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//===-- primary64.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_PRIMARY64_H_
#define SCUDO_PRIMARY64_H_
#include "bytemap.h"
#include "common.h"
#include "list.h"
#include "local_cache.h"
#include "memtag.h"
#include "options.h"
#include "release.h"
#include "stats.h"
#include "string_utils.h"
namespace scudo {
// SizeClassAllocator64 is an allocator tuned for 64-bit address space.
//
// It starts by reserving NumClasses * 2^RegionSizeLog bytes, equally divided in
// Regions, specific to each size class. Note that the base of that mapping is
// random (based to the platform specific map() capabilities), and that each
// Region actually starts at a random offset from its base.
//
// Regions are mapped incrementally on demand to fulfill allocation requests,
// those mappings being split into equally sized Blocks based on the size class
// they belong to. The Blocks created are shuffled to prevent predictable
// address patterns (the predictability increases with the size of the Blocks).
//
// The 1st Region (for size class 0) holds the TransferBatches. This is a
// structure used to transfer arrays of available pointers from the class size
// freelist to the thread specific freelist, and back.
//
// The memory used by this allocator is never unmapped, but can be partially
// released if the platform allows for it.
template <typename Config> class SizeClassAllocator64 {
public:
typedef typename Config::PrimaryCompactPtrT CompactPtrT;
static const uptr CompactPtrScale = Config::PrimaryCompactPtrScale;
typedef typename Config::SizeClassMap SizeClassMap;
typedef SizeClassAllocator64<Config> ThisT;
typedef SizeClassAllocatorLocalCache<ThisT> CacheT;
typedef typename CacheT::TransferBatch TransferBatch;
static uptr getSizeByClassId(uptr ClassId) {
return (ClassId == SizeClassMap::BatchClassId)
? roundUpTo(sizeof(TransferBatch), 1U << CompactPtrScale)
: SizeClassMap::getSizeByClassId(ClassId);
}
static bool canAllocate(uptr Size) { return Size <= SizeClassMap::MaxSize; }
void initLinkerInitialized(s32 ReleaseToOsInterval) {
// Reserve the space required for the Primary.
PrimaryBase = reinterpret_cast<uptr>(
map(nullptr, PrimarySize, nullptr, MAP_NOACCESS, &Data));
u32 Seed;
const u64 Time = getMonotonicTime();
if (!getRandom(reinterpret_cast<void *>(&Seed), sizeof(Seed)))
Seed = static_cast<u32>(Time ^ (PrimaryBase >> 12));
const uptr PageSize = getPageSizeCached();
for (uptr I = 0; I < NumClasses; I++) {
RegionInfo *Region = getRegionInfo(I);
// The actual start of a region is offseted by a random number of pages.
Region->RegionBeg =
getRegionBaseByClassId(I) + (getRandomModN(&Seed, 16) + 1) * PageSize;
Region->RandState = getRandomU32(&Seed);
Region->ReleaseInfo.LastReleaseAtNs = Time;
}
setOption(Option::ReleaseInterval, static_cast<sptr>(ReleaseToOsInterval));
}
void init(s32 ReleaseToOsInterval) {
memset(this, 0, sizeof(*this));
initLinkerInitialized(ReleaseToOsInterval);
}
void unmapTestOnly() {
unmap(reinterpret_cast<void *>(PrimaryBase), PrimarySize, UNMAP_ALL, &Data);
}
TransferBatch *popBatch(CacheT *C, uptr ClassId) {
DCHECK_LT(ClassId, NumClasses);
RegionInfo *Region = getRegionInfo(ClassId);
ScopedLock L(Region->Mutex);
TransferBatch *B = Region->FreeList.front();
if (B) {
Region->FreeList.pop_front();
} else {
B = populateFreeList(C, ClassId, Region);
if (UNLIKELY(!B))
return nullptr;
}
DCHECK_GT(B->getCount(), 0);
Region->Stats.PoppedBlocks += B->getCount();
return B;
}
void pushBatch(uptr ClassId, TransferBatch *B) {
DCHECK_GT(B->getCount(), 0);
RegionInfo *Region = getRegionInfo(ClassId);
ScopedLock L(Region->Mutex);
Region->FreeList.push_front(B);
Region->Stats.PushedBlocks += B->getCount();
if (ClassId != SizeClassMap::BatchClassId)
releaseToOSMaybe(Region, ClassId);
}
void disable() {
// The BatchClassId must be locked last since other classes can use it.
for (sptr I = static_cast<sptr>(NumClasses) - 1; I >= 0; I--) {
if (static_cast<uptr>(I) == SizeClassMap::BatchClassId)
continue;
getRegionInfo(static_cast<uptr>(I))->Mutex.lock();
}
getRegionInfo(SizeClassMap::BatchClassId)->Mutex.lock();
}
void enable() {
getRegionInfo(SizeClassMap::BatchClassId)->Mutex.unlock();
for (uptr I = 0; I < NumClasses; I++) {
if (I == SizeClassMap::BatchClassId)
continue;
getRegionInfo(I)->Mutex.unlock();
}
}
template <typename F> void iterateOverBlocks(F Callback) {
for (uptr I = 0; I < NumClasses; I++) {
if (I == SizeClassMap::BatchClassId)
continue;
const RegionInfo *Region = getRegionInfo(I);
const uptr BlockSize = getSizeByClassId(I);
const uptr From = Region->RegionBeg;
const uptr To = From + Region->AllocatedUser;
for (uptr Block = From; Block < To; Block += BlockSize)
Callback(Block);
}
}
void getStats(ScopedString *Str) {
// TODO(kostyak): get the RSS per region.
uptr TotalMapped = 0;
uptr PoppedBlocks = 0;
uptr PushedBlocks = 0;
for (uptr I = 0; I < NumClasses; I++) {
RegionInfo *Region = getRegionInfo(I);
if (Region->MappedUser)
TotalMapped += Region->MappedUser;
PoppedBlocks += Region->Stats.PoppedBlocks;
PushedBlocks += Region->Stats.PushedBlocks;
}
Str->append("Stats: SizeClassAllocator64: %zuM mapped (%zuM rss) in %zu "
"allocations; remains %zu\n",
TotalMapped >> 20, 0, PoppedBlocks,
PoppedBlocks - PushedBlocks);
for (uptr I = 0; I < NumClasses; I++)
getStats(Str, I, 0);
}
bool setOption(Option O, sptr Value) {
if (O == Option::ReleaseInterval) {
const s32 Interval = Max(
Min(static_cast<s32>(Value), Config::PrimaryMaxReleaseToOsIntervalMs),
Config::PrimaryMinReleaseToOsIntervalMs);
atomic_store_relaxed(&ReleaseToOsIntervalMs, Interval);
return true;
}
// Not supported by the Primary, but not an error either.
return true;
}
uptr releaseToOS() {
uptr TotalReleasedBytes = 0;
for (uptr I = 0; I < NumClasses; I++) {
if (I == SizeClassMap::BatchClassId)
continue;
RegionInfo *Region = getRegionInfo(I);
ScopedLock L(Region->Mutex);
TotalReleasedBytes += releaseToOSMaybe(Region, I, /*Force=*/true);
}
return TotalReleasedBytes;
}
const char *getRegionInfoArrayAddress() const {
return reinterpret_cast<const char *>(RegionInfoArray);
}
static uptr getRegionInfoArraySize() { return sizeof(RegionInfoArray); }
uptr getCompactPtrBaseByClassId(uptr ClassId) {
// If we are not compacting pointers, base everything off of 0.
if (sizeof(CompactPtrT) == sizeof(uptr) && CompactPtrScale == 0)
return 0;
return getRegionInfo(ClassId)->RegionBeg;
}
CompactPtrT compactPtr(uptr ClassId, uptr Ptr) {
DCHECK_LE(ClassId, SizeClassMap::LargestClassId);
return compactPtrInternal(getCompactPtrBaseByClassId(ClassId), Ptr);
}
void *decompactPtr(uptr ClassId, CompactPtrT CompactPtr) {
DCHECK_LE(ClassId, SizeClassMap::LargestClassId);
return reinterpret_cast<void *>(
decompactPtrInternal(getCompactPtrBaseByClassId(ClassId), CompactPtr));
}
static BlockInfo findNearestBlock(const char *RegionInfoData, uptr Ptr) {
const RegionInfo *RegionInfoArray =
reinterpret_cast<const RegionInfo *>(RegionInfoData);
uptr ClassId;
uptr MinDistance = -1UL;
for (uptr I = 0; I != NumClasses; ++I) {
if (I == SizeClassMap::BatchClassId)
continue;
uptr Begin = RegionInfoArray[I].RegionBeg;
uptr End = Begin + RegionInfoArray[I].AllocatedUser;
if (Begin > End || End - Begin < SizeClassMap::getSizeByClassId(I))
continue;
uptr RegionDistance;
if (Begin <= Ptr) {
if (Ptr < End)
RegionDistance = 0;
else
RegionDistance = Ptr - End;
} else {
RegionDistance = Begin - Ptr;
}
if (RegionDistance < MinDistance) {
MinDistance = RegionDistance;
ClassId = I;
}
}
BlockInfo B = {};
if (MinDistance <= 8192) {
B.RegionBegin = RegionInfoArray[ClassId].RegionBeg;
B.RegionEnd = B.RegionBegin + RegionInfoArray[ClassId].AllocatedUser;
B.BlockSize = SizeClassMap::getSizeByClassId(ClassId);
B.BlockBegin =
B.RegionBegin + uptr(sptr(Ptr - B.RegionBegin) / sptr(B.BlockSize) *
sptr(B.BlockSize));
while (B.BlockBegin < B.RegionBegin)
B.BlockBegin += B.BlockSize;
while (B.RegionEnd < B.BlockBegin + B.BlockSize)
B.BlockBegin -= B.BlockSize;
}
return B;
}
AtomicOptions Options;
private:
static const uptr RegionSize = 1UL << Config::PrimaryRegionSizeLog;
static const uptr NumClasses = SizeClassMap::NumClasses;
static const uptr PrimarySize = RegionSize * NumClasses;
// Call map for user memory with at least this size.
static const uptr MapSizeIncrement = 1UL << 18;
// Fill at most this number of batches from the newly map'd memory.
static const u32 MaxNumBatches = SCUDO_ANDROID ? 4U : 8U;
struct RegionStats {
uptr PoppedBlocks;
uptr PushedBlocks;
};
struct ReleaseToOsInfo {
uptr PushedBlocksAtLastRelease;
uptr RangesReleased;
uptr LastReleasedBytes;
u64 LastReleaseAtNs;
};
struct UnpaddedRegionInfo {
HybridMutex Mutex;
SinglyLinkedList<TransferBatch> FreeList;
uptr RegionBeg = 0;
RegionStats Stats = {};
u32 RandState = 0;
uptr MappedUser = 0; // Bytes mapped for user memory.
uptr AllocatedUser = 0; // Bytes allocated for user memory.
MapPlatformData Data = {};
ReleaseToOsInfo ReleaseInfo = {};
bool Exhausted = false;
};
struct RegionInfo : UnpaddedRegionInfo {
char Padding[SCUDO_CACHE_LINE_SIZE -
(sizeof(UnpaddedRegionInfo) % SCUDO_CACHE_LINE_SIZE)] = {};
};
static_assert(sizeof(RegionInfo) % SCUDO_CACHE_LINE_SIZE == 0, "");
uptr PrimaryBase = 0;
MapPlatformData Data = {};
atomic_s32 ReleaseToOsIntervalMs = {};
alignas(SCUDO_CACHE_LINE_SIZE) RegionInfo RegionInfoArray[NumClasses];
RegionInfo *getRegionInfo(uptr ClassId) {
DCHECK_LT(ClassId, NumClasses);
return &RegionInfoArray[ClassId];
}
uptr getRegionBaseByClassId(uptr ClassId) const {
return PrimaryBase + (ClassId << Config::PrimaryRegionSizeLog);
}
static CompactPtrT compactPtrInternal(uptr Base, uptr Ptr) {
return static_cast<CompactPtrT>((Ptr - Base) >> CompactPtrScale);
}
static uptr decompactPtrInternal(uptr Base, CompactPtrT CompactPtr) {
return Base + (static_cast<uptr>(CompactPtr) << CompactPtrScale);
}
NOINLINE TransferBatch *populateFreeList(CacheT *C, uptr ClassId,
RegionInfo *Region) {
const uptr Size = getSizeByClassId(ClassId);
const u32 MaxCount = TransferBatch::getMaxCached(Size);
const uptr RegionBeg = Region->RegionBeg;
const uptr MappedUser = Region->MappedUser;
const uptr TotalUserBytes = Region->AllocatedUser + MaxCount * Size;
// Map more space for blocks, if necessary.
if (TotalUserBytes > MappedUser) {
// Do the mmap for the user memory.
const uptr MapSize =
roundUpTo(TotalUserBytes - MappedUser, MapSizeIncrement);
const uptr RegionBase = RegionBeg - getRegionBaseByClassId(ClassId);
if (UNLIKELY(RegionBase + MappedUser + MapSize > RegionSize)) {
if (!Region->Exhausted) {
Region->Exhausted = true;
ScopedString Str(1024);
getStats(&Str);
Str.append(
"Scudo OOM: The process has exhausted %zuM for size class %zu.\n",
RegionSize >> 20, Size);
Str.output();
}
return nullptr;
}
if (MappedUser == 0)
Region->Data = Data;
if (UNLIKELY(!map(
reinterpret_cast<void *>(RegionBeg + MappedUser), MapSize,
"scudo:primary",
MAP_ALLOWNOMEM | MAP_RESIZABLE |
(useMemoryTagging<Config>(Options.load()) ? MAP_MEMTAG : 0),
&Region->Data)))
return nullptr;
Region->MappedUser += MapSize;
C->getStats().add(StatMapped, MapSize);
}
const u32 NumberOfBlocks = Min(
MaxNumBatches * MaxCount,
static_cast<u32>((Region->MappedUser - Region->AllocatedUser) / Size));
DCHECK_GT(NumberOfBlocks, 0);
constexpr u32 ShuffleArraySize =
MaxNumBatches * TransferBatch::MaxNumCached;
CompactPtrT ShuffleArray[ShuffleArraySize];
DCHECK_LE(NumberOfBlocks, ShuffleArraySize);
const uptr CompactPtrBase = getCompactPtrBaseByClassId(ClassId);
uptr P = RegionBeg + Region->AllocatedUser;
for (u32 I = 0; I < NumberOfBlocks; I++, P += Size)
ShuffleArray[I] = compactPtrInternal(CompactPtrBase, P);
// No need to shuffle the batches size class.
if (ClassId != SizeClassMap::BatchClassId)
shuffle(ShuffleArray, NumberOfBlocks, &Region->RandState);
for (u32 I = 0; I < NumberOfBlocks;) {
TransferBatch *B =
C->createBatch(ClassId, reinterpret_cast<void *>(decompactPtrInternal(
CompactPtrBase, ShuffleArray[I])));
if (UNLIKELY(!B))
return nullptr;
const u32 N = Min(MaxCount, NumberOfBlocks - I);
B->setFromArray(&ShuffleArray[I], N);
Region->FreeList.push_back(B);
I += N;
}
TransferBatch *B = Region->FreeList.front();
Region->FreeList.pop_front();
DCHECK(B);
DCHECK_GT(B->getCount(), 0);
const uptr AllocatedUser = Size * NumberOfBlocks;
C->getStats().add(StatFree, AllocatedUser);
Region->AllocatedUser += AllocatedUser;
return B;
}
void getStats(ScopedString *Str, uptr ClassId, uptr Rss) {
RegionInfo *Region = getRegionInfo(ClassId);
if (Region->MappedUser == 0)
return;
const uptr InUse = Region->Stats.PoppedBlocks - Region->Stats.PushedBlocks;
const uptr TotalChunks = Region->AllocatedUser / getSizeByClassId(ClassId);
Str->append("%s %02zu (%6zu): mapped: %6zuK popped: %7zu pushed: %7zu "
"inuse: %6zu total: %6zu rss: %6zuK releases: %6zu last "
"released: %6zuK region: 0x%zx (0x%zx)\n",
Region->Exhausted ? "F" : " ", ClassId,
getSizeByClassId(ClassId), Region->MappedUser >> 10,
Region->Stats.PoppedBlocks, Region->Stats.PushedBlocks, InUse,
TotalChunks, Rss >> 10, Region->ReleaseInfo.RangesReleased,
Region->ReleaseInfo.LastReleasedBytes >> 10, Region->RegionBeg,
getRegionBaseByClassId(ClassId));
}
NOINLINE uptr releaseToOSMaybe(RegionInfo *Region, uptr ClassId,
bool Force = false) {
const uptr BlockSize = getSizeByClassId(ClassId);
const uptr PageSize = getPageSizeCached();
DCHECK_GE(Region->Stats.PoppedBlocks, Region->Stats.PushedBlocks);
const uptr BytesInFreeList =
Region->AllocatedUser -
(Region->Stats.PoppedBlocks - Region->Stats.PushedBlocks) * BlockSize;
if (BytesInFreeList < PageSize)
return 0; // No chance to release anything.
const uptr BytesPushed = (Region->Stats.PushedBlocks -
Region->ReleaseInfo.PushedBlocksAtLastRelease) *
BlockSize;
if (BytesPushed < PageSize)
return 0; // Nothing new to release.
// Releasing smaller blocks is expensive, so we want to make sure that a
// significant amount of bytes are free, and that there has been a good
// amount of batches pushed to the freelist before attempting to release.
if (BlockSize < PageSize / 16U) {
if (!Force && BytesPushed < Region->AllocatedUser / 16U)
return 0;
// We want 8x% to 9x% free bytes (the larger the block, the lower the %).
if ((BytesInFreeList * 100U) / Region->AllocatedUser <
(100U - 1U - BlockSize / 16U))
return 0;
}
if (!Force) {
const s32 IntervalMs = atomic_load_relaxed(&ReleaseToOsIntervalMs);
if (IntervalMs < 0)
return 0;
if (Region->ReleaseInfo.LastReleaseAtNs +
static_cast<u64>(IntervalMs) * 1000000 >
getMonotonicTime()) {
return 0; // Memory was returned recently.
}
}
ReleaseRecorder Recorder(Region->RegionBeg, &Region->Data);
const uptr CompactPtrBase = getCompactPtrBaseByClassId(ClassId);
auto DecompactPtr = [CompactPtrBase](CompactPtrT CompactPtr) {
return decompactPtrInternal(CompactPtrBase, CompactPtr);
};
auto SkipRegion = [](UNUSED uptr RegionIndex) { return false; };
releaseFreeMemoryToOS(Region->FreeList, Region->AllocatedUser, 1U,
BlockSize, &Recorder, DecompactPtr, SkipRegion);
if (Recorder.getReleasedRangesCount() > 0) {
Region->ReleaseInfo.PushedBlocksAtLastRelease =
Region->Stats.PushedBlocks;
Region->ReleaseInfo.RangesReleased += Recorder.getReleasedRangesCount();
Region->ReleaseInfo.LastReleasedBytes = Recorder.getReleasedBytes();
}
Region->ReleaseInfo.LastReleaseAtNs = getMonotonicTime();
return Recorder.getReleasedBytes();
}
};
} // namespace scudo
#endif // SCUDO_PRIMARY64_H_