From 30817eb4e418ea36a7245fddb2efdeab9526f455 Mon Sep 17 00:00:00 2001
From: vanjeff <vanjeff@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Fri, 30 Jun 2006 08:40:03 +0000
Subject: 1.Updated some functions header of BaseLib with new MWG spec
 2.Rollback EnablePaging64.asm

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@669 6f19259b-4bc3-4df7-8a09-765794883524
---
 MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm | 39 ++++++++------------------
 1 file changed, 12 insertions(+), 27 deletions(-)

(limited to 'MdePkg/Library/BaseLib/Ia32')

diff --git a/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm b/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm
index 97d859e966..6c9b0ea76b 100644
--- a/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm
+++ b/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm
@@ -26,13 +26,9 @@
     .code
 
 InternalX86EnablePaging64 PROC
-    cli
-
-    mov     ebx, [esp + 4]              ; save CS
-    mov     eax, OFFSET cs_address
-    mov     word ptr [eax], bx          ; Update CS selector for far jump
-
-    mov     eax, cr4 
+    cli
+    mov     [esp], @F                   ; offset for far retf
+    mov     eax, cr4
     or      al, (1 SHL 5)
     mov     cr4, eax                    ; enable PAE
     mov     ecx, 0c0000080h
@@ -41,30 +37,19 @@ InternalX86EnablePaging64 PROC
     wrmsr
     mov     eax, cr0
     bts     eax, 31
-    mov     cr0, eax                    ; enable paging
-    retf
-    jmp     go_to_long_mode
-go_to_long_mode:
-
-    ;
-    ; This is the next instruction after enabling paging.  Jump to long mode
-    ;
-    db      067h
-    db      0eah                        ;   Far Jump Offset:Selector to reload CS
-    dd      OFFSET in_long_mode         ;   Offset is ensuing instruction boundary
-cs_address:
-    dw      0h                          ;   CS selector will be updated at runtime 
-
-in_long_mode:                           ; now in long mode
+    mov     cr0, eax                    ; enable paging
+    retf
+@@:                                     ; long mode starts here
+    DB      67h, 48h
+    mov     ebx, [esp]                  ; mov rbx, [esp]
     DB      67h, 48h
-    mov     ebx, [esp + 8]              ; mov rbx, [esp]
-    DB      67h, 48h
                   
-    mov     ecx, [esp + 10h]            ; mov rcx, [esp + 8]
+    mov     ecx, [esp + 8]              ; mov rcx, [esp + 8]
     DB      67h, 48h
-    mov     edx, [esp + 18h]            ; mov rdx, [esp + 10h]
+    mov     edx, [esp + 10h]            ; mov rdx, [esp + 10h]
     DB      67h, 48h
-    mov     esp, [esp + 20h]            ; mov rsp, [esp + 18h]
+    mov     esp, [esp + 18h]            ; mov rsp, [esp + 18h]
     DB      48h
+    add     esp, -20h                   ; add rsp, -20h
     call    ebx                         ; call rbx
     jmp     $
 InternalX86EnablePaging64 ENDP
-- 
cgit v1.2.3