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#------------------------------------------------------------------------------
#
# Copyright (c) 2009 - 2015, 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:
#
# SmiEntry.S
#
# Abstract:
#
# Code template of the SMI handler for a particular processor
#
#------------------------------------------------------------------------------
ASM_GLOBAL ASM_PFX(gcSmiHandlerTemplate)
ASM_GLOBAL ASM_PFX(gcSmiHandlerSize)
ASM_GLOBAL ASM_PFX(gSmiCr3)
ASM_GLOBAL ASM_PFX(gSmiStack)
ASM_GLOBAL ASM_PFX(gSmbase)
ASM_GLOBAL ASM_PFX(gSmiHandlerIdtr)
#
# Constants relating to PROCESSOR_SMM_DESCRIPTOR
#
.equ DSC_OFFSET, 0xfb00
.equ DSC_GDTPTR, 0x30
.equ DSC_GDTSIZ, 0x38
.equ DSC_CS, 14
.equ DSC_DS, 16
.equ DSC_SS, 18
.equ DSC_OTHERSEG, 20
#
# Constants relating to CPU State Save Area
#
.equ SSM_DR6, 0xffd0
.equ SSM_DR7, 0xffc8
.equ PROTECT_MODE_CS, 0x08
.equ PROTECT_MODE_DS, 0x20
.equ LONG_MODE_CS, 0x38
.equ TSS_SEGMENT, 0x40
.equ GDT_SIZE, 0x50
.text
ASM_PFX(gcSmiHandlerTemplate):
_SmiEntryPoint:
#
# The encoding of BX in 16-bit addressing mode is the same as of RDI in 64-
# bit addressing mode. And that coincidence has been used in the following
# "64-bit like" 16-bit code. Be aware that once RDI is referenced as a
# base address register, it is actually BX that is referenced.
#
.byte 0xbb # mov bx, imm16
.word _GdtDesc - _SmiEntryPoint + 0x8000
#
# fix GDT descriptor
#
.byte 0x2e,0xa1 # mov ax, cs:[offset16]
.word DSC_OFFSET + DSC_GDTSIZ
.byte 0x48 # dec ax
.byte 0x2e
movl %eax, (%rdi) # mov cs:[bx], ax
.byte 0x66,0x2e,0xa1 # mov eax, cs:[offset16]
.word DSC_OFFSET + DSC_GDTPTR
.byte 0x2e
movw %ax, 2(%rdi)
.byte 0x66,0x2e
lgdt (%rdi)
#
# Patch ProtectedMode Segment
#
.byte 0xb8
.word PROTECT_MODE_CS
.byte 0x2e
movl %eax, -2(%rdi)
#
# Patch ProtectedMode entry
#
.byte 0x66, 0xbf # mov edi, SMBASE
ASM_PFX(gSmbase): .space 4
lea ((ProtectedMode - _SmiEntryPoint) + 0x8000)(%edi), %ax
.byte 0x2e
movw %ax, -6(%rdi)
#
# Switch into ProtectedMode
#
movq %cr0, %rbx
.byte 0x66
andl $0x9ffafff3, %ebx
.byte 0x66
orl $0x00000023, %ebx
movq %rbx, %cr0
.byte 0x66, 0xea
.space 6
_GdtDesc: .space 6
ProtectedMode:
movw $PROTECT_MODE_DS, %ax
movl %eax, %ds
movl %eax, %es
movl %eax, %fs
movl %eax, %gs
movl %eax, %ss
.byte 0xbc # mov esp, imm32
ASM_PFX(gSmiStack): .space 4
jmp ProtFlatMode
ProtFlatMode:
.byte 0xb8
ASM_PFX(gSmiCr3): .space 4
movq %rax, %cr3
movl $0x668,%eax # as cr4.PGE is not set here, refresh cr3
movq %rax, %cr4 # in PreModifyMtrrs() to flush TLB.
# Load TSS
subl $8, %esp # reserve room in stack
sgdt (%rsp)
movl 2(%rsp), %eax # eax = GDT base
addl $8, %esp
movb $0x89, %dl
movb %dl, (TSS_SEGMENT + 5)(%rax) # clear busy flag
movl $TSS_SEGMENT, %eax
ltr %ax
#
# Switch to LongMode
#
pushq $LONG_MODE_CS # push cs hardcore here
call Base # push return address for retf later
Base:
addl $(LongMode - Base), (%rsp) # offset for far retf, seg is the 1st arg
movl $0xc0000080, %ecx
rdmsr
orb $1,%ah
wrmsr
movq %cr0, %rbx
orl $0x080010000, %ebx # enable paging + WP
movq %rbx, %cr0
retf
LongMode: # long mode (64-bit code) starts here
movabsq $ASM_PFX(gSmiHandlerIdtr), %rax
lidt (%rax)
lea (DSC_OFFSET)(%rdi), %ebx
movw DSC_DS(%rbx), %ax
movl %eax,%ds
movw DSC_OTHERSEG(%rbx), %ax
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movw DSC_SS(%rbx), %ax
movl %eax,%ss
# jmp _SmiHandler ; instruction is not needed
_SmiHandler:
movq (%rsp), %rbx
# Save FP registers
subq $0x208, %rsp
.byte 0x48 # FXSAVE64
fxsave (%rsp)
addq $-0x20, %rsp
movq %rbx, %rcx
movabsq $ASM_PFX(CpuSmmDebugEntry), %rax
call *%rax
movq %rbx, %rcx
movabsq $ASM_PFX(SmiRendezvous), %rax
call *%rax
movq %rbx, %rcx
movabsq $ASM_PFX(CpuSmmDebugExit), %rax
call *%rax
addq $0x20, %rsp
#
# Restore FP registers
#
.byte 0x48 # FXRSTOR64
fxrstor (%rsp)
rsm
ASM_PFX(gcSmiHandlerSize): .word . - _SmiEntryPoint
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