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#*****************************************************************************
#*
#* Copyright (c) 2006 - 2011, 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
#* 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.
#*
#* Module Name:
#*
#* Thunk.asm
#*
#* Abstract:
#*
#* Real mode thunk
#*
#*****************************************************************************
#include <EfiBind.h>
.686p:
.globl ASM_PFX(mCode16Size)
.data
mCode16Size: .long _TEXT16SIZE
.data
NullSegSel: .quad 0
_16BitCsSel:
.word -1
.word 0
.byte 0
.byte 0x9b
.byte 0x8f # 16-bit segment
.byte 0
_16BitSsSel:
.word -1
.word 0
.byte 0
.byte 0x93
.byte 0x8f # 16-bit segment
.byte 0
_16Gdtr:
.word _16Gdtr - NullSegSel - 1
.long NullSegSel
.text
ASM_PFX(Thunk16):
push %ebp
push %ebx
push %esi
push %edi
push %ds
push %es
push %fs
push %gs
mov 0x24(%esp),%esi
movzwl 0x32(%esi),%edx
mov 0xc(%esi),%edi
add $0xffffffb0,%edi
push %edi #; save stack offset
imul $0x10,%edx,%eax #; eax <- edx*16
add %eax,%edi #; edi <- linear address of 16-bit stack
push $0xd
pop %ecx
rep movsl %ds:(%esi),%es:(%edi) #; copy context to 16-bit stack
#; copy eflags to stack frame
mov -12(%esi), %eax
mov %eax, -72(%edi)
pop %ebx #; ebx <- 16-bit stack offset
mov $L_Lable1,%eax
stos %eax,%es:(%edi)
movl %cs,%eax
stos %ax,%es:(%edi)
mov 0x28(%esp),%eax
stos %ax,%es:(%edi)
mov %esp,%eax
stos %eax,%es:(%edi)
movl %ss,%eax
stos %ax,%es:(%edi)
sgdtl (%edi)
sidtl 0x24(%esp)
mov %cr0,%esi
mov %esi,0x6(%edi) #; save CR0
and $0x7ffffffe,%esi #; esi <- CR0 to set
mov %cr4,%eax
mov %eax,0xa(%edi) #; save CR4
and $0xcf,%al #; clear PAE & PSE
mov %edx,%edi #; edi <- 16-bit stack segment
mov 0x2c(%esp),%edx
shl $0x10,%edx
push %edx
pop %edx
mov $(_16BitSsSel - NullSegSel),%dx
lgdtl _16Gdtr #bugbug mismatch.
.byte 0xea
.long L_16Bit #bugbug mismatch.
.word _16BitCsSel - NullSegSel
L_16Bit:
.byte 0x66
movw %dx,%ss
mov %esi,%cr0
mov %eax,%cr4
.byte 0x67
.byte 0xff
.byte 0x6c
.byte 0x24
.byte 0xfc
L_Lable1:
xor %eax,%eax
movw %ss,%ax
shl $0x4,%eax
add %esp,%eax
lss 0x3c(%esp),%esp
lidtl 0x24(%esp)
pop %gs
pop %fs
pop %es
pop %ds
pop %edi
pop %esi
pop %ebx
pop %ebp
ret
.code16
_Code16Addr:
ASM_PFX(RealMode):
movw %di, %ss # set up stack
movl %ebx, %esp
lidt %cs:_16Idtr - _Code16Addr #lidt fword ptr cs:[_16Idtr - _Code16Addr]
.byte 0x66
popaw
popw %ds
popw %es
popw %fs
popw %gs
sub 60, %esp
popfw
testw $1, 74(%esp) #(_STK16 ptr [esp + STACK_PARAM_SIZE + sizeof(IA32_REGS)]).ThunkFlags, 1
jz 1f
pushf # push Flags when it's INT#
1:
pushw %cs
# push @FarCallRet - _Code16Addr
.byte 0x68 # push /iw
.word FarCallRet - _Code16Addr
jz 2f
ljmp *66(%esp) #[esp + 6 + STACK_PARAM_SIZE + sizeof(IA32_REGS) - 8]
2:
ljmp *64(%esp) #[esp + 4 + STACK_PARAM_SIZE + sizeof(IA32_REGS) - 8]
FarCallRet:
add 60, %esp
pushfl
pushw %gs
pushw %fs
pushw %es
pushw %ds
pushal
cli
.byte 0x66 # sizeof (IA32_REGS) = 13 * 4 = 52
lgdt 66(%esp) #lgdt (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr
mov 76(%esp), %eax
movl %eax, %cr4
mov 72(%esp), %eax
movl %eax, %cr0 # restore CR0
ljmpl *52(%esp)
#RealMode ENDP
.text
_16Idtr:
.word 0x3ff #_16Idtr FWORD (1 SHL 10) - 1
.byte 0x00
_TEXT16END:
_TEXT16SIZE = _TEXT16END - _Code16Addr
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