--- /dev/null
+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2006, Intel Corporation
+# All rights reserved. This program and the accompanying materials
+# are licensed and made available under the terms and conditions of the BSD License
+# which accompanies this distribution. The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+# Module Name:
+#
+# SwitchStack.S
+#
+# Abstract:
+#
+#------------------------------------------------------------------------------
+
+
+#------------------------------------------------------------------------------
+# Routine Description:
+#
+# Routine for switching stacks with 1 parameter
+#
+# Arguments:
+#
+# (rdi) EntryPoint - Entry point with new stack.
+# (rsi) Context1 - Parameter1 for entry point.
+# (rdx) Context2 - Parameter2 for entry point.
+# (rcx) NewStack - Pointer to new stack.
+#
+# Returns:
+#
+# None
+#
+#------------------------------------------------------------------------------
+.global _InternalSwitchStack;
+_InternalSwitchStack:
+ mov %rcx, %rax
+ mov %rdx, %rcx
+ mov %r8, %rdx
+ lea -0x20(%r9), %rsp
+ call *%rax