1 files changed, 53 insertions, 0 deletions
diff --git a/EmulatorPkg/Unix/Host/X64/SwitchStack.S b/EmulatorPkg/Unix/Host/X64/SwitchStack.S
new file mode 100644
index 0000000000..8a57b781b5
--- /dev/null
+++ b/EmulatorPkg/Unix/Host/X64/SwitchStack.S
@@ -0,0 +1,53 @@
+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+# Portitions copyright (c) 2011, Apple Inc. 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.
+#
+#------------------------------------------------------------------------------
+
+
+#------------------------------------------------------------------------------
+# Routine Description:
+#
+#   Routine for switching stacks with 2 parameters EFI ABI
+#   Convert UNIX to EFI ABI
+#
+# Arguments:
+#
+#   (rdi) EntryPoint    - Entry point with new stack.
+#   (rsi) Context1      - Parameter1 for entry point. (rcx)
+#   (rdx) Context2      - Parameter2 for entry point. (rdx) 
+#   (rcx) NewStack      - The pointer to new stack.
+#
+# Returns:
+#
+#   None
+#
+#------------------------------------------------------------------------------
+ASM_GLOBAL ASM_PFX(PeiSwitchStacks)
+ASM_PFX(PeiSwitchStacks):
+    pushq   $0            // tells gdb to stop unwinding frame
+    movq    %rsp, %rbp
+
+    movq    %rcx, %rsp    // update stack pointer
+    
+    movq    %rdi, %rax    // entry point to %rax
+    movq    %rsi, %rcx    // Adjust Context1
+                          // Context2 already in the rigth spot
+    
+    #
+    # Reserve space for register parameters (rcx, rdx, r8 & r9) on the stack,
+    # in case the callee wishes to spill them.
+    #
+    subq    $32, %rsp  // 32-byte shadow space plus alignment pad
+    call    *%rax
+
+  
+