diff options
Diffstat (limited to 'lib/scudo/scudo_allocator_secondary.h')
-rw-r--r-- | lib/scudo/scudo_allocator_secondary.h | 76 |
1 files changed, 39 insertions, 37 deletions
diff --git a/lib/scudo/scudo_allocator_secondary.h b/lib/scudo/scudo_allocator_secondary.h index dbfb22565f9c..f2002ed986c3 100644 --- a/lib/scudo/scudo_allocator_secondary.h +++ b/lib/scudo/scudo_allocator_secondary.h @@ -23,23 +23,24 @@ class ScudoLargeMmapAllocator { public: - void Init() { - PageSize = GetPageSizeCached(); + PageSizeCached = GetPageSizeCached(); } void *Allocate(AllocatorStats *Stats, uptr Size, uptr Alignment) { - uptr UserSize = Size - AlignedChunkHeaderSize; + const uptr UserSize = Size - AlignedChunkHeaderSize; // The Scudo frontend prevents us from allocating more than // MaxAllowedMallocSize, so integer overflow checks would be superfluous. - uptr MapSize = Size + SecondaryHeaderSize; + uptr MapSize = Size + AlignedReservedAddressRangeSize; if (Alignment > MinAlignment) MapSize += Alignment; + const uptr PageSize = PageSizeCached; MapSize = RoundUpTo(MapSize, PageSize); // Account for 2 guard pages, one before and one after the chunk. MapSize += 2 * PageSize; - uptr MapBeg = reinterpret_cast<uptr>(MmapNoAccess(MapSize)); + ReservedAddressRange AddressRange; + uptr MapBeg = AddressRange.Init(MapSize); if (MapBeg == ~static_cast<uptr>(0)) return ReturnNullOrDieOnFailure::OnOOM(); // A page-aligned pointer is assumed after that, so check it now. @@ -62,27 +63,27 @@ class ScudoLargeMmapAllocator { PageSize; CHECK_GE(NewMapBeg, MapBeg); if (NewMapBeg != MapBeg) { - UnmapOrDie(reinterpret_cast<void *>(MapBeg), NewMapBeg - MapBeg); + AddressRange.Unmap(MapBeg, NewMapBeg - MapBeg); MapBeg = NewMapBeg; } UserEnd = UserBeg + UserSize; } uptr NewMapEnd = RoundUpTo(UserEnd, PageSize) + PageSize; if (NewMapEnd != MapEnd) { - UnmapOrDie(reinterpret_cast<void *>(NewMapEnd), MapEnd - NewMapEnd); + AddressRange.Unmap(NewMapEnd, MapEnd - NewMapEnd); MapEnd = NewMapEnd; } MapSize = MapEnd - MapBeg; } CHECK_LE(UserEnd, MapEnd - PageSize); - // Actually mmap the memory, preserving the guard pages on either side. - CHECK_EQ(MapBeg + PageSize, reinterpret_cast<uptr>( - MmapFixedOrDie(MapBeg + PageSize, MapSize - 2 * PageSize))); - uptr Ptr = UserBeg - AlignedChunkHeaderSize; - SecondaryHeader *Header = getHeader(Ptr); - Header->MapBeg = MapBeg; - Header->MapSize = MapSize; + // Actually mmap the memory, preserving the guard pages on either side + CHECK_EQ(MapBeg + PageSize, + AddressRange.Map(MapBeg + PageSize, MapSize - 2 * PageSize)); + const uptr Ptr = UserBeg - AlignedChunkHeaderSize; + ReservedAddressRange *StoredRange = getReservedAddressRange(Ptr); + *StoredRange = AddressRange; + // The primary adds the whole class size to the stats when allocating a // chunk, so we will do something similar here. But we will not account for // the guard pages. @@ -96,42 +97,43 @@ class ScudoLargeMmapAllocator { } void Deallocate(AllocatorStats *Stats, void *Ptr) { - SecondaryHeader *Header = getHeader(Ptr); + // Since we're unmapping the entirety of where the ReservedAddressRange + // actually is, copy onto the stack. + const uptr PageSize = PageSizeCached; + ReservedAddressRange AddressRange = *getReservedAddressRange(Ptr); { SpinMutexLock l(&StatsMutex); - Stats->Sub(AllocatorStatAllocated, Header->MapSize - 2 * PageSize); - Stats->Sub(AllocatorStatMapped, Header->MapSize - 2 * PageSize); + Stats->Sub(AllocatorStatAllocated, AddressRange.size() - 2 * PageSize); + Stats->Sub(AllocatorStatMapped, AddressRange.size() - 2 * PageSize); } - UnmapOrDie(reinterpret_cast<void *>(Header->MapBeg), Header->MapSize); + AddressRange.Unmap(reinterpret_cast<uptr>(AddressRange.base()), + AddressRange.size()); } uptr GetActuallyAllocatedSize(void *Ptr) { - SecondaryHeader *Header = getHeader(Ptr); - // Deduct PageSize as MapSize includes the trailing guard page. - uptr MapEnd = Header->MapBeg + Header->MapSize - PageSize; + ReservedAddressRange *StoredRange = getReservedAddressRange(Ptr); + // Deduct PageSize as ReservedAddressRange size includes the trailing guard + // page. + uptr MapEnd = reinterpret_cast<uptr>(StoredRange->base()) + + StoredRange->size() - PageSizeCached; return MapEnd - reinterpret_cast<uptr>(Ptr); } private: - // A Secondary allocated chunk header contains the base of the mapping and - // its size, which comprises the guard pages. - struct SecondaryHeader { - uptr MapBeg; - uptr MapSize; - }; - // Check that sizeof(SecondaryHeader) is a multiple of MinAlignment. - COMPILER_CHECK((sizeof(SecondaryHeader) & (MinAlignment - 1)) == 0); - - SecondaryHeader *getHeader(uptr Ptr) { - return reinterpret_cast<SecondaryHeader*>(Ptr - sizeof(SecondaryHeader)); + ReservedAddressRange *getReservedAddressRange(uptr Ptr) { + return reinterpret_cast<ReservedAddressRange*>( + Ptr - sizeof(ReservedAddressRange)); } - SecondaryHeader *getHeader(const void *Ptr) { - return getHeader(reinterpret_cast<uptr>(Ptr)); + ReservedAddressRange *getReservedAddressRange(const void *Ptr) { + return getReservedAddressRange(reinterpret_cast<uptr>(Ptr)); } - const uptr SecondaryHeaderSize = sizeof(SecondaryHeader); - const uptr HeadersSize = SecondaryHeaderSize + AlignedChunkHeaderSize; - uptr PageSize; + static constexpr uptr AlignedReservedAddressRangeSize = + (sizeof(ReservedAddressRange) + MinAlignment - 1) & ~(MinAlignment - 1); + static constexpr uptr HeadersSize = + AlignedReservedAddressRangeSize + AlignedChunkHeaderSize; + + uptr PageSizeCached; SpinMutex StatsMutex; }; |