1 //===-- sanitizer_allocator_primary32.h -------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Part of the Sanitizer Allocator.
10 //
11 //===----------------------------------------------------------------------===//
12 #ifndef SANITIZER_ALLOCATOR_H
13 #error This file must be included inside sanitizer_allocator.h
14 #endif
15 
16 template<class SizeClassAllocator> struct SizeClassAllocator32LocalCache;
17 
18 // SizeClassAllocator32 -- allocator for 32-bit address space.
19 // This allocator can theoretically be used on 64-bit arch, but there it is less
20 // efficient than SizeClassAllocator64.
21 //
22 // [kSpaceBeg, kSpaceBeg + kSpaceSize) is the range of addresses which can
23 // be returned by MmapOrDie().
24 //
25 // Region:
26 //   a result of a single call to MmapAlignedOrDieOnFatalError(kRegionSize,
27 //                                                             kRegionSize).
28 // Since the regions are aligned by kRegionSize, there are exactly
29 // kNumPossibleRegions possible regions in the address space and so we keep
30 // a ByteMap possible_regions to store the size classes of each Region.
31 // 0 size class means the region is not used by the allocator.
32 //
33 // One Region is used to allocate chunks of a single size class.
34 // A Region looks like this:
35 // UserChunk1 .. UserChunkN <gap> MetaChunkN .. MetaChunk1
36 //
37 // In order to avoid false sharing the objects of this class should be
38 // chache-line aligned.
39 
40 struct SizeClassAllocator32FlagMasks {  //  Bit masks.
41   enum {
42     kRandomShuffleChunks = 1,
43     kUseSeparateSizeClassForBatch = 2,
44   };
45 };
46 
47 template <class Params>
48 class SizeClassAllocator32 {
49  private:
50   static const u64 kTwoLevelByteMapSize1 =
51       (Params::kSpaceSize >> Params::kRegionSizeLog) >> 12;
52   static const u64 kMinFirstMapSizeTwoLevelByteMap = 4;
53 
54  public:
55   using AddressSpaceView = typename Params::AddressSpaceView;
56   static const uptr kSpaceBeg = Params::kSpaceBeg;
57   static const u64 kSpaceSize = Params::kSpaceSize;
58   static const uptr kMetadataSize = Params::kMetadataSize;
59   typedef typename Params::SizeClassMap SizeClassMap;
60   static const uptr kRegionSizeLog = Params::kRegionSizeLog;
61   typedef typename Params::MapUnmapCallback MapUnmapCallback;
62   using ByteMap = typename conditional<
63       (kTwoLevelByteMapSize1 < kMinFirstMapSizeTwoLevelByteMap),
64       FlatByteMap<(Params::kSpaceSize >> Params::kRegionSizeLog),
65                   AddressSpaceView>,
66       TwoLevelByteMap<kTwoLevelByteMapSize1, 1 << 12, AddressSpaceView>>::type;
67 
68   COMPILER_CHECK(!SANITIZER_SIGN_EXTENDED_ADDRESSES ||
69                  (kSpaceSize & (kSpaceSize - 1)) == 0);
70 
71   static const bool kRandomShuffleChunks = Params::kFlags &
72       SizeClassAllocator32FlagMasks::kRandomShuffleChunks;
73   static const bool kUseSeparateSizeClassForBatch = Params::kFlags &
74       SizeClassAllocator32FlagMasks::kUseSeparateSizeClassForBatch;
75 
76   struct TransferBatch {
77     static const uptr kMaxNumCached = SizeClassMap::kMaxNumCachedHint - 2;
78     void SetFromArray(void *batch[], uptr count) {
79       DCHECK_LE(count, kMaxNumCached);
80       count_ = count;
81       for (uptr i = 0; i < count; i++)
82         batch_[i] = batch[i];
83     }
84     uptr Count() const { return count_; }
85     void Clear() { count_ = 0; }
86     void Add(void *ptr) {
87       batch_[count_++] = ptr;
88       DCHECK_LE(count_, kMaxNumCached);
89     }
90     void CopyToArray(void *to_batch[]) const {
91       for (uptr i = 0, n = Count(); i < n; i++)
92         to_batch[i] = batch_[i];
93     }
94 
95     // How much memory do we need for a batch containing n elements.
96     static uptr AllocationSizeRequiredForNElements(uptr n) {
97       return sizeof(uptr) * 2 + sizeof(void *) * n;
98     }
99     static uptr MaxCached(uptr size) {
100       return Min(kMaxNumCached, SizeClassMap::MaxCachedHint(size));
101     }
102 
103     TransferBatch *next;
104 
105    private:
106     uptr count_;
107     void *batch_[kMaxNumCached];
108   };
109 
110   static const uptr kBatchSize = sizeof(TransferBatch);
111   COMPILER_CHECK((kBatchSize & (kBatchSize - 1)) == 0);
112   COMPILER_CHECK(kBatchSize == SizeClassMap::kMaxNumCachedHint * sizeof(uptr));
113 
114   static uptr ClassIdToSize(uptr class_id) {
115     return (class_id == SizeClassMap::kBatchClassID) ?
116         kBatchSize : SizeClassMap::Size(class_id);
117   }
118 
119   typedef SizeClassAllocator32<Params> ThisT;
120   typedef SizeClassAllocator32LocalCache<ThisT> AllocatorCache;
121 
122   void Init(s32 release_to_os_interval_ms, uptr heap_start = 0) {
123     CHECK(!heap_start);
124     possible_regions.Init();
125     internal_memset(size_class_info_array, 0, sizeof(size_class_info_array));
126   }
127 
128   s32 ReleaseToOSIntervalMs() const {
129     return kReleaseToOSIntervalNever;
130   }
131 
132   void SetReleaseToOSIntervalMs(s32 release_to_os_interval_ms) {
133     // This is empty here. Currently only implemented in 64-bit allocator.
134   }
135 
136   void ForceReleaseToOS() {
137     // Currently implemented in 64-bit allocator only.
138   }
139 
140   void *MapWithCallback(uptr size) {
141     void *res = MmapOrDie(size, PrimaryAllocatorName);
142     MapUnmapCallback().OnMap((uptr)res, size);
143     return res;
144   }
145 
146   void UnmapWithCallback(uptr beg, uptr size) {
147     MapUnmapCallback().OnUnmap(beg, size);
148     UnmapOrDie(reinterpret_cast<void *>(beg), size);
149   }
150 
151   static bool CanAllocate(uptr size, uptr alignment) {
152     return size <= SizeClassMap::kMaxSize &&
153       alignment <= SizeClassMap::kMaxSize;
154   }
155 
156   void *GetMetaData(const void *p) {
157     CHECK(kMetadataSize);
158     CHECK(PointerIsMine(p));
159     uptr mem = reinterpret_cast<uptr>(p);
160     uptr beg = ComputeRegionBeg(mem);
161     uptr size = ClassIdToSize(GetSizeClass(p));
162     u32 offset = mem - beg;
163     uptr n = offset / (u32)size;  // 32-bit division
164     uptr meta = (beg + kRegionSize) - (n + 1) * kMetadataSize;
165     return reinterpret_cast<void*>(meta);
166   }
167 
168   NOINLINE TransferBatch *AllocateBatch(AllocatorStats *stat, AllocatorCache *c,
169                                         uptr class_id) {
170     DCHECK_LT(class_id, kNumClasses);
171     SizeClassInfo *sci = GetSizeClassInfo(class_id);
172     SpinMutexLock l(&sci->mutex);
173     if (sci->free_list.empty()) {
174       if (UNLIKELY(!PopulateFreeList(stat, c, sci, class_id)))
175         return nullptr;
176       DCHECK(!sci->free_list.empty());
177     }
178     TransferBatch *b = sci->free_list.front();
179     sci->free_list.pop_front();
180     return b;
181   }
182 
183   NOINLINE void DeallocateBatch(AllocatorStats *stat, uptr class_id,
184                                 TransferBatch *b) {
185     DCHECK_LT(class_id, kNumClasses);
186     CHECK_GT(b->Count(), 0);
187     SizeClassInfo *sci = GetSizeClassInfo(class_id);
188     SpinMutexLock l(&sci->mutex);
189     sci->free_list.push_front(b);
190   }
191 
192   bool PointerIsMine(const void *p) const {
193     uptr mem = reinterpret_cast<uptr>(p);
194     if (SANITIZER_SIGN_EXTENDED_ADDRESSES)
195       mem &= (kSpaceSize - 1);
196     if (mem < kSpaceBeg || mem >= kSpaceBeg + kSpaceSize)
197       return false;
198     return GetSizeClass(p) != 0;
199   }
200 
201   uptr GetSizeClass(const void *p) const {
202     uptr id = ComputeRegionId(reinterpret_cast<uptr>(p));
203     return possible_regions.contains(id) ? possible_regions[id] : 0;
204   }
205 
206   void *GetBlockBegin(const void *p) {
207     CHECK(PointerIsMine(p));
208     uptr mem = reinterpret_cast<uptr>(p);
209     uptr beg = ComputeRegionBeg(mem);
210     uptr size = ClassIdToSize(GetSizeClass(p));
211     u32 offset = mem - beg;
212     u32 n = offset / (u32)size;  // 32-bit division
213     uptr res = beg + (n * (u32)size);
214     return reinterpret_cast<void*>(res);
215   }
216 
217   uptr GetActuallyAllocatedSize(void *p) {
218     CHECK(PointerIsMine(p));
219     return ClassIdToSize(GetSizeClass(p));
220   }
221 
222   static uptr ClassID(uptr size) { return SizeClassMap::ClassID(size); }
223 
224   uptr TotalMemoryUsed() {
225     // No need to lock here.
226     uptr res = 0;
227     for (uptr i = 0; i < kNumPossibleRegions; i++)
228       if (possible_regions[i])
229         res += kRegionSize;
230     return res;
231   }
232 
233   void TestOnlyUnmap() {
234     for (uptr i = 0; i < kNumPossibleRegions; i++)
235       if (possible_regions[i])
236         UnmapWithCallback((i * kRegionSize), kRegionSize);
237   }
238 
239   // ForceLock() and ForceUnlock() are needed to implement Darwin malloc zone
240   // introspection API.
241   void ForceLock() SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
242     for (uptr i = 0; i < kNumClasses; i++) {
243       GetSizeClassInfo(i)->mutex.Lock();
244     }
245   }
246 
247   void ForceUnlock() SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
248     for (int i = kNumClasses - 1; i >= 0; i--) {
249       GetSizeClassInfo(i)->mutex.Unlock();
250     }
251   }
252 
253   // Iterate over all existing chunks.
254   // The allocator must be locked when calling this function.
255   void ForEachChunk(ForEachChunkCallback callback, void *arg) const {
256     for (uptr region = 0; region < kNumPossibleRegions; region++)
257       if (possible_regions.contains(region) && possible_regions[region]) {
258         uptr chunk_size = ClassIdToSize(possible_regions[region]);
259         uptr max_chunks_in_region = kRegionSize / (chunk_size + kMetadataSize);
260         uptr region_beg = region * kRegionSize;
261         for (uptr chunk = region_beg;
262              chunk < region_beg + max_chunks_in_region * chunk_size;
263              chunk += chunk_size) {
264           // Too slow: CHECK_EQ((void *)chunk, GetBlockBegin((void *)chunk));
265           callback(chunk, arg);
266         }
267       }
268   }
269 
270   void PrintStats() {}
271 
272   static uptr AdditionalSize() { return 0; }
273 
274   typedef SizeClassMap SizeClassMapT;
275   static const uptr kNumClasses = SizeClassMap::kNumClasses;
276 
277  private:
278   static const uptr kRegionSize = 1 << kRegionSizeLog;
279   static const uptr kNumPossibleRegions = kSpaceSize / kRegionSize;
280 
281   struct ALIGNED(SANITIZER_CACHE_LINE_SIZE) SizeClassInfo {
282     StaticSpinMutex mutex;
283     IntrusiveList<TransferBatch> free_list;
284     u32 rand_state;
285   };
286   COMPILER_CHECK(sizeof(SizeClassInfo) % kCacheLineSize == 0);
287 
288   uptr ComputeRegionId(uptr mem) const {
289     if (SANITIZER_SIGN_EXTENDED_ADDRESSES)
290       mem &= (kSpaceSize - 1);
291     const uptr res = mem >> kRegionSizeLog;
292     CHECK_LT(res, kNumPossibleRegions);
293     return res;
294   }
295 
296   uptr ComputeRegionBeg(uptr mem) const { return mem & ~(kRegionSize - 1); }
297 
298   uptr AllocateRegion(AllocatorStats *stat, uptr class_id) {
299     DCHECK_LT(class_id, kNumClasses);
300     const uptr res = reinterpret_cast<uptr>(MmapAlignedOrDieOnFatalError(
301         kRegionSize, kRegionSize, PrimaryAllocatorName));
302     if (UNLIKELY(!res))
303       return 0;
304     MapUnmapCallback().OnMap(res, kRegionSize);
305     stat->Add(AllocatorStatMapped, kRegionSize);
306     CHECK(IsAligned(res, kRegionSize));
307     possible_regions[ComputeRegionId(res)] = class_id;
308     return res;
309   }
310 
311   SizeClassInfo *GetSizeClassInfo(uptr class_id) {
312     DCHECK_LT(class_id, kNumClasses);
313     return &size_class_info_array[class_id];
314   }
315 
316   bool PopulateBatches(AllocatorCache *c, SizeClassInfo *sci, uptr class_id,
317                        TransferBatch **current_batch, uptr max_count,
318                        uptr *pointers_array, uptr count) {
319     // If using a separate class for batches, we do not need to shuffle it.
320     if (kRandomShuffleChunks && (!kUseSeparateSizeClassForBatch ||
321         class_id != SizeClassMap::kBatchClassID))
322       RandomShuffle(pointers_array, count, &sci->rand_state);
323     TransferBatch *b = *current_batch;
324     for (uptr i = 0; i < count; i++) {
325       if (!b) {
326         b = c->CreateBatch(class_id, this, (TransferBatch*)pointers_array[i]);
327         if (UNLIKELY(!b))
328           return false;
329         b->Clear();
330       }
331       b->Add((void*)pointers_array[i]);
332       if (b->Count() == max_count) {
333         sci->free_list.push_back(b);
334         b = nullptr;
335       }
336     }
337     *current_batch = b;
338     return true;
339   }
340 
341   bool PopulateFreeList(AllocatorStats *stat, AllocatorCache *c,
342                         SizeClassInfo *sci, uptr class_id) {
343     const uptr region = AllocateRegion(stat, class_id);
344     if (UNLIKELY(!region))
345       return false;
346     if (kRandomShuffleChunks)
347       if (UNLIKELY(sci->rand_state == 0))
348         // The random state is initialized from ASLR (PIE) and time.
349         sci->rand_state = reinterpret_cast<uptr>(sci) ^ NanoTime();
350     const uptr size = ClassIdToSize(class_id);
351     const uptr n_chunks = kRegionSize / (size + kMetadataSize);
352     const uptr max_count = TransferBatch::MaxCached(size);
353     DCHECK_GT(max_count, 0);
354     TransferBatch *b = nullptr;
355     constexpr uptr kShuffleArraySize = 48;
356     uptr shuffle_array[kShuffleArraySize];
357     uptr count = 0;
358     for (uptr i = region; i < region + n_chunks * size; i += size) {
359       shuffle_array[count++] = i;
360       if (count == kShuffleArraySize) {
361         if (UNLIKELY(!PopulateBatches(c, sci, class_id, &b, max_count,
362                                       shuffle_array, count)))
363           return false;
364         count = 0;
365       }
366     }
367     if (count) {
368       if (UNLIKELY(!PopulateBatches(c, sci, class_id, &b, max_count,
369                                     shuffle_array, count)))
370         return false;
371     }
372     if (b) {
373       CHECK_GT(b->Count(), 0);
374       sci->free_list.push_back(b);
375     }
376     return true;
377   }
378 
379   ByteMap possible_regions;
380   SizeClassInfo size_class_info_array[kNumClasses];
381 };
382