Support Linux and OSX on MemoryAlloc and CompareExchange128, some cleanup

ChocolArm64/ChocolArm64.csproj

@@ -14,6 +14,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Mono.Posix.NETStandard" Version="1.0.0" />
     <PackageReference Include="System.Runtime.Intrinsics.Experimental" Version="4.5.0-rc1" />
   </ItemGroup>
 

ChocolArm64/Instructions/InstEmitMemoryEx.cs

@@ -93,9 +93,9 @@ namespace ChocolArm64.Instructions
 
             if (pair)
             {
-                //Exclusive loads should be atomic, for pairwise loads, the need to
+                //Exclusive loads should be atomic. For pairwise loads, we need to
-                //read all the data at once. for a 32-bits pairwise load, we do a
+                //read all the data at once. For a 32-bits pairwise load, we do a
-                //simple 64-bits load, for 128-bits load, we need to call a special
+                //simple 64-bits load, for a 128-bits load, we need to call a special
                 //method to read 128-bits atomically.
                 if (op.Size == 2)
                 {
@@ -169,7 +169,7 @@ namespace ChocolArm64.Instructions
             }
             else
             {
-                //8, 16, 32 or 64-bits load, or 64-bits pair load.
+                //8, 16, 32 or 64-bits (non-pairwise) load.
                 context.EmitLdarg(TranslatedSub.MemoryArgIdx);
                 context.EmitLdtmp();
 
@@ -181,24 +181,6 @@ namespace ChocolArm64.Instructions
                 }
 
                 context.EmitStintzr(op.Rt);
-
-                if (pair)
-                {
-                    context.EmitLdarg(TranslatedSub.MemoryArgIdx);
-                    context.EmitLdtmp();
-                    context.EmitLdc_I8(1 << op.Size);
-
-                    context.Emit(OpCodes.Add);
-
-                    EmitReadZxCall(context, op.Size);
-
-                    if (exclusive)
-                    {
-                        WriteExclusiveValue(nameof(CpuThreadState.ExclusiveValueHigh));
-                    }
-
-                    context.EmitStintzr(op.Rt2);
-                }
             }
         }
 

ChocolArm64/Memory/CompareExchange128.cs

@@ -23,7 +23,17 @@ namespace ChocolArm64.Memory
 
         static CompareExchange128()
         {
-            byte[] interlockedCompareExchange128Code = new byte[]
+            //TODO: Also check if cmpxchg16b is supported on cpu flags.
+            if (RuntimeInformation.OSArchitecture != Architecture.X64)
+            {
+                throw new PlatformNotSupportedException();
+            }
+
+            byte[] interlockedCompareExchange128Code;
+
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                interlockedCompareExchange128Code = new byte[]
                 {
                     0x53,                         // push rbx
                     0x49, 0x8B, 0x00,             // mov  rax, [r8]
@@ -39,6 +49,27 @@ namespace ChocolArm64.Memory
                     0x5B,                         // pop  rbx
                     0xC3                          // ret
                 };
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                interlockedCompareExchange128Code = new byte[]
+                {
+                        0x53,                         // push %rbx
+                        0x49, 0x89, 0xd1,             // mov  %rdx,%r9
+                        0x48, 0x89, 0xcb,             // mov  %rcx,%rbx
+                        0x48, 0x89, 0xf0,             // mov  %rsi,%rax
+                        0x4c, 0x89, 0xca,             // mov  %r9,%rdx
+                        0x4c, 0x89, 0xc1,             // mov  %r8,%rcx
+                        0xf0, 0x48, 0x0f, 0xc7, 0x0f, // lock cmpxchg16b (%rdi)
+                        0x5b,                         // pop  %rbx
+                        0xc3                          // retq
+                };
+            }
+            else
+            {
+                throw new PlatformNotSupportedException();
+            }
 
             ulong codeLength = (ulong)interlockedCompareExchange128Code.Length;
 

ChocolArm64/Memory/MemoryAlloc.cs

@@ -16,6 +16,11 @@ namespace ChocolArm64.Memory
 
                 return MemoryAllocWindows.Allocate(sizeNint);
             }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryAllocUnix.Allocate(size);
+            }
             else
             {
                 throw new PlatformNotSupportedException();
@@ -30,24 +35,41 @@ namespace ChocolArm64.Memory
 
                 return MemoryAllocWindows.AllocateWriteTracked(sizeNint);
             }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryAllocUnix.Allocate(size);
+            }
             else
             {
                 throw new PlatformNotSupportedException();
             }
         }
 
-        public static bool Reprotect(IntPtr address, ulong size, MemoryProtection permission)
+        public static void Reprotect(IntPtr address, ulong size, MemoryProtection permission)
         {
+            bool result;
+
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
             {
                 IntPtr sizeNint = new IntPtr((long)size);
 
-                return MemoryAllocWindows.Reprotect(address, sizeNint, permission);
+                result = MemoryAllocWindows.Reprotect(address, sizeNint, permission);
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                result = MemoryAllocUnix.Reprotect(address, size, permission);
             }
             else
             {
                 throw new PlatformNotSupportedException();
             }
+
+            if (!result)
+            {
+                throw new MemoryProtectionException(permission);
+            }
         }
 
         public static bool Free(IntPtr address)
@@ -56,6 +78,11 @@ namespace ChocolArm64.Memory
             {
                 return MemoryAllocWindows.Free(address);
             }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ||
+                     RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return MemoryAllocUnix.Free(address);
+            }
             else
             {
                 throw new PlatformNotSupportedException();
@@ -69,6 +96,9 @@ namespace ChocolArm64.Memory
             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 MemoryAllocWindows.GetModifiedPages(address, size, addresses, out count);

ChocolArm64/Memory/MemoryAllocUnix.cs

@@ -0,0 +1,70 @@
+using Mono.Unix.Native;
+using System;
+
+namespace ChocolArm64.Memory
+{
+    static class MemoryAllocUnix
+    {
+        public static IntPtr Allocate(ulong size)
+        {
+            ulong pageSize = (ulong)Syscall.sysconf(SysconfName._SC_PAGESIZE);
+
+            const MmapProts prot = MmapProts.PROT_READ | MmapProts.PROT_WRITE;
+
+            const MmapFlags flags = MmapFlags.MAP_PRIVATE | MmapFlags.MAP_ANONYMOUS;
+
+            IntPtr ptr = Syscall.mmap(IntPtr.Zero, size + pageSize, prot, flags, -1, 0);
+
+            if (ptr == IntPtr.Zero)
+            {
+                throw new OutOfMemoryException();
+            }
+
+            unsafe
+            {
+                ptr = new IntPtr(ptr.ToInt64() + (long)pageSize);
+
+                *((ulong*)ptr - 1) = size;
+            }
+
+            return ptr;
+        }
+
+        public static bool Reprotect(IntPtr address, ulong size, Memory.MemoryProtection protection)
+        {
+            MmapProts prot = GetProtection(protection);
+
+            return Syscall.mprotect(address, size, prot) == 0;
+        }
+
+        private static MmapProts GetProtection(Memory.MemoryProtection protection)
+        {
+            switch (protection)
+            {
+                case Memory.MemoryProtection.None:           return MmapProts.PROT_NONE;
+                case Memory.MemoryProtection.Read:           return MmapProts.PROT_READ;
+                case Memory.MemoryProtection.ReadAndWrite:   return MmapProts.PROT_READ | MmapProts.PROT_WRITE;
+                case Memory.MemoryProtection.ReadAndExecute: return MmapProts.PROT_READ | MmapProts.PROT_EXEC;
+                case Memory.MemoryProtection.Execute:        return MmapProts.PROT_EXEC;
+
+                default: throw new ArgumentException($"Invalid permission \"{protection}\".");
+            }
+        }
+
+        public static bool Free(IntPtr address)
+        {
+            ulong pageSize = (ulong)Syscall.sysconf(SysconfName._SC_PAGESIZE);
+
+            ulong size;
+
+            unsafe
+            {
+                size = *((ulong*)address - 1);
+
+                address = new IntPtr(address.ToInt64() - (long)pageSize);
+            }
+
+            return Syscall.munmap(address, size + pageSize) == 0;
+        }
+    }
+}

ChocolArm64/Memory/MemoryProtectionException.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace ChocolArm64.Memory
+{
+    class MemoryProtectionException : Exception
+    {
+        public MemoryProtectionException(MemoryProtection protection) :
+            base($"Failed to set memory protection to \"{protection}\".") { }
+    }
+}