mirror of https://github.com/acidanthera/audk.git
237 lines
6.8 KiB
ArmAsm
237 lines
6.8 KiB
ArmAsm
#*****************************************************************************
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#*
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#* Copyright (c) 2008 - 2009, 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.S
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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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.data
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.globl ASM_PFX(mCode16Size)
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.data
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mCode16Size: .long _Code16End - _Code16Addr
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NullSegSel: .quad 0
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_16CsSegSel:
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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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_16DsSegSel:
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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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.code:
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#IA32_REGS STRUC 4t
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#_EDI DD ?
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#_ESI DD ?
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#_EBP DD ?
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#_ESP DD ?
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#_EBX DD ?
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#_EDX DD ?
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#_ECX DD ?
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#_EAX DD ?
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#_DS DW ?
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#_ES DW ?
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#_FS DW ?
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#_GS DW ?
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#_RFLAGS DQ ?
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#_EIP DD ?
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#_CS DW ?
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#_SS DW ?
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#IA32_REGS ENDS
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#_STK16 STRUC 1t
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#RetEip DD ?
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#RetCs DW ?
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#ThunkFlags DW ?
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#SavedGdtr FWORD ?
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#Resvd1 DW ?
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#SavedCr0 DD ?
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#SavedCr4 DD ?
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#_STK16 ENDS
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ASM_PFX(Thunk16):
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push %rbp
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push %rbx
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push %rsi
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push %rdi
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push %r12
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push %r13
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push %r14
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push %r15
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pushq %fs
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pushq %gs
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movl %ds,%r12d
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movl %es,%r13d
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movl %ss,%r14d
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mov %rsp,%r15
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mov %rcx,%rsi
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movzwq 0x36(%rsi),%r10 #movzx r10, (IA32_REGS ptr [rsi])._SS
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xor %rdi,%rdi
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mov 0xc(%rsi),%edi #mov edi, (IA32_REGS ptr [rsi])._ESP
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add $0xffffffffffffffb0,%rdi #add rdi, - sizeof (IA32_REGS) - sizeof (_STK16)
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push %rdi
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imul $0x10,%r10,%rax
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add %rax,%rdi
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pushq $0xe #push sizeof (IA32_REGS) / 4
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pop %rcx
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rep movsl %ds:(%rsi),%es:(%rdi)
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pop %rbx #rbx <- 16-bit stack offset
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lea Label,%eax #42 <_Thunk16+0x42>
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stos %eax,%es:(%rdi)
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movl %cs,%eax #return segment
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stos %ax,%es:(%rdi)
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mov %edx,%eax #THUNK Flags
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stos %ax,%es:(%rdi)
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sgdt 0x58(%rsp) #save GDTR
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mov 0x58(%rsp),%rax
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stos %rax,%es:(%rdi)
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mov %cr0,%rax #save CR0
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mov %eax,%esi #esi <- CR0 to set
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stos %eax,%es:(%rdi)
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mov %cr4,%rax #save CR4
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stos %eax,%es:(%rdi)
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sidt 0x58(%rsp) #save IDTR
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and $0x7ffffffe,%esi #clear PE & PG bits
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mov %r10,%rdi #rdi <- 16-bit stack segment
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shl $0x10,%r8
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push %r8 #far jmp address
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lea Label_16Bit,%eax
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push %rax
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movw $0x8,0x4(%rsp)
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lgdt _16Gdtr #bugbug: may not match.
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lret
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Label_16Bit:
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.byte 0x66
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movl $0xc0000080,%ecx
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mov %rsi,%cr0 #disable PE & PG
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rdmsr
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and $0xfe,%ah
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wrmsr #clear LME bit
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mov %cr4,%rax
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and $0xcf,%al #clear PAE & PSE
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mov %rax,%cr4
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lret
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Label:
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xor %rax,%rax
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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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mov %r15,%rsp
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lidt 0x58(%rsp)
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movl %r12d,%ds
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movl %r13d,%es
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movl %r14d,%ss
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popq %gs
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popq %fs
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pop %r15
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pop %r14
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pop %r13
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pop %r12
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pop %rdi
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pop %rsi
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pop %rbx
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pop %rbp
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retq
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.p2align 4
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_Code16Addr:
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ASM_PFX(RealMode):
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movl %edi,%ss
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mov %bx,%sp #set up 16-bit stack
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.byte 0x2e
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.byte 0x0f
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.byte 0x01
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.byte 0x1e
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.word _16Idtr - _Code16Addr #lidt _16Idtr
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.byte 0x66
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.byte 0x61 #popad
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.byte 0x1f #pop ds
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.byte 0x07 #pop es
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popq %fs
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popq %gs
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add $0x8,%esp #skip RFLAGS
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.byte 0x67 #test [esp + 0eh], 1
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.byte 0xf7
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.byte 0x44
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.byte 0x24
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.byte 0x0e
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.byte 0x01
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.byte 0x00
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jz 1f
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pushfq #pushf, actually
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1:
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.byte 0x0e #push cs
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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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.byte 0x66
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ljmp *6(%esp)
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2:
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.byte 0x66
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ljmp *4(%esp)
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FarCallRet:
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.byte 0x66
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push $0x00 #push a dword of zero
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.byte 0x66
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pushf #pushfd, actually
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pushq %gs
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pushq %fs
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.byte 0x06 #push %es
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.byte 0x1e #push %ds
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.byte 0x66
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.byte 0x60
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cli
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.byte 0x66 #sizeof (IA32_REGS) = 13 * 4 = 52
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lgdt 64(%esp) #lgdt (_STK16 ptr [esp + sizeof (IA32_REGS)]).SavedGdtr
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.byte 0x66
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mov 76(%esp), %eax
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mov %rax, %cr4
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.byte 0x66
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mov $0xc0000080, %ecx
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rdmsr
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orb $1, %ah
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wrmsr
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.byte 0x66
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mov 72(%esp), %eax
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mov %rax, %cr0 #restore CR0
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.byte 0x66
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ljmpl *52(%esp)
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_16Idtr:
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.word 0x3ff #FWORD (1 SHL 10) - 1
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.byte 0x00
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