ryujinx/Ryujinx.Memory/WindowsShared/PlaceholderManager.cs

636 lines
25 KiB
C#
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using System;
using System.Diagnostics;
using System.Runtime.Versioning;
using System.Threading;
namespace Ryujinx.Memory.WindowsShared
{
/// <summary>
/// Windows memory placeholder manager.
/// </summary>
[SupportedOSPlatform("windows")]
class PlaceholderManager
{
private const ulong MinimumPageSize = 0x1000;
[ThreadStatic]
private static int _threadLocalPartialUnmapsCount;
private readonly IntervalTree<ulong, ulong> _mappings;
private readonly IntervalTree<ulong, MemoryPermission> _protections;
private readonly ReaderWriterLock _partialUnmapLock;
private int _partialUnmapsCount;
/// <summary>
/// Creates a new instance of the Windows memory placeholder manager.
/// </summary>
public PlaceholderManager()
{
_mappings = new IntervalTree<ulong, ulong>();
_protections = new IntervalTree<ulong, MemoryPermission>();
_partialUnmapLock = new ReaderWriterLock();
}
/// <summary>
/// Reserves a range of the address space to be later mapped as shared memory views.
/// </summary>
/// <param name="address">Start address of the region to reserve</param>
/// <param name="size">Size in bytes of the region to reserve</param>
public void ReserveRange(ulong address, ulong size)
{
lock (_mappings)
{
_mappings.Add(address, address + size, ulong.MaxValue);
}
}
/// <summary>
/// Maps a shared memory view on a previously reserved memory region.
/// </summary>
/// <param name="sharedMemory">Shared memory that will be the backing storage for the view</param>
/// <param name="srcOffset">Offset in the shared memory to map</param>
/// <param name="location">Address to map the view into</param>
/// <param name="size">Size of the view in bytes</param>
public void MapView(IntPtr sharedMemory, ulong srcOffset, IntPtr location, IntPtr size)
{
_partialUnmapLock.AcquireReaderLock(Timeout.Infinite);
try
{
UnmapViewInternal(sharedMemory, location, size);
MapViewInternal(sharedMemory, srcOffset, location, size);
}
finally
{
_partialUnmapLock.ReleaseReaderLock();
}
}
/// <summary>
/// Maps a shared memory view on a previously reserved memory region.
/// </summary>
/// <param name="sharedMemory">Shared memory that will be the backing storage for the view</param>
/// <param name="srcOffset">Offset in the shared memory to map</param>
/// <param name="location">Address to map the view into</param>
/// <param name="size">Size of the view in bytes</param>
/// <exception cref="WindowsApiException">Thrown when the Windows API returns an error mapping the memory</exception>
private void MapViewInternal(IntPtr sharedMemory, ulong srcOffset, IntPtr location, IntPtr size)
{
SplitForMap((ulong)location, (ulong)size, srcOffset);
var ptr = WindowsApi.MapViewOfFile3(
sharedMemory,
WindowsApi.CurrentProcessHandle,
location,
srcOffset,
size,
0x4000,
MemoryProtection.ReadWrite,
IntPtr.Zero,
0);
if (ptr == IntPtr.Zero)
{
throw new WindowsApiException("MapViewOfFile3");
}
}
/// <summary>
/// Splits a larger placeholder, slicing at the start and end address, for a new memory mapping.
/// </summary>
/// <param name="address">Address to split</param>
/// <param name="size">Size of the new region</param>
/// <param name="backingOffset">Offset in the shared memory that will be mapped</param>
private void SplitForMap(ulong address, ulong size, ulong backingOffset)
{
ulong endAddress = address + size;
var overlaps = Array.Empty<IntervalTreeNode<ulong, ulong>>();
lock (_mappings)
{
int count = _mappings.Get(address, endAddress, ref overlaps);
Debug.Assert(count == 1);
Debug.Assert(!IsMapped(overlaps[0].Value));
var overlap = overlaps[0];
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong overlapStart = overlap.Start;
ulong overlapEnd = overlap.End;
ulong overlapValue = overlap.Value;
_mappings.Remove(overlap);
bool overlapStartsBefore = overlapStart < address;
bool overlapEndsAfter = overlapEnd > endAddress;
if (overlapStartsBefore && overlapEndsAfter)
{
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)size,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(overlapStart, address, overlapValue);
_mappings.Add(endAddress, overlapEnd, AddBackingOffset(overlapValue, endAddress - overlapStart));
}
else if (overlapStartsBefore)
{
ulong overlappedSize = overlapEnd - address;
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)overlappedSize,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(overlapStart, address, overlapValue);
}
else if (overlapEndsAfter)
{
ulong overlappedSize = endAddress - overlapStart;
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)overlapStart,
(IntPtr)overlappedSize,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(endAddress, overlapEnd, AddBackingOffset(overlapValue, overlappedSize));
}
_mappings.Add(address, endAddress, backingOffset);
}
}
/// <summary>
/// Unmaps a view that has been previously mapped with <see cref="MapView"/>.
/// </summary>
/// <remarks>
/// For "partial unmaps" (when not the entire mapped range is being unmapped), it might be
/// necessary to unmap the whole range and then remap the sub-ranges that should remain mapped.
/// </remarks>
/// <param name="sharedMemory">Shared memory that the view being unmapped belongs to</param>
/// <param name="location">Address to unmap</param>
/// <param name="size">Size of the region to unmap in bytes</param>
public void UnmapView(IntPtr sharedMemory, IntPtr location, IntPtr size)
{
_partialUnmapLock.AcquireReaderLock(Timeout.Infinite);
try
{
UnmapViewInternal(sharedMemory, location, size);
}
finally
{
_partialUnmapLock.ReleaseReaderLock();
}
}
/// <summary>
/// Unmaps a view that has been previously mapped with <see cref="MapView"/>.
/// </summary>
/// <remarks>
/// For "partial unmaps" (when not the entire mapped range is being unmapped), it might be
/// necessary to unmap the whole range and then remap the sub-ranges that should remain mapped.
/// </remarks>
/// <param name="sharedMemory">Shared memory that the view being unmapped belongs to</param>
/// <param name="location">Address to unmap</param>
/// <param name="size">Size of the region to unmap in bytes</param>
/// <exception cref="WindowsApiException">Thrown when the Windows API returns an error unmapping or remapping the memory</exception>
private void UnmapViewInternal(IntPtr sharedMemory, IntPtr location, IntPtr size)
{
ulong startAddress = (ulong)location;
ulong unmapSize = (ulong)size;
ulong endAddress = startAddress + unmapSize;
var overlaps = Array.Empty<IntervalTreeNode<ulong, ulong>>();
int count;
lock (_mappings)
{
count = _mappings.Get(startAddress, endAddress, ref overlaps);
}
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
if (IsMapped(overlap.Value))
{
if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
{
throw new WindowsApiException("UnmapViewOfFile2");
}
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong overlapStart = overlap.Start;
ulong overlapEnd = overlap.End;
ulong overlapValue = overlap.Value;
lock (_mappings)
{
_mappings.Remove(overlap);
_mappings.Add(overlapStart, overlapEnd, ulong.MaxValue);
}
bool overlapStartsBefore = overlapStart < startAddress;
bool overlapEndsAfter = overlapEnd > endAddress;
if (overlapStartsBefore || overlapEndsAfter)
{
// If the overlap extends beyond the region we are unmapping,
// then we need to re-map the regions that are supposed to remain mapped.
// This is necessary because Windows does not support partial view unmaps.
// That is, you can only fully unmap a view that was previously mapped, you can't just unmap a chunck of it.
LockCookie lockCookie = _partialUnmapLock.UpgradeToWriterLock(Timeout.Infinite);
_partialUnmapsCount++;
if (overlapStartsBefore)
{
ulong remapSize = startAddress - overlapStart;
MapViewInternal(sharedMemory, overlapValue, (IntPtr)overlapStart, (IntPtr)remapSize);
RestoreRangeProtection(overlapStart, remapSize);
}
if (overlapEndsAfter)
{
ulong overlappedSize = endAddress - overlapStart;
ulong remapBackingOffset = overlapValue + overlappedSize;
ulong remapAddress = overlapStart + overlappedSize;
ulong remapSize = overlapEnd - endAddress;
MapViewInternal(sharedMemory, remapBackingOffset, (IntPtr)remapAddress, (IntPtr)remapSize);
RestoreRangeProtection(remapAddress, remapSize);
}
_partialUnmapLock.DowngradeFromWriterLock(ref lockCookie);
}
}
}
CoalesceForUnmap(startAddress, unmapSize);
RemoveProtection(startAddress, unmapSize);
}
/// <summary>
/// Coalesces adjacent placeholders after unmap.
/// </summary>
/// <param name="address">Address of the region that was unmapped</param>
/// <param name="size">Size of the region that was unmapped in bytes</param>
private void CoalesceForUnmap(ulong address, ulong size)
{
ulong endAddress = address + size;
var overlaps = Array.Empty<IntervalTreeNode<ulong, ulong>>();
int unmappedCount = 0;
lock (_mappings)
{
int count = _mappings.Get(address - MinimumPageSize, endAddress + MinimumPageSize, ref overlaps);
if (count < 2)
{
// Nothing to coalesce if we only have 1 or no overlaps.
return;
}
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
if (!IsMapped(overlap.Value))
{
if (address > overlap.Start)
{
address = overlap.Start;
}
if (endAddress < overlap.End)
{
endAddress = overlap.End;
}
_mappings.Remove(overlap);
unmappedCount++;
}
}
_mappings.Add(address, endAddress, ulong.MaxValue);
}
if (unmappedCount > 1)
{
size = endAddress - address;
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)size,
AllocationType.Release | AllocationType.CoalescePlaceholders));
}
}
/// <summary>
/// Reprotects a region of memory that has been mapped.
/// </summary>
/// <param name="address">Address of the region to reprotect</param>
/// <param name="size">Size of the region to reprotect in bytes</param>
/// <param name="permission">New permissions</param>
/// <returns>True if the reprotection was successful, false otherwise</returns>
public bool ReprotectView(IntPtr address, IntPtr size, MemoryPermission permission)
{
_partialUnmapLock.AcquireReaderLock(Timeout.Infinite);
try
{
return ReprotectViewInternal(address, size, permission, false);
}
finally
{
_partialUnmapLock.ReleaseReaderLock();
}
}
/// <summary>
/// Reprotects a region of memory that has been mapped.
/// </summary>
/// <param name="address">Address of the region to reprotect</param>
/// <param name="size">Size of the region to reprotect in bytes</param>
/// <param name="permission">New permissions</param>
/// <param name="throwOnError">Throw an exception instead of returning an error if the operation fails</param>
/// <returns>True if the reprotection was successful or if <paramref name="throwOnError"/> is true, false otherwise</returns>
/// <exception cref="WindowsApiException">If <paramref name="throwOnError"/> is true, it is thrown when the Windows API returns an error reprotecting the memory</exception>
private bool ReprotectViewInternal(IntPtr address, IntPtr size, MemoryPermission permission, bool throwOnError)
{
ulong reprotectAddress = (ulong)address;
ulong reprotectSize = (ulong)size;
ulong endAddress = reprotectAddress + reprotectSize;
var overlaps = Array.Empty<IntervalTreeNode<ulong, ulong>>();
int count;
lock (_mappings)
{
count = _mappings.Get(reprotectAddress, endAddress, ref overlaps);
}
bool success = true;
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
ulong mappedAddress = overlap.Start;
ulong mappedSize = overlap.End - overlap.Start;
if (mappedAddress < reprotectAddress)
{
ulong delta = reprotectAddress - mappedAddress;
mappedAddress = reprotectAddress;
mappedSize -= delta;
}
ulong mappedEndAddress = mappedAddress + mappedSize;
if (mappedEndAddress > endAddress)
{
ulong delta = mappedEndAddress - endAddress;
mappedSize -= delta;
}
if (!WindowsApi.VirtualProtect((IntPtr)mappedAddress, (IntPtr)mappedSize, WindowsApi.GetProtection(permission), out _))
{
if (throwOnError)
{
throw new WindowsApiException("VirtualProtect");
}
success = false;
}
// We only keep track of "non-standard" protections,
// that is, everything that is not just RW (which is the default when views are mapped).
if (permission == MemoryPermission.ReadAndWrite)
{
RemoveProtection(mappedAddress, mappedSize);
}
else
{
AddProtection(mappedAddress, mappedSize, permission);
}
}
return success;
}
/// <summary>
/// Checks the result of a VirtualFree operation, throwing if needed.
/// </summary>
/// <param name="success">Operation result</param>
/// <exception cref="WindowsApiException">Thrown if <paramref name="success"/> is false</exception>
private static void CheckFreeResult(bool success)
{
if (!success)
{
throw new WindowsApiException("VirtualFree");
}
}
/// <summary>
/// Adds an offset to a backing offset. This will do nothing if the backing offset is the special "unmapped" value.
/// </summary>
/// <param name="backingOffset">Backing offset</param>
/// <param name="offset">Offset to be added</param>
/// <returns>Added offset or just <paramref name="backingOffset"/> if the region is unmapped</returns>
private static ulong AddBackingOffset(ulong backingOffset, ulong offset)
{
if (backingOffset == ulong.MaxValue)
{
return backingOffset;
}
return backingOffset + offset;
}
/// <summary>
/// Checks if a region is unmapped.
/// </summary>
/// <param name="backingOffset">Backing offset to check</param>
/// <returns>True if the backing offset is the special "unmapped" value, false otherwise</returns>
private static bool IsMapped(ulong backingOffset)
{
return backingOffset != ulong.MaxValue;
}
/// <summary>
/// Adds a protection to the list of protections.
/// </summary>
/// <param name="address">Address of the protected region</param>
/// <param name="size">Size of the protected region in bytes</param>
/// <param name="permission">Memory permissions of the region</param>
private void AddProtection(ulong address, ulong size, MemoryPermission permission)
{
ulong endAddress = address + size;
var overlaps = Array.Empty<IntervalTreeNode<ulong, MemoryPermission>>();
int count;
lock (_protections)
{
count = _protections.Get(address, endAddress, ref overlaps);
if (count == 1 &&
overlaps[0].Start <= address &&
overlaps[0].End >= endAddress &&
overlaps[0].Value == permission)
{
return;
}
ulong startAddress = address;
for (int index = 0; index < count; index++)
{
var protection = overlaps[index];
ulong protAddress = protection.Start;
ulong protEndAddress = protection.End;
MemoryPermission protPermission = protection.Value;
_protections.Remove(protection);
if (protection.Value == permission)
{
if (startAddress > protAddress)
{
startAddress = protAddress;
}
if (endAddress < protEndAddress)
{
endAddress = protEndAddress;
}
}
else
{
if (startAddress > protAddress)
{
_protections.Add(protAddress, startAddress, protPermission);
}
if (endAddress < protEndAddress)
{
_protections.Add(endAddress, protEndAddress, protPermission);
}
}
}
_protections.Add(startAddress, endAddress, permission);
}
}
/// <summary>
/// Removes protection from the list of protections.
/// </summary>
/// <param name="address">Address of the protected region</param>
/// <param name="size">Size of the protected region in bytes</param>
private void RemoveProtection(ulong address, ulong size)
{
ulong endAddress = address + size;
var overlaps = Array.Empty<IntervalTreeNode<ulong, MemoryPermission>>();
int count;
lock (_protections)
{
count = _protections.Get(address, endAddress, ref overlaps);
for (int index = 0; index < count; index++)
{
var protection = overlaps[index];
ulong protAddress = protection.Start;
ulong protEndAddress = protection.End;
MemoryPermission protPermission = protection.Value;
_protections.Remove(protection);
if (address > protAddress)
{
_protections.Add(protAddress, address, protPermission);
}
if (endAddress < protEndAddress)
{
_protections.Add(endAddress, protEndAddress, protPermission);
}
}
}
}
/// <summary>
/// Restores the protection of a given memory region that was remapped, using the protections list.
/// </summary>
/// <param name="address">Address of the remapped region</param>
/// <param name="size">Size of the remapped region in bytes</param>
private void RestoreRangeProtection(ulong address, ulong size)
{
ulong endAddress = address + size;
var overlaps = Array.Empty<IntervalTreeNode<ulong, MemoryPermission>>();
int count;
lock (_protections)
{
count = _protections.Get(address, endAddress, ref overlaps);
}
ulong startAddress = address;
for (int index = 0; index < count; index++)
{
var protection = overlaps[index];
ulong protAddress = protection.Start;
ulong protEndAddress = protection.End;
if (protAddress < address)
{
protAddress = address;
}
if (protEndAddress > endAddress)
{
protEndAddress = endAddress;
}
ReprotectViewInternal((IntPtr)protAddress, (IntPtr)(protEndAddress - protAddress), protection.Value, true);
}
}
/// <summary>
/// Checks if an access violation handler should retry execution due to a fault caused by partial unmap.
/// </summary>
/// <remarks>
/// Due to Windows limitations, <see cref="UnmapView"/> might need to unmap more memory than requested.
/// The additional memory that was unmapped is later remapped, however this leaves a time gap where the
/// memory might be accessed but is unmapped. Users of the API must compensate for that by catching the
/// access violation and retrying if it happened between the unmap and remap operation.
/// This method can be used to decide if retrying in such cases is necessary or not.
/// </remarks>
/// <returns>True if execution should be retried, false otherwise</returns>
public bool RetryFromAccessViolation()
{
_partialUnmapLock.AcquireReaderLock(Timeout.Infinite);
bool retry = _threadLocalPartialUnmapsCount != _partialUnmapsCount;
if (retry)
{
_threadLocalPartialUnmapsCount = _partialUnmapsCount;
}
_partialUnmapLock.ReleaseReaderLock();
return retry;
}
}
}