From b15aae9f2e33b8a24d2c1abd86422763642bc9c6 Mon Sep 17 00:00:00 2001
From: Samer El-Haj-Mahmoud elhaj <Samer El-Haj-Mahmoud elhaj@hp.com>
Date: Mon, 22 Sep 2014 05:54:41 +0000
Subject: [PATCH] Fix X64 native function call prolog. Prepare space for at
 least 4 arguments, even if the native function's arguments are less than 4.
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From MSDN x64 Software Conventions, Overview of x64 Calling Conventions:
“The caller is responsible for allocating space for parameters to the
callee, and must always allocate sufficient space for the 4 register
parameters, even if the callee doesn’t have that many parameters.
This aids in the simplicity of supporting C unprototyped functions,
and vararg C/C++ functions.”

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Samer El-Haj-Mahmoud elhaj@hp.com
Reviewed by: Jiewen Yao <Jiewen.Yao@intel.com>
Reviewed by: Feng Tian <Feng.Tian@intel.com>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16152 6f19259b-4bc3-4df7-8a09-765794883524
---
 .../Universal/EbcDxe/X64/EbcLowLevel.S        | 29 ++++++++++++++++++-
 .../Universal/EbcDxe/X64/EbcLowLevel.asm      | 28 ++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.S b/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.S
index 859cbce24c..b01486a871 100644
--- a/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.S
+++ b/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.S
@@ -3,7 +3,7 @@
 #    This code provides low level routines that support the Virtual Machine
 #   for option ROMs.
 #  
-#  Copyright (c) 2007 - 2011, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2007 - 2014, 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
@@ -46,7 +46,34 @@ ASM_PFX(EbcLLCALLEXNative):
 
       # Set stack pointer to new value
       sub    %rdx, %r8  
+      
+      #
+      # Fix X64 native function call prolog. Prepare space for at least 4 arguments,
+      # even if the native function's arguments are less than 4.
+      #
+      # From MSDN x64 Software Conventions, Overview of x64 Calling Conventions:
+      #   "The caller is responsible for allocating space for parameters to the
+      #   callee, and must always allocate sufficient space for the 4 register
+      #   parameters, even if the callee doesn't have that many parameters.
+      #   This aids in the simplicity of supporting C unprototyped functions,
+      #   and vararg C/C++ functions."
+      #
+      cmp    $0x20, %r8
+      jae    skip_expansion
+      mov    $0x20, %r8
+skip_expansion:
+      
       sub    %r8,  %rsp 
+      
+      #
+      # Fix X64 native function call 16-byte alignment.
+      #
+      # From MSDN x64 Software Conventions, Stack Usage:
+      #   "The stack will always be maintained 16-byte aligned, except within 
+      #   the prolog (for example, after the return address is pushed)."
+      #
+      and    $0xFFFFFFFFFFFFFFF0, %rsp
+      
       mov    %rsp, %rcx
       sub    $0x20, %rsp 
       call   ASM_PFX(CopyMem)
diff --git a/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.asm b/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.asm
index a79fdcabff..1fbd165be7 100644
--- a/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.asm
+++ b/MdeModulePkg/Universal/EbcDxe/X64/EbcLowLevel.asm
@@ -4,6 +4,7 @@
 ;    for option ROMs.
 ;  
 ;  Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+;  Copyright (c) 2014 Hewlett-Packard Development Company, L.P.<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
@@ -50,7 +51,34 @@ EbcLLCALLEXNative        PROC    PUBLIC
 
       ; Set stack pointer to new value
       sub    r8,  rdx
+
+      ;
+      ; Fix X64 native function call prolog. Prepare space for at least 4 arguments,
+      ; even if the native function's arguments are less than 4.
+      ;
+      ; From MSDN x64 Software Conventions, Overview of x64 Calling Conventions:
+      ;   "The caller is responsible for allocating space for parameters to the
+      ;   callee, and must always allocate sufficient space for the 4 register
+      ;   parameters, even if the callee doesn't have that many parameters.
+      ;   This aids in the simplicity of supporting C unprototyped functions,
+      ;   and vararg C/C++ functions."
+      ;
+      cmp    r8, 20h
+      jae    skip_expansion
+      mov    r8, 20h
+skip_expansion:
+      
       sub    rsp, r8
+
+      ;
+      ; Fix X64 native function call 16-byte alignment.
+      ;
+      ; From MSDN x64 Software Conventions, Stack Usage:
+      ;   "The stack will always be maintained 16-byte aligned, except within 
+      ;   the prolog (for example, after the return address is pushed)."
+      ;
+      and    rsp, NOT 0fh
+
       mov    rcx, rsp
       sub    rsp, 20h
       call   CopyMem
-- 
2.39.2