1 files changed, 223 insertions, 0 deletions
diff --git a/src/Ryujinx.Cpu/Jit/HostTracked/NativePageTable.cs b/src/Ryujinx.Cpu/Jit/HostTracked/NativePageTable.cs
new file mode 100644
index 00000000..e3174e3f
--- /dev/null
+++ b/src/Ryujinx.Cpu/Jit/HostTracked/NativePageTable.cs
@@ -0,0 +1,223 @@
+using Ryujinx.Cpu.Signal;
+using Ryujinx.Memory;
+using System;
+using System.Diagnostics;
+using System.Numerics;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Cpu.Jit.HostTracked
+{
+    sealed class NativePageTable : IDisposable
+    {
+        private delegate ulong TrackingEventDelegate(ulong address, ulong size, bool write);
+
+        private const int PageBits = 12;
+        private const int PageSize = 1 << PageBits;
+        private const int PageMask = PageSize - 1;
+
+        private const int PteSize = 8;
+
+        private readonly int _bitsPerPtPage;
+        private readonly int _entriesPerPtPage;
+        private readonly int _pageCommitmentBits;
+
+        private readonly PageTable<ulong> _pageTable;
+        private readonly MemoryBlock _nativePageTable;
+        private readonly ulong[] _pageCommitmentBitmap;
+        private readonly ulong _hostPageSize;
+
+        private readonly TrackingEventDelegate _trackingEvent;
+
+        private bool _disposed;
+
+        public IntPtr PageTablePointer => _nativePageTable.Pointer;
+
+        public NativePageTable(ulong asSize)
+        {
+            ulong hostPageSize = MemoryBlock.GetPageSize();
+
+            _entriesPerPtPage = (int)(hostPageSize / sizeof(ulong));
+            _bitsPerPtPage = BitOperations.Log2((uint)_entriesPerPtPage);
+            _pageCommitmentBits = PageBits + _bitsPerPtPage;
+
+            _hostPageSize = hostPageSize;
+            _pageTable = new PageTable<ulong>();
+            _nativePageTable = new MemoryBlock((asSize / PageSize) * PteSize + _hostPageSize, MemoryAllocationFlags.Reserve);
+            _pageCommitmentBitmap = new ulong[(asSize >> _pageCommitmentBits) / (sizeof(ulong) * 8)];
+
+            ulong ptStart = (ulong)_nativePageTable.Pointer;
+            ulong ptEnd = ptStart + _nativePageTable.Size;
+
+            _trackingEvent = VirtualMemoryEvent;
+
+            bool added = NativeSignalHandler.AddTrackedRegion((nuint)ptStart, (nuint)ptEnd, Marshal.GetFunctionPointerForDelegate(_trackingEvent));
+
+            if (!added)
+            {
+                throw new InvalidOperationException("Number of allowed tracked regions exceeded.");
+            }
+        }
+
+        public void Map(ulong va, ulong pa, ulong size, AddressSpacePartitioned addressSpace, MemoryBlock backingMemory, bool privateMap)
+        {
+            while (size != 0)
+            {
+                _pageTable.Map(va, pa);
+
+                EnsureCommitment(va);
+
+                if (privateMap)
+                {
+                    _nativePageTable.Write((va / PageSize) * PteSize, GetPte(va, addressSpace.GetPointer(va, PageSize)));
+                }
+                else
+                {
+                    _nativePageTable.Write((va / PageSize) * PteSize, GetPte(va, backingMemory.GetPointer(pa, PageSize)));
+                }
+
+                va += PageSize;
+                pa += PageSize;
+                size -= PageSize;
+            }
+        }
+
+        public void Unmap(ulong va, ulong size)
+        {
+            IntPtr guardPagePtr = GetGuardPagePointer();
+
+            while (size != 0)
+            {
+                _pageTable.Unmap(va);
+                _nativePageTable.Write((va / PageSize) * PteSize, GetPte(va, guardPagePtr));
+
+                va += PageSize;
+                size -= PageSize;
+            }
+        }
+
+        public ulong Read(ulong va)
+        {
+            ulong pte = _nativePageTable.Read<ulong>((va / PageSize) * PteSize);
+
+            pte += va & ~(ulong)PageMask;
+
+            return pte + (va & PageMask);
+        }
+
+        public void Update(ulong va, IntPtr ptr, ulong size)
+        {
+            ulong remainingSize = size;
+
+            while (remainingSize != 0)
+            {
+                EnsureCommitment(va);
+
+                _nativePageTable.Write((va / PageSize) * PteSize, GetPte(va, ptr));
+
+                va += PageSize;
+                ptr += PageSize;
+                remainingSize -= PageSize;
+            }
+        }
+
+        private void EnsureCommitment(ulong va)
+        {
+            ulong bit = va >> _pageCommitmentBits;
+
+            int index = (int)(bit / (sizeof(ulong) * 8));
+            int shift = (int)(bit % (sizeof(ulong) * 8));
+
+            ulong mask = 1UL << shift;
+
+            ulong oldMask = _pageCommitmentBitmap[index];
+
+            if ((oldMask & mask) == 0)
+            {
+                lock (_pageCommitmentBitmap)
+                {
+                    oldMask = _pageCommitmentBitmap[index];
+
+                    if ((oldMask & mask) != 0)
+                    {
+                        return;
+                    }
+
+                    _nativePageTable.Commit(bit * _hostPageSize, _hostPageSize);
+
+                    Span<ulong> pageSpan = MemoryMarshal.Cast<byte, ulong>(_nativePageTable.GetSpan(bit * _hostPageSize, (int)_hostPageSize));
+
+                    Debug.Assert(pageSpan.Length == _entriesPerPtPage);
+
+                    IntPtr guardPagePtr = GetGuardPagePointer();
+
+                    for (int i = 0; i < pageSpan.Length; i++)
+                    {
+                        pageSpan[i] = GetPte((bit << _pageCommitmentBits) | ((ulong)i * PageSize), guardPagePtr);
+                    }
+
+                    _pageCommitmentBitmap[index] = oldMask | mask;
+                }
+            }
+        }
+
+        private IntPtr GetGuardPagePointer()
+        {
+            return _nativePageTable.GetPointer(_nativePageTable.Size - _hostPageSize, _hostPageSize);
+        }
+
+        private static ulong GetPte(ulong va, IntPtr ptr)
+        {
+            Debug.Assert((va & PageMask) == 0);
+
+            return (ulong)ptr - va;
+        }
+
+        public ulong GetPhysicalAddress(ulong va)
+        {
+            return _pageTable.Read(va) + (va & PageMask);
+        }
+
+        private ulong VirtualMemoryEvent(ulong address, ulong size, bool write)
+        {
+            if (address < _nativePageTable.Size - _hostPageSize)
+            {
+                // Some prefetch instructions do not cause faults with invalid addresses.
+                // Retry if we are hitting a case where the page table is unmapped, the next
+                // run will execute the actual instruction.
+                // The address loaded from the page table will be invalid, and it should hit the else case
+                // if the instruction faults on unmapped or protected memory.
+
+                ulong va = address * (PageSize / sizeof(ulong));
+
+                EnsureCommitment(va);
+
+                return (ulong)_nativePageTable.Pointer + address;
+            }
+            else
+            {
+                throw new InvalidMemoryRegionException();
+            }
+        }
+
+        private void Dispose(bool disposing)
+        {
+            if (!_disposed)
+            {
+                if (disposing)
+                {
+                    NativeSignalHandler.RemoveTrackedRegion((nuint)_nativePageTable.Pointer);
+
+                    _nativePageTable.Dispose();
+                }
+
+                _disposed = true;
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(disposing: true);
+            GC.SuppressFinalize(this);
+        }
+    }
+}