Fixed race in task switching code

svn path=/trunk/; revision=133

reactos/ntoskrnl/hal/x86/usercall.asm

@@ -7,6 +7,37 @@ bits 32
 section .text
 extern __SystemServiceTable
 global _interrupt_handler2e
+global _PsBeginThreadWithContextInternal
+extern _KeLowerIrql
+
+_PsBeginThreadWithContextInternal:
+         push dword 0
+	 call _KeLowerIrql
+	 pop eax
+	 
+         pop eax           ; Context flags
+	 
+	 pop eax           ; Dr0
+	 pop eax           ; Dr1
+	 pop eax           ; Dr2
+	 pop eax           ; Dr3
+	 pop eax           ; Dr6
+	 pop eax           ; Dr7
+	 
+	 add esp,112      ; Floating point save 
+	 
+         pop gs
+	 pop fs
+	 pop es
+	 pop ds
+         pop edi
+	 pop esi
+	 pop ebx
+	 pop edx
+	 pop ecx
+	 pop eax
+	 pop ebp
+	 iret
 
 _interrupt_handler2e:
          push ds