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author | Kostya Kortchinsky <kostyak@google.com> | 2019-05-07 15:40:09 +0000 |
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committer | Kostya Kortchinsky <kostyak@google.com> | 2019-05-07 15:40:09 +0000 |
commit | b51c88520398ccc01b44826d37aea23d17ac51a3 (patch) | |
tree | b6961f88f074294ae94bff968864d4d6a7b4594f /lib/scudo/standalone/quarantine.h | |
parent | f2983bc4737aae7c3f1e2209811f2e3e5147478f (diff) | |
download | compiler-rt-b51c88520398ccc01b44826d37aea23d17ac51a3.tar.gz |
[scudo][standalone] Introduce the Quarantine
Summary:
The Quarantine is used to hold chunks for a little while prior to
actually releasing them for potential reuse. The code is pretty much
the same as the sanitizer_common one, with additional shuffling of
the quarantine batches to decrease predictability of allocation
patterns when it is enabled.
Reviewers: vitalybuka, eugenis, hctim, morehouse
Reviewed By: morehouse
Subscribers: mgorny, delcypher, jfb, #sanitizers, llvm-commits
Tags: #llvm, #sanitizers
Differential Revision: https://reviews.llvm.org/D61385
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@360163 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/scudo/standalone/quarantine.h')
-rw-r--r-- | lib/scudo/standalone/quarantine.h | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/lib/scudo/standalone/quarantine.h b/lib/scudo/standalone/quarantine.h new file mode 100644 index 000000000..99b83f395 --- /dev/null +++ b/lib/scudo/standalone/quarantine.h @@ -0,0 +1,291 @@ +//===-- quarantine.h --------------------------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef SCUDO_QUARANTINE_H_ +#define SCUDO_QUARANTINE_H_ + +#include "list.h" +#include "mutex.h" +#include "string_utils.h" + +namespace scudo { + +struct QuarantineBatch { + // With the following count, a batch (and the header that protects it) occupy + // 4096 bytes on 32-bit platforms, and 8192 bytes on 64-bit. + static const u32 MaxCount = 1019; + QuarantineBatch *Next; + uptr Size; + u32 Count; + void *Batch[MaxCount]; + + void init(void *Ptr, uptr Size) { + Count = 1; + Batch[0] = Ptr; + this->Size = Size + sizeof(QuarantineBatch); // Account for the Batch Size. + } + + // The total size of quarantined nodes recorded in this batch. + uptr getQuarantinedSize() const { return Size - sizeof(QuarantineBatch); } + + void push_back(void *Ptr, uptr Size) { + DCHECK_LT(Count, MaxCount); + Batch[Count++] = Ptr; + this->Size += Size; + } + + bool canMerge(const QuarantineBatch *const From) const { + return Count + From->Count <= MaxCount; + } + + void merge(QuarantineBatch *const From) { + DCHECK_LE(Count + From->Count, MaxCount); + DCHECK_GE(Size, sizeof(QuarantineBatch)); + + for (uptr I = 0; I < From->Count; ++I) + Batch[Count + I] = From->Batch[I]; + Count += From->Count; + Size += From->getQuarantinedSize(); + + From->Count = 0; + From->Size = sizeof(QuarantineBatch); + } + + void shuffle(u32 State) { ::scudo::shuffle(Batch, Count, &State); } +}; + +COMPILER_CHECK(sizeof(QuarantineBatch) <= (1U << 13)); // 8Kb. + +// Per-thread cache of memory blocks. +template <typename Callback> class QuarantineCache { +public: + void initLinkerInitialized() {} + void init() { + memset(this, 0, sizeof(*this)); + initLinkerInitialized(); + } + + // Total memory used, including internal accounting. + uptr getSize() const { return atomic_load_relaxed(&Size); } + // Memory used for internal accounting. + uptr getOverheadSize() const { return List.size() * sizeof(QuarantineBatch); } + + void enqueue(Callback Cb, void *Ptr, uptr Size) { + if (List.empty() || List.back()->Count == QuarantineBatch::MaxCount) { + QuarantineBatch *B = + reinterpret_cast<QuarantineBatch *>(Cb.allocate(sizeof(*B))); + DCHECK(B); + B->init(Ptr, Size); + enqueueBatch(B); + } else { + List.back()->push_back(Ptr, Size); + addToSize(Size); + } + } + + void transfer(QuarantineCache *From) { + List.append_back(&From->List); + addToSize(From->getSize()); + atomic_store_relaxed(&From->Size, 0); + } + + void enqueueBatch(QuarantineBatch *B) { + List.push_back(B); + addToSize(B->Size); + } + + QuarantineBatch *dequeueBatch() { + if (List.empty()) + return nullptr; + QuarantineBatch *B = List.front(); + List.pop_front(); + subFromSize(B->Size); + return B; + } + + void mergeBatches(QuarantineCache *ToDeallocate) { + uptr ExtractedSize = 0; + QuarantineBatch *Current = List.front(); + while (Current && Current->Next) { + if (Current->canMerge(Current->Next)) { + QuarantineBatch *Extracted = Current->Next; + // Move all the chunks into the current batch. + Current->merge(Extracted); + DCHECK_EQ(Extracted->Count, 0); + DCHECK_EQ(Extracted->Size, sizeof(QuarantineBatch)); + // Remove the next batch From the list and account for its Size. + List.extract(Current, Extracted); + ExtractedSize += Extracted->Size; + // Add it to deallocation list. + ToDeallocate->enqueueBatch(Extracted); + } else { + Current = Current->Next; + } + } + subFromSize(ExtractedSize); + } + + void printStats() const { + uptr BatchCount = 0; + uptr TotalOverheadBytes = 0; + uptr TotalBytes = 0; + uptr TotalQuarantineChunks = 0; + for (const QuarantineBatch &Batch : List) { + BatchCount++; + TotalBytes += Batch.Size; + TotalOverheadBytes += Batch.Size - Batch.getQuarantinedSize(); + TotalQuarantineChunks += Batch.Count; + } + const uptr QuarantineChunksCapacity = + BatchCount * QuarantineBatch::MaxCount; + const uptr ChunksUsagePercent = + (QuarantineChunksCapacity == 0) + ? 0 + : TotalQuarantineChunks * 100 / QuarantineChunksCapacity; + const uptr TotalQuarantinedBytes = TotalBytes - TotalOverheadBytes; + const uptr MemoryOverheadPercent = + (TotalQuarantinedBytes == 0) + ? 0 + : TotalOverheadBytes * 100 / TotalQuarantinedBytes; + Printf("Global quarantine stats: batches: %zd; bytes: %zd (user: %zd); " + "chunks: %zd (capacity: %zd); %zd%% chunks used; %zd%% memory " + "overhead\n", + BatchCount, TotalBytes, TotalQuarantinedBytes, TotalQuarantineChunks, + QuarantineChunksCapacity, ChunksUsagePercent, MemoryOverheadPercent); + } + +private: + IntrusiveList<QuarantineBatch> List; + atomic_uptr Size; + + void addToSize(uptr add) { atomic_store_relaxed(&Size, getSize() + add); } + void subFromSize(uptr sub) { atomic_store_relaxed(&Size, getSize() - sub); } +}; + +// The callback interface is: +// void Callback::recycle(Node *Ptr); +// void *Callback::allocate(uptr Size); +// void Callback::deallocate(void *Ptr); +template <typename Callback, typename Node> class GlobalQuarantine { +public: + typedef QuarantineCache<Callback> CacheT; + + void initLinkerInitialized(uptr Size, uptr CacheSize) { + // Thread local quarantine size can be zero only when global quarantine size + // is zero (it allows us to perform just one atomic read per put() call). + CHECK((Size == 0 && CacheSize == 0) || CacheSize != 0); + + atomic_store_relaxed(&MaxSize, Size); + atomic_store_relaxed(&MinSize, Size / 10 * 9); // 90% of max size. + atomic_store_relaxed(&MaxCacheSize, CacheSize); + + Cache.initLinkerInitialized(); + CacheMutex.initLinkerInitialized(); + RecyleMutex.initLinkerInitialized(); + } + void init(uptr Size, uptr CacheSize) { + memset(this, 0, sizeof(*this)); + initLinkerInitialized(Size, CacheSize); + } + + uptr getMaxSize() const { return atomic_load_relaxed(&MaxSize); } + uptr getCacheSize() const { return atomic_load_relaxed(&MaxCacheSize); } + + void put(CacheT *C, Callback Cb, Node *Ptr, uptr Size) { + C->enqueue(Cb, Ptr, Size); + if (C->getSize() > getCacheSize()) + drain(C, Cb); + } + + void NOINLINE drain(CacheT *C, Callback Cb) { + { + SpinMutexLock L(&CacheMutex); + Cache.transfer(C); + } + if (Cache.getSize() > getMaxSize() && RecyleMutex.tryLock()) + recycle(atomic_load_relaxed(&MinSize), Cb); + } + + void NOINLINE drainAndRecycle(CacheT *C, Callback Cb) { + { + SpinMutexLock L(&CacheMutex); + Cache.transfer(C); + } + RecyleMutex.lock(); + recycle(0, Cb); + } + + void printStats() const { + // It assumes that the world is stopped, just as the allocator's printStats. + Printf("Quarantine limits: global: %zdM; thread local: %zdK\n", + getMaxSize() >> 20, getCacheSize() >> 10); + Cache.printStats(); + } + +private: + // Read-only data. + alignas(SCUDO_CACHE_LINE_SIZE) StaticSpinMutex CacheMutex; + CacheT Cache; + alignas(SCUDO_CACHE_LINE_SIZE) StaticSpinMutex RecyleMutex; + atomic_uptr MinSize; + atomic_uptr MaxSize; + alignas(SCUDO_CACHE_LINE_SIZE) atomic_uptr MaxCacheSize; + + void NOINLINE recycle(uptr MinSize, Callback Cb) { + CacheT Tmp; + Tmp.init(); + { + SpinMutexLock L(&CacheMutex); + // Go over the batches and merge partially filled ones to + // save some memory, otherwise batches themselves (since the memory used + // by them is counted against quarantine limit) can overcome the actual + // user's quarantined chunks, which diminishes the purpose of the + // quarantine. + const uptr CacheSize = Cache.getSize(); + const uptr OverheadSize = Cache.getOverheadSize(); + DCHECK_GE(CacheSize, OverheadSize); + // Do the merge only when overhead exceeds this predefined limit (might + // require some tuning). It saves us merge attempt when the batch list + // quarantine is unlikely to contain batches suitable for merge. + constexpr uptr OverheadThresholdPercents = 100; + if (CacheSize > OverheadSize && + OverheadSize * (100 + OverheadThresholdPercents) > + CacheSize * OverheadThresholdPercents) { + Cache.mergeBatches(&Tmp); + } + // Extract enough chunks from the quarantine to get below the max + // quarantine size and leave some leeway for the newly quarantined chunks. + while (Cache.getSize() > MinSize) + Tmp.enqueueBatch(Cache.dequeueBatch()); + } + RecyleMutex.unlock(); + doRecycle(&Tmp, Cb); + } + + void NOINLINE doRecycle(CacheT *C, Callback Cb) { + while (QuarantineBatch *B = C->dequeueBatch()) { + const u32 Seed = static_cast<u32>( + (reinterpret_cast<uptr>(B) ^ reinterpret_cast<uptr>(C)) >> 4); + B->shuffle(Seed); + constexpr uptr NumberOfPrefetch = 8UL; + CHECK(NumberOfPrefetch <= ARRAY_SIZE(B->Batch)); + for (uptr I = 0; I < NumberOfPrefetch; I++) + PREFETCH(B->Batch[I]); + for (uptr I = 0, Count = B->Count; I < Count; I++) { + if (I + NumberOfPrefetch < Count) + PREFETCH(B->Batch[I + NumberOfPrefetch]); + Cb.recycle(reinterpret_cast<Node *>(B->Batch[I])); + } + Cb.deallocate(B); + } + } +}; + +} // namespace scudo + +#endif // SCUDO_QUARANTINE_H_ |