1 files changed, 186 insertions, 0 deletions
diff --git a/src/ARMeilleure/Signal/WindowsPartialUnmapHandler.cs b/src/ARMeilleure/Signal/WindowsPartialUnmapHandler.cs
new file mode 100644
index 00000000..941e36e5
--- /dev/null
+++ b/src/ARMeilleure/Signal/WindowsPartialUnmapHandler.cs
@@ -0,0 +1,186 @@
+using ARMeilleure.IntermediateRepresentation;
+using ARMeilleure.Translation;
+using Ryujinx.Common.Memory.PartialUnmaps;
+using System;
+
+using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
+
+namespace ARMeilleure.Signal
+{
+    /// <summary>
+    /// Methods to handle signals caused by partial unmaps. See the structs for C# implementations of the methods.
+    /// </summary>
+    internal static class WindowsPartialUnmapHandler
+    {
+        public static Operand EmitRetryFromAccessViolation(EmitterContext context)
+        {
+            IntPtr partialRemapStatePtr = PartialUnmapState.GlobalState;
+            IntPtr localCountsPtr = IntPtr.Add(partialRemapStatePtr, PartialUnmapState.LocalCountsOffset);
+
+            // Get the lock first.
+            EmitNativeReaderLockAcquire(context, IntPtr.Add(partialRemapStatePtr, PartialUnmapState.PartialUnmapLockOffset));
+
+            IntPtr getCurrentThreadId = WindowsSignalHandlerRegistration.GetCurrentThreadIdFunc();
+            Operand threadId = context.Call(Const((ulong)getCurrentThreadId), OperandType.I32);
+            Operand threadIndex = EmitThreadLocalMapIntGetOrReserve(context, localCountsPtr, threadId, Const(0));
+
+            Operand endLabel = Label();
+            Operand retry = context.AllocateLocal(OperandType.I32);
+            Operand threadIndexValidLabel = Label();
+
+            context.BranchIfFalse(threadIndexValidLabel, context.ICompareEqual(threadIndex, Const(-1)));
+
+            context.Copy(retry, Const(1)); // Always retry when thread local cannot be allocated.
+
+            context.Branch(endLabel);
+
+            context.MarkLabel(threadIndexValidLabel);
+
+            Operand threadLocalPartialUnmapsPtr = EmitThreadLocalMapIntGetValuePtr(context, localCountsPtr, threadIndex);
+            Operand threadLocalPartialUnmaps = context.Load(OperandType.I32, threadLocalPartialUnmapsPtr);
+            Operand partialUnmapsCount = context.Load(OperandType.I32, Const((ulong)IntPtr.Add(partialRemapStatePtr, PartialUnmapState.PartialUnmapsCountOffset)));
+
+            context.Copy(retry, context.ICompareNotEqual(threadLocalPartialUnmaps, partialUnmapsCount));
+
+            Operand noRetryLabel = Label();
+
+            context.BranchIfFalse(noRetryLabel, retry);
+
+            // if (retry) {
+
+            context.Store(threadLocalPartialUnmapsPtr, partialUnmapsCount);
+
+            context.Branch(endLabel);
+
+            context.MarkLabel(noRetryLabel);
+
+            // }
+
+            context.MarkLabel(endLabel);
+
+            // Finally, release the lock and return the retry value.
+            EmitNativeReaderLockRelease(context, IntPtr.Add(partialRemapStatePtr, PartialUnmapState.PartialUnmapLockOffset));
+
+            return retry;
+        }
+
+        public static Operand EmitThreadLocalMapIntGetOrReserve(EmitterContext context, IntPtr threadLocalMapPtr, Operand threadId, Operand initialState)
+        {
+            Operand idsPtr = Const((ulong)IntPtr.Add(threadLocalMapPtr, ThreadLocalMap<int>.ThreadIdsOffset));
+
+            Operand i = context.AllocateLocal(OperandType.I32);
+
+            context.Copy(i, Const(0));
+
+            // (Loop 1) Check all slots for a matching Thread ID (while also trying to allocate)
+
+            Operand endLabel = Label();
+
+            Operand loopLabel = Label();
+            context.MarkLabel(loopLabel);
+
+            Operand offset = context.Multiply(i, Const(sizeof(int)));
+            Operand idPtr = context.Add(idsPtr, context.SignExtend32(OperandType.I64, offset));
+
+            // Check that this slot has the thread ID.
+            Operand existingId = context.CompareAndSwap(idPtr, threadId, threadId);
+
+            // If it was already the thread ID, then we just need to return i.
+            context.BranchIfTrue(endLabel, context.ICompareEqual(existingId, threadId));
+
+            context.Copy(i, context.Add(i, Const(1)));
+
+            context.BranchIfTrue(loopLabel, context.ICompareLess(i, Const(ThreadLocalMap<int>.MapSize)));
+
+            // (Loop 2) Try take a slot that is 0 with our Thread ID.
+
+            context.Copy(i, Const(0)); // Reset i.
+
+            Operand loop2Label = Label();
+            context.MarkLabel(loop2Label);
+
+            Operand offset2 = context.Multiply(i, Const(sizeof(int)));
+            Operand idPtr2 = context.Add(idsPtr, context.SignExtend32(OperandType.I64, offset2));
+
+            // Try and swap in the thread id on top of 0.
+            Operand existingId2 = context.CompareAndSwap(idPtr2, Const(0), threadId);
+
+            Operand idNot0Label = Label();
+
+            // If it was 0, then we need to initialize the struct entry and return i.
+            context.BranchIfFalse(idNot0Label, context.ICompareEqual(existingId2, Const(0)));
+
+            Operand structsPtr = Const((ulong)IntPtr.Add(threadLocalMapPtr, ThreadLocalMap<int>.StructsOffset));
+            Operand structPtr = context.Add(structsPtr, context.SignExtend32(OperandType.I64, offset2));
+            context.Store(structPtr, initialState);
+
+            context.Branch(endLabel);
+
+            context.MarkLabel(idNot0Label);
+
+            context.Copy(i, context.Add(i, Const(1)));
+
+            context.BranchIfTrue(loop2Label, context.ICompareLess(i, Const(ThreadLocalMap<int>.MapSize)));
+
+            context.Copy(i, Const(-1)); // Could not place the thread in the list.
+
+            context.MarkLabel(endLabel);
+
+            return context.Copy(i);
+        }
+
+        private static Operand EmitThreadLocalMapIntGetValuePtr(EmitterContext context, IntPtr threadLocalMapPtr, Operand index)
+        {
+            Operand offset = context.Multiply(index, Const(sizeof(int)));
+            Operand structsPtr = Const((ulong)IntPtr.Add(threadLocalMapPtr, ThreadLocalMap<int>.StructsOffset));
+
+            return context.Add(structsPtr, context.SignExtend32(OperandType.I64, offset));
+        }
+
+        private static void EmitThreadLocalMapIntRelease(EmitterContext context, IntPtr threadLocalMapPtr, Operand threadId, Operand index)
+        {
+            Operand offset = context.Multiply(index, Const(sizeof(int)));
+            Operand idsPtr = Const((ulong)IntPtr.Add(threadLocalMapPtr, ThreadLocalMap<int>.ThreadIdsOffset));
+            Operand idPtr = context.Add(idsPtr, context.SignExtend32(OperandType.I64, offset));
+
+            context.CompareAndSwap(idPtr, threadId, Const(0));
+        }
+
+        private static void EmitAtomicAddI32(EmitterContext context, Operand ptr, Operand additive)
+        {
+            Operand loop = Label();
+            context.MarkLabel(loop);
+
+            Operand initial = context.Load(OperandType.I32, ptr);
+            Operand newValue = context.Add(initial, additive);
+
+            Operand replaced = context.CompareAndSwap(ptr, initial, newValue);
+
+            context.BranchIfFalse(loop, context.ICompareEqual(initial, replaced));
+        }
+
+        private static void EmitNativeReaderLockAcquire(EmitterContext context, IntPtr nativeReaderLockPtr)
+        {
+            Operand writeLockPtr = Const((ulong)IntPtr.Add(nativeReaderLockPtr, NativeReaderWriterLock.WriteLockOffset));
+
+            // Spin until we can acquire the write lock.
+            Operand spinLabel = Label();
+            context.MarkLabel(spinLabel);
+
+            // Old value must be 0 to continue (we gained the write lock)
+            context.BranchIfTrue(spinLabel, context.CompareAndSwap(writeLockPtr, Const(0), Const(1)));
+
+            // Increment reader count.
+            EmitAtomicAddI32(context, Const((ulong)IntPtr.Add(nativeReaderLockPtr, NativeReaderWriterLock.ReaderCountOffset)), Const(1));
+
+            // Release write lock.
+            context.CompareAndSwap(writeLockPtr, Const(1), Const(0));
+        }
+
+        private static void EmitNativeReaderLockRelease(EmitterContext context, IntPtr nativeReaderLockPtr)
+        {
+            // Decrement reader count.
+            EmitAtomicAddI32(context, Const((ulong)IntPtr.Add(nativeReaderLockPtr, NativeReaderWriterLock.ReaderCountOffset)), Const(-1));
+        }
+    }
+}