mirror of https://github.com/acidanthera/audk.git
184 lines
4.9 KiB
ArmAsm
184 lines
4.9 KiB
ArmAsm
#*****************************************************************************
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#*
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#* Copyright (c) 2006 - 2007, Intel Corporation
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#* All rights reserved. This program and the accompanying materials
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#* are licensed and made available under the terms and conditions of the BSD License
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#* which accompanies this distribution. The full text of the license may be found at
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#* http://opensource.org/licenses/bsd-license.php
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#*
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#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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#*
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#* Module Name:
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#*
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#* Thunk.asm
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#*
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#* Abstract:
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#*
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#* Real mode thunk
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#*
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#*****************************************************************************
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#include <EfiBind.h>
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.686p:
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.globl ASM_PFX(mCode16Size)
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.data
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mCode16Size: .long _TEXT16SIZE
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.data
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NullSegSel: .quad 0
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_16BitCsSel:
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.word -1
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.word 0
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.byte 0
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.byte 0x9b
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.byte 0x8f # 16-bit segment
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.byte 0
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_16BitSsSel:
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.word -1
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.word 0
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.byte 0
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.byte 0x93
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.byte 0x8f # 16-bit segment
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.byte 0
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_16Gdtr:
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.word _16Gdtr - NullSegSel - 1
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.long NullSegSel
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.text
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.align 16
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ASM_PFX(Thunk16):
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push %ebp
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push %ebx
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push %esi
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push %edi
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push %ds
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push %es
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push %fs
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push %gs
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mov 0x24(%esp),%esi
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movzwl 0x32(%esi),%edx
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mov 0xc(%esi),%edi
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add $0xffffffb0,%edi
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push %edi #; save stack offset
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imul $0x10,%edx,%eax #; eax <- edx*16
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add %eax,%edi #; edi <- linear address of 16-bit stack
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push $0xd
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pop %ecx
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rep movsl %ds:(%esi),%es:(%edi) #; copy context to 16-bit stack
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pop %ebx #; ebx <- 16-bit stack offset
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mov $L_Label1,%eax
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stos %eax,%es:(%edi)
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movl %cs,%eax
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stos %ax,%es:(%edi)
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mov 0x28(%esp),%eax
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stos %ax,%es:(%edi)
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mov %esp,%eax
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stos %eax,%es:(%edi)
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movl %ss,%eax
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stos %ax,%es:(%edi)
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sgdtl (%edi)
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sidtl 0x24(%esp)
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mov %cr0,%esi
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mov %esi,0x6(%edi) #; save CR0
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and $0x7ffffffe,%esi #; esi <- CR0 to set
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mov %cr4,%eax
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mov %eax,0xa(%edi) #; save CR4
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and $0xcf,%al #; clear PAE & PSE
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mov %edx,%edi #; edi <- 16-bit stack segment
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mov 0x2c(%esp),%edx
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shl $0x10,%edx
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push %edx
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pop %edx
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mov $(_16BitSsSel - NullSegSel),%dx
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lgdtl _16Gdtr #bugbug mismatch.
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.byte 0xea
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.long L_16Bit #bugbug mismatch.
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.word _16BitCsSel - NullSegSel
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L_16Bit:
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.byte 0x66
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movw %dx,%ss
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mov %esi,%cr0
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mov %eax,%cr4
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.byte 0x67
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.byte 0xff
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.byte 0x6c
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.byte 0x24
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.byte 0xfc
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L_Lable1:
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movl %ss,%eax
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shl $0x4,%eax
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add %esp,%eax
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lss 0x3c(%esp),%esp
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lidtl 0x24(%esp)
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pop %gs
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pop %fs
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pop %es
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pop %ds
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pop %edi
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pop %esi
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pop %ebx
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pop %ebp
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ret
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.code16
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_Code16Addr:
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ASM_PFX(RealMode):
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movw %di, %ss # set up stack
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movl %ebx, %esp
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lidt %cs:_16Idtr - _Code16Addr #lidt fword ptr cs:[_16Idtr - _Code16Addr]
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.byte 0x66
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popaw
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popw %ds
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popw %es
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popw %fs
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popw %gs
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addw $4, %sp # skip EFlags
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testw $1, 14(%esp) #(_STK16 ptr [esp + 8]).ThunkFlags, 1
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jz 1f
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pushf
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1:
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pushw %cs
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# push @FarCallRet - _Code16Addr
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.byte 0x68 # push /iw
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.word FarCallRet - _Code16Addr
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jz 2f
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ljmp *6(%esp) #bugbug
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2:
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ljmp *4(%esp) #bugbug
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FarCallRet:
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pushfl
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pushw %gs
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pushw %fs
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pushw %es
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pushw %ds
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pushal
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cli
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.byte 0x66 # sizeof (IA32_REGS) = 13 * 4 = 52
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lgdt 66(%esp) #lgdt (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr
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mov 76(%esp), %eax
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movl %eax, %cr4
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mov 72(%esp), %eax
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movl %eax, %cr0 # restore CR0
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ljmpl *52(%esp)
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#RealMode ENDP
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.text
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_16Idtr:
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.word 0x3ff #_16Idtr FWORD (1 SHL 10) - 1
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.byte 0x00
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_TEXT16END:
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_TEXT16SIZE = _TEXT16END - _Code16Addr
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