#------------------------------------------------------------------------------

#

# Copyright (c) 2006 - 2009, 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:

#

# DisablePaging64.S

#

# Abstract:

#

# AsmDisablePaging64 function

#

# Notes:

#

#------------------------------------------------------------------------------

#------------------------------------------------------------------------------

# VOID

# EFIAPI

# InternalX86DisablePaging64 (

# IN UINT16 Cs,

# IN UINT32 EntryPoint,

# IN UINT32 Context1, OPTIONAL

# IN UINT32 Context2, OPTIONAL

# IN UINT32 NewStack

# );

#------------------------------------------------------------------------------

ASM_GLOBAL ASM_PFX(InternalX86DisablePaging64)

ASM_PFX(InternalX86DisablePaging64):

cli

lea L1(%rip), %rsi # rsi <- The start address of transition code

mov 0x28(%rsp), %edi # rdi <- New stack

lea _mTransitionEnd(%rip), %rax # rax <- end of transition code

sub %rsi, %rax # rax <- The size of transition piece code

add $4, %rax # round rax up to the next 4 byte boundary

and $0xfc, %al

sub %rax, %rdi # rdi <- use stack to hold transition code

mov %edi, %r10d # r10 <- The start address of transicition code below 4G

push %rcx # save rcx to stack

mov %rax, %rcx # rcx <- The size of transition piece code

rep

movsb # copy transition code to (new stack - 64byte) below 4G

pop %rcx # restore rcx

mov %r8d, %esi

mov %r9d, %edi

mov %r10d, %eax

sub $4, %eax

push %rcx # push Cs to stack

push %r10 # push address of transition code on stack

.byte 0x48, 0xcb # retq: Use far return to load CS register from stack

# (Use raw byte code since some GNU assemblers generates incorrect code for "retq")

L1:

mov %eax,%esp # set up new stack

mov %cr0,%rax

btr $0x1f,%eax # clear CR0.PG

mov %rax,%cr0 # disable paging

mov %edx,%ebx # save EntryPoint to ebx, for rdmsr will overwrite edx

mov $0xc0000080,%ecx

rdmsr

and $0xfe,%ah # clear LME

wrmsr

mov %cr4,%rax

and $0xdf,%al # clear PAE

mov %rax,%cr4

push %rdi # push Context2

push %rsi # push Context1

callq *%rbx # transfer control to EntryPoint

jmp . # no one should get here

_mTransitionEnd :