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|
;============================================================================
;演示保护模式下异常和中断的演示
;编译选项请参见 makefile TAB = 8
;============================================================================
.686p
Include pm.inc
option casemap:none
Stack_Len equ 1024 ;堆栈大小
;============================================================================
GdtSeg Segment use32 ;全局描述符
; ;段基址 ;段界限 ;属性
Dummy: Descriptor 0, 0, 0 ;空的描述符
Normal: Descriptor 0, 0ffffh, DA_DRW ;规范段描述符
g_CodeTempDesc: Descriptor 0, 0ffffh, DA_C ;非一致代码
g_DataDesc: Descriptor 0, 0fffffh, DA_DRWG ;全局4G数据段
g_VideoDesc: Descriptor 0b8000h,0ffffh, DA_DRW ;全局视频操作段
g_IdtCode32Desc: Descriptor 0, IdtCode32SegLen-1, DA_CR or DA_32 ;中断处理函数描述符
g_CodeReadKeyDesc: Descriptor 0, ReadKeyTssLen-1, DA_386TSS ;读取键盘任务TSS
g_LdtDemoDesc: Descriptor 0, L_DemoLdtSegLen-1, DA_LDT ;局部描述符
g_LdtReadKeyDesc: Descriptor 0, L_ReadKeySegLen-1, DA_LDT ;读取键盘的LDT描述符
g_DemoTssDesc: Descriptor 0, L_DemoTssSegLen-1, DA_386TSS ;Demo任务的TSS
;----------------------------------------------------------------------------
NormalSelector equ Normal - GdtSeg ;规范段选择子
g_DataSelector equ g_DataDesc - GdtSeg ;全局数据段
g_VideoSelector equ g_VideoDesc - GdtSeg ;全局视频段选择子
g_CodeTempSelector equ g_CodeTempDesc - GdtSeg ;代码段选择子
g_IdtCodeSelector equ g_IdtCode32Desc - GdtSeg ;中断处理函数描述符选择子
g_CodeReadKeySelector equ g_CodeReadKeyDesc - GdtSeg ;TSS选择子
g_LdtDemoSelector equ g_LdtDemoDesc - GdtSeg ;Demo的局部描述符段
g_LdtReadKeySelector equ g_LdtReadKeyDesc - GdtSeg ;读取键盘的LDT描述符选择子
g_DemoTssSelector equ g_DemoTssDesc - GdtSeg ;Demo任务的TSS选择子
;----------------------------------------------------------------------------
GDTLen equ $ - GdtSeg ;GDT长度
GDT_Ptr word GDTLen-1 ;VGDT
dword 0
_IDT_Ptr word IdtSegLen -1 ;IDT长度
dword 0 ;VIDT
_RegSp word ? ;用于保存SS:SP
_RegSs word ?
;----------------------------------------------------------------------------
SzTitle byte 13,10, 9, "Please select the presentation you need anomaly!", 13, 10
byte 9, " 0:Division error!", 13, 10
byte 9, " 4:Overflow error!", 13, 10
byte 9, " B:Fault segment does not exist!", 13, 10
byte 9, " C:Stack segment fault!", 13, 10
byte 9, " D:General Protection Fault!", 13, 10,13, 10
byte 9, "Input:$"
GdtSeg Ends
;============================================================================
IdtSeg Segment use32 ;中断描述符
; 门 目标选择子, 偏移, DCount, 属性
Gate g_IdtCodeSelector, _IdtDiv, 0, DA_386IGate ;0h除法错误
repeat 3
Gate g_IdtCodeSelector, _IdtOther,0, DA_386IGate ;1h-3h陷阱门处理地址
endm
Gate g_IdtCodeSelector, _IdtOf, 0, DA_386IGate ;4号异常处理(溢出)
repeat 6
Gate g_IdtCodeSelector, _IdtOther,0, DA_386IGate ;5-0ah陷阱门处理地址
endm
Gate g_IdtCodeSelector, _IdtNp, 0, DA_386IGate ;0bh号异常处理(段不存在故障)
Gate g_IdtCodeSelector, _IdtSs, 0, DA_386IGate ;0ch号异常处理(堆栈段故障)
Gate g_IdtCodeSelector, _IdtGp, 0, DA_386IGate ;0dh号异常处理(通用保护故障)
repeat 240
Gate g_IdtCodeSelector, _IdtOther, 0, DA_386IGate ;0eh-0edh 240个中断处理地址
endm
Gate g_IdtCodeSelector, _IdtShowMsg,0, DA_386IGate ;0feh号异常处理(显示中断)
Gate g_CodeReadKeySelector, 0, 0, DA_TaskGate ;0ffh号异常处理(键盘中断处理)任务门
IdtSegLen equ $ - IdtSeg ;IDT长度
IdtSeg Ends
;============================================================================
ReadKeyTss Segment use32 ;读取键盘TSS
StReadKey TSS <0>
byte 0ffh
ReadKeyTssLen equ $ - ReadKeyTss
ReadKeyTss Ends
;============================================================================
ReadKeyCodeSeg Segment use16 ;读取键盘的代码段
_GetKey equ $ - ReadKeyCodeSeg
GetKey Proc far ;在实模式下读取键盘
local _Vidt:fword
mov ax, GdtSeg
mov ds, ax
mov ebp, esp
mov ax, L_DemoData
mov es, ax
lss sp, dword ptr ds:[_RegSp] ;恢复SS:sp
lidt fword ptr ds:[_IDT_Ptr] ;恢复实模式中断
sti
lea dx, SzTitle ;字符串
mov ah, 9 ;功能号
int 21h ;调用DOS中断
;----------------------------------------------------------------------------
@@: mov ah, 0
int 16h ;读取键盘
push ax
mov dl, al
mov ah, 2
int 21h ;显示用户的按键
pop ax
.if al == '0' || al == '4' || al == 'b' || al == 'B' || \
al == 'c' || al == 'C' || al == 'd' || al == 'D'
mov byte ptr es:[SzAsciiBuf], al
jmp @f
.Endif
jmp @b
@@:
;----------------------------------------------------------------------------
;还原IDT,回到保护模式
cli
mov word ptr ss:[_Vidt], IdtSegLen ;IDT长度
mov eax, IdtSeg
shl eax, 4
mov dword ptr ss:[_Vidt+2], eax
lidt fword ptr ss:[_Vidt] ;装载IDT
mov eax, cr0
or al, 1
mov cr0, eax ;开启分页进入保护模式
Jmp16 <L_ReadKeyCodeSelector>, <_ReadKeyEnd> ;跳回保护模式
;----------------------------------------------------------------------------
GetKey Endp
;----------------------------------------------------------------------------
_ReadKeyBegin equ $ - ReadKeyCodeSeg ;读取键盘的入口
ReadKeyBegin Proc
push ds
push es
push fs
push gs
mov ax, NormalSelector
mov ss, ax
mov ds, ax
mov eax, cr0
and al, 11111110b
mov cr0, eax ;先转实模式
Jmp16 <seg ReadKeyCodeSeg>, < _GetKey >
ReadKeyBegin Endp
;----------------------------------------------------------------------------
_ReadKeyEnd equ $ - ReadKeyCodeSeg
ReadKeyEnd Proc ;读取键盘完成了
mov ax, L_ReadKeyStackSelector
mov ss, ax
mov esp, ebp ;恢复ss:esp
pop gs
pop fs
pop es
pop ds
iretd
ReadKeyEnd Endp
ReadKeyCodeSegLen equ $ - ReadKeyCodeSeg
ReadKeyCodeSeg Ends
;============================================================================
LdtSeg Segment use32 ;局部描述符
LdtSegLen equ $ - LdtSeg
LdtSeg Ends
;============================================================================
IdtCodeSeg Segment use32 ;中断处理函数地址
_IdtDiv equ $ - IdtCodeSeg
IdtDiv Proc ;除法错误
lea esi, SzDivMsg
mov ecx, sizeof SzDivMsg
int 0feh ;中断嵌中断
mov ax, 10h ;简单处理除法异常
mov cl, 2h
iretd
IdtDiv Endp
;----------------------------------------------------------------------------
_IdtOf equ $ - IdtCodeSeg ;溢出错误
IdtOf Proc
lea esi, SzOverMsg
mov ecx, sizeof SzDivMsg
int 0feh ;显示溢出错误字符串
iretd
IdtOf Endp
;----------------------------------------------------------------------------
;;将al中的数字转成ASCII加上显示属性并在EAX中返回
_HexToAscii Proc uses ebx
mov bl, al
and al, 0fh
add al, 90h
daa
adc al, 40h
daa
mov ah, 0ch
shl eax, 16 ;转换低位
mov al, bl
shr al, 4
and al, 0fh
add al, 90h
daa
adc al, 40h ;将高位转成ASCII
daa
mov ah, 0ch ;属性
ret
_HexToAscii Endp
;============================================================================
_ShowErrorCode Proc _dwErrorCode ;显示出错码
mov eax, _dwErrorCode
mov edx, eax
shr eax, 16
call _HexToAscii ;显示段不存在故障错误码
stosd
mov eax, edx
call _HexToAscii
stosd
ret
_ShowErrorCode Endp
;----------------------------------------------------------------------------
_IdtNp equ $ - IdtCodeSeg
IdtNp Proc ;段不存在故障
lea esi, SzSegFaultMsg
mov ecx, sizeof SzSegFaultMsg
int 0feh
pop eax
Invoke _ShowErrorCode,eax ;显示出错码
pop eax
add eax, 2 ;调整返回地址+2
push eax
iretd
IdtNp Endp
;----------------------------------------------------------------------------
_IdtSs equ $ - IdtCodeSeg
IdtSs Proc ;堆栈段故障
lea esi, SzStackFaultMsg
mov ecx, sizeof SzStackFaultMsg
int 0feh
pop eax
Invoke _ShowErrorCode, eax ;显示出错码
pop eax
add eax, 4 ;调整返回地址+4
push eax
iretd
IdtSs Endp
;----------------------------------------------------------------------------
_IdtGp equ $ - IdtCodeSeg
IdtGp Proc ;通用保护故障
lea esi, SzGeneralMsg
mov ecx, sizeof SzGeneralMsg
int 0feh
pop eax
Invoke _ShowErrorCode, eax ;显示出错码
pop eax
add eax, 2 ;调整返回地址+2
push eax
iretd
IdtGp Endp
;----------------------------------------------------------------------------
_IdtShowMsg equ $ - IdtCodeSeg
;----------------------------------------------------------------------------
;显示字符串中断 esi-->字符串地址
;ecx :字符串长度
;ds 数据段 es:视频输出段
;----------------------------------------------------------------------------
IdtShowMsg Proc
mov edi, (80 * 2 * 10 ) +( 40 * 2 ) ;20行10列
cld
@@: lodsb
mov ah, 0ch
stosw
loop @b
iretd
IdtShowMsg Endp
;----------------------------------------------------------------------------
_IdtOther equ $ - IdtCodeSeg
IdtOther Proc ;其他类型的错误
lea esi, SzOtherMsg
mov edi, (80 * 2 * 20 ) +( 10 * 2 ) ;20行10列
mov ecx, sizeof SzOtherMsg
@@: lodsb
mov ah, 0ch
stosw
loop @b
iretd
IdtOther Endp
IdtCode32SegLen equ $ - IdtCodeSeg
IdtCodeSeg Ends
;============================================================================
;============================================================================
L_DemoTssSeg Segment use32 ;演示任务的TSS
StDemoTss TSS <0>
byte 0ffh
L_DemoTssSegLen equ $ - L_DemoTssSeg
L_DemoTssSeg Ends
;============================================================================
L_DemoStack Segment use32 ;演示任务的堆栈
byte Stack_Len dup (0)
L_DemoStack Ends
;============================================================================
L_ReadKeyStack Segment use32 ;读取键盘任务的堆栈
byte Stack_Len dup (0)
L_ReadKeyStack Ends
;============================================================================
L_DemoData Segment use32 ;演示任务的数据段
SzDivMsg byte "Division Error!"
SzOverMsg byte "Overflow Error!"
SzSegFaultMsg byte "Fault segment Error Code: 0x"
SzStackFaultMsg byte "Stack segment fault!"
SzGeneralMsg byte "General Protection Fault!"
SzOtherMsg byte "Such a thing can not happen!"
SzAsciiBuf byte 0
L_DemoDataLen equ $ - L_DemoData
L_DemoData Ends
;============================================================================
L_DemoLdtSeg Segment use32 ;演示任务段的描述符
; ;段基址 ;段界限 ;属性
L_DemoTssAliasDesc: Descriptor 0, L_DemoTssSegLen-1, DA_DRW ;TSS别名段
L_DemoStackDesc: Descriptor 0, Stack_Len-1, DA_DRWA ;堆栈段
L_DemoDataDesc: Descriptor 0, L_DemoDataLen-1, DA_DRW ;数据段
L_DemoNpDesc: Descriptor 0, 0ffffh, DA_DRW -80h ;模拟段不存在的描述符
;----------------------------------------------------------------------------
L_DemoTssAliasSelector equ L_DemoTssAliasDesc - L_DemoLdtSeg + SA_TIL ;TSS别名段选择子
L_DemoStackSelector equ L_DemoStackDesc - L_DemoLdtSeg + SA_TIL ;堆栈段选择子
L_DemoDataSelector equ L_DemoDataDesc - L_DemoLdtSeg + SA_TIL ;数据段选择子
L_DemoNpSelector equ L_DemoNpDesc - L_DemoLdtSeg + SA_TIL ;模拟段不存在的选择子
L_DemoLdtSegLen equ $ - L_DemoLdtSeg
L_DemoLdtSeg Ends
;============================================================================
L_ReadKeySeg Segment use32 ;读取键盘的LDT
L_ReadKeyStackDesc: Descriptor 0, Stack_Len-1, DA_DRWA ;堆栈段
L_ReadKeyCodeDesc: Descriptor 0, 0ffffh, DA_CR ;代码段
;----------------------------------------------------------------------------
L_ReadKeyStackSelector equ L_ReadKeyStackDesc - L_ReadKeySeg + SA_TIL ;堆栈段选择子
L_ReadKeyCodeSelector equ L_ReadKeyCodeDesc - L_ReadKeySeg + SA_TIL ;代码段
L_ReadKeySegLen equ $ - L_ReadKeySeg
L_ReadKeySeg Ends
;============================================================================
;16位段, 由实模式跳入
;============================================================================
g_Code16Seg Segment use16
_GoToProtect Proc ;返回实模式
mov ax, NormalSelector
mov fs, ax ;规范选择子
mov es, ax
mov ds, ax
mov ss, ax
mov gs, ax
clts ;清除任务标记
mov eax, cr0 ;关PE位, 进入实模式
and al, 0feh
mov cr0, eax
;刷新段选择子缓冲区, 退回实模式
Jmp16 <seg StartCodeSeg >, < offset _RealProtect >
_GoToProtect Endp
;----------------------------------------------------------------------------
_ProtectEntry Proc ;实模式跳入入口
mov ax, g_LdtDemoSelector
lldt ax ;装载LDTR
mov ax, L_DemoStackSelector
mov ss, ax
mov esp, Stack_Len ;置SS:ESP
mov ax, L_DemoTssAliasSelector
mov gs, ax ;TSS别名段
mov word ptr gs:[TSS.regLdtr], g_LdtDemoSelector
;----------------------------------------------------------------------------
;初始化读取键盘的TSS段
mov ax, g_DataSelector
mov fs, ax
xor ebx, ebx
mov bx, ReadKeyTss
shl ebx, 4 ;fs:ebx-->ReadKeyTss
mov word ptr fs:[ebx+TSS.regEip], _ReadKeyBegin
mov dword ptr fs:[ebx+TSS.regEsp], Stack_Len
mov word ptr fs:[ebx+TSS.regLdtr], g_LdtReadKeySelector
mov word ptr fs:[ebx+TSS.regSs], L_ReadKeyStackSelector
mov word ptr fs:[ebx+TSS.regCs], L_ReadKeyCodeSelector
;----------------------------------------------------------------------------
mov ax, g_DemoTssSelector
ltr ax
mov ax, L_DemoDataSelector
mov ds, ax ;装载数据段
mov ax, g_VideoSelector
mov es, ax ;视频段
int 0ffh ;调用0ffh号中断获取按键
;----------------------------------------------------------------------------
;已经得到用户输入的异常, 现在需要做的就是根据输入演示异常
mov ax, L_DemoDataSelector
mov ds, ax
mov al, byte ptr ds:[SzAsciiBuf]
cld
.if al == '0' ;模拟除法溢出
mov ax, 2000h
mov cl, 2
div cl ;除数存不下,异常
;----------------------------------------------------------------------------
.Elseif al == '4' ;模拟溢出异常
mov al, 9ch ;-100
add al, 9ch ;-100
into
;----------------------------------------------------------------------------
.Elseif al == 'b' || al == 'B' ;模拟段不存在异常
mov ax, L_DemoNpSelector ;此段没有初始化, 会异常
mov gs, ax
;----------------------------------------------------------------------------
.Elseif al == 'c' || al == 'C' ;堆栈出错异常
mov ebp, esp
mov al, byte ptr [ebp]
;----------------------------------------------------------------------------
.Elseif al == 'd' || al == 'D' ;模拟通用保护异常
mov ax, g_DemoTssSelector
mov gs, ax ;段是不能够装入TSS的, 异常
.Endif
;----------------------------------------------------------------------------
call _GoToProtect ;返回保护模式
_ProtectEntry Endp
g_Code16Seg Ends
;============================================================================
;起始代码段初始化保护模式的各个结构, 然后跳入保护模式
;============================================================================
StartCodeSeg Segment use16
_InitGdt Proc uses es ;初始化全局描述符表
xor eax, eax
mov ax, GdtSeg
mov es, ax ;es-->全局描述符表
;----------------------------------------------------------------------------
shl eax, 4
mov dword ptr es:[GDT_Ptr+2], eax ;初始化VGDT描述符
;----------------------------------------------------------------------------
xor eax, eax
mov ax, g_Code16Seg ;初始化十六位的代码段
shl eax, 4
mov word ptr es:[g_CodeTempDesc+2], ax ;段基址低位
shr eax, 16
mov byte ptr es:[g_CodeTempDesc+4], al ;段基址高地址低位
mov byte ptr es:[g_CodeTempDesc+7], ah ;段基址高地址高位
;----------------------------------------------------------------------------
xor eax, eax
mov ax, IdtCodeSeg ;初始化中断处理函数地址
shl eax, 4
mov word ptr es:[g_IdtCode32Desc+2], ax
shr eax, 16
mov byte ptr es:[g_IdtCode32Desc+4], al
mov byte ptr es:[g_IdtCode32Desc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_DemoLdtSeg ;Demo任务的LDT段
shl eax, 4
mov word ptr es:[g_LdtDemoDesc+2], ax
shr eax, 16
mov byte ptr es:[g_LdtDemoDesc+4], al
mov byte ptr es:[g_LdtDemoDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_ReadKeySeg ;读取键盘任务的LDT
shl eax, 4
mov word ptr es:[g_LdtReadKeyDesc+2], ax
shr eax, 16
mov byte ptr es:[g_LdtReadKeyDesc+4], al
mov byte ptr es:[g_LdtReadKeyDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_DemoTssSeg ;Demo任务的TSS段
shl eax, 4
mov word ptr es:[g_DemoTssDesc+2], ax
shr eax, 16
mov byte ptr es:[g_DemoTssDesc+4], al
mov byte ptr es:[g_DemoTssDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, ReadKeyTss ;读取任务的中断任务
shl eax, 4
mov word ptr es:[g_CodeReadKeyDesc+2], ax
shr eax, 16
mov byte ptr es:[g_CodeReadKeyDesc+4], al
mov byte ptr es:[g_CodeReadKeyDesc+7], ah
;----------------------------------------------------------------------------
lgdt fword ptr es:[GDT_Ptr] ;装载GDT
ret
_InitGdt Endp
;----------------------------------------------------------------------------
_InitDemoLdt Proc uses ds
mov ax, L_DemoLdtSeg
mov ds, ax
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_DemoTssSeg ;初始化DemoTSS别名段
shl eax, 4
mov word ptr ds:[L_DemoTssAliasDesc+2], ax
shr eax, 16
mov byte ptr ds:[L_DemoTssAliasDesc+4], al
mov byte ptr ds:[L_DemoTssAliasDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_DemoStack ;初始化Demo堆栈段
shl eax, 4
mov word ptr ds:[L_DemoStackDesc+2], ax
shr eax, 16
mov byte ptr ds:[L_DemoStackDesc+4], al
mov byte ptr ds:[L_DemoStackDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_DemoData ;初始化Demo堆栈段
shl eax, 4
mov word ptr ds:[L_DemoDataDesc+2], ax
shr eax, 16
mov byte ptr ds:[L_DemoDataDesc+4], al
mov byte ptr ds:[L_DemoDataDesc+7], ah
;----------------------------------------------------------------------------
ret
_InitDemoLdt Endp
;----------------------------------------------------------------------------
_InitReadKeyLdt Proc uses ds ;初始化读取键盘的LDT
mov ax, L_ReadKeySeg
mov ds, ax
;----------------------------------------------------------------------------
xor eax, eax
mov ax, L_ReadKeyStack ;初始化读取键盘任务的堆栈
shl eax, 4
mov word ptr ds:[L_ReadKeyStackDesc+2], ax
shr eax, 16
mov byte ptr ds:[L_ReadKeyStackDesc+4], al
mov byte ptr ds:[L_ReadKeyStackDesc+7], ah
;----------------------------------------------------------------------------
xor eax, eax
mov ax, ReadKeyCodeSeg ;初始化读取键盘任务的代码段
shl eax, 4
mov word ptr ds:[L_ReadKeyCodeDesc+2], ax
shr eax, 16
mov byte ptr ds:[L_ReadKeyCodeDesc+4], al
mov byte ptr ds:[L_ReadKeyCodeDesc+7], ah
;----------------------------------------------------------------------------
ret
_InitReadKeyLdt Endp
;----------------------------------------------------------------------------
_InitIdt Proc uses es ;初始化IDT
local _Vidt:fword
xor eax, eax
mov ax, GdtSeg
mov es, ax ;es-->全局描述符表
sidt fword ptr es:[_IDT_Ptr] ;保存IDT
mov word ptr ss:[_Vidt], IdtSegLen ;IDT长度
mov eax, IdtSeg
shl eax, 4
mov dword ptr ss:[_Vidt+2], eax
cli ;关中断
lidt fword ptr ss:[_Vidt] ;装载IDT
ret
_InitIdt Endp
;----------------------------------------------------------------------------
Jmain Proc
call _InitGdt ;初始化GDT全局描述符
call _InitIdt ;初始化IDT中断描述符
call _InitDemoLdt ;初始化Demo LDT局部描述符
call _InitReadKeyLdt ;初始化中断读取键盘的 LDT局部描述符
;----------------------------------------------------------------------------
mov ax, GdtSeg
mov ds, ax
mov ds:[_RegSs], ss
mov ds:[_RegSp], sp ;保存SS:SP
_EnableA20 ;关中断开A20地址线
mov eax, cr0
or eax, 1
mov cr0, eax ;开启分段, 进入保护模式
;----------------------------------------------------------------------------
Jmp16 g_CodeTempSelector, <offset _ProtectEntry>;跳入保护模式
Jmain Endp
;----------------------------------------------------------------------------
_RealProtect Proc ;返回保护模式
mov ax, GdtSeg
mov ds, ax
lss sp, dword ptr ds:[_RegSp] ;恢复SS:SP
lidt fword ptr ds:[_IDT_Ptr] ;恢复IDT
_DisableA20 ;关A20地址线, 开中断
sti
mov ax, 4c00h
int 21h
_RealProtect Endp
StartCodeSeg Ends
End Jmain
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