Updated atomic functions to avoid fpu instructions

ergo720 · Aug 8, 2024 · 8886602 · 8886602
1 parent 01e6eff
commit 8886602
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Showing 2 changed files with 16 additions and 11 deletions.
diff --git a/nboxkrnl/io/hdd/fatx.cpp b/nboxkrnl/io/hdd/fatx.cpp
@@ -844,10 +844,8 @@ static NTSTATUS XBOXAPI FatxIrpQueryInformation(PDEVICE_OBJECT DeviceObject, PIR
 	case FileNetworkOpenInformation: {
 		PFILE_NETWORK_OPEN_INFORMATION NetworkOpenInformation = (PFILE_NETWORK_OPEN_INFORMATION)Irp->UserBuffer;
 		// NOTE: FileInfo->LastAccessTime must be read atomically because FatxIrpRead acquires a shared lock, which means it can update it while we are trying to write it here
-		LARGE_INTEGER LastAccessTime;
-		atomic_load64(&LastAccessTime.QuadPart, &FileInfo->LastAccessTime.QuadPart);
 		NetworkOpenInformation->CreationTime = FileInfo->CreationTime;
-		NetworkOpenInformation->LastAccessTime = LastAccessTime;
+		NetworkOpenInformation->LastAccessTime.QuadPart = atomic_load64(&FileInfo->LastAccessTime.QuadPart);
 		NetworkOpenInformation->LastWriteTime = FileInfo->LastWriteTime;
 		NetworkOpenInformation->ChangeTime = FileInfo->LastWriteTime;
 		if (FileInfo->Flags & FILE_DIRECTORY_FILE) {

diff --git a/nboxkrnl/kernel.hpp b/nboxkrnl/kernel.hpp
@@ -231,18 +231,25 @@ static inline VOID CDECL disable()
 static inline VOID CDECL atomic_store64(LONGLONG *dst, LONGLONG val)
 {
 	__asm {
-		mov eax, dword ptr [dst]
-		fild val
-		fistp qword ptr [eax]
+		pushfd
+		cli
 	}
+
+	*dst = val;
+
+	__asm popfd
 }
 
-static inline VOID CDECL atomic_load64(LONGLONG *dst, LONGLONG *src)
+static inline LONGLONG CDECL atomic_load64(LONGLONG *src)
 {
 	__asm {
-		mov eax, dword ptr [dst]
-		mov ecx, dword ptr [src]
-		fild qword ptr [ecx]
-		fistp qword ptr [eax]
+		pushfd
+		cli
 	}
+
+	LONGLONG val = *src;
+
+	__asm popfd
+
+	return val;
 }