Optimize address translation and write tracking on the MMU (#571)

* Implement faster address translation and write tracking on the MMU

* Rename MemoryAlloc to MemoryManagement, and other nits

* Support multi-level page tables

* Fix typo

* Reword comment a bit

* Support scalar vector loads/stores on the memory fast path, and minor fixes

* Add missing cast

* Alignment

* Fix VirtualFree function signature

* Change MemoryProtection enum to uint aswell for consistency

1 files changed, 114 insertions, 0 deletions

diff --git a/ChocolArm64/Memory/MemoryManagement.cs b/ChocolArm64/Memory/MemoryManagement.cs
new file mode 100644
index 00000000..fa4bc4fa
--- /dev/null
+++ b/ChocolArm64/Memory/MemoryManagement.cs
@@ -0,0 +1,114 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace ChocolArm64.Memory
+{
+    public static class MemoryManagement
+    {
+        public static bool HasWriteWatchSupport => RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+
+        public static IntPtr Allocate(ulong size)
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                IntPtr sizeNint = new IntPtr((long)size);
+
+                return MemoryManagementWindows.Allocate(sizeNint);
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryManagementUnix.Allocate(size);
+            }
+            else
+            {
+                throw new PlatformNotSupportedException();
+            }
+        }
+
+        public static IntPtr AllocateWriteTracked(ulong size)
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                IntPtr sizeNint = new IntPtr((long)size);
+
+                return MemoryManagementWindows.AllocateWriteTracked(sizeNint);
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryManagementUnix.Allocate(size);
+            }
+            else
+            {
+                throw new PlatformNotSupportedException();
+            }
+        }
+
+        public static void Reprotect(IntPtr address, ulong size, MemoryProtection permission)
+        {
+            bool result;
+
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                IntPtr sizeNint = new IntPtr((long)size);
+
+                result = MemoryManagementWindows.Reprotect(address, sizeNint, permission);
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                result = MemoryManagementUnix.Reprotect(address, size, permission);
+            }
+            else
+            {
+                throw new PlatformNotSupportedException();
+            }
+
+            if (!result)
+            {
+                throw new MemoryProtectionException(permission);
+            }
+        }
+
+        public static bool Free(IntPtr address)
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return MemoryManagementWindows.Free(address);
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryManagementUnix.Free(address);
+            }
+            else
+            {
+                throw new PlatformNotSupportedException();
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool GetModifiedPages(
+            IntPtr    address,
+            IntPtr    size,
+            IntPtr[]  addresses,
+            out ulong count)
+        {
+            //This is only supported on windows, but returning
+            //false (failed) is also valid for platforms without
+            //write tracking support on the OS.
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return MemoryManagementWindows.GetModifiedPages(address, size, addresses, out count);
+            }
+            else
+            {
+                count = 0;
+
+                return false;
+            }
+        }
+    }
+}
\ No newline at end of file