::align(align, size, aligned_ptr, aligned_size); |
| 142 | |
| 143 | // Trim beginning |
| 144 | if (aligned_ptr != ptr) { |
| 145 | ptrdiff_t extra = reinterpret_cast<uintptr_t>(aligned_ptr) |
| 146 | - reinterpret_cast<uintptr_t>(ptr); |
| 147 | munmap(ptr, extra); |
| 148 | map_size -= extra; |
| 149 | ptr = aligned_ptr; |
| 150 | } |
| 151 | |
| 152 | // Trim end |
| 153 | if (map_size != size) { |
| 154 | assert(map_size > size); |
| 155 | assert(ptr != NULL); |
| 156 | munmap(reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(ptr) + size), |
| 157 | map_size - size); |
| 158 | } |
| 159 | |
| 160 | #define PR_SET_VMA 0x53564d41 |
| 161 | #define PR_SET_VMA_ANON_NAME 0 |
| 162 | prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, |
| 163 | reinterpret_cast<uintptr_t>(ptr), size, "leak_detector_malloc"); |
| 164 | |
| 165 | return ptr; |
| 166 | } |
| 167 | |
| 168 | class Chunk { |
| 169 | public: |
| 170 | static void* operator new(std::size_t count) noexcept; |
| 171 | static void operator delete(void* ptr); |
| 172 | Chunk(HeapImpl* heap, int bucket); |
| 173 | ~Chunk() {} |
| 174 | |
| 175 | void *Alloc(); |
| 176 | void Free(void* ptr); |
| 177 | void Purge(); |
| 178 | bool Empty(); |
| 179 | |
| 180 | static Chunk* ptr_to_chunk(void* ptr) { |
| 181 | return reinterpret_cast<Chunk*>(reinterpret_cast<uintptr_t>(ptr) |
| 182 | & ~(kChunkSize - 1)); |
| 183 | } |
| 184 | static bool is_chunk(void* ptr) { |
| 185 | return (reinterpret_cast<uintptr_t>(ptr) & (kChunkSize - 1)) != 0; |
| 186 | } |
| 187 | |
| 188 | unsigned int free_count() { |
| 189 | return free_count_; |
| 190 | } |
| 191 | HeapImpl* heap() { |
| 192 | return heap_; |
| 193 | } |
| 194 | LinkedList<Chunk*> node_; // linked list sorted by minimum free count |
| 195 | |
| 196 | private: |
| 197 | DISALLOW_COPY_AND_ASSIGN(Chunk); |
| 198 | HeapImpl* heap_; |
| 199 | unsigned int bucket_; |
| 200 | unsigned int allocation_size_; // size of allocations in chunk, min 8 bytes |
| 201 | unsigned int max_allocations_; // maximum number of allocations in the chunk |
| 202 | unsigned int first_free_bitmap_; // index into bitmap for first non-full entry |
| 203 | unsigned int free_count_; // number of available allocations |
| 204 | unsigned int frees_since_purge_; // number of calls to Free since last Purge |
| 205 | |
| 206 | // bitmap of pages that have been dirtied |
| 207 | uint32_t dirty_pages_[div_round_up(kUsablePagesPerChunk, 32)]; |
| 208 | |
| 209 | // bitmap of free allocations. |
| 210 | uint32_t free_bitmap_[kUsableChunkSize / kMinBucketAllocationSize / 32]; |
| 211 | |
| 212 | char data_[0]; |
| 213 | |
| 214 | unsigned int ptr_to_n(void* ptr) { |
| 215 | ptrdiff_t offset = reinterpret_cast<uintptr_t>(ptr) |
| 216 | - reinterpret_cast<uintptr_t>(data_); |
| 217 | return offset / allocation_size_; |
| 218 | } |
| 219 | void* n_to_ptr(unsigned int n) { |
| 220 | return data_ + n * allocation_size_; |
| 221 | } |
| 222 | }; |
| 223 | static_assert(sizeof(Chunk) <= kPageSize, "header must fit in page"); |
| 224 | |
| 225 | // Override new operator on chunk to use mmap to allocate kChunkSize |
| 226 | void* Chunk::operator new(std::size_t count __attribute__((unused))) noexcept { |
| 227 | assert(count == sizeof(Chunk)); |
| 228 | void* mem = MapAligned(kChunkSize, kChunkSize); |
| 229 | if (!mem) { |
| 230 | abort(); //throw std::bad_alloc; |
| 231 | } |
| 232 | |
| 233 | return mem; |
| 234 | } |
| 235 | |
| 236 | // Override new operator on chunk to use mmap to allocate kChunkSize |
| 237 | void Chunk::operator delete(void *ptr) { |
| 238 | assert(reinterpret_cast<Chunk*>(ptr) == ptr_to_chunk(ptr)); |
| 239 | munmap(ptr, kChunkSize); |
| 240 | } |
| 241 | |
| 242 | Chunk::Chunk(HeapImpl* heap, int bucket) : |
| 243 | node_(this), heap_(heap), bucket_(bucket), allocation_size_( |
| 244 | bucket_to_size(bucket)), max_allocations_( |
| 245 | kUsableChunkSize / allocation_size_), first_free_bitmap_(0), free_count_( |
| 246 | max_allocations_), frees_since_purge_(0) { |
| 247 | memset(dirty_pages_, 0, sizeof(dirty_pages_)); |
| 248 | memset(free_bitmap_, 0xff, sizeof(free_bitmap_)); |
| 249 | } |
| 250 | |
| 251 | bool Chunk::Empty() { |
| 252 | return free_count_ == max_allocations_; |
| 253 | } |
| 254 | |
| 255 | void* Chunk::Alloc() { |
| 256 | assert(free_count_ > 0); |
| 257 | |
| 258 | unsigned int i = first_free_bitmap_; |
| 259 | while (free_bitmap_[i] == 0) |
| 260 | i++; |
| 261 | assert(i < ARRAY_SIZE(free_bitmap_)); |
| 262 | unsigned int bit = __builtin_ffs(free_bitmap_[i]) - 1; |
| 263 | assert(free_bitmap_[i] & (1U << bit)); |
| 264 | free_bitmap_[i] &= ~(1U << bit); |
| 265 | unsigned int n = i * 32 + bit; |
| 266 | assert(n < max_allocations_); |
| 267 | |
| 268 | unsigned int page = n * allocation_size_ / kPageSize; |
| 269 | assert(page / 32 < ARRAY_SIZE(dirty_pages_)); |
| 270 | dirty_pages_[page / 32] |= 1U << (page % 32); |
| 271 | |
| 272 | free_count_--; |
| 273 | if (free_count_ == 0) { |
| 274 | heap_->MoveToFullList(this, bucket_); |
| 275 | } |
| 276 | |
| 277 | return n_to_ptr(n); |
| 278 | } |
| 279 | |
| 280 | void Chunk::Free(void* ptr) { |
| 281 | assert(is_chunk(ptr)); |
| 282 | assert(ptr_to_chunk(ptr) == this); |
| 283 | |
| 284 | unsigned int n = ptr_to_n(ptr); |
| 285 | unsigned int i = n / 32; |
| 286 | unsigned int bit = n % 32; |
| 287 | |
| 288 | assert(i < ARRAY_SIZE(free_bitmap_)); |
| 289 | assert(!(free_bitmap_[i] & (1U << bit))); |
| 290 | free_bitmap_[i] |= 1U << bit; |
| 291 | free_count_++; |
| 292 | |
| 293 | if (i < first_free_bitmap_) { |
| 294 | first_free_bitmap_ = i; |
| 295 | } |
| 296 | |
| 297 | if (free_count_ == 1) { |
| 298 | heap_->MoveToFreeList(this, bucket_); |
| 299 | } else { |
| 300 | // TODO(ccross): move down free list if necessary |
| 301 | } |
| 302 | |
| 303 | if (frees_since_purge_++ * allocation_size_ > 16 * kPageSize) { |
| 304 | Purge(); |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | void Chunk::Purge() { |
| 309 | frees_since_purge_ = 0; |
| 310 | |
| 311 | //unsigned int allocsPerPage = kPageSize / allocation_size_; |
| 312 | } |
| 313 | |
| 314 | // Override new operator on HeapImpl to use mmap to allocate a page |
| 315 | void* HeapImpl::operator new(std::size_t count __attribute__((unused))) |
| 316 | noexcept { |
| 317 | assert(count == sizeof(HeapImpl)); |
| 318 | void* mem = MapAligned(kPageSize, kPageSize); |
| 319 | if (!mem) { |
| 320 | abort(); //throw std::bad_alloc; |
| 321 | } |
| 322 | |
| 323 | heap_count++; |
| 324 | return mem; |
| 325 | } |
| 326 | |
| 327 | void HeapImpl::operator delete(void *ptr) { |
| 328 | munmap(ptr, kPageSize); |
| 329 | } |
| 330 | |
| 331 | HeapImpl::HeapImpl() : |
| 332 | free_chunks_(), full_chunks_(), map_allocation_list_(NULL) { |
| 333 | } |
| 334 | |
| 335 | bool HeapImpl::Empty() { |
| 336 | for (unsigned int i = 0; i < kNumBuckets; i++) { |
| 337 | for (LinkedList<Chunk*> *it = free_chunks_[i].next(); it->data() != NULL; it = it->next()) { |
| 338 | if (!it->data()->Empty()) { |
| 339 | return false; |
| 340 | } |
| 341 | } |
| 342 | for (LinkedList<Chunk*> *it = full_chunks_[i].next(); it->data() != NULL; it = it->next()) { |
| 343 | if (!it->data()->Empty()) { |
| 344 | return false; |
| 345 | } |
| 346 | } |
| 347 | } |
| 348 | |
| 349 | return true; |
| 350 | } |
| 351 | |
| 352 | HeapImpl::~HeapImpl() { |
| 353 | for (unsigned int i = 0; i < kNumBuckets; i++) { |
| 354 | while (!free_chunks_[i].empty()) { |
| 355 | Chunk *chunk = free_chunks_[i].next()->data(); |
| 356 | chunk->node_.remove(); |
| 357 | delete chunk; |
| 358 | } |
| 359 | while (!full_chunks_[i].empty()) { |
| 360 | Chunk *chunk = full_chunks_[i].next()->data(); |
| 361 | chunk->node_.remove(); |
| 362 | delete chunk; |
| 363 | } |
| 364 | } |
| 365 | } |
| 366 | |
| 367 | void* HeapImpl::Alloc(size_t size) { |
| 368 | std::lock_guard<std::mutex> lk(m_); |
| 369 | return AllocLocked(size); |
| 370 | } |
| 371 | |
| 372 | void* HeapImpl::AllocLocked(size_t size) { |
| 373 | if (__predict_false(size > kMaxBucketAllocationSize)) { |
| 374 | return MapAlloc(size); |
| 375 | } |
| 376 | int bucket = size_to_bucket(size); |
| 377 | if (__predict_false(free_chunks_[bucket].empty())) { |
| 378 | Chunk *chunk = new Chunk(this, bucket); |
| 379 | free_chunks_[bucket].insert(chunk->node_); |
| 380 | } |
| 381 | return free_chunks_[bucket].next()->data()->Alloc(); |
| 382 | } |
| 383 | |
| 384 | void HeapImpl::Free(void *ptr) { |
| 385 | std::lock_guard<std::mutex> lk(m_); |
| 386 | FreeLocked(ptr); |
| 387 | } |
| 388 | |
| 389 | void HeapImpl::FreeLocked(void *ptr) { |
| 390 | if (!Chunk::is_chunk(ptr)) { |
| 391 | HeapImpl::MapFree(ptr); |
| 392 | } else { |
| 393 | Chunk* chunk = Chunk::ptr_to_chunk(ptr); |
| 394 | assert(chunk->heap() == this); |
| 395 | chunk->Free(ptr); |
| 396 | } |
| 397 | } |
| 398 | |
| 399 | void* HeapImpl::MapAlloc(size_t size) { |
| 400 | size = (size + kPageSize - 1) & ~(kPageSize - 1); |
| 401 | |
| 402 | MapAllocation* allocation = reinterpret_cast<MapAllocation*>(AllocLocked( |
| 403 | sizeof(MapAllocation))); |
| 404 | void* ptr = MapAligned(size, kChunkSize); |
| 405 | if (!ptr) { |
| 406 | FreeLocked(allocation); |
| 407 | abort(); //throw std::bad_alloc; |
| 408 | } |
| 409 | allocation->ptr = ptr; |
| 410 | allocation->size = size; |
| 411 | allocation->next = map_allocation_list_; |
| 412 | map_allocation_list_ = allocation; |
| 413 | |
| 414 | return ptr; |
| 415 | } |
| 416 | |
| 417 | void HeapImpl::MapFree(void *ptr) { |
| 418 | MapAllocation **allocation = &map_allocation_list_; |
| 419 | while (*allocation && (*allocation)->ptr != ptr) |
| 420 | allocation = &(*allocation)->next; |
| 421 | |
| 422 | assert(*allocation != nullptr); |
| 423 | |
| 424 | munmap((*allocation)->ptr, (*allocation)->size); |
| 425 | FreeLocked(*allocation); |
| 426 | |
| 427 | *allocation = (*allocation)->next; |
| 428 | } |
| 429 | |
| 430 | void HeapImpl::MoveToFreeList(Chunk *chunk, int bucket) { |
| 431 | MoveToList(chunk, &free_chunks_[bucket]); |
| 432 | } |
| 433 | |
| 434 | void HeapImpl::MoveToFullList(Chunk *chunk, int bucket) { |
| 435 | MoveToList(chunk, &full_chunks_[bucket]); |
| 436 | } |
| 437 | |
| 438 | void HeapImpl::MoveToList(Chunk *chunk, LinkedList<Chunk*>* head) { |
| 439 | // Remove from old list |
| 440 | chunk->node_.remove(); |
| 441 | |
| 442 | LinkedList<Chunk*> *node = head; |
| 443 | // Insert into new list, sorted by lowest free count |
| 444 | while (node->next() != head && node->data() != nullptr |
| 445 | && node->data()->free_count() < chunk->free_count()) |
| 446 | node = node->next(); |
| 447 | |
| 448 | node->insert(chunk->node_); |
| 449 | } |
| 450 | |
| 451 | Heap::Heap() { |
| 452 | // HeapImpl overloads the operator new in order to mmap itself instead of |
| 453 | // allocating with new. |
| 454 | // Can't use a shared_ptr to store the result because shared_ptr needs to |
| 455 | // allocate, and Allocator<T> is still being constructed. |
| 456 | impl_ = new HeapImpl(); |
| 457 | owns_impl_ = true; |
| 458 | } |
| 459 | |
| 460 | Heap::~Heap() { |
| 461 | if (owns_impl_) { |
| 462 | delete impl_; |
| 463 | } |
| 464 | } |
| 465 | |
| 466 | void* Heap::allocate(size_t size) { |
| 467 | return impl_->Alloc(size); |
| 468 | } |
| 469 | |
| 470 | void Heap::deallocate(void* ptr) { |
| 471 | impl_->Free(ptr); |
| 472 | } |
| 473 | |
| 474 | void Heap::deallocate(HeapImpl*impl, void* ptr) { |
| 475 | impl->Free(ptr); |
| 476 | } |
| 477 | |
| 478 | bool Heap::empty() { |
| 479 | return impl_->Empty(); |
| 480 | } |