Files
sharpemu/src/SharpEmu.Core/Memory/PhysicalVirtualMemory.cs
T
Slick Daddy 33be88bdf9 memory: back the free pages of a partially-overlapping fixed mapping (#458)
A SCE_KERNEL_MAP_FIXED request whose window partially overlaps an
existing allocation was failing outright: AllocateAt reserves the whole
range in one all-or-nothing VirtualAlloc, which returns 0 on partial
overlap. The mapping call then returned NOT_FOUND while leaving the free
tail unmapped, so the guest faulted (0xC0000005) writing into it.

Add IGuestAddressSpace.TryBackFixedRange, which walks the range via the
host Query (VirtualQuery reports contiguous same-state runs) and fills
only the free sub-ranges, leaving already-backed pages untouched. This
matches the fixed-mapping contract on hardware. Route the fixed
reservation path through it via a new backPartialOverlap flag.

Co-authored-by: slick-daddy <slick-daddy@users.noreply.github.com>
2026-07-20 09:08:29 +03:00

1659 lines
54 KiB
C#

// Copyright (C) 2026 SharpEmu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
using System.Runtime.InteropServices;
using SharpEmu.Core.Loader;
using SharpEmu.HLE;
using SharpEmu.HLE.Host;
using SharpEmu.Logging;
namespace SharpEmu.Core.Memory;
public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryAllocator, IGuestAddressSpace, IDisposable
{
private static readonly SharpEmuLogger Log = SharpEmuLog.For("VMEM");
private readonly ReaderWriterLockSlim _gate = new(LockRecursionPolicy.SupportsRecursion);
private readonly object _guestAllocationGate = new();
private readonly object _allocationSearchHintGate = new();
private readonly List<MemoryRegion> _regions = new();
private readonly Dictionary<(ulong DesiredAddress, ulong Alignment, bool Executable), ulong> _allocationSearchHints = new();
private readonly Dictionary<ulong, ProgramHeaderFlags> _pageProtections = new();
private bool _disposed;
[ThreadStatic]
private static CommittedRangeCache? _committedRangeCache;
private long _mappingGeneration;
private const ulong PageSize = 0x1000;
private const ulong GuestAllocationArenaAddress = 0x00006000_0000_0000;
private const ulong GuestAllocationArenaSize = 0x0100_0000;
private const ulong GuestAllocationArenaStartOffset = PageSize;
private const ulong LargeDataReserveThreshold = 0x4000_0000UL; // 1 GiB
private const ulong FullCommitRegionLimit = 4UL << 30;
private const ulong DefaultLazyReservePrimeBytes = 0x0400_0000UL; // 64 MiB
private const ulong LazyReservePrimeChunkBytes = 0x0200_0000UL; // 32 MiB
private const int CommittedRangeCacheCapacity = 4;
private sealed class CommittedRangeCache
{
private readonly CommittedRange[] _ranges = new CommittedRange[CommittedRangeCacheCapacity];
private PhysicalVirtualMemory? _owner;
private long _generation;
private int _count;
private int _nextReplacement;
public bool Contains(
PhysicalVirtualMemory owner,
long generation,
ulong start,
ulong end)
{
if (!ReferenceEquals(_owner, owner) || _generation != generation)
{
return false;
}
for (var index = 0; index < _count; index++)
{
var range = _ranges[index];
if (start >= range.Start && end <= range.End)
{
return true;
}
}
return false;
}
public void Add(
PhysicalVirtualMemory owner,
long generation,
ulong start,
ulong end)
{
if (!ReferenceEquals(_owner, owner) || _generation != generation)
{
_owner = owner;
_generation = generation;
_count = 0;
_nextReplacement = 0;
}
for (var index = 0; index < _count; index++)
{
var range = _ranges[index];
if (start <= range.End && end >= range.Start)
{
_ranges[index] = new CommittedRange(
Math.Min(start, range.Start),
Math.Max(end, range.End));
return;
}
}
if (_count < _ranges.Length)
{
_ranges[_count++] = new CommittedRange(start, end);
return;
}
_ranges[_nextReplacement] = new CommittedRange(start, end);
_nextReplacement = (_nextReplacement + 1) % _ranges.Length;
}
}
private readonly record struct CommittedRange(ulong Start, ulong End);
// Raw Windows PAGE_* values retained for the internal region/protection
// bookkeeping: regions and saved old-protection values always carry the raw
// value of the host platform in use, and these classification helpers only
// ever see values this class itself assigned (see IHostMemory.ProtectRaw).
private const uint PAGE_EXECUTE_READ = 0x20;
private const uint PAGE_EXECUTE_READWRITE = 0x40;
private const uint PAGE_EXECUTE = 0x10;
private const uint PAGE_EXECUTE_WRITECOPY = 0x80;
private const uint PAGE_READWRITE = 0x04;
private const uint PAGE_READONLY = 0x02;
private readonly IHostMemory _hostMemory;
private ulong _guestAllocationArenaBase;
private readonly SortedDictionary<ulong, ulong> _guestAllocationFreeRanges = new();
private readonly Dictionary<ulong, (ulong Offset, ulong Size)> _guestAllocations = new();
private static readonly ulong LazyReservePrimeBytes = ResolveLazyReservePrimeBytes();
public PhysicalVirtualMemory(IHostMemory? hostMemory = null)
{
_hostMemory = hostMemory ?? CrossPlatformHostMemory.Instance;
}
private sealed class CrossPlatformHostMemory : IHostMemory
{
public static readonly CrossPlatformHostMemory Instance = new();
public ulong Allocate(ulong desiredAddress, ulong size, HostPageProtection protection) =>
unchecked((ulong)HostMemory.Alloc(
(void*)desiredAddress,
(nuint)size,
HostMemory.MEM_RESERVE | HostMemory.MEM_COMMIT,
ToRawProtection(protection)));
public ulong Reserve(ulong desiredAddress, ulong size, HostPageProtection protection) =>
unchecked((ulong)HostMemory.Alloc(
(void*)desiredAddress,
(nuint)size,
HostMemory.MEM_RESERVE,
ToRawProtection(protection)));
public bool Commit(ulong address, ulong size, HostPageProtection protection) =>
HostMemory.Alloc(
(void*)address,
(nuint)size,
HostMemory.MEM_COMMIT,
ToRawProtection(protection)) != null;
public bool Free(ulong address) =>
HostMemory.Free((void*)address, 0, HostMemory.MEM_RELEASE);
public bool Protect(
ulong address,
ulong size,
HostPageProtection protection,
out uint rawOldProtection) =>
HostMemory.Protect(
(void*)address,
(nuint)size,
ToRawProtection(protection),
out rawOldProtection);
public bool ProtectRaw(
ulong address,
ulong size,
uint rawProtection,
out uint rawOldProtection) =>
HostMemory.Protect((void*)address, (nuint)size, rawProtection, out rawOldProtection);
public bool Query(ulong address, out HostRegionInfo info)
{
if (HostMemory.Query((void*)address, out var raw) == 0)
{
info = default;
return false;
}
var state = raw.State switch
{
HostMemory.MEM_FREE_STATE => HostRegionState.Free,
HostMemory.MEM_RESERVE => HostRegionState.Reserved,
_ => HostRegionState.Committed,
};
info = new HostRegionInfo(
raw.BaseAddress,
raw.AllocationBase,
raw.RegionSize,
state,
raw.State,
FromRawProtection(raw.Protect),
raw.Protect,
raw.AllocationProtect);
return true;
}
public void FlushInstructionCache(ulong address, ulong size) =>
HostMemory.FlushInstructionCache((void*)address, (nuint)size);
private static uint ToRawProtection(HostPageProtection protection) => protection switch
{
HostPageProtection.NoAccess => HostMemory.PAGE_NOACCESS,
HostPageProtection.ReadOnly => HostMemory.PAGE_READONLY,
HostPageProtection.ReadWrite => HostMemory.PAGE_READWRITE,
HostPageProtection.Execute => HostMemory.PAGE_EXECUTE,
HostPageProtection.ReadExecute => HostMemory.PAGE_EXECUTE_READ,
HostPageProtection.ReadWriteExecute => HostMemory.PAGE_EXECUTE_READWRITE,
HostPageProtection.ExecuteWriteCopy => 0x80,
_ => HostMemory.PAGE_NOACCESS,
};
private static HostPageProtection FromRawProtection(uint protection) => protection switch
{
HostMemory.PAGE_READONLY => HostPageProtection.ReadOnly,
HostMemory.PAGE_READWRITE => HostPageProtection.ReadWrite,
HostMemory.PAGE_EXECUTE => HostPageProtection.Execute,
HostMemory.PAGE_EXECUTE_READ => HostPageProtection.ReadExecute,
HostMemory.PAGE_EXECUTE_READWRITE => HostPageProtection.ReadWriteExecute,
0x80 => HostPageProtection.ExecuteWriteCopy,
_ => HostPageProtection.NoAccess,
};
}
public bool TryAllocateAtExact(ulong desiredAddress, ulong size, bool executable, out ulong actualAddress)
{
actualAddress = 0;
if (size == 0)
{
return false;
}
var alignedSize = (size + 0xFFF) & ~0xFFFUL;
var protection = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
var hostProtection = executable ? HostPageProtection.ReadWriteExecute : HostPageProtection.ReadWrite;
var result = _hostMemory.Allocate(desiredAddress, alignedSize, hostProtection);
if (result == 0)
{
return false;
}
actualAddress = result;
if (actualAddress != desiredAddress)
{
_hostMemory.Free(result);
actualAddress = 0;
return false;
}
_gate.EnterWriteLock();
try
{
InsertRegionSorted(new MemoryRegion
{
VirtualAddress = actualAddress,
Size = alignedSize,
IsExecutable = executable,
IsReservedOnly = false,
Protection = protection
});
}
finally
{
_gate.ExitWriteLock();
}
var allocationKind = executable ? "executable memory" : "data memory";
TraceVmem($"Allocated exact {allocationKind}: 0x{actualAddress:X16} - 0x{actualAddress + alignedSize:X16} ({alignedSize} bytes)");
return true;
}
public string DescribeAddressForDiagnostics(ulong address)
{
if (!_hostMemory.Query(address, out var info))
{
return "unable to query host memory at this address";
}
return info.State switch
{
HostRegionState.Free => "address reports free, but the exact-address reservation still failed",
HostRegionState.Reserved =>
$"already reserved by another host allocation (base=0x{info.AllocationBase:X16}, size=0x{info.RegionSize:X})",
HostRegionState.Committed =>
$"already committed by another host allocation (base=0x{info.AllocationBase:X16}, size=0x{info.RegionSize:X}, protect=0x{info.RawProtection:X})",
_ => $"in an unexpected host state (raw=0x{info.RawState:X})",
};
}
public ulong AllocateAt(ulong desiredAddress, ulong size, bool executable = true, bool allowAlternative = true)
{
if (size == 0)
throw new ArgumentOutOfRangeException(nameof(size), "Size must be greater than zero");
var alignedSize = (size + 0xFFF) & ~0xFFFUL;
var protection = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
var hostProtection = executable ? HostPageProtection.ReadWriteExecute : HostPageProtection.ReadWrite;
var reservedOnly = false;
var preferReserveOnly = !executable &&
alignedSize >= LargeDataReserveThreshold &&
alignedSize > FullCommitRegionLimit;
ulong result = 0;
if (preferReserveOnly)
{
result = _hostMemory.Reserve(desiredAddress, alignedSize, HostPageProtection.ReadWrite);
if (result == 0 && allowAlternative)
{
result = _hostMemory.Reserve(0, alignedSize, HostPageProtection.ReadWrite);
}
if (result != 0)
{
reservedOnly = true;
}
}
if (result == 0)
{
result = _hostMemory.Allocate(desiredAddress, alignedSize, hostProtection);
}
if (result == 0)
{
if (!allowAlternative)
{
throw new InvalidOperationException($"Failed to allocate exact mapping at 0x{desiredAddress:X16} ({alignedSize} bytes)");
}
TraceVmem($"Could not allocate at 0x{desiredAddress:X16}, trying any address...");
result = _hostMemory.Allocate(0, alignedSize, hostProtection);
if (result == 0)
{
if (!executable)
{
result = _hostMemory.Reserve(desiredAddress, alignedSize, HostPageProtection.ReadWrite);
if (result == 0 && allowAlternative)
{
result = _hostMemory.Reserve(0, alignedSize, HostPageProtection.ReadWrite);
}
if (result != 0)
{
reservedOnly = true;
}
}
if (result == 0)
{
throw new OutOfMemoryException($"Failed to allocate {alignedSize} bytes of virtual memory");
}
}
}
var actualAddress = result;
var lazyPrimeState = "n/a";
if (reservedOnly)
{
var primeBytes = Math.Min(alignedSize, LazyReservePrimeBytes);
if (primeBytes != 0)
{
ulong committedBytes = 0;
while (committedBytes < primeBytes)
{
var remaining = primeBytes - committedBytes;
var chunkBytes = Math.Min(remaining, LazyReservePrimeChunkBytes);
var commitAddress = actualAddress + committedBytes;
if (!_hostMemory.Commit(commitAddress, chunkBytes, HostPageProtection.ReadWrite))
{
break;
}
committedBytes += chunkBytes;
}
if (committedBytes != 0)
{
lazyPrimeState = committedBytes == primeBytes
? $"ok:{committedBytes:X}"
: $"partial:{committedBytes:X}/{primeBytes:X}";
TraceVmem($"Primed lazy region: 0x{actualAddress:X16} - 0x{actualAddress + committedBytes:X16} ({committedBytes} bytes)");
}
else
{
lazyPrimeState = $"fail:{primeBytes:X}";
TraceVmem($"Failed to prime lazy region at 0x{actualAddress:X16} ({primeBytes} bytes), continuing with on-demand commit");
}
}
else
{
lazyPrimeState = "skip:0";
}
}
_gate.EnterWriteLock();
try
{
InsertRegionSorted(new MemoryRegion
{
VirtualAddress = actualAddress,
Size = alignedSize,
IsExecutable = executable,
IsReservedOnly = reservedOnly,
Protection = protection
});
}
finally
{
_gate.ExitWriteLock();
}
var allocationKind = reservedOnly
? "reserved data memory (lazy commit)"
: (executable ? "executable memory" : "data memory");
TraceVmem($"Allocated {allocationKind}: 0x{actualAddress:X16} - 0x{actualAddress + alignedSize:X16} ({alignedSize} bytes) lazy_prime={lazyPrimeState}");
return actualAddress;
}
public bool TryBackFixedRange(ulong address, ulong size, bool executable)
{
if (size == 0)
{
return false;
}
var start = AlignDown(address, PageSize);
var end = AlignUp(address + size, PageSize);
if (end <= start)
{
return false;
}
var hostProtection = executable ? HostPageProtection.ReadWriteExecute : HostPageProtection.ReadWrite;
// Walk the range page-run by page-run. VirtualQuery reports the largest run
// of same-state pages from the queried address, so a single query advances
// us over whole free or occupied stretches. Only free stretches get backed;
// stretches already reserved or committed by another allocation are left as
// they are, which is exactly what a fixed mapping does on hardware.
var cursor = start;
var backedAny = false;
while (cursor < end)
{
if (!_hostMemory.Query(cursor, out var info))
{
return false;
}
var queriedEnd = info.RegionSize > ulong.MaxValue - info.BaseAddress
? ulong.MaxValue
: info.BaseAddress + info.RegionSize;
var runEnd = Math.Min(end, queriedEnd);
if (runEnd <= cursor)
{
return false;
}
if (info.State == HostRegionState.Free)
{
var runSize = runEnd - cursor;
var allocated = _hostMemory.Allocate(cursor, runSize, hostProtection);
if (allocated != cursor)
{
if (allocated != 0)
{
_hostMemory.Free(allocated);
}
return false;
}
var protection = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
_gate.EnterWriteLock();
try
{
InsertRegionSorted(new MemoryRegion
{
VirtualAddress = cursor,
Size = runSize,
IsExecutable = executable,
IsReservedOnly = false,
Protection = protection
});
}
finally
{
_gate.ExitWriteLock();
}
TraceVmem($"Backed fixed range gap: 0x{cursor:X16} - 0x{runEnd:X16} ({runSize} bytes)");
backedAny = true;
}
cursor = runEnd;
}
return backedAny;
}
public bool TryAllocateAtOrAbove(
ulong desiredAddress,
ulong size,
bool executable,
ulong alignment,
out ulong actualAddress)
{
actualAddress = 0;
if (size == 0)
{
return false;
}
var alignedSize = AlignUp(size, PageSize);
var effectiveAlignment = Math.Max(PageSize, alignment == 0 ? PageSize : alignment);
var requestedCursor = AlignUp(desiredAddress, effectiveAlignment);
var cursor = GetAllocationSearchCursor(desiredAddress, requestedCursor, effectiveAlignment, executable);
// macOS needs alignment over-allocation; Linux uses exact-address search.
if (OperatingSystem.IsMacOS())
{
var reserveSize = effectiveAlignment > PageSize
? alignedSize + effectiveAlignment
: alignedSize;
try
{
var posixAddress = AllocateAt(cursor, reserveSize, executable, allowAlternative: true);
if (posixAddress != 0)
{
var alignedBase = AlignUp(posixAddress, effectiveAlignment);
if (alignedBase + alignedSize <= posixAddress + reserveSize)
{
actualAddress = alignedBase;
UpdateAllocationSearchCursor(desiredAddress, effectiveAlignment, executable, alignedBase + alignedSize);
return true;
}
ReleaseUntrackedAllocation(posixAddress);
}
}
catch
{
}
return false;
}
for (var attempt = 0; attempt < 0x10000; attempt++)
{
if (cursor == 0 || ulong.MaxValue - cursor < alignedSize)
{
return false;
}
if (TryGetOverlappingRegionEnd(cursor, alignedSize, out var overlapEnd))
{
cursor = AlignUp(overlapEnd, effectiveAlignment);
continue;
}
if (TryAllocateAtExact(cursor, alignedSize, executable, out actualAddress))
{
UpdateAllocationSearchCursor(desiredAddress, effectiveAlignment, executable, actualAddress + alignedSize);
return true;
}
cursor = AlignUp(cursor + effectiveAlignment, effectiveAlignment);
}
return false;
}
private void ReleaseUntrackedAllocation(ulong address)
{
_gate.EnterWriteLock();
try
{
for (var i = 0; i < _regions.Count; i++)
{
if (_regions[i].VirtualAddress == address)
{
_regions.RemoveAt(i);
break;
}
}
}
finally
{
_gate.ExitWriteLock();
}
Interlocked.Increment(ref _mappingGeneration);
_hostMemory.Free(address);
}
public bool TryAllocateGuestMemory(ulong size, ulong alignment, out ulong address)
{
address = 0;
if (size == 0 || alignment == 0 || (alignment & (alignment - 1)) != 0)
{
return false;
}
lock (_guestAllocationGate)
{
if (_guestAllocationArenaBase == 0)
{
try
{
_guestAllocationArenaBase = AllocateAt(
GuestAllocationArenaAddress,
GuestAllocationArenaSize,
executable: false,
allowAlternative: true);
_guestAllocationFreeRanges.Add(
GuestAllocationArenaStartOffset,
GuestAllocationArenaSize - GuestAllocationArenaStartOffset);
}
catch (Exception)
{
return false;
}
}
ulong rangeOffset = 0;
ulong rangeSize = 0;
ulong alignedOffset = 0;
var found = false;
foreach (var range in _guestAllocationFreeRanges)
{
alignedOffset = AlignUp(range.Key, alignment);
if (alignedOffset >= range.Key &&
alignedOffset - range.Key <= range.Value &&
size <= range.Value - (alignedOffset - range.Key))
{
rangeOffset = range.Key;
rangeSize = range.Value;
found = true;
break;
}
}
if (!found)
{
return false;
}
_guestAllocationFreeRanges.Remove(rangeOffset);
if (alignedOffset > rangeOffset)
{
_guestAllocationFreeRanges.Add(rangeOffset, alignedOffset - rangeOffset);
}
var allocationEnd = alignedOffset + size;
var rangeEnd = rangeOffset + rangeSize;
if (allocationEnd < rangeEnd)
{
_guestAllocationFreeRanges.Add(allocationEnd, rangeEnd - allocationEnd);
}
address = _guestAllocationArenaBase + alignedOffset;
_guestAllocations.Add(address, (alignedOffset, size));
return true;
}
}
public bool TryFreeGuestMemory(ulong address)
{
lock (_guestAllocationGate)
{
if (!_guestAllocations.Remove(address, out var allocation))
{
return false;
}
var freeOffset = allocation.Offset;
var freeSize = allocation.Size;
ulong? previousOffset = null;
ulong? nextOffset = null;
foreach (var range in _guestAllocationFreeRanges)
{
if (range.Key < freeOffset)
{
previousOffset = range.Key;
continue;
}
nextOffset = range.Key;
break;
}
if (previousOffset is { } previous &&
previous + _guestAllocationFreeRanges[previous] == freeOffset)
{
freeOffset = previous;
freeSize += _guestAllocationFreeRanges[previous];
_guestAllocationFreeRanges.Remove(previous);
}
if (nextOffset is { } next && freeOffset + freeSize == next)
{
freeSize += _guestAllocationFreeRanges[next];
_guestAllocationFreeRanges.Remove(next);
}
_guestAllocationFreeRanges.Add(freeOffset, freeSize);
return true;
}
}
public bool TryProtect(ulong address, ulong size, GuestPageProtection protection)
{
if (size == 0)
{
return false;
}
return _hostMemory.Protect(address, size, ResolveProtection(protection), out _);
}
// Reproduces the decomposition KernelMemoryCompatExports.ResolveHostProtection
// performed before this seam existed; the Windows backend maps each case back
// to the identical PAGE_* value.
private static HostPageProtection ResolveProtection(GuestPageProtection protection)
{
var read = (protection & GuestPageProtection.Read) != 0;
var write = (protection & GuestPageProtection.Write) != 0;
var execute = (protection & GuestPageProtection.Execute) != 0;
if (execute)
{
return write
? HostPageProtection.ReadWriteExecute
: read
? HostPageProtection.ReadExecute
: HostPageProtection.Execute;
}
return write
? HostPageProtection.ReadWrite
: read
? HostPageProtection.ReadOnly
: HostPageProtection.NoAccess;
}
public void Clear()
{
lock (_guestAllocationGate)
{
_gate.EnterWriteLock();
try
{
foreach (var region in _regions)
{
_hostMemory.Free(region.VirtualAddress);
}
_regions.Clear();
_pageProtections.Clear();
lock (_allocationSearchHintGate)
{
_allocationSearchHints.Clear();
}
Interlocked.Increment(ref _mappingGeneration);
}
finally
{
_gate.ExitWriteLock();
}
_guestAllocationArenaBase = 0;
_guestAllocationFreeRanges.Clear();
_guestAllocations.Clear();
}
}
public void Map(ulong virtualAddress, ulong memorySize, ulong fileOffset, ReadOnlySpan<byte> fileData, ProgramHeaderFlags protection)
{
if (memorySize == 0)
throw new ArgumentOutOfRangeException(nameof(memorySize));
if ((ulong)fileData.Length > memorySize)
throw new ArgumentOutOfRangeException(nameof(fileData), "File size cannot exceed memory size");
var mapStart = AlignDown(virtualAddress, PageSize);
var segmentEnd = checked(virtualAddress + memorySize);
var mapEnd = AlignUp(segmentEnd, PageSize);
var mapSize = checked(mapEnd - mapStart);
_gate.EnterWriteLock();
try
{
var existingRegion = FindRegion(mapStart, mapSize);
if (existingRegion == null)
{
var isExecutable = (protection & ProgramHeaderFlags.Execute) != 0;
AllocateAt(mapStart, mapSize, isExecutable, allowAlternative: false);
}
var stageProtection = (protection & ProgramHeaderFlags.Execute) != 0
? ProgramHeaderFlags.Read | ProgramHeaderFlags.Write | ProgramHeaderFlags.Execute
: ProgramHeaderFlags.Read | ProgramHeaderFlags.Write;
SetProtection(mapStart, mapSize, stageProtection);
if (!fileData.IsEmpty)
{
var destPtr = (void*)virtualAddress;
fixed (byte* srcPtr = fileData)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)memorySize, (nuint)fileData.Length);
}
}
var zeroFillSize = memorySize - (ulong)fileData.Length;
if (zeroFillSize != 0)
{
NativeMemory.Clear((void*)(virtualAddress + (ulong)fileData.Length), (nuint)zeroFillSize);
}
ApplySegmentProtection(mapStart, mapEnd, protection);
TraceVmem($"Mapped segment: 0x{virtualAddress:X16} - 0x{virtualAddress + memorySize:X16} (file: {fileData.Length} bytes, prot: {protection})");
}
finally
{
_gate.ExitWriteLock();
}
}
private void ApplySegmentProtection(ulong mapStart, ulong mapEnd, ProgramHeaderFlags flags)
{
var runStart = mapStart;
var runFlags = ProgramHeaderFlags.None;
var hasRun = false;
for (var pageAddress = mapStart; pageAddress < mapEnd; pageAddress += PageSize)
{
_pageProtections.TryGetValue(pageAddress, out var existingFlags);
var mergedFlags = existingFlags | flags;
_pageProtections[pageAddress] = mergedFlags;
if (!hasRun)
{
runStart = pageAddress;
runFlags = mergedFlags;
hasRun = true;
}
else if (mergedFlags != runFlags)
{
SetProtection(runStart, pageAddress - runStart, runFlags);
runStart = pageAddress;
runFlags = mergedFlags;
}
}
if (hasRun)
{
SetProtection(runStart, mapEnd - runStart, runFlags);
}
}
private void SetProtection(ulong address, ulong size, ProgramHeaderFlags flags)
{
HostPageProtection protection;
if (flags == ProgramHeaderFlags.None)
{
protection = HostPageProtection.NoAccess;
}
else if ((flags & ProgramHeaderFlags.Execute) != 0)
{
protection = (flags & ProgramHeaderFlags.Write) != 0
? HostPageProtection.ReadWriteExecute
: HostPageProtection.ReadExecute;
}
else if ((flags & ProgramHeaderFlags.Write) != 0)
{
protection = HostPageProtection.ReadWrite;
}
else
{
protection = HostPageProtection.ReadOnly;
}
if (!_hostMemory.Protect(address, size, protection, out _))
{
throw new InvalidOperationException($"Failed to set memory protection at 0x{address:X16}");
}
if ((flags & ProgramHeaderFlags.Execute) != 0)
{
_hostMemory.FlushInstructionCache(address, size);
}
}
public IReadOnlyList<VirtualMemoryRegion> SnapshotRegions()
{
_gate.EnterReadLock();
try
{
var snapshot = new VirtualMemoryRegion[_regions.Count];
for (var i = 0; i < _regions.Count; i++)
{
var r = _regions[i];
snapshot[i] = new VirtualMemoryRegion(
r.VirtualAddress,
r.Size,
0,
r.Size,
r.IsExecutable ? ProgramHeaderFlags.Execute | ProgramHeaderFlags.Read : ProgramHeaderFlags.Read);
}
return snapshot;
}
finally
{
_gate.ExitReadLock();
}
}
public bool TryRead(ulong virtualAddress, Span<byte> destination)
{
var requiresExclusiveAccess = false;
_gate.EnterReadLock();
try
{
var region = FindRegion(virtualAddress, (ulong)destination.Length);
if (region is not null &&
TryResolveRegionOffset(
virtualAddress,
(ulong)destination.Length,
region,
out var offset))
{
var srcPtr = (void*)(region.VirtualAddress + offset);
if (destination.IsEmpty)
{
return true;
}
if (region.IsReservedOnly)
{
if (!EnsureRangeCommitted((ulong)srcPtr, (ulong)destination.Length, region))
{
return false;
}
}
if (!CanReadWithoutProtectionChange((ulong)srcPtr, (ulong)destination.Length, region))
{
requiresExclusiveAccess = true;
}
else
{
fixed (byte* destPtr = destination)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)destination.Length, (nuint)destination.Length);
}
return true;
}
}
}
finally
{
_gate.ExitReadLock();
}
if (!requiresExclusiveAccess)
{
return false;
}
_gate.EnterWriteLock();
try
{
return TryReadExclusive(virtualAddress, destination);
}
finally
{
_gate.ExitWriteLock();
}
}
public bool TryCompare(ulong virtualAddress, ReadOnlySpan<byte> expected)
{
_gate.EnterReadLock();
try
{
var region = FindRegion(virtualAddress, (ulong)expected.Length);
if (region is null ||
!TryResolveRegionOffset(
virtualAddress,
(ulong)expected.Length,
region,
out var offset))
{
return false;
}
if (expected.IsEmpty)
{
return true;
}
var srcPtr = (void*)(region.VirtualAddress + offset);
if (region.IsReservedOnly &&
!EnsureRangeCommitted((ulong)srcPtr, (ulong)expected.Length, region))
{
return false;
}
if (!CanReadWithoutProtectionChange((ulong)srcPtr, (ulong)expected.Length, region))
{
return false;
}
return new ReadOnlySpan<byte>(srcPtr, expected.Length).SequenceEqual(expected);
}
finally
{
_gate.ExitReadLock();
}
}
public bool TryWrite(ulong virtualAddress, ReadOnlySpan<byte> source)
{
// A managed write into a page the guest-image write tracker has
// protected surfaces as a fatal AccessViolation — the runtime turns
// SIGSEGV in managed code into an exception before the resumable
// signal bridge can restore access (native guest stores recover
// there). Pre-visit the span so tracked pages are unprotected and
// their owners dirtied before the copy; guest addresses are
// host-identical, matching the tracker's fault addresses.
GuestImageWriteTracker.NotifyManagedWrite(virtualAddress, (ulong)source.Length);
var requiresExclusiveAccess = false;
_gate.EnterReadLock();
try
{
var region = FindRegion(virtualAddress, (ulong)source.Length);
if (region is not null &&
TryResolveRegionOffset(
virtualAddress,
(ulong)source.Length,
region,
out var offset))
{
var destPtr = (void*)(region.VirtualAddress + offset);
if (source.IsEmpty)
{
return true;
}
if (region.IsReservedOnly)
{
if (!EnsureRangeCommitted((ulong)destPtr, (ulong)source.Length, region))
{
return false;
}
}
if (!CanWriteWithoutProtectionChange((ulong)destPtr, (ulong)source.Length, region))
{
requiresExclusiveAccess = true;
}
else
{
fixed (byte* srcPtr = source)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)source.Length, (nuint)source.Length);
}
NotifyGuestWriteWatch(virtualAddress, source);
return true;
}
}
}
finally
{
_gate.ExitReadLock();
}
if (!requiresExclusiveAccess)
{
return false;
}
_gate.EnterWriteLock();
try
{
return TryWriteExclusive(virtualAddress, source);
}
finally
{
_gate.ExitWriteLock();
}
}
private static void NotifyGuestWriteWatch(ulong virtualAddress, ReadOnlySpan<byte> source)
{
if (GuestWriteWatch.Armed)
{
GuestWriteWatch.Check(virtualAddress, source);
}
}
public bool TryCopy(ulong destinationAddress, ulong sourceAddress, ulong length)
{
if (length == 0)
{
return true;
}
if (length > int.MaxValue)
{
return false;
}
// Match TryWrite's managed-write notification before touching an
// identity-mapped guest page protected by the image tracker.
GuestImageWriteTracker.NotifyManagedWrite(destinationAddress, length);
_gate.EnterReadLock();
try
{
var sourceRegion = FindRegion(sourceAddress, length);
var destinationRegion = FindRegion(destinationAddress, length);
if (sourceRegion is null || destinationRegion is null ||
!TryResolveRegionOffset(sourceAddress, length, sourceRegion, out var sourceOffset) ||
!TryResolveRegionOffset(destinationAddress, length, destinationRegion, out var destinationOffset))
{
return false;
}
var sourcePointer = sourceRegion.VirtualAddress + sourceOffset;
var destinationPointer = destinationRegion.VirtualAddress + destinationOffset;
if ((sourceRegion.IsReservedOnly &&
!EnsureRangeCommitted(sourcePointer, length, sourceRegion)) ||
(destinationRegion.IsReservedOnly &&
!EnsureRangeCommitted(destinationPointer, length, destinationRegion)) ||
!CanReadWithoutProtectionChange(sourcePointer, length, sourceRegion) ||
!CanWriteWithoutProtectionChange(destinationPointer, length, destinationRegion))
{
return false;
}
// Span.CopyTo has memmove overlap semantics, so this allocation-free
// path safely serves both libc memcpy and libc memmove.
new ReadOnlySpan<byte>((void*)sourcePointer, checked((int)length)).CopyTo(
new Span<byte>((void*)destinationPointer, checked((int)length)));
NotifyGuestWriteWatch(
destinationAddress,
new ReadOnlySpan<byte>((void*)destinationPointer, checked((int)length)));
return true;
}
finally
{
_gate.ExitReadLock();
}
}
private bool TryReadExclusive(ulong virtualAddress, Span<byte> destination)
{
var region = FindRegion(virtualAddress, (ulong)destination.Length);
if (region is not null &&
TryResolveRegionOffset(
virtualAddress,
(ulong)destination.Length,
region,
out var offset))
{
var srcPtr = (void*)(region.VirtualAddress + offset);
if (!EnsureRangeCommitted((ulong)srcPtr, (ulong)destination.Length, region))
{
return false;
}
if (CanReadWithoutProtectionChange((ulong)srcPtr, (ulong)destination.Length, region))
{
fixed (byte* destPtr = destination)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)destination.Length, (nuint)destination.Length);
}
return true;
}
if (!TryTemporarilyProtectForRead((ulong)srcPtr, (ulong)destination.Length, region, out var touchedPages))
{
return false;
}
try
{
fixed (byte* destPtr = destination)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)destination.Length, (nuint)destination.Length);
}
}
finally
{
RestorePageProtections(touchedPages);
}
return true;
}
return false;
}
private bool TryWriteExclusive(ulong virtualAddress, ReadOnlySpan<byte> source)
{
var region = FindRegion(virtualAddress, (ulong)source.Length);
if (region is not null &&
TryResolveRegionOffset(
virtualAddress,
(ulong)source.Length,
region,
out var offset))
{
var destPtr = (void*)(region.VirtualAddress + offset);
if (!EnsureRangeCommitted((ulong)destPtr, (ulong)source.Length, region))
{
return false;
}
if (CanWriteWithoutProtectionChange((ulong)destPtr, (ulong)source.Length, region))
{
fixed (byte* srcPtr = source)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)source.Length, (nuint)source.Length);
}
NotifyGuestWriteWatch(virtualAddress, source);
return true;
}
if (!_hostMemory.Protect((ulong)destPtr, (ulong)source.Length, HostPageProtection.ReadWriteExecute, out var oldProtect))
{
return false;
}
try
{
fixed (byte* srcPtr = source)
{
Buffer.MemoryCopy(srcPtr, destPtr, (nuint)source.Length, (nuint)source.Length);
}
}
finally
{
_hostMemory.ProtectRaw((ulong)destPtr, (ulong)source.Length, oldProtect, out _);
if (IsExecutableProtection(oldProtect))
{
_hostMemory.FlushInstructionCache((ulong)destPtr, (ulong)source.Length);
}
}
NotifyGuestWriteWatch(virtualAddress, source);
return true;
}
return false;
}
public bool TryWriteUInt64(ulong virtualAddress, ulong value)
{
Span<byte> buffer = stackalloc byte[sizeof(ulong)];
BitConverter.TryWriteBytes(buffer, value);
return TryWrite(virtualAddress, buffer);
}
public void* GetPointer(ulong virtualAddress)
{
_gate.EnterReadLock();
try
{
var region = FindRegion(virtualAddress, 1);
if (region is null ||
(region.IsReservedOnly && !EnsureRangeCommitted(virtualAddress, 1, region)))
{
return null;
}
return (void*)virtualAddress;
}
finally
{
_gate.ExitReadLock();
}
}
public bool IsAccessible(ulong virtualAddress, ulong size)
{
_gate.EnterReadLock();
try
{
return FindRegion(virtualAddress, size) is not null;
}
finally
{
_gate.ExitReadLock();
}
}
private MemoryRegion? FindRegion(ulong address, ulong size)
{
var low = 0;
var high = _regions.Count - 1;
MemoryRegion? candidate = null;
while (low <= high)
{
var middle = low + ((high - low) >> 1);
var region = _regions[middle];
if (region.VirtualAddress <= address)
{
candidate = region;
low = middle + 1;
}
else
{
high = middle - 1;
}
}
return candidate is not null &&
TryResolveRegionOffset(address, size, candidate, out _)
? candidate
: null;
}
private void InsertRegionSorted(MemoryRegion region)
{
var low = 0;
var high = _regions.Count;
while (low < high)
{
var middle = low + ((high - low) >> 1);
if (_regions[middle].VirtualAddress < region.VirtualAddress)
{
low = middle + 1;
}
else
{
high = middle;
}
}
_regions.Insert(low, region);
}
private bool TryGetOverlappingRegionEnd(ulong address, ulong size, out ulong overlapEnd)
{
overlapEnd = 0;
if (size == 0 || ulong.MaxValue - address < size - 1)
{
return false;
}
var end = address + size;
_gate.EnterReadLock();
try
{
foreach (var region in _regions)
{
var regionEnd = region.VirtualAddress + region.Size;
if (region.VirtualAddress >= end)
{
break;
}
if (regionEnd <= address)
{
continue;
}
if (address < regionEnd && region.VirtualAddress < end)
{
overlapEnd = Math.Max(overlapEnd, regionEnd);
}
}
}
finally
{
_gate.ExitReadLock();
}
return overlapEnd != 0;
}
private ulong GetAllocationSearchCursor(
ulong desiredAddress,
ulong requestedCursor,
ulong alignment,
bool executable)
{
lock (_allocationSearchHintGate)
{
var key = (desiredAddress, alignment, executable);
if (_allocationSearchHints.TryGetValue(key, out var hintedCursor) &&
hintedCursor > requestedCursor)
{
return AlignUp(hintedCursor, alignment);
}
}
return requestedCursor;
}
private void UpdateAllocationSearchCursor(
ulong desiredAddress,
ulong alignment,
bool executable,
ulong nextCursor)
{
lock (_allocationSearchHintGate)
{
_allocationSearchHints[(desiredAddress, alignment, executable)] = AlignUp(nextCursor, alignment);
}
}
private static bool TryResolveRegionOffset(ulong address, ulong size, MemoryRegion region, out ulong offset)
{
offset = 0;
if (address < region.VirtualAddress)
{
return false;
}
offset = address - region.VirtualAddress;
if (offset > region.Size)
{
return false;
}
if (size > region.Size - offset)
{
return false;
}
return true;
}
private static bool IsExecutableProtection(uint protection)
{
return protection is PAGE_EXECUTE or PAGE_EXECUTE_READ or PAGE_EXECUTE_READWRITE or PAGE_EXECUTE_WRITECOPY;
}
private bool CanReadWithoutProtectionChange(ulong address, ulong size, MemoryRegion region) =>
CanAccessWithoutProtectionChange(address, size, region, write: false);
private bool CanWriteWithoutProtectionChange(ulong address, ulong size, MemoryRegion region) =>
CanAccessWithoutProtectionChange(address, size, region, write: true);
private bool CanAccessWithoutProtectionChange(ulong address, ulong size, MemoryRegion region, bool write)
{
var startPage = AlignDown(address, PageSize);
var endPage = AlignUp(address + size, PageSize);
for (var pageAddress = startPage; pageAddress < endPage; pageAddress += PageSize)
{
if (_pageProtections.TryGetValue(pageAddress, out var flags))
{
if (write ? (flags & ProgramHeaderFlags.Write) == 0 : (flags & ProgramHeaderFlags.Read) == 0)
{
return false;
}
}
else if (write ? !IsWritableProtection(region.Protection) : !IsReadableProtection(region.Protection))
{
return false;
}
}
return true;
}
private static bool IsReadableProtection(uint protection)
{
return protection is PAGE_READONLY or PAGE_READWRITE or PAGE_EXECUTE_READ or PAGE_EXECUTE_READWRITE;
}
private static bool IsWritableProtection(uint protection)
{
return protection is PAGE_READWRITE or PAGE_EXECUTE_READWRITE;
}
private static HostPageProtection GetCommitProtection(MemoryRegion region)
{
return region.IsExecutable ? HostPageProtection.ReadWriteExecute : HostPageProtection.ReadWrite;
}
private bool EnsureRangeCommitted(ulong address, ulong size, MemoryRegion region)
{
if (size == 0 || !region.IsReservedOnly)
{
return true;
}
var startPage = AlignDown(address, PageSize);
var endPage = AlignUp(address + size, PageSize);
var mappingGeneration = Volatile.Read(ref _mappingGeneration);
var committedRangeCache = _committedRangeCache ??= new CommittedRangeCache();
if (committedRangeCache.Contains(this, mappingGeneration, startPage, endPage))
{
return true;
}
var commitProtection = GetCommitProtection(region);
var pageAddress = startPage;
while (pageAddress < endPage)
{
if (!_hostMemory.Query(pageAddress, out var info))
{
return false;
}
var queriedEnd = info.RegionSize > ulong.MaxValue - info.BaseAddress
? ulong.MaxValue
: info.BaseAddress + info.RegionSize;
var rangeEnd = Math.Min(endPage, queriedEnd);
if (rangeEnd <= pageAddress)
{
return false;
}
if (info.State == HostRegionState.Committed)
{
// The host query proved this whole range is committed. Retain
// that result instead of caching only the caller's small span.
CacheCommittedRange(info.BaseAddress, queriedEnd, mappingGeneration);
pageAddress = rangeEnd;
continue;
}
if (info.State != HostRegionState.Reserved)
{
return false;
}
var commitSize = rangeEnd - pageAddress;
if (!_hostMemory.Commit(pageAddress, commitSize, commitProtection))
{
return false;
}
CacheCommittedRange(pageAddress, rangeEnd, mappingGeneration);
pageAddress = rangeEnd;
}
CacheCommittedRange(startPage, endPage, mappingGeneration);
return true;
}
private void CacheCommittedRange(ulong startPage, ulong endPage, long mappingGeneration)
{
(_committedRangeCache ??= new CommittedRangeCache()).Add(
this,
mappingGeneration,
startPage,
endPage);
}
private bool TryTemporarilyProtectForRead(
ulong address,
ulong size,
MemoryRegion region,
out List<(ulong Address, uint Protection)> touchedPages)
{
touchedPages = new List<(ulong Address, uint Protection)>();
var startPage = AlignDown(address, PageSize);
var endPage = AlignUp(address + size, PageSize);
var temporaryProtection = region.IsExecutable ? HostPageProtection.ReadWriteExecute : HostPageProtection.ReadWrite;
for (var pageAddress = startPage; pageAddress < endPage; pageAddress += PageSize)
{
if (!_hostMemory.Protect(pageAddress, PageSize, temporaryProtection, out var oldProtection))
{
RestorePageProtections(touchedPages);
touchedPages.Clear();
return false;
}
touchedPages.Add((pageAddress, oldProtection));
}
return true;
}
private void RestorePageProtections(List<(ulong Address, uint Protection)> touchedPages)
{
foreach (var (pageAddress, protection) in touchedPages)
{
_hostMemory.ProtectRaw(pageAddress, PageSize, protection, out _);
}
}
private static ulong AlignDown(ulong value, ulong alignment)
{
var mask = alignment - 1;
return value & ~mask;
}
private static ulong AlignUp(ulong value, ulong alignment)
{
var mask = alignment - 1;
return checked((value + mask) & ~mask);
}
private static ulong ResolveLazyReservePrimeBytes()
{
var configured = Environment.GetEnvironmentVariable("SHARPEMU_LAZY_RESERVE_PRIME_MB");
if (ulong.TryParse(configured, out var megabytes))
{
return megabytes == 0
? 0
: checked(Math.Min(megabytes, 4096UL) * 1024UL * 1024UL);
}
return DefaultLazyReservePrimeBytes;
}
private static void TraceVmem(string message)
{
if (!string.Equals(Environment.GetEnvironmentVariable("SHARPEMU_LOG_VMEM"), "1", StringComparison.Ordinal))
{
return;
}
Log.Debug(message);
}
public void Dispose()
{
if (!_disposed)
{
Clear();
_disposed = true;
}
}
private class MemoryRegion
{
public ulong VirtualAddress { get; set; }
public ulong Size { get; set; }
public bool IsExecutable { get; set; }
public bool IsReservedOnly { get; set; }
public uint Protection { get; set; }
}
}