From 080681592188f45228616983f9e1610ab9e86615 Mon Sep 17 00:00:00 2001
From: oliviermartin <oliviermartin@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Tue, 8 Nov 2011 18:49:22 +0000
Subject: MdePkg/BaseLib: Replaced inline assembly for ARMGCC by GCC assembly
 source file

The registers used to passed arguments to the DxeCore entrypoint in the inline
assembly function InternalSwitchStackAsm() where switched at compilation time.
This change replaces the inline assembly by a pure assembly source file to
avoid this kind of optimization.

Note: Inline assembly is generally not recommanded in system programming.

Reviewed-by: lgao4



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12674 6f19259b-4bc3-4df7-8a09-765794883524
---
 MdePkg/Library/BaseLib/Arm/SwitchStack.S | 68 ++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 MdePkg/Library/BaseLib/Arm/SwitchStack.S

(limited to 'MdePkg/Library/BaseLib/Arm/SwitchStack.S')

diff --git a/MdePkg/Library/BaseLib/Arm/SwitchStack.S b/MdePkg/Library/BaseLib/Arm/SwitchStack.S
new file mode 100644
index 0000000000..413de99ba5
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Arm/SwitchStack.S
@@ -0,0 +1,68 @@
+//------------------------------------------------------------------------------ 
+//
+// Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
+// Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+// Portions copyright (c) 2011, ARM Limited. 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.
+//
+//------------------------------------------------------------------------------
+  
+.text
+.align 5
+
+GCC_ASM_EXPORT(InternalSwitchStackAsm)
+GCC_ASM_EXPORT(CpuPause)            
+  
+/**
+//
+//  This allows the caller to switch the stack and goes to the new entry point
+//
+// @param      EntryPoint   The pointer to the location to enter
+// @param      Context      Parameter to pass in
+// @param      Context2     Parameter2 to pass in
+// @param      NewStack     New Location of the stack
+//
+// @return     Nothing. Goes to the Entry Point passing in the new parameters
+//
+VOID
+EFIAPI
+InternalSwitchStackAsm (
+  SWITCH_STACK_ENTRY_POINT EntryPoint,
+  VOID  *Context,
+  VOID  *Context2,
+  VOID  *NewStack
+  );
+**/
+ASM_PFX(InternalSwitchStackAsm):
+    MOV   LR, R0
+    MOV   SP, R3
+    MOV   R0, R1
+    MOV   R1, R2
+    BX    LR
+
+/**
+//
+//  Requests CPU to pause for a short period of time.
+//
+//  Requests CPU to pause for a short period of time. Typically used in MP
+//  systems to prevent memory starvation while waiting for a spin lock.
+//
+VOID
+EFIAPI
+CpuPause (
+  VOID
+  )
+**/
+ASM_PFX(CpuPause):
+    nop
+    nop
+    nop
+    nop
+    nop
+    BX    LR
-- 
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