From 48c8b6a299918612436e84ab22b55be6b88a90a2 Mon Sep 17 00:00:00 2001
From: li-elvin <li-elvin@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Mon, 7 Jan 2013 07:12:19 +0000
Subject: [PATCH] Current Thunk16.asm implementation clears reserved bits,
 which does not follow IA32 SDM. Now the fix is to only clear PAE and PSE bit
 of CR4 for real mode.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14037 6f19259b-4bc3-4df7-8a09-765794883524
---
 MdePkg/Library/BaseLib/Ia32/Thunk16.S   | 4 ++--
 MdePkg/Library/BaseLib/Ia32/Thunk16.asm | 4 ++--
 MdePkg/Library/BaseLib/X64/Thunk16.S    | 4 ++--
 MdePkg/Library/BaseLib/X64/Thunk16.asm  | 4 ++--
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.S b/MdePkg/Library/BaseLib/Ia32/Thunk16.S
index 0555cf1bfd..8356c5a1c7 100644
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.S
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.S
@@ -1,6 +1,6 @@
 #------------------------------------------------------------------------------
 #
-# Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2006 - 2013, 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
@@ -175,7 +175,7 @@ ASM_PFX(InternalAsmThunk16):
     andl    $0x7ffffffe, %eax           # clear PE, PG bits
     movl    %cr4, %ebp
     mov     %ebp, 0xfffffff1(%edx)
-    andl    $0x300, %ebp                # clear all but PCE and OSFXSR bits
+    andl    $0xffffffcf, %ebp           # clear PAE, PSE bits
     pushl   $0x10
     pop     %ecx                        # ecx <- selector for data segments
     lgdtl   0x20(%edx)
diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
index 6df0a4a46a..3e84aedf3d 100644
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
@@ -3,7 +3,7 @@
 
 ;------------------------------------------------------------------------------
 ;
-; Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2006 - 2013, 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
@@ -237,7 +237,7 @@ InternalAsmThunk16  PROC    USES    ebp ebx esi edi ds  es  fs  gs
     and     eax, 7ffffffeh              ; clear PE, PG bits
     mov     ebp, cr4
     mov     [edx + (SavedCr4 - SavedCr0)], ebp
-    and     ebp, 300h                   ; clear all but PCE and OSFXSR bits
+    and     ebp, NOT 30h                ; clear PAE, PSE bits
     push    10h
     pop     ecx                         ; ecx <- selector for data segments
     lgdt    fword ptr [edx + (_16Gdtr - SavedCr0)]
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.S b/MdePkg/Library/BaseLib/X64/Thunk16.S
index d037a71043..a521aff31b 100644
--- a/MdePkg/Library/BaseLib/X64/Thunk16.S
+++ b/MdePkg/Library/BaseLib/X64/Thunk16.S
@@ -1,6 +1,6 @@
 #------------------------------------------------------------------------------
 #
-# Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2006 - 2013, 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
@@ -295,7 +295,7 @@ ASM_PFX(InternalAsmThunk16):
     andl    $0x7ffffffe,%eax            # clear PE, PG bits
     movq    %cr4, %rbp
     movl    %ebp, (%rcx)                # save CR4 in SavedCr4
-    andl    $0x300,%ebp                 # clear all but PCE and OSFXSR bits
+    andl    $0xffffffcf,%ebp            # clear PAE, PSE bits
     movl    %r8d, %esi                  # esi <- 16-bit stack segment
     .byte      0x6a, DATA32
     popq    %rdx
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.asm b/MdePkg/Library/BaseLib/X64/Thunk16.asm
index 8b208fdb58..01051341f6 100644
--- a/MdePkg/Library/BaseLib/X64/Thunk16.asm
+++ b/MdePkg/Library/BaseLib/X64/Thunk16.asm
@@ -3,7 +3,7 @@
 
 ;------------------------------------------------------------------------------
 ;
-; Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2006 - 2013, 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
@@ -282,7 +282,7 @@ InternalAsmThunk16  PROC    USES    rbp rbx rsi rdi
     and     eax, 7ffffffeh              ; clear PE, PG bits
     mov     rbp, cr4
     mov     [rcx], ebp                  ; save CR4 in SavedCr4
-    and     ebp, 300h                   ; clear all but PCE and OSFXSR bits
+    and     ebp, NOT 30h                ; clear PAE, PSE bits
     mov     esi, r8d                    ; esi <- 16-bit stack segment
     DB      6ah, DATA32                 ; push DATA32
     pop     rdx                         ; rdx <- 32-bit data segment selector
-- 
2.39.2