mirror of https://github.com/acidanthera/audk.git
203 lines
6.6 KiB
ArmAsm
203 lines
6.6 KiB
ArmAsm
#------------------------------------------------------------------------------
|
|
#
|
|
# Copyright (c) 2006, Intel Corporation
|
|
# 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.
|
|
#
|
|
# Module Name:
|
|
#
|
|
# Thunk16.S
|
|
#
|
|
# Abstract:
|
|
#
|
|
# Real mode thunk
|
|
#
|
|
#------------------------------------------------------------------------------
|
|
|
|
#include <Library/BaseLib.h>
|
|
|
|
.globl ASM_PFX(m16Start), ASM_PFX(m16Size), ASM_PFX(mThunk16Attr), ASM_PFX(m16Gdt), ASM_PFX(m16GdtrBase), ASM_PFX(mTransition)
|
|
.globl ASM_PFX(InternalAsmThunk16)
|
|
|
|
ASM_PFX(m16Start):
|
|
|
|
SavedGdt: .space 6
|
|
|
|
ASM_PFX(BackFromUserCode):
|
|
push %ss
|
|
push %cs
|
|
.byte 0x66
|
|
call L_Base1 # push eip
|
|
L_Base1:
|
|
pushfw # pushfd actually
|
|
cli # disable interrupts
|
|
push %gs
|
|
push %fs
|
|
push %es
|
|
push %ds
|
|
pushaw # pushad actually
|
|
.byte 0x66, 0xba # mov edx, imm32
|
|
ASM_PFX(ThunkAttr): .space 4
|
|
testb $THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15, %dl
|
|
jz 1f
|
|
movl $0x15cd2401, %eax # mov ax, 2401h & int 15h
|
|
cli # disable interrupts
|
|
jnc 2f
|
|
1:
|
|
testb $THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL, %dl
|
|
jz 2f
|
|
inb $0x92, %al
|
|
orb $2, %al
|
|
outb %al, $0x92 # deactivate A20M#
|
|
2:
|
|
movl %ss, %eax
|
|
.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:0xfffffff2(%edi)
|
|
.byte 0x66, 0xb8 # mov eax, imm32
|
|
SavedCr0: .space 4
|
|
movl %eax, %cr0
|
|
.byte 0xb8 # mov ax, imm16
|
|
SavedSs: .space 2
|
|
movl %eax, %ss
|
|
.byte 0x66, 0xbc # mov esp, imm32
|
|
SavedEsp: .space 4
|
|
.byte 0x66
|
|
lret # return to protected mode
|
|
|
|
_EntryPoint: .long ASM_PFX(ToUserCode) - ASM_PFX(m16Start)
|
|
.word 0x8
|
|
_16Idtr: .word 0x3ff
|
|
.long 0
|
|
_16Gdtr: .word GdtEnd - _NullSegDesc - 1
|
|
_16GdtrBase: .long _NullSegDesc
|
|
|
|
ASM_PFX(ToUserCode):
|
|
movl %ss, %edx
|
|
movl %ecx, %ss # set new segment selectors
|
|
movl %ecx, %ds
|
|
movl %ecx, %es
|
|
movl %ecx, %fs
|
|
movl %ecx, %gs
|
|
movl %eax, %cr0
|
|
movl %ebp, %cr4 # real mode starts at next instruction
|
|
movl %esi, %ss # set up 16-bit stack segment
|
|
xchgw %bx, %sp # set up 16-bit stack pointer
|
|
.byte 0x66
|
|
call L_Base # push eip
|
|
L_Base:
|
|
popw %bp # ebp <- offset L_Base
|
|
.byte 0x67; # address size override
|
|
push 54(%esp)
|
|
lea 0xc(%esi), %eax
|
|
push %eax
|
|
lret
|
|
|
|
L_RealMode:
|
|
mov %edx, %cs:0xffffffc5(%esi)
|
|
mov %bx, %cs:0xffffffcb(%esi)
|
|
lidtw %cs:0xffffffd7(%esi)
|
|
popaw # popad actually
|
|
pop %ds
|
|
pop %es
|
|
pop %fs
|
|
pop %gs
|
|
popfw # popfd
|
|
lretw # transfer control to user code
|
|
|
|
_NullSegDesc: .quad 0
|
|
_16CsDesc:
|
|
.word -1
|
|
.word 0
|
|
.byte 0
|
|
.byte 0x9b
|
|
.byte 0x8f # 16-bit segment, 4GB limit
|
|
.byte 0
|
|
_16DsDesc:
|
|
.word -1
|
|
.word 0
|
|
.byte 0
|
|
.byte 0x93
|
|
.byte 0x8f # 16-bit segment, 4GB limit
|
|
.byte 0
|
|
GdtEnd:
|
|
|
|
#
|
|
# @param RegSet Pointer to a IA32_DWORD_REGS structure
|
|
# @param Transition Pointer to the transition code
|
|
# @return The address of the 16-bit stack after returning from user code
|
|
#
|
|
ASM_PFX(InternalAsmThunk16):
|
|
push %ebp
|
|
push %ebx
|
|
push %esi
|
|
push %edi
|
|
push %ds
|
|
push %es
|
|
push %fs
|
|
push %gs
|
|
movl 36(%esp), %esi # esi <- RegSet
|
|
movzwl 0x32(%esi), %edx
|
|
mov 0xc(%esi), %edi
|
|
add $0xffffffc8, %edi
|
|
movl %edi, %ebx # ebx <- stack offset
|
|
imul $0x10, %edx, %eax
|
|
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 0x5e(%eax), %edx
|
|
movl %eax, %ecx
|
|
andl $0xf, %ecx
|
|
shll $12, %eax
|
|
lea 0x6(%ecx), %ecx
|
|
movw %cx, %ax
|
|
stosl # [edi] <- return address of user code
|
|
sgdtl 0xffffffa2(%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, 0xfffffff1(%edx)
|
|
andl $0x300, %ebp # clear all but PCE and OSFXSR bits
|
|
pushl $0x10
|
|
pop %ecx # ecx <- selector for data segments
|
|
lgdtl 0x20(%edx)
|
|
pushfl
|
|
lcall *0x14(%edx)
|
|
popfl
|
|
lidtl 0x24(%esp)
|
|
lea 0xffffffcc(%ebp), %eax
|
|
pop %gs
|
|
pop %fs
|
|
pop %es
|
|
pop %ds
|
|
pop %edi
|
|
pop %esi
|
|
pop %ebx
|
|
pop %ebp
|
|
ret
|
|
|
|
.const:
|
|
|
|
ASM_PFX(m16Size): .word _InternalAsmThunk16 - ASM_PFX(m16Start)
|
|
ASM_PFX(mThunk16Attr): .word _ThunkAttr - ASM_PFX(m16Start)
|
|
ASM_PFX(m16Gdt): .word _NullSegDesc - ASM_PFX(m16Start)
|
|
ASM_PFX(m16GdtrBase): .word _16GdtrBase - ASM_PFX(m16Start)
|
|
ASM_PFX(mTransition): .word _EntryPoint - ASM_PFX(m16Start)
|