Added to support X64 port (with SV5 ABI). May be able to remove after we port everything, but Sec, to EFI X64 ABI.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@10683 6f19259b-4bc3-4df7-8a09-765794883524

UnixPkg/Library/UnixBaseLib/X64/SwitchStack.asm

@@ -0,0 +1,51 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+; 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.Asm
+;
+; Abstract:
+;
+;------------------------------------------------------------------------------
+
+    .code
+
+;------------------------------------------------------------------------------
+; Routine Description:
+;
+;   Routine for switching stacks with 2 parameters
+;
+; Arguments:
+;
+;   (rcx) EntryPoint    - Entry point with new stack.
+;   (rdx) Context1      - Parameter1 for entry point.
+;   (r8)  Context2      - Parameter2 for entry point.
+;   (r9)  NewStack      - The pointer to new stack.
+;
+; Returns:
+;
+;   None
+;
+;------------------------------------------------------------------------------
+InternalSwitchStack PROC
+    mov     rax, rcx
+    mov     rcx, rdx
+    mov     rdx, r8
+    ;
+    ; Reserve space for register parameters (rcx, rdx, r8 & r9) on the stack,
+    ; in case the callee wishes to spill them.
+    ;
+    lea     rsp, [r9 - 20h]
+    call    rax
+InternalSwitchStack ENDP
+
+    END