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

2 files changed, 68 insertions, 76 deletions

diff --git a/MdePkg/Library/BaseLib/Arm/GccInline.c b/MdePkg/Library/BaseLib/Arm/GccInline.c
deleted file mode 100644
index 0c6b016042..0000000000
--- a/MdePkg/Library/BaseLib/Arm/GccInline.c
+++ /dev/null
@@ -1,76 +0,0 @@
-/** @file

-  GCC inline implementation of BaseLib processor specific functions.

-  

-  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>

-  Portions copyright (c) 2008 - 2009, Apple Inc. 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.

-

-**/

-

-#include "BaseLibInternals.h"

-

-/**

-  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__ __volatile__ (

-    "nop\n\t"

-    "nop\n\t"

-    "nop\n\t"

-    "nop\n\t"

-    "nop\n\t"

-    );

-}

-

-/**

-  Transfers control to a function starting with a new stack.

-

-  This internal worker function transfers control to the function

-  specified by EntryPoint using the new stack specified by NewStack

-  and passing in the parameters specified by Context1 and Context2.

-  Context1 and Context2 are optional and may be NULL.

-  The function EntryPoint must never return.

-

-  @param EntryPoint   The pointer to the function to enter.

-  @param Context1     The first parameter to pass in.

-  @param Context2     The second Parameter to pass in

-  @param NewStack     The new Location of the stack

-

-**/

-VOID

-EFIAPI

-InternalSwitchStackAsm (

-  SWITCH_STACK_ENTRY_POINT EntryPoint,

-  VOID  *Context1,

-  VOID  *Context2,

-  VOID  *NewStack

-  )

-{

-  __asm__ __volatile__ (

-    "mov  lr, %0\n\t"

-    "mov  sp, %3\n\t"

-    "mov  %r0, %1\n\t"

-    "mov  %r1, %2\n\t"

-    "bx   lr\n\t"

-    : /* no output operand */

-    : "r" (EntryPoint),

-      "r" (Context1),

-      "r" (Context2),

-      "r" (NewStack)

-    );

-}

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