Question

我正在阅读this assembly tutorial，我得到了工作的例子，所以我决定尝试改进它。一旦我这样做，它就停止了工作，所以我试着将它转换为AT＆amp; T语法，这样我就可以用gcc编译它并得到调试信息（因为我在OS X上，并且nasm不会为它生成调试信息Mach-O格式）。

我尝试转换有效的原始程序，但是在我使用AT＆amp; T语法编写它之后它停止了工作。我用gdb来调试它，发现我期望包含argc的<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <div id="profileUploadModal" class="modal fade" role="dialog"> <div class="modal-dialog">  <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal">×</button> <h4 class="modal-title">Upload profilepicture</h4> </div> <div class="modal-body" style="text-align: center;"> <div class="bbody">  <form id="upload_form" enctype="multipart/form-data" method="post" action="upload.php" onsubmit="return checkForm()">  <input type="hidden" id="x1" name="x1" /> <input type="hidden" id="y1" name="y1" /> <input type="hidden" id="x2" name="x2" /> <input type="hidden" id="y2" name="y2" /> <h2>Step1: Please select image file</h2> <div> <input type="file" name="image_file" id="image_file" onchange="fileSelectHandler()" /> </div> <div class="error"></div> <div class="step2"> <h2>Step2: Please select a crop region</h2> <img id="preview" /> <div class="info"> <label>File size</label> <input type="text" id="filesize" name="filesize" /> <label>Type</label> <input type="text" id="filetype" name="filetype" /> <label>Image dimension</label> <input type="text" id="filedim" name="filedim" /> <label>W</label> <input type="text" id="w" name="w" /> <label>H</label> <input type="text" id="h" name="h" /> </div> <input type="submit" value="Upload" /> </div> </form> </div> </div> </div> </div> </div>包含值%rsp。英特尔语法版本不会发生这种情况。

所以我的问题是，为什么0x93b2e5ad在AT＆amp; T版本中的argc值不正确，而在英特尔版本中却没有？

这是原始的英特尔语法版本（我稍微修改了教程中的版本）：

%rsp

以下是我将其转换为AT＆amp; T语法后的代码：

section .data
    WRONG_ARGC db "Must be two command line argument", 0xa
    WRONG_ARGC_SIZE equ 34
section .text
    global start
start:
    pop rcx
    cmp rcx, 3
    jne argcError

    add rsp, 8
    pop rsi
    call str_to_int

    mov r10, rax
    pop rsi
    call str_to_int
    mov r11, rax

    add r10, r11
    mov rax, r10
    xor r12, r12

    jmp int_to_str

argcError:
    mov rax, 0x2000004
    mov rdi, 1
    mov rsi, WRONG_ARGC
    mov rdx, WRONG_ARGC_SIZE
    syscall
    jmp exit

; set rdi to exit status before calling
exit:
    mov rax, 0x2000001
    syscall

str_to_int:
    xor rax, rax
    mov rcx, 10
next:
    cmp [rsi], byte 0
    je return_str
    mov bl, [rsi]
    sub bl, 48
    mul rcx
    add rax, rbx
    inc rsi
    jmp next
return_str:
    ret

int_to_str:
    mov rdx, 0
    mov rbx, 10
    div rbx
    add rdx, 48
    ; push rdx
    dec rsp
    mov rsp, rdx

    inc r12
    cmp rax, 0
    jne int_to_str
    jmp print

print:
    ; mov rax, 1
    ; mul r12
    mov rax, r12
    ; mov r12, 8
    ; mul r12
    mov rdx, rax

    mov rax, 0x2000004
    mov rdi, 1
    mov rsi, rsp
    syscall

    mov rdi, 0
    jmp exit

我编译了这样的英特尔版本：

.data
    WRONG_ARGC: .ascii "Must be two command line argument\n"
    WRONG_ARGC_SIZE: .quad 34
.text
    .globl _main
_main:
    popq %rcx
    cmpq $3, %rcx
    jne argcError

    addq $8, %rsp
    popq %rsi
    call str_to_int

    movq %rax, %r10
    popq %rsi
    call str_to_int
    movq %rax, %r11

    addq %r11, %r10
    movq %r10, %rax
    xorq %r12, %r12

    jmp int_to_str

argcError:
    movq $0x2000004, %rax
    movq $1, %rdi
    movq WRONG_ARGC@GOTPCREL(%rsi), %rsi
    movq WRONG_ARGC_SIZE@GOTPCREL(%rsi), %rdx
    syscall
    jmp exit

# set rdi to exit status before calling
exit:
    movq $0x2000001, %rax
    syscall

str_to_int:
    xorq %rax, %rax
    movq $10, %rcx
next:
    cmpq $0, (%rsi)
    je return_str
    movb (%rsi), %bl
    subb $48, %bl
    mulq %rcx
    addq %rbx, %rax
    incq %rsi
    jmp next
return_str:
    ret

int_to_str:
    movq $0, %rdx
    movq $10, %rbx
    divq %rbx
    addq $48, %rdx
    push %rdx
    #decq %rsp
    #movq %rdx, %rsp

    incq %r12
    cmpq $0, %rax
    jne int_to_str
    jmp print

print:
    movq $1, %rax
    mulq %r12
    movq %r12, %rax
    movq $8, %r12
    mulq %r12
    movq %rax, %rdx

    movq $0x2000004, %rax
    movq $1, %rdi
    movq %rsp, %rsi
    syscall

    movq $0, %rdi
    jmp exit

我编译了这样的AT＆amp; T版本：

nasm -f macho64 -o add_intel.o add_intel.s
ld -o add_intel add_intel.s

使用AT＆amp; T语法时错误的argc

0 个答案: