Move partial unmap handler to the native signal handler (#3437)

* Initial commit with a lot of testing stuff.

* Partial Unmap Cleanup Part 1

* Fix some minor issues, hopefully windows tests.

* Disable partial unmap tests on macos for now

Weird issue.

* Goodbye magic number

* Add COMPlus_EnableAlternateStackCheck for tests

`COMPlus_EnableAlternateStackCheck` is needed for NullReferenceException handling to work on linux after registering the signal handler, due to how dotnet registers its own signal handler.

* Address some feedback

* Force retry when memory is mapped in memory tracking

This case existed before, but returning `false` no longer retries, so it would crash immediately after unprotecting the memory... Now, we return `true` to deliberately retry.

This case existed before (was just broken by this change) and I don't really want to look into fixing the issue right now. Technically, this means that on guest code partial unmaps will retry _due to this_ rather than hitting the handler. I don't expect this to cause any issues.

This should fix random crashes in Xenoblade Chronicles 2.

* Use IsRangeMapped

* Suppress MockMemoryManager.UnmapEvent warning

This event is not signalled by the mock memory manager.

* Remove 4kb mapping

ARMeilleure/Signal/TestMethods.cs

@@ -0,0 +1,84 @@
+using ARMeilleure.IntermediateRepresentation;
+using ARMeilleure.Translation;
+using System;
+
+using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
+
+namespace ARMeilleure.Signal
+{
+    public struct NativeWriteLoopState
+    {
+        public int Running;
+        public int Error;
+    }
+
+    public static class TestMethods
+    {
+        public delegate bool DebugPartialUnmap();
+        public delegate int DebugThreadLocalMapGetOrReserve(int threadId, int initialState);
+        public delegate void DebugNativeWriteLoop(IntPtr nativeWriteLoopPtr, IntPtr writePtr);
+
+        public static DebugPartialUnmap GenerateDebugPartialUnmap()
+        {
+            EmitterContext context = new EmitterContext();
+
+            var result = WindowsPartialUnmapHandler.EmitRetryFromAccessViolation(context);
+
+            context.Return(result);
+
+            // Compile and return the function.
+
+            ControlFlowGraph cfg = context.GetControlFlowGraph();
+
+            OperandType[] argTypes = new OperandType[] { OperandType.I64 };
+
+            return Compiler.Compile(cfg, argTypes, OperandType.I32, CompilerOptions.HighCq).Map<DebugPartialUnmap>();
+        }
+
+        public static DebugThreadLocalMapGetOrReserve GenerateDebugThreadLocalMapGetOrReserve(IntPtr structPtr)
+        {
+            EmitterContext context = new EmitterContext();
+
+            var result = WindowsPartialUnmapHandler.EmitThreadLocalMapIntGetOrReserve(context, structPtr, context.LoadArgument(OperandType.I32, 0), context.LoadArgument(OperandType.I32, 1));
+
+            context.Return(result);
+
+            // Compile and return the function.
+
+            ControlFlowGraph cfg = context.GetControlFlowGraph();
+
+            OperandType[] argTypes = new OperandType[] { OperandType.I64 };
+
+            return Compiler.Compile(cfg, argTypes, OperandType.I32, CompilerOptions.HighCq).Map<DebugThreadLocalMapGetOrReserve>();
+        }
+
+        public static DebugNativeWriteLoop GenerateDebugNativeWriteLoop()
+        {
+            EmitterContext context = new EmitterContext();
+
+            // Loop a write to the target address until "running" is false.
+
+            Operand structPtr = context.Copy(context.LoadArgument(OperandType.I64, 0));
+            Operand writePtr = context.Copy(context.LoadArgument(OperandType.I64, 1));
+
+            Operand loopLabel = Label();
+            context.MarkLabel(loopLabel);
+
+            context.Store(writePtr, Const(12345));
+
+            Operand running = context.Load(OperandType.I32, structPtr);
+
+            context.BranchIfTrue(loopLabel, running);
+
+            context.Return();
+
+            // Compile and return the function.
+
+            ControlFlowGraph cfg = context.GetControlFlowGraph();
+
+            OperandType[] argTypes = new OperandType[] { OperandType.I64 };
+
+            return Compiler.Compile(cfg, argTypes, OperandType.None, CompilerOptions.HighCq).Map<DebugNativeWriteLoop>();
+        }
+    }
+}