zircon/third_party/ulib/scudo/release.h - fuchsia - Git at Google

 //===-- release.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_RELEASE_H_
 #define SCUDO_RELEASE_H_

 #include "common.h"
 #include "list.h"

 namespace scudo {

 class MemoryMapper {
 public:
   MemoryMapper(uptr Addr = 0, OpaquePlatformData *Extra = nullptr)
       : ReleasedRangesCount(0), ReleasedBytes(0), BaseAddress(Addr),
         PlatformData(Extra) {}

   uptr getReleasedRangesCount() const { return ReleasedRangesCount; }

   uptr getReleasedBytes() const { return ReleasedBytes; }

   // Releases [From, To) range of pages back to OS.
   void releasePageRangeToOS(uptr From, uptr To) {
     const uptr Offset = From - BaseAddress;
     const uptr Size = To - From;
     releasePagesToOS(BaseAddress, Offset, Size, PlatformData);
     ReleasedRangesCount++;
     ReleasedBytes += Size;
   }

 private:
   uptr ReleasedRangesCount;
   uptr ReleasedBytes;
   uptr BaseAddress;
   OpaquePlatformData *PlatformData;
 };

 // A packed array of Counters. Each counter occupies 2^N bits, enough to store
 // counter's MaxValue. Ctor will try to allocate the required Buffer via map()
 // and the caller is expected to check whether the initialization was successful
 // by checking isAllocated() result. For the performance sake, none of the
 // accessors check the validity of the arguments, It is assumed that Index is
 // always in [0, N) range and the value is not incremented past MaxValue.
 class PackedCounterArray {
 public:
   PackedCounterArray(uptr NumCounters, uptr MaxValue) : N(NumCounters) {
     CHECK_GT(NumCounters, 0);
     CHECK_GT(MaxValue, 0);
     constexpr uptr MaxCounterBits = sizeof(*Buffer) * 8UL;
     // Rounding counter storage size up to the power of two allows for using
     // bit shifts calculating particular counter's Index and offset.
     const uptr CounterSizeBits =
         roundUpToPowerOfTwo(getMostSignificantSetBitIndex(MaxValue) + 1);
     CHECK_LE(CounterSizeBits, MaxCounterBits);
     CounterSizeBitsLog = getLog2(CounterSizeBits);
     CounterMask = ~0ULL >> (MaxCounterBits - CounterSizeBits);

     const uptr PackingRatio = MaxCounterBits >> CounterSizeBitsLog;
     CHECK_GT(PackingRatio, 0);
     PackingRatioLog = getLog2(PackingRatio);
     BitOffsetMask = PackingRatio - 1;

     BufferSize = (roundUpTo(N, 1ULL << PackingRatioLog) >> PackingRatioLog) *
                  sizeof(*Buffer);
     Buffer = reinterpret_cast<u64 *>(
         map(nullptr, BufferSize, "scudo:counters", MAP_ALLOWNOMEM));
   }
   ~PackedCounterArray() {
     if (isAllocated())
       unmap(reinterpret_cast<void *>(Buffer), BufferSize);
   }

   bool isAllocated() const { return !!Buffer; }

   uptr getCount() const { return N; }

   uptr get(uptr I) const {
     DCHECK_LT(I, N);
     const uptr Index = I >> PackingRatioLog;
     const uptr BitOffset = (I & BitOffsetMask) << CounterSizeBitsLog;
     return (Buffer[Index] >> BitOffset) & CounterMask;
   }

   void inc(uptr I) const {
     DCHECK_LT(get(I), CounterMask);
     const uptr Index = I >> PackingRatioLog;
     const uptr BitOffset = (I & BitOffsetMask) << CounterSizeBitsLog;
     Buffer[Index] += 1ULL << BitOffset;
   }

   void incRange(uptr From, uptr To) const {
     DCHECK_LE(From, To);
     for (uptr I = From; I <= To; I++)
       inc(I);
   }

 private:
   const uptr N;
   uptr CounterSizeBitsLog;
   u64 CounterMask;
   uptr PackingRatioLog;
   u64 BitOffsetMask;

   uptr BufferSize;
   u64 *Buffer;
 };

 class FreePagesRangeTracker {
 public:
   explicit FreePagesRangeTracker(MemoryMapper *MM, uptr Base)
       : Mapper(MM), BaseAddress(Base),
         PageSizeLog(getLog2(getPageSizeCached())), InRange(false),
         CurrentPage(0), CurrentRangeStatePage(0) {}

   void processNextPage(bool Freed) {
     if (Freed) {
       if (!InRange) {
         CurrentRangeStatePage = CurrentPage;
         InRange = true;
       }
     } else {
       closeOpenedRange();
     }
     CurrentPage++;
   }

   void finish() { closeOpenedRange(); }

 private:
   void closeOpenedRange() {
     if (InRange) {
       Mapper->releasePageRangeToOS(BaseAddress +
                                        (CurrentRangeStatePage << PageSizeLog),
                                    BaseAddress + (CurrentPage << PageSizeLog));
       InRange = false;
     }
   }

   MemoryMapper *const Mapper;
   const uptr BaseAddress;
   const uptr PageSizeLog;
   bool InRange;
   uptr CurrentPage;
   uptr CurrentRangeStatePage;
 };

 template <class TransferBatchT>
 NOINLINE void
 releaseFreeMemoryToOS(const IntrusiveList<TransferBatchT> *FreeList, uptr Base,
                       uptr AllocatedPagesCount, uptr ChunkSize,
                       MemoryMapper *MM) {
   const uptr PageSize = getPageSizeCached();

   // Figure out the number of chunks per page and whether we can take a fast
   // path (the number of chunks per page is the same for all pages).
   uptr FullPagesChunkCountMax;
   bool SameChunkCountPerPage;
   if (ChunkSize <= PageSize && PageSize % ChunkSize == 0) {
     // Same number of chunks per page, no cross overs.
     FullPagesChunkCountMax = PageSize / ChunkSize;
     SameChunkCountPerPage = true;
   } else if (ChunkSize <= PageSize && PageSize % ChunkSize != 0 &&
              ChunkSize % (PageSize % ChunkSize) == 0) {
     // Some chunks are crossing page boundaries, which means that the page
     // contains one or two partial chunks, but all pages contain the same
     // number of chunks.
     FullPagesChunkCountMax = PageSize / ChunkSize + 1;
     SameChunkCountPerPage = true;
   } else if (ChunkSize <= PageSize) {
     // Some chunks are crossing page boundaries, which means that the page
     // contains one or two partial chunks.
     FullPagesChunkCountMax = PageSize / ChunkSize + 2;
     SameChunkCountPerPage = false;
   } else if (ChunkSize > PageSize && ChunkSize % PageSize == 0) {
     // One chunk covers multiple pages, no cross overs.
     FullPagesChunkCountMax = 1;
     SameChunkCountPerPage = true;
   } else if (ChunkSize > PageSize) {
     // One chunk covers multiple pages, Some chunks are crossing page
     // boundaries. Some pages contain one chunk, some contain two.
     FullPagesChunkCountMax = 2;
     SameChunkCountPerPage = false;
   } else {
     UNREACHABLE("All ChunkSize/PageSize ratios must be handled.");
   }

   PackedCounterArray Counters(AllocatedPagesCount, FullPagesChunkCountMax);
   if (!Counters.isAllocated())
     return;

   const uptr PageSizeLog = getLog2(PageSize);
   const uptr End = Base + AllocatedPagesCount * PageSize;

   // Iterate over free chunks and count how many free chunks affect each
   // allocated page.
   if (ChunkSize <= PageSize && PageSize % ChunkSize == 0) {
     // Each chunk affects one page only.
     for (auto It = FreeList->begin(); It != FreeList->end(); ++It) {
       for (u32 I = 0; I < (*It).getCount(); I++) {
         const uptr P = (uptr)((*It).get(I));
         if (P >= Base && P < End)
           Counters.inc((P - Base) >> PageSizeLog);
       }
     }
   } else {
     // In all other cases chunks might affect more than one page.
     for (auto It = FreeList->begin(); It != FreeList->end(); ++It) {
       for (u32 I = 0; I < (*It).getCount(); I++) {
         const uptr P = (uptr)((*It).get(I));
         if (P >= Base && P < End)
           Counters.incRange((P - Base) >> PageSizeLog,
                             (P - Base + ChunkSize - 1) >> PageSizeLog);
       }
     }
   }

   // Iterate over pages detecting ranges of pages with chunk Counters equal
   // to the expected number of chunks for the particular page.
   FreePagesRangeTracker RangeTracker(MM, Base);
   if (SameChunkCountPerPage) {
     // Fast path, every page has the same number of chunks affecting it.
     for (uptr I = 0; I < Counters.getCount(); I++)
       RangeTracker.processNextPage(Counters.get(I) == FullPagesChunkCountMax);
   } else {
     // Show path, go through the pages keeping count how many chunks affect
     // each page.
     const uptr Pn = ChunkSize < PageSize ? PageSize / ChunkSize : 1;
     const uptr Pnc = Pn * ChunkSize;
     // The idea is to increment the current page pointer by the first chunk
     // size, middle portion size (the portion of the page covered by chunks
     // except the first and the last one) and then the last chunk size, adding
     // up the number of chunks on the current page and checking on every step
     // whether the page boundary was crossed.
     uptr PrevPageBoundary = 0;
     uptr CurrentBoundary = 0;
     for (uptr I = 0; I < Counters.getCount(); I++) {
       uptr PageBoundary = PrevPageBoundary + PageSize;
       uptr ChunksPerPage = Pn;
       if (CurrentBoundary < PageBoundary) {
         if (CurrentBoundary > PrevPageBoundary)
           ChunksPerPage++;
         CurrentBoundary += Pnc;
         if (CurrentBoundary < PageBoundary) {
           ChunksPerPage++;
           CurrentBoundary += ChunkSize;
         }
       }
       PrevPageBoundary = PageBoundary;

       RangeTracker.processNextPage(Counters.get(I) == ChunksPerPage);
     }
   }
   RangeTracker.finish();
 }

 } // namespace scudo

 #endif // SCUDO_RELEASE_H_
	//===-- release.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_RELEASE_H_
	#define SCUDO_RELEASE_H_

	#include "common.h"
	#include "list.h"

	namespace scudo {

	class MemoryMapper {
	public:
	MemoryMapper(uptr Addr = 0, OpaquePlatformData *Extra = nullptr)
	: ReleasedRangesCount(0), ReleasedBytes(0), BaseAddress(Addr),
	PlatformData(Extra) {}

	uptr getReleasedRangesCount() const { return ReleasedRangesCount; }

	uptr getReleasedBytes() const { return ReleasedBytes; }

	// Releases [From, To) range of pages back to OS.
	void releasePageRangeToOS(uptr From, uptr To) {
	const uptr Offset = From - BaseAddress;
	const uptr Size = To - From;
	releasePagesToOS(BaseAddress, Offset, Size, PlatformData);
	ReleasedRangesCount++;
	ReleasedBytes += Size;
	}

	private:
	uptr ReleasedRangesCount;
	uptr ReleasedBytes;
	uptr BaseAddress;
	OpaquePlatformData *PlatformData;
	};

	// A packed array of Counters. Each counter occupies 2^N bits, enough to store
	// counter's MaxValue. Ctor will try to allocate the required Buffer via map()
	// and the caller is expected to check whether the initialization was successful
	// by checking isAllocated() result. For the performance sake, none of the
	// accessors check the validity of the arguments, It is assumed that Index is
	// always in [0, N) range and the value is not incremented past MaxValue.
	class PackedCounterArray {
	public:
	PackedCounterArray(uptr NumCounters, uptr MaxValue) : N(NumCounters) {
	CHECK_GT(NumCounters, 0);
	CHECK_GT(MaxValue, 0);
	constexpr uptr MaxCounterBits = sizeof(Buffer) 8UL;
	// Rounding counter storage size up to the power of two allows for using
	// bit shifts calculating particular counter's Index and offset.
	const uptr CounterSizeBits =
	roundUpToPowerOfTwo(getMostSignificantSetBitIndex(MaxValue) + 1);
	CHECK_LE(CounterSizeBits, MaxCounterBits);
	CounterSizeBitsLog = getLog2(CounterSizeBits);
	CounterMask = ~0ULL >> (MaxCounterBits - CounterSizeBits);

	const uptr PackingRatio = MaxCounterBits >> CounterSizeBitsLog;
	CHECK_GT(PackingRatio, 0);
	PackingRatioLog = getLog2(PackingRatio);
	BitOffsetMask = PackingRatio - 1;

	BufferSize = (roundUpTo(N, 1ULL << PackingRatioLog) >> PackingRatioLog) *
	sizeof(*Buffer);
	Buffer = reinterpret_cast<u64 *>(
	map(nullptr, BufferSize, "scudo:counters", MAP_ALLOWNOMEM));
	}
	~PackedCounterArray() {
	if (isAllocated())
	unmap(reinterpret_cast<void *>(Buffer), BufferSize);
	}

	bool isAllocated() const { return !!Buffer; }

	uptr getCount() const { return N; }

	uptr get(uptr I) const {
	DCHECK_LT(I, N);
	const uptr Index = I >> PackingRatioLog;
	const uptr BitOffset = (I & BitOffsetMask) << CounterSizeBitsLog;
	return (Buffer[Index] >> BitOffset) & CounterMask;
	}

	void inc(uptr I) const {
	DCHECK_LT(get(I), CounterMask);
	const uptr Index = I >> PackingRatioLog;
	const uptr BitOffset = (I & BitOffsetMask) << CounterSizeBitsLog;
	Buffer[Index] += 1ULL << BitOffset;
	}

	void incRange(uptr From, uptr To) const {
	DCHECK_LE(From, To);
	for (uptr I = From; I <= To; I++)
	inc(I);
	}

	private:
	const uptr N;
	uptr CounterSizeBitsLog;
	u64 CounterMask;
	uptr PackingRatioLog;
	u64 BitOffsetMask;

	uptr BufferSize;
	u64 *Buffer;
	};

	class FreePagesRangeTracker {
	public:
	explicit FreePagesRangeTracker(MemoryMapper *MM, uptr Base)
	: Mapper(MM), BaseAddress(Base),
	PageSizeLog(getLog2(getPageSizeCached())), InRange(false),
	CurrentPage(0), CurrentRangeStatePage(0) {}

	void processNextPage(bool Freed) {
	if (Freed) {
	if (!InRange) {
	CurrentRangeStatePage = CurrentPage;
	InRange = true;
	}
	} else {
	closeOpenedRange();
	}
	CurrentPage++;
	}

	void finish() { closeOpenedRange(); }

	private:
	void closeOpenedRange() {
	if (InRange) {
	Mapper->releasePageRangeToOS(BaseAddress +
	(CurrentRangeStatePage << PageSizeLog),
	BaseAddress + (CurrentPage << PageSizeLog));
	InRange = false;
	}
	}

	MemoryMapper *const Mapper;
	const uptr BaseAddress;
	const uptr PageSizeLog;
	bool InRange;
	uptr CurrentPage;
	uptr CurrentRangeStatePage;
	};

	template <class TransferBatchT>
	NOINLINE void
	releaseFreeMemoryToOS(const IntrusiveList<TransferBatchT> *FreeList, uptr Base,
	uptr AllocatedPagesCount, uptr ChunkSize,
	MemoryMapper *MM) {
	const uptr PageSize = getPageSizeCached();

	// Figure out the number of chunks per page and whether we can take a fast
	// path (the number of chunks per page is the same for all pages).
	uptr FullPagesChunkCountMax;
	bool SameChunkCountPerPage;
	if (ChunkSize <= PageSize && PageSize % ChunkSize == 0) {
	// Same number of chunks per page, no cross overs.
	FullPagesChunkCountMax = PageSize / ChunkSize;
	SameChunkCountPerPage = true;
	} else if (ChunkSize <= PageSize && PageSize % ChunkSize != 0 &&
	ChunkSize % (PageSize % ChunkSize) == 0) {
	// Some chunks are crossing page boundaries, which means that the page
	// contains one or two partial chunks, but all pages contain the same
	// number of chunks.
	FullPagesChunkCountMax = PageSize / ChunkSize + 1;
	SameChunkCountPerPage = true;
	} else if (ChunkSize <= PageSize) {
	// Some chunks are crossing page boundaries, which means that the page
	// contains one or two partial chunks.
	FullPagesChunkCountMax = PageSize / ChunkSize + 2;
	SameChunkCountPerPage = false;
	} else if (ChunkSize > PageSize && ChunkSize % PageSize == 0) {
	// One chunk covers multiple pages, no cross overs.
	FullPagesChunkCountMax = 1;
	SameChunkCountPerPage = true;
	} else if (ChunkSize > PageSize) {
	// One chunk covers multiple pages, Some chunks are crossing page
	// boundaries. Some pages contain one chunk, some contain two.
	FullPagesChunkCountMax = 2;
	SameChunkCountPerPage = false;
	} else {
	UNREACHABLE("All ChunkSize/PageSize ratios must be handled.");
	}

	PackedCounterArray Counters(AllocatedPagesCount, FullPagesChunkCountMax);
	if (!Counters.isAllocated())
	return;

	const uptr PageSizeLog = getLog2(PageSize);
	const uptr End = Base + AllocatedPagesCount * PageSize;

	// Iterate over free chunks and count how many free chunks affect each
	// allocated page.
	if (ChunkSize <= PageSize && PageSize % ChunkSize == 0) {
	// Each chunk affects one page only.
	for (auto It = FreeList->begin(); It != FreeList->end(); ++It) {
	for (u32 I = 0; I < (*It).getCount(); I++) {
	const uptr P = (uptr)((*It).get(I));
	if (P >= Base && P < End)
	Counters.inc((P - Base) >> PageSizeLog);
	}
	}
	} else {
	// In all other cases chunks might affect more than one page.
	for (auto It = FreeList->begin(); It != FreeList->end(); ++It) {
	for (u32 I = 0; I < (*It).getCount(); I++) {
	const uptr P = (uptr)((*It).get(I));
	if (P >= Base && P < End)
	Counters.incRange((P - Base) >> PageSizeLog,
	(P - Base + ChunkSize - 1) >> PageSizeLog);
	}
	}
	}

	// Iterate over pages detecting ranges of pages with chunk Counters equal
	// to the expected number of chunks for the particular page.
	FreePagesRangeTracker RangeTracker(MM, Base);
	if (SameChunkCountPerPage) {
	// Fast path, every page has the same number of chunks affecting it.
	for (uptr I = 0; I < Counters.getCount(); I++)
	RangeTracker.processNextPage(Counters.get(I) == FullPagesChunkCountMax);
	} else {
	// Show path, go through the pages keeping count how many chunks affect
	// each page.
	const uptr Pn = ChunkSize < PageSize ? PageSize / ChunkSize : 1;
	const uptr Pnc = Pn * ChunkSize;
	// The idea is to increment the current page pointer by the first chunk
	// size, middle portion size (the portion of the page covered by chunks
	// except the first and the last one) and then the last chunk size, adding
	// up the number of chunks on the current page and checking on every step
	// whether the page boundary was crossed.
	uptr PrevPageBoundary = 0;
	uptr CurrentBoundary = 0;
	for (uptr I = 0; I < Counters.getCount(); I++) {
	uptr PageBoundary = PrevPageBoundary + PageSize;
	uptr ChunksPerPage = Pn;
	if (CurrentBoundary < PageBoundary) {
	if (CurrentBoundary > PrevPageBoundary)
	ChunksPerPage++;
	CurrentBoundary += Pnc;
	if (CurrentBoundary < PageBoundary) {
	ChunksPerPage++;
	CurrentBoundary += ChunkSize;
	}
	}
	PrevPageBoundary = PageBoundary;

	RangeTracker.processNextPage(Counters.get(I) == ChunksPerPage);
	}
	}
	RangeTracker.finish();
	}

	} // namespace scudo

	#endif // SCUDO_RELEASE_H_