From 0fc52707024fb431a34fe402564abfe39541df3f Mon Sep 17 00:00:00 2001
From: Luke Usher <luke.usher@outlook.com>
Date: Fri, 27 Jul 2018 22:14:09 +0100
Subject: [PATCH] Prevent side-effects of the lock/unlock action for FS

---
 src/CxbxKrnl/EmuFS.cpp | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/src/CxbxKrnl/EmuFS.cpp b/src/CxbxKrnl/EmuFS.cpp
index b4b491371..15b3026e9 100644
--- a/src/CxbxKrnl/EmuFS.cpp
+++ b/src/CxbxKrnl/EmuFS.cpp
@@ -130,35 +130,32 @@ xboxkrnl::KPCR* KeGetPcr();
 
 uint32_t fs_lock = 0;
 
-__declspec(naked) void LockFSInternal()
-{
-	__asm {
-		mov eax, 1
-		xchg eax, [fs_lock]
-		test eax, eax
-		jnz LockFSInternal
-		ret
-	}
-}
-
 __declspec(naked) void LockFS()
 {
-	__asm {
-		push eax
-		call LockFSInternal
-		pop eax
-		ret
+	__asm {
+		pushfd
+		pushad
+		spinlock :
+		mov eax, 1
+		xchg eax, fs_lock
+		test eax, eax
+		jnz spinlock
+		popad
+		popfd
+		ret
 	}
 }
 
 __declspec(naked) void UnlockFS()
 {
-	__asm {
-		push eax
-		xor eax, eax
-		xchg eax, [fs_lock]
-		pop eax
-		ret
+	__asm {
+		pushfd
+		pushad
+		xor eax, eax
+		xchg eax, fs_lock
+		popad
+		popfd
+		ret
 	}
 }