1 //===-- tsan_dense_alloc.h --------------------------------------*- C++ -*-===// 2 // 3 // This file is distributed under the University of Illinois Open Source 4 // License. See LICENSE.TXT for details. 5 // 6 //===----------------------------------------------------------------------===// 7 // 8 // This file is a part of ThreadSanitizer (TSan), a race detector. 9 // 10 // A DenseSlabAlloc is a freelist-based allocator of fixed-size objects. 11 // DenseSlabAllocCache is a thread-local cache for DenseSlabAlloc. 12 // The only difference with traditional slab allocators is that DenseSlabAlloc 13 // allocates/free indices of objects and provide a functionality to map 14 // the index onto the real pointer. The index is u32, that is, 2 times smaller 15 // than uptr (hense the Dense prefix). 16 //===----------------------------------------------------------------------===// 17 #ifndef TSAN_DENSE_ALLOC_H 18 #define TSAN_DENSE_ALLOC_H 19 20 #include "sanitizer_common/sanitizer_common.h" 21 #include "tsan_defs.h" 22 #include "tsan_mutex.h" 23 24 namespace __tsan { 25 26 class DenseSlabAllocCache { 27 static const uptr kSize = 128; 28 typedef u32 IndexT; 29 uptr pos; 30 IndexT cache[kSize]; 31 template<typename T, uptr kL1Size, uptr kL2Size> friend class DenseSlabAlloc; 32 }; 33 34 template<typename T, uptr kL1Size, uptr kL2Size> 35 class DenseSlabAlloc { 36 public: 37 typedef DenseSlabAllocCache Cache; 38 typedef typename Cache::IndexT IndexT; 39 DenseSlabAlloc(const char * name)40 explicit DenseSlabAlloc(const char *name) { 41 // Check that kL1Size and kL2Size are sane. 42 CHECK_EQ(kL1Size & (kL1Size - 1), 0); 43 CHECK_EQ(kL2Size & (kL2Size - 1), 0); 44 CHECK_GE(1ull << (sizeof(IndexT) * 8), kL1Size * kL2Size); 45 // Check that it makes sense to use the dense alloc. 46 CHECK_GE(sizeof(T), sizeof(IndexT)); 47 internal_memset(map_, 0, sizeof(map_)); 48 freelist_ = 0; 49 fillpos_ = 0; 50 name_ = name; 51 } 52 ~DenseSlabAlloc()53 ~DenseSlabAlloc() { 54 for (uptr i = 0; i < kL1Size; i++) { 55 if (map_[i] != 0) 56 UnmapOrDie(map_[i], kL2Size * sizeof(T)); 57 } 58 } 59 Alloc(Cache * c)60 IndexT Alloc(Cache *c) { 61 if (c->pos == 0) 62 Refill(c); 63 return c->cache[--c->pos]; 64 } 65 Free(Cache * c,IndexT idx)66 void Free(Cache *c, IndexT idx) { 67 DCHECK_NE(idx, 0); 68 if (c->pos == Cache::kSize) 69 Drain(c); 70 c->cache[c->pos++] = idx; 71 } 72 Map(IndexT idx)73 T *Map(IndexT idx) { 74 DCHECK_NE(idx, 0); 75 DCHECK_LE(idx, kL1Size * kL2Size); 76 return &map_[idx / kL2Size][idx % kL2Size]; 77 } 78 FlushCache(Cache * c)79 void FlushCache(Cache *c) { 80 SpinMutexLock lock(&mtx_); 81 while (c->pos) { 82 IndexT idx = c->cache[--c->pos]; 83 *(IndexT*)Map(idx) = freelist_; 84 freelist_ = idx; 85 } 86 } 87 InitCache(Cache * c)88 void InitCache(Cache *c) { 89 c->pos = 0; 90 internal_memset(c->cache, 0, sizeof(c->cache)); 91 } 92 93 private: 94 T *map_[kL1Size]; 95 SpinMutex mtx_; 96 IndexT freelist_; 97 uptr fillpos_; 98 const char *name_; 99 Refill(Cache * c)100 void Refill(Cache *c) { 101 SpinMutexLock lock(&mtx_); 102 if (freelist_ == 0) { 103 if (fillpos_ == kL1Size) { 104 Printf("ThreadSanitizer: %s overflow (%zu*%zu). Dying.\n", 105 name_, kL1Size, kL2Size); 106 Die(); 107 } 108 VPrintf(2, "ThreadSanitizer: growing %s: %zu out of %zu*%zu\n", 109 name_, fillpos_, kL1Size, kL2Size); 110 T *batch = (T*)MmapOrDie(kL2Size * sizeof(T), name_); 111 // Reserve 0 as invalid index. 112 IndexT start = fillpos_ == 0 ? 1 : 0; 113 for (IndexT i = start; i < kL2Size; i++) { 114 new(batch + i) T; 115 *(IndexT*)(batch + i) = i + 1 + fillpos_ * kL2Size; 116 } 117 *(IndexT*)(batch + kL2Size - 1) = 0; 118 freelist_ = fillpos_ * kL2Size + start; 119 map_[fillpos_++] = batch; 120 } 121 for (uptr i = 0; i < Cache::kSize / 2 && freelist_ != 0; i++) { 122 IndexT idx = freelist_; 123 c->cache[c->pos++] = idx; 124 freelist_ = *(IndexT*)Map(idx); 125 } 126 } 127 Drain(Cache * c)128 void Drain(Cache *c) { 129 SpinMutexLock lock(&mtx_); 130 for (uptr i = 0; i < Cache::kSize / 2; i++) { 131 IndexT idx = c->cache[--c->pos]; 132 *(IndexT*)Map(idx) = freelist_; 133 freelist_ = idx; 134 } 135 } 136 }; 137 138 } // namespace __tsan 139 140 #endif // TSAN_DENSE_ALLOC_H 141