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fix(memory): reserve only large regions (#608)

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* fix(memory): reserve only large regions

* Potential fix for pull request finding
This commit is contained in:
Andrew
2026-07-25 07:25:53 -04:00
committed by GitHub
parent 5b602c0232
commit 8f9456229a
1 changed files with 49 additions and 40 deletions
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src/SharpEmu.Core/Memory/PhysicalVirtualMemory.cs
+49 -40
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@@ -238,7 +238,15 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
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);
// Reserve address space only for very large non-executable regions; commit is done lazily later.
var reservedOnly = !executable &&
alignedSize >= LargeDataReserveThreshold &&
alignedSize > FullCommitRegionLimit;
var result = reservedOnly
? _hostMemory.Reserve(desiredAddress, alignedSize, HostPageProtection.ReadWrite)
: _hostMemory.Allocate(desiredAddress, alignedSize, hostProtection);
if (result == 0)
{
return false;
@@ -252,6 +260,8 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
return false;
}
var state = reservedOnly ? ReserveRegion(actualAddress, alignedSize) : "n/a";
_gate.EnterWriteLock();
try
{
@@ -260,7 +270,7 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
VirtualAddress = actualAddress,
Size = alignedSize,
IsExecutable = executable,
IsReservedOnly = false,
IsReservedOnly = reservedOnly,
Protection = protection
});
}
@@ -269,6 +279,7 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
_gate.ExitWriteLock();
}
var allocationKind = executable ? "executable memory" : "data memory";
TraceVmem($"Allocated exact {allocationKind}: 0x{actualAddress:X16} - 0x{actualAddress + alignedSize:X16} ({alignedSize} bytes)");
return true;
@@ -361,44 +372,7 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
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";
}
}
var lazyPrimeState = reservedOnly ? ReserveRegion(actualAddress, alignedSize) : "n/a";
_gate.EnterWriteLock();
try
@@ -425,6 +399,41 @@ public sealed unsafe class PhysicalVirtualMemory : IVirtualMemory, IGuestMemoryA
return actualAddress;
}
private string ReserveRegion(ulong actualAddress, ulong alignedSize)
{
var primeBytes = Math.Min(alignedSize, LazyReservePrimeBytes);
if (primeBytes == 0)
{
return "skip: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)
{
var state = committedBytes == primeBytes
? $"ok:{committedBytes:X}"
: $"partial:{committedBytes:X}/{primeBytes:X}";
TraceVmem($"region: 0x{actualAddress:X16} - 0x{actualAddress + committedBytes:X16} ({committedBytes} bytes)");
return state;
}
TraceVmem($"Failed to reserve region at 0x{actualAddress:X16} ({primeBytes} bytes)!");
return $"fail:{primeBytes:X}";
}
public bool TryBackFixedRange(ulong address, ulong size, bool executable)
{
if (size == 0)