assembly 如何在gdb下修复分段错误

我发现一个非常奇怪的错误发生在我的程序的一个简单版本。我试图为操作系统添加不同的文件和缓冲区，但是当我尝试测试第5个文件时，我一直得到一个错误，运行第4个文件。为了尝试区分文件段，我有一个简单的print方法来显示字符串。现在文件被配置为显示不同的字符串，但我每次都得到相同的字符串。
我尝试一次调试一个文件，但是当我查看gdb段时，我在第四个文件中更改的内容仍然存在。唯一的其他事情，我可以做的是改变顺序的文件显示第一，但它总是不断取代第5个文件或把一个空的读取这种方式。
以下是我的资料来源，供参考

;    ReTimerOS
;    Copyright (C) 2022,2023  Christopher Hoy
;
;    This file is part of ReTimerOS
;    ReTimerOS is free software: you can redistribute it and/or modify
;    it under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.
;
;    This program is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.
;
;    You should have received a copy of the GNU General Public License
;    along with this program.  If not, see <https://www.gnu.org/licenses/>.

[org 0x7c00]

[bits 16]

mov cx,0
mov ds,cx
mov es,cx

cld

mov si,msgString 
call kprint

mov bx,0x0000_9400
mov cl,5
mov bx,msgString
mov bx,0x0000_9400
mov cl,5
mov al,1
call read_section
mov cx,0x940
mov es,cx
mov bx,0
mov cl,5
mov al,1
call read_section    

mov bx,0x0000_9200
mov cl,4
mov bx,msgString
mov bx,0x0000_9200
mov cl,4
mov al,1
call read_section
mov cx,0x920
mov es,cx
mov bx,0
mov cl,4
mov al,1
call read_section

mov bx,0x0000_9000
mov cl,3
mov bx,msgString
mov bx,0x0000_9000
mov cl,3
mov al,1
call read_section
mov cx,0x900
mov es,cx
mov bx,0
mov cl,3
mov al,1
call read_section

mov bx,0x0000_7e00
mov cl,2
mov bx,msgString
mov bx,0x0000_7e00
mov cl,2
mov al,1
call read_section
mov cx,0x7e0
mov es,cx
mov bx,0
mov cl,2
mov al,1
call read_section
mov bx,0x0000_7e00
    

pusha

;jmp 0x7e00
jmp 0x9200
;jmp 0x9400

;jmp 0x11000    

jmp $

kprint:
    cld
    mov ah,0x0E

kstring:
    lodsb
    int 0x10
    cmp al,0x00
    jnz kstring
    ret

read_section:
    
    mov ah,0x02
;   mov al,1
    mov ch,0
    mov dh,0
    int 0x13
    jc .disk_check

    ret

.disk_check:    
    mov si,checkString
    call kprint
    jmp $
.done:
    ret

;section .data  

align 4
BOOT_DRIVE: db 0
msgString:  db 'Game platform premier',10,13,0
checkString:    db 'Section did not load',10,13,0
checkString2:   db 'disk complete',10,13,0

times 510 -($-$$) db 0
dw 0xaa55

stage1.asm

;    ReTimerOS
;    Copyright (C) 2022,2023  Christopher Hoy
;
;    This file is part of ReTimerOS
;    ReTimerOS is free software: you can redistribute it and/or modify
;    it under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.
;
;    This program is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.
;
;    You should have received a copy of the GNU General Public License
;    along with this program.  If not, see <https://www.gnu.org/licenses/>.


;%define REBASE_ADDRESS(A)  (0x7E00 + ((A) - protectedGate1))

%define BUILD_GDT_DESC(bounds,base,access,flags) \
((( base & 0x00FFFFFF) << 16) | \
(( base & 0xFF000000) << 32) | \
( bounds & 0x0000FFFF) |        \
(( bounds & 0x000F0000) << 32) | \
(( access & 0xFF) << 40) |      \
(( flags & 0x0F) << 52))        


[ORG 0x7E00]

[BITS 16]

;section .text

protectedGate1:

;mov bx,0x0000_9000
    
    mov si,String 
    call kprint

;   jmp $
;   jmp 0x9000
;   jmp 0x11000

    cld
    cli

    in al,0x92
    or al,2
    out 0x92,al

    lgdt[gdt32Ptr]
    lidt[IdtPipe]

    mov eax, cr0
    or eax,1
    mov cr0, eax

;   mov [saved_segment],ds

;   jmp code32_post:REBASE_ADDRESS(__protected_mode_32)
    jmp code32_post:__protected_mode_32



;   jmp $
;   jmp code32_post:__protected_mode_32

kprint:
    cld
    mov ah,0x0E
kstring:
    lodsb
    int 0x10
    cmp al,0x00
    jnz kstring
    ret


;section .text

[bits 32]
; 32 bit protected mode
__protected_mode_32:use32
;    mov ax, 0x10
    mov ax,data32_post
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
;    mov ss, ax
    ; restate cr3
    mov cr3, ebx
    ; restate esp
    mov esp, edx

    mov cx,[gate_voucher]
    cmp word [gate_voucher],0
    jnz loopcheck
    mov word [gate_voucher],1

    jmp BIOS32_PREP
loopcheck:
    hlt
    jmp loopcheck

;   jmp 0x8000

BIOS32_PREP:use32

    pusha
    mov edx, esp
    cli
    ; clear cr3 by saving cr3 data in ebx register
    xor ecx, ecx
    mov ebx, cr3
    mov cr3, ecx

    jmp code16_post:__protected_mode_16

[bits 16]
; 16 bit protected mode
__protected_mode_16:use16
    ; jumping to 16 bit real mode

    xor eax,eax
    xor ecx,ecx

;   mov ax, 0x38
    mov cx,data16_post

    mov ds, cx
    mov es, cx
    mov fs, cx
    mov gs, cx
    mov ss, cx
    ; turn off protected mode
    ; set bit 0 to 0
    mov eax, cr0
    and al,  ~0x01
    mov cr0, eax

    jmp 0x9000

;section .data 

String: db 'platform 2',10,13,0
checkString:    db 'check',10,13,0

gdt32:
    dq BUILD_GDT_DESC(0,0,0,0)
gdt32code:
    dq BUILD_GDT_DESC(0x0000ffff,0,10011010b,1100b)
gdt32data:
    dq BUILD_GDT_DESC(0x0000ffff,0,10010010b,1100b)
gdt16code:
    dq BUILD_GDT_DESC(0x0000ffff,0,10011010b,1000b)
gdt16data:
    dq BUILD_GDT_DESC(0x0000ffff,0,10010010b,1000b)

.stub1:

    code32_post: equ gdt32code -gdt32
    data32_post: equ gdt32data -gdt32
;.stub:
    code16_post: equ gdt16code -gdt32
    data16_post: equ gdt16data -gdt32

;   tss32_post: equ gdt32tss -gdt32
    
    gdt32Len: equ $-gdt32   
    gdt32Ptr: dw gdt32Len-1
        dd gdt32

save_cr0    dd 0
save_cr3    dd 0
saved_segment   resd 0
gate_voucher    dw 0
saved_stack resw 0



IdtPipe:
    dw 0x03ff
    dd 0



times 512-($-$$) db 0

;%include 'gdt.inc'

stage3.asm

;[org 0x9200]

[BITS 16]

;section .text
;    ReTimerOS
;    Copyright (C) 2022,2023  Christopher Hoy
;
;    This file is part of ReTimerOS
;    ReTimerOS is free software: you can redistribute it and/or modify
;    it under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.
;
;    This program is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.
;
;    You should have received a copy of the GNU General Public License
;    along with this program.  If not, see <https://www.gnu.org/licenses/>.

%define REBASE_ADDRESS(A)  (0x9000 + ((A) - BIOS32_PREP))

%define BUILD_GDT_DESC(bounds,base,access,flags) \
((( base & 0x00FFFFFF) << 16) | \
(( base & 0xFF000000) << 32) | \
( bounds & 0x0000FFFF) |        \
(( bounds & 0x000F0000) << 32) | \
(( access & 0xFF) << 40) |      \
(( flags & 0x0F) << 52))        
;[org 0xA000]

[bits 32]
BIOS32_PREP:use32

    pusha
    ;pushf
    ; save current esp to edx
    mov edx, esp
    ; jumping to 16 bit protected mode
    ; disable interrupts
    cli
    ; clear cr3 by saving cr3 data in ebx register
    xor ecx, ecx
    mov ebx, cr3
    mov cr3, ecx

    jmp code16_post:REBASE_ADDRESS(__protected_mode_16)
;   jmp code16_post:__protected_mode_16

[bits 16]
; 16 bit protected mode
__protected_mode_16:use16
    ; jumping to 16 bit real mode

    xor eax,eax
    xor ecx,ecx

;   mov ax, 0x38
    mov cx,data16_post

;    mov ax,0

    mov ds, cx
    mov es, cx
    mov fs, cx
    mov gs, cx
    mov ss, cx
    ; turn off protected mode
    ; set bit 0 to 0
    mov eax, cr0
    and al,  ~0x01
    mov cr0, eax

    jmp 0x0:REBASE_ADDRESS(__real_mode_16)

__real_mode_16:use16
    xor cx, cx
    mov ds, cx
    mov es, cx
    mov fs, cx
    mov gs, cx
    mov ss, cx
;    mov sp, 0x8c00
   mov sp, 0x6c00
 
    ; enable bios interrupts to call
    sti
    ; save current context, all general, segment registers, flags
    pusha
    mov cx, ss
    push cx
    mov cx, gs
    push cx
    mov cx, fs
    push cx
    mov cx, es
    push cx
    mov cx, ds
    push cx
    pushf
    ; get current stack pointer & save it to current_esp
    mov ax, sp
;    mov edi, current_esp
    mov di, current_esp
;    mov di, far 0001_0000:current_esp
;push ds
;   mov eax,0x00010000
;   mov ds,eax
;   mov edi, current_esp
;pop ds

    stosw
    ; load our custom registers context
    mov esp, REBASE_ADDRESS(bios32_in_reg16_ptr)
;    mov sp, REBASE_ADDRESS(bios32_in_reg16_ptr)

    ; only use some general register from the given context
    popa
    ; set a new stack for bios interrupt
;    mov sp, 0x9c00
   mov sp, 0x7c00

    ; call immediate interrupt opcode to execute context

    pusha
;   mov bp,sp

;   jmp bios32_GraphicCtrlA
;   jmp 0x7e00
;   jmp 0x9200
    jmp 0x9400
;   jmp 0xD000
;   jmp 0x10000

;   mov cx,0x1000
;   mov es,cx
;   mov ds,cx
;   jmp 0:ds

;   mov ebp,0x00010000
;   push ebp
;   push 0x10000
;   retw
    
    poll_function:
    ;   mov si,page_str1
        popa
        ; get our output context here
        mov esp, REBASE_ADDRESS(bios32_out_reg16_ptr)
    
        add sp, 28 ; restore stack used for calling our context
        ; save current context, all general, segment registers, flags
        pushf
        mov cx, ss
        push cx
        mov cx, gs
        push cx
        mov cx, fs
        push cx
        mov cx, es
        push cx
        mov cx, ds
        push cx
        pusha
        ; restate the current_esp to continue
        mov esi, current_esp
    ;    mov si, current_esp
    
        lodsw
        mov sp, ax
        ; restore all current context, all general, segment registers, flags
        popf
        pop cx
        mov ds, cx
        pop cx
        mov es, cx
        pop cx
        mov fs, cx
        pop cx
        mov gs, cx
        pop cx
        mov ss, cx
        popa
    
    
    ;[bits 16]
    protectedGate2:use16
        cld
        cli
    
        in al,0x92
        or al,2
        out 0x92,al
    
        lgdt[gdt32Ptr]
        lidt[IdtPipe]
    
        mov eax, cr0
        or eax,1
        mov cr0, eax
    
        jmp code32_post:0x0000_7e00
;       jmp code32_post:0x0000_9200

        bios32_in_reg16_ptr:
            resw 14
        bios32_out_reg16_ptr:
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
                        dd 0xaaaaaaaa
        
        current_esp:    dw 0x0000
        

gdt32:
    dq BUILD_GDT_DESC(0,0,0,0)
gdt32code:
    dq BUILD_GDT_DESC(0x0000ffff,0,10011010b,1100b)
gdt32data:
    dq BUILD_GDT_DESC(0x0000ffff,0,10010010b,1100b)
gdt16code:
    dq BUILD_GDT_DESC(0x0000ffff,0,10011010b,1000b)
gdt16data:
    dq BUILD_GDT_DESC(0x0000ffff,0,10010010b,1000b)

.stub1:

    code32_post: equ gdt32code -gdt32
    data32_post: equ gdt32data -gdt32
;.stub:
    code16_post: equ gdt16code -gdt32
    data16_post: equ gdt16data -gdt32

;   tss32_post: equ gdt32tss -gdt32
    
    gdt32Len: equ $-gdt32   
    gdt32Ptr: dw gdt32Len-1
        dd gdt32

        IdtPipe:
            dw 0x03ff
            dd 0
        
    
times 512-($-$$) db 0

stage4.asm

;[org 0x9000]

[BITS 16]

;section .text

prep_module2:
;   jmp 0xD000
;   jmp 0x9400

vm_module:
    sub dword [vidmem_ptr],VIDEO_TEXT_ADDR

    mov si,String
        
    call printstr_task

loopcheck: jmp $

printstr_task:
    
    push cx    

    mov bp,0b800h
    mov es,bp
    mov bp,[vidmem_ptr]

prep:

    mov cx,0
    mov es,cx
    mov ax,ROWS
    mov bx,es:0x044a
    mul bx
    add ax,COLS1
;   shl ax,1
    mov bp,ax
    add bp,[vidmem_ptr]
        
;check even and odd placements
    
;   wizard tests 1.7
    add bp,0x690
    times 20 inc bp
    ;bodary

;check even and odd placements
    
    mov cx,0b800H
    mov es,cx
    mov ch,COLOR_ATTR_BSC

    jmp gettext

output:
;   pop word vidmem_address
    pop ax
    mov dx,ax
    mov es:[bp],dx

    add bp,byte 2

gettext:

    mov cl,byte [ds:si]
    inc si
;   mov [vidmem_address],cx
    push cx
    test cl,cl
    jnz output
    mov [vidmem_ptr],bp

    pop word [bp]
    pop ax

    mov cx,0
    mov ds,cx
    
    ret

    jmp $

;dw 0xaa55

;section .data
VIDEO_TEXT_ADDR EQU 0XB8000
COLOR_ATTR_PSC  EQU 0X6A
COLOR_ATTR_BSC  EQU 0X5F
PM_MODE_STACK   EQU 0X80000
VM_STACK_SEG    EQU 0X0000
VM_STACK_OFS    EQU 0X0000
VM_CS_SEG       EQU 0X0000
FLAGS_VM_CMP    EQU 17
FLAGS_CMP1  EQU 1
FLAGS_CMP_IF    EQU 9
RING0_PROC_STACK_SIZE   EQU 2048
;TSS_IO_MAP_SIZE        EQU 0
TSS_IO_MAP_SIZE         EQU 0x400/8
;VM_STACK_ADDRESS   EQU vidmem_address
ROWS    EQU 25
COLS1   EQU 80
BACK1   EQU 05h
FRONT1  EQU 12h
CHECKER EQU 0

align 4
vidmem_ptr: dd VIDEO_TEXT_ADDR
pm_str: db 'protected mode string ',0
pm_str_length: equ $-pm_str
vm_str: db 'virtual',0
;vidmem_address: dw 0

String: db 'Check',0

;times 512-($-$$) db 0

test_1.asm

;[org 0x9000]

[BITS 16]

;section .text

prep_module2:
;   jmp 0xD000
;   jmp 0x9400

vm_module:
    sub dword [vidmem_ptr],VIDEO_TEXT_ADDR

    mov si,vm_str
        
    call printstr_task

loopcheck: jmp $

printstr_task:
    
    push cx    

    mov bp,0b800h
    mov es,bp
    mov bp,[vidmem_ptr]

prep:

    mov cx,0
    mov es,cx
    mov ax,ROWS
    mov bx,es:0x044a
    mul bx
    add ax,COLS1
;   shl ax,1
    mov bp,ax
    add bp,[vidmem_ptr]
        
;check even and odd placements
    
;   wizard tests 1.7
    add bp,0x690
    times 20 inc bp
    ;bodary

;check even and odd placements
    
    mov cx,0b800H
    mov es,cx
    mov ch,COLOR_ATTR_BSC

    jmp gettext

output:
;   pop word vidmem_address
    pop ax
    mov dx,ax
    mov es:[bp],dx

    add bp,byte 2

gettext:

    mov cl,byte [ds:si]
    inc si
;   mov [vidmem_address],cx
    push cx
    test cl,cl
    jnz output
    mov [vidmem_ptr],bp

    pop word [bp]
    pop ax

    mov cx,0
    mov ds,cx
    
    ret

    jmp $

;dw 0xaa55

;section .data
VIDEO_TEXT_ADDR EQU 0XB8000
COLOR_ATTR_PSC  EQU 0X6A
COLOR_ATTR_BSC  EQU 0X5F
PM_MODE_STACK   EQU 0X80000
VM_STACK_SEG    EQU 0X0000
VM_STACK_OFS    EQU 0X0000
VM_CS_SEG       EQU 0X0000
FLAGS_VM_CMP    EQU 17
FLAGS_CMP1  EQU 1
FLAGS_CMP_IF    EQU 9
RING0_PROC_STACK_SIZE   EQU 2048
;TSS_IO_MAP_SIZE        EQU 0
TSS_IO_MAP_SIZE         EQU 0x400/8
;VM_STACK_ADDRESS   EQU vidmem_address
ROWS    EQU 25
COLS1   EQU 80
BACK1   EQU 05h
FRONT1  EQU 12h
CHECKER EQU 0

align 4
vidmem_ptr: dd VIDEO_TEXT_ADDR
pm_str: db 'protected mode string ',0
pm_str_length: equ $-pm_str
vm_str: db 'virtual',0
;vidmem_address: dw 0

String: db 'Check',0

;times 512-($-$$) db 0

run.sh

nasm -f bin boot.asm -o boot.bin
    nasm -f bin stage1.asm -o stage1.bin


    nasm -f elf stage3.asm -o stage3_2.o
    ld -g -m elf_i386 -Ttext 0x9000 stage3_2.o -o stage3_2.bin --oformat binary 

    nasm -f elf stage4.asm -o stage4_2.o
    ld -g -m elf_i386 -Ttext 0x9200 stage4_2.o -o stage4_2.bin --oformat binary 

    nasm -f elf test_1.asm -o test_1.o
    ld -g -m elf_i386 -Ttext 0x9400 test_1.o -o test_1.bin --oformat binary 

    dd if=/dev/zero of=os.bin bs=512 count=2875
    cat boot.bin    \
        stage1.bin  \
        stage3_2.bin\
        stage4_2.bin\
        test_1.bin  \
    os.bin>os.img

rm -rf *\.bin

qemu-system-i386 -hda os.img

下面是我的gdb配置config1文件

define settings1
    add-symbol-file boot.o 0x7c00
    target remote | qemu-system-i386 -S -hda os.bin -gdb stdio
end

define build1
    add-symbol-file boot.o 0x7c00 \
    y
end

define build2
    target remote | qemu-system-i386 -S -fda os.img -gdb stdio
end

gdb命令

source -s -v config1
build2
b *0x9200
stepi

assembly 如何在gdb下修复分段错误

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