mirror of https://github.com/acidanthera/audk.git
315 lines
12 KiB
NASM
315 lines
12 KiB
NASM
|
|
#include "BaseLibInternals.h"
|
|
|
|
;------------------------------------------------------------------------------
|
|
;
|
|
; Copyright (c) 2006 - 2008, 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:
|
|
;
|
|
; Thunk.asm
|
|
;
|
|
; Abstract:
|
|
;
|
|
; Real mode thunk
|
|
;
|
|
;------------------------------------------------------------------------------
|
|
|
|
EXTERNDEF m16Start:BYTE
|
|
EXTERNDEF m16Size:WORD
|
|
EXTERNDEF mThunk16Attr:WORD
|
|
EXTERNDEF m16Gdt:WORD
|
|
EXTERNDEF m16GdtrBase:WORD
|
|
EXTERNDEF mTransition:WORD
|
|
|
|
IA32_REGS STRUC 4t
|
|
_EDI DD ?
|
|
_ESI DD ?
|
|
_EBP DD ?
|
|
_ESP DD ?
|
|
_EBX DD ?
|
|
_EDX DD ?
|
|
_ECX DD ?
|
|
_EAX DD ?
|
|
_DS DW ?
|
|
_ES DW ?
|
|
_FS DW ?
|
|
_GS DW ?
|
|
_EFLAGS DQ ?
|
|
_EIP DD ?
|
|
_CS DW ?
|
|
_SS DW ?
|
|
IA32_REGS ENDS
|
|
|
|
.const
|
|
|
|
m16Size DW InternalAsmThunk16 - m16Start
|
|
mThunk16Attr DW _ThunkAttr - m16Start
|
|
m16Gdt DW _NullSeg - m16Start
|
|
m16GdtrBase DW _16GdtrBase - m16Start
|
|
mTransition DW _EntryPoint - m16Start
|
|
|
|
.code
|
|
|
|
m16Start LABEL BYTE
|
|
|
|
SavedGdt LABEL FWORD
|
|
DW ?
|
|
DQ ?
|
|
|
|
;------------------------------------------------------------------------------
|
|
; _BackFromUserCode() takes control in real mode after 'retf' has been executed
|
|
; by user code. It will be shadowed to somewhere in memory below 1MB.
|
|
;------------------------------------------------------------------------------
|
|
_BackFromUserCode PROC
|
|
;
|
|
; The order of saved registers on the stack matches the order they appears
|
|
; in IA32_REGS structure. This facilitates wrapper function to extract them
|
|
; into that structure.
|
|
;
|
|
; Some instructions for manipulation of segment registers have to be written
|
|
; in opcode since 64-bit MASM prevents accesses to those registers.
|
|
;
|
|
DB 16h ; push ss
|
|
DB 0eh ; push cs
|
|
DB 66h
|
|
call @Base ; push eip
|
|
@Base:
|
|
DB 66h
|
|
push 0 ; reserved high order 32 bits of EFlags
|
|
pushf ; pushfd actually
|
|
cli ; disable interrupts
|
|
push gs
|
|
push fs
|
|
DB 6 ; push es
|
|
DB 1eh ; push ds
|
|
DB 66h, 60h ; pushad
|
|
DB 66h, 0bah ; mov edx, imm32
|
|
_ThunkAttr DD ?
|
|
test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15
|
|
jz @1
|
|
mov eax, 15cd2401h ; mov ax, 2401h & int 15h
|
|
cli ; disable interrupts
|
|
jnc @2
|
|
@1:
|
|
test dl, THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL
|
|
jz @2
|
|
in al, 92h
|
|
or al, 2
|
|
out 92h, al ; deactivate A20M#
|
|
@2:
|
|
mov eax, ss
|
|
lea bp, [esp + sizeof (IA32_REGS)]
|
|
;
|
|
; rsi in the following 2 instructions is indeed bp in 16-bit code
|
|
;
|
|
mov word ptr (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._ESP, bp
|
|
DB 66h
|
|
mov ebx, (IA32_REGS ptr [rsi - sizeof (IA32_REGS)])._EIP
|
|
shl ax, 4 ; shl eax, 4
|
|
add bp, ax ; add ebp, eax
|
|
mov ax, cs
|
|
shl ax, 4
|
|
lea ax, [eax + ebx + (@64BitCode - @Base)]
|
|
DB 66h, 2eh, 89h, 87h ; mov cs:[bx + (@64Eip - @Base)], eax
|
|
DW @64Eip - @Base
|
|
DB 66h, 0b8h ; mov eax, imm32
|
|
SavedCr4 DD ?
|
|
mov cr4, rax
|
|
;
|
|
; rdi in the instruction below is indeed bx in 16-bit code
|
|
;
|
|
DB 66h, 2eh ; 2eh is "cs:" segment override
|
|
lgdt fword ptr [rdi + (SavedGdt - @Base)]
|
|
DB 66h
|
|
mov ecx, 0c0000080h
|
|
rdmsr
|
|
or ah, 1
|
|
wrmsr
|
|
DB 66h, 0b8h ; mov eax, imm32
|
|
SavedCr0 DD ?
|
|
mov cr0, rax
|
|
DB 66h, 0eah ; jmp far cs:@64Bit
|
|
@64Eip DD ?
|
|
SavedCs DW ?
|
|
@64BitCode:
|
|
db 090h
|
|
db 067h, 0bch ; mov esp, imm32
|
|
SavedSp DD ? ; restore stack
|
|
nop
|
|
ret
|
|
_BackFromUserCode ENDP
|
|
|
|
_EntryPoint DD _ToUserCode - m16Start
|
|
DW CODE16
|
|
_16Gdtr LABEL FWORD
|
|
DW GDT_SIZE - 1
|
|
_16GdtrBase DQ _NullSeg
|
|
_16Idtr FWORD (1 SHL 10) - 1
|
|
|
|
;------------------------------------------------------------------------------
|
|
; _ToUserCode() takes control in real mode before passing control to user code.
|
|
; It will be shadowed to somewhere in memory below 1MB.
|
|
;------------------------------------------------------------------------------
|
|
_ToUserCode PROC
|
|
mov ss, edx ; set new segment selectors
|
|
mov ds, edx
|
|
mov es, edx
|
|
mov fs, edx
|
|
mov gs, edx
|
|
DB 66h
|
|
mov ecx, 0c0000080h
|
|
mov cr0, rax ; real mode starts at next instruction
|
|
rdmsr
|
|
and ah, NOT 1
|
|
wrmsr
|
|
mov cr4, rbp
|
|
mov ss, esi ; set up 16-bit stack segment
|
|
mov sp, bx ; set up 16-bit stack pointer
|
|
DB 66h ; make the following call 32-bit
|
|
call @Base ; push eip
|
|
@Base:
|
|
pop bp ; ebp <- address of @Base
|
|
push [esp + sizeof (IA32_REGS) + 2]
|
|
lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code
|
|
push rax
|
|
retf ; execution begins at next instruction
|
|
@RealMode:
|
|
DB 66h, 2eh ; CS and operand size override
|
|
lidt fword ptr [rsi + (_16Idtr - @Base)]
|
|
DB 66h, 61h ; popad
|
|
DB 1fh ; pop ds
|
|
DB 07h ; pop es
|
|
pop fs
|
|
pop gs
|
|
popf ; popfd
|
|
lea sp, [esp + 4] ; skip high order 32 bits of EFlags
|
|
DB 66h ; make the following retf 32-bit
|
|
retf ; transfer control to user code
|
|
_ToUserCode ENDP
|
|
|
|
CODE16 = _16Code - $
|
|
DATA16 = _16Data - $
|
|
DATA32 = _32Data - $
|
|
|
|
_NullSeg DQ 0
|
|
_16Code LABEL QWORD
|
|
DW -1
|
|
DW 0
|
|
DB 0
|
|
DB 9bh
|
|
DB 8fh ; 16-bit segment, 4GB limit
|
|
DB 0
|
|
_16Data LABEL QWORD
|
|
DW -1
|
|
DW 0
|
|
DB 0
|
|
DB 93h
|
|
DB 8fh ; 16-bit segment, 4GB limit
|
|
DB 0
|
|
_32Data LABEL QWORD
|
|
DW -1
|
|
DW 0
|
|
DB 0
|
|
DB 93h
|
|
DB 0cfh ; 16-bit segment, 4GB limit
|
|
DB 0
|
|
|
|
GDT_SIZE = $ - _NullSeg
|
|
|
|
;------------------------------------------------------------------------------
|
|
; IA32_REGISTER_SET *
|
|
; EFIAPI
|
|
; InternalAsmThunk16 (
|
|
; IN IA32_REGISTER_SET *RegisterSet,
|
|
; IN OUT VOID *Transition
|
|
; );
|
|
;------------------------------------------------------------------------------
|
|
InternalAsmThunk16 PROC USES rbp rbx rsi rdi
|
|
mov rbx, ds
|
|
push rbx ; Save ds segment register on the stack
|
|
mov rbx, es
|
|
push rbx ; Save es segment register on the stack
|
|
mov rbx, ss
|
|
push rbx ; Save ss segment register on the stack
|
|
|
|
push fs
|
|
push gs
|
|
mov rsi, rcx
|
|
movzx r8d, (IA32_REGS ptr [rsi])._SS
|
|
mov edi, (IA32_REGS ptr [rsi])._ESP
|
|
lea rdi, [edi - (sizeof (IA32_REGS) + 4)]
|
|
imul eax, r8d, 16 ; eax <- r8d(stack segment) * 16
|
|
mov ebx, edi ; ebx <- stack for 16-bit code
|
|
push sizeof (IA32_REGS) / 4
|
|
add edi, eax ; edi <- linear address of 16-bit stack
|
|
pop rcx
|
|
rep movsd ; copy RegSet
|
|
lea ecx, [rdx + (SavedCr4 - m16Start)]
|
|
mov eax, edx ; eax <- transition code address
|
|
and edx, 0fh
|
|
shl eax, 12 ; segment address in high order 16 bits
|
|
lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address
|
|
stosd ; [edi] <- return address of user code
|
|
|
|
sgdt fword ptr [rsp + 60h] ; save GDT stack in argument space
|
|
movzx r10, word ptr [rsp + 60h] ; r10 <- GDT limit
|
|
lea r11, [rcx + (InternalAsmThunk16 - SavedCr4) + 0xf]
|
|
and r11, 0xfffffff0 ; r11 <- 16-byte aligned shadowed GDT table in real mode buffer
|
|
|
|
mov word ptr [rcx + (SavedGdt - SavedCr4)], r10w ; save the limit of shadowed GDT table
|
|
mov qword ptr [rcx + (SavedGdt - SavedCr4) + 2], r11 ; save the base address of shadowed GDT table
|
|
|
|
mov rsi, qword ptr [rsp + 62h] ; rsi <- the original GDT base address
|
|
xchg rcx, r10 ; save rcx to r10 and initialize rcx to be the limit of GDT table
|
|
inc rcx ; rcx <- the size of memory to copy
|
|
xchg rdi, r11 ; save rdi to r11 and initialize rdi to the base address of shadowed GDT table
|
|
rep movsb ; perform memory copy to shadow GDT table
|
|
mov rcx, r10 ; restore the orignal rcx before memory copy
|
|
mov rdi, r11 ; restore the original rdi before memory copy
|
|
|
|
sidt fword ptr [rsp + 50h] ; save IDT stack in argument space
|
|
mov rax, cr0
|
|
mov [rcx + (SavedCr0 - SavedCr4)], eax
|
|
and eax, 7ffffffeh ; clear PE, PG bits
|
|
mov rbp, cr4
|
|
mov [rcx], ebp ; save CR4 in SavedCr4
|
|
and ebp, 300h ; clear all but PCE and OSFXSR bits
|
|
mov esi, r8d ; esi <- 16-bit stack segment
|
|
DB 6ah, DATA32 ; push DATA32
|
|
pop rdx ; rdx <- 32-bit data segment selector
|
|
lgdt fword ptr [rcx + (_16Gdtr - SavedCr4)]
|
|
mov ss, edx
|
|
pushfq
|
|
lea edx, [rdx + DATA16 - DATA32]
|
|
lea r8, @RetFromRealMode
|
|
push r8
|
|
mov r8d, cs
|
|
mov [rcx + (SavedCs - SavedCr4)], r8w
|
|
mov [rcx + (SavedSp - SavedCr4)], esp
|
|
jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]
|
|
@RetFromRealMode:
|
|
popfq
|
|
lgdt fword ptr [rsp + 60h] ; restore protected mode GDTR
|
|
lidt fword ptr [rsp + 50h] ; restore protected mode IDTR
|
|
lea eax, [rbp - sizeof (IA32_REGS)]
|
|
pop gs
|
|
pop fs
|
|
pop rbx
|
|
mov ss, rbx
|
|
pop rbx
|
|
mov es, rbx
|
|
pop rbx
|
|
mov ds, rbx
|
|
ret
|
|
InternalAsmThunk16 ENDP
|
|
|
|
END
|