1 files changed, 52 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseLib/X64/SwitchStack.S b/Core/MdePkg/Library/BaseLib/X64/SwitchStack.S
new file mode 100644
index 0000000000..dc8d80e40b
--- /dev/null
+++ b/Core/MdePkg/Library/BaseLib/X64/SwitchStack.S
@@ -0,0 +1,52 @@
+#------------------------------------------------------------------------------
+#
+# 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.S
+#
+# Abstract:
+#
+#------------------------------------------------------------------------------
+
+
+#------------------------------------------------------------------------------
+# 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
+#
+#------------------------------------------------------------------------------
+ASM_GLOBAL ASM_PFX(InternalSwitchStack)
+ASM_PFX(InternalSwitchStack):
+	  pushq   %rbp            
+  	movq    %rsp, %rbp
+    
+    mov     %rcx, %rax  // Shift registers for new call
+    mov     %rdx, %rcx
+    mov     %r8, %rdx
+    #
+    # Reserve space for register parameters (rcx, rdx, r8 & r9) on the stack,
+    # in case the callee wishes to spill them.
+    #
+    lea     -0x20(%r9), %rsp
+    pushq   $0        // stop gdb stack unwind
+    jmp     *%rax     // call EntryPoint ()