From c8641de387850f5a0c0666b51efaa495bc3a277d Mon Sep 17 00:00:00 2001
From: lgao4 <lgao4@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Wed, 28 Dec 2011 09:48:15 +0000
Subject: Roll back the previous change in MdePkg BaseLib Ia32 Thunk16.S and
 EcpPkg GlueLib BaseLib Ia32 Thunk16.S, and still use the hard code offset in
 them to avoid GCC compiler create the unexpected instruction.

Signed-off-by: lgao4
Reviewed-by: rsun3



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12898 6f19259b-4bc3-4df7-8a09-765794883524
---
 .../EdkIIGlueLib/Library/BaseLib/Ia32/Thunk16.S    | 63 +++++++---------------
 1 file changed, 20 insertions(+), 43 deletions(-)

(limited to 'EdkCompatibilityPkg')

diff --git a/EdkCompatibilityPkg/Foundation/Library/EdkIIGlueLib/Library/BaseLib/Ia32/Thunk16.S b/EdkCompatibilityPkg/Foundation/Library/EdkIIGlueLib/Library/BaseLib/Ia32/Thunk16.S
index a2ba94bdaa..0f144e714b 100644
--- a/EdkCompatibilityPkg/Foundation/Library/EdkIIGlueLib/Library/BaseLib/Ia32/Thunk16.S
+++ b/EdkCompatibilityPkg/Foundation/Library/EdkIIGlueLib/Library/BaseLib/Ia32/Thunk16.S
@@ -24,27 +24,6 @@
 .globl ASM_PFX(m16Start), ASM_PFX(m16Size), ASM_PFX(mThunk16Attr), ASM_PFX(m16Gdt), ASM_PFX(m16GdtrBase), ASM_PFX(mTransition)
 .globl ASM_PFX(InternalAsmThunk16)
 
-# define the structure of IA32_REGS
-.set  _EDI, 0       #size 4
-.set  _ESI, 4       #size 4
-.set  _EBP, 8       #size 4
-.set  _ESP, 12      #size 4
-.set  _EBX, 16      #size 4
-.set  _EDX, 20      #size 4
-.set  _ECX, 24      #size 4
-.set  _EAX, 28      #size 4
-.set  _DS,  32      #size 2
-.set  _ES,  34      #size 2
-.set  _FS,  36      #size 2
-.set  _GS,  38      #size 2
-.set  _EFLAGS, 40   #size 4
-.set  _EIP, 44      #size 4
-.set  _CS, 48       #size 2
-.set  _SS, 50       #size 2
-.set  IA32_REGS_SIZE, 52
-
-    .text
-
 ASM_PFX(m16Start):
 
 SavedGdt:     .space  6
@@ -78,17 +57,15 @@ ASM_PFX(ThunkAttr): .space  4
 2:
     xorw    %ax, %ax                    # xor eax, eax
     movl    %ss, %eax                   # mov ax, ss
-    .byte   0x67
-    lea     IA32_REGS_SIZE(%esp), %bp
-    .byte   0x66
-    mov     %ebp, (_ESP - IA32_REGS_SIZE)(%esi)
-    mov     (_EIP - IA32_REGS_SIZE)(%esi), %ebx
+    .byte   0x67, 0x66, 0x8d, 0x6c, 0x24, 0x34, 0x66
+    mov     %ebp, 0xffffffd8(%esi)
+    mov     0xfffffff8(%esi), %ebx
     shlw    $4, %ax                     # shl eax, 4
     addw    %ax, %bp                    # add ebp, eax
     .byte   0x66, 0xb8                   # mov eax, imm32
 SavedCr4:   .space  4
     movl    %eax, %cr4
-    lgdtw   %cs:(SavedGdt - L_Base1)(%edi)
+    lgdtw   %cs:0xfffffff2(%edi)
     .byte   0x66, 0xb8                   # mov eax, imm32
 SavedCr0:   .space  4
     movl    %eax, %cr0
@@ -123,15 +100,15 @@ ASM_PFX(ToUserCode):
 L_Base:
     popw    %bp                         # ebp <- offset L_Base
     .byte   0x67;                       # address size override
-    push    (IA32_REGS_SIZE + 2)(%esp)
-    lea     (L_RealMode - L_Base)(%esi), %eax
+    push    54(%esp)
+    lea     0xc(%esi), %eax
     push    %eax
     lret
 
 L_RealMode:
-    mov     %edx, %cs:(SavedSs - L_Base)(%esi)
-    mov     %bx, %cs:(SavedEsp - L_Base)(%esi)
-    lidtw   %cs:(_16Idtr - L_Base)(%esi)
+    mov     %edx, %cs:0xffffffc5(%esi)
+    mov     %bx, %cs:0xffffffcb(%esi)
+    lidtw   %cs:0xffffffd7(%esi)
     popaw                               # popad actually
     pop     %ds
     pop     %es
@@ -172,41 +149,41 @@ ASM_PFX(InternalAsmThunk16):
     push    %fs
     push    %gs
     movl    36(%esp), %esi              # esi <- RegSet
-    movzwl  _SS(%esi), %edx
-    mov     _ESP(%esi), %edi
-    add     $(-(IA32_REGS_SIZE + 4)), %edi
+    movzwl  0x32(%esi), %edx
+    mov     0xc(%esi), %edi
+    add     $0xffffffc8, %edi
     movl    %edi, %ebx                  # ebx <- stack offset
     imul    $0x10, %edx, %eax
-    push    $(IA32_REGS_SIZE / 4)
+    push    $0xd
     addl    %eax, %edi                  # edi <- linear address of 16-bit stack
     pop     %ecx
     rep
     movsl                               # copy RegSet
     movl    40(%esp), %eax              # eax <- address of transition code
     movl    %edx, %esi                  # esi <- 16-bit stack segment
-    lea     (SavedCr0 - ASM_PFX(m16Start))(%eax), %edx
+    lea     0x61(%eax), %edx
     movl    %eax, %ecx
     andl    $0xf, %ecx
     shll    $12, %eax
-    lea     (ASM_PFX(BackFromUserCode) - ASM_PFX(m16Start))(%ecx), %ecx
+    lea     0x6(%ecx), %ecx
     movw    %cx, %ax
     stosl                               # [edi] <- return address of user code
-    sgdtl   (SavedGdt - SavedCr0)(%edx)
+    sgdtl   0xffffff9f(%edx)
     sidtl   0x24(%esp)
     movl    %cr0, %eax
     movl    %eax, (%edx)                # save CR0 in SavedCr0
     andl    $0x7ffffffe, %eax           # clear PE, PG bits
     movl    %cr4, %ebp
-    mov     %ebp, (SavedCr4 - SavedCr0)(%edx)
+    mov     %ebp, 0xfffffff1(%edx)
     andl    $0x300, %ebp                # clear all but PCE and OSFXSR bits
     pushl   $0x10
     pop     %ecx                        # ecx <- selector for data segments
-    lgdtl   (_16Gdtr - SavedCr0)(%edx)
+    lgdtl   0x20(%edx)
     pushfl
-    lcall   *(_EntryPoint - SavedCr0)(%edx)
+    lcall   *0x14(%edx)
     popfl
     lidtl   0x24(%esp)
-    lea     -IA32_REGS_SIZE(%ebp), %eax
+    lea     0xffffffcc(%ebp), %eax
     pop     %gs
     pop     %fs
     pop     %es
-- 
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