从程序集调用C函数(printf)时出现段错误 [英] Segfault while calling C function (printf) from Assembly

问题描述

我正在Linux上使用NASM编写一个基本的汇编程序，该程序从C库(printf)中调用一个函数.不幸的是，我在这样做时遇到了分段错误.注释掉对printf的调用，可以使程序正常运行.

I am using NASM on linux to write a basic assembly program that calls a function from the C libraries (printf). Unfortunately, I am incurring a segmentation fault while doing so. Commenting out the call to printf allows the program to run without error.

; Build using these commands:
;   nasm -f elf64 -g -F stabs <filename>.asm 
;   gcc <filename>.o -o <filename>
;

SECTION .bss    ; Section containing uninitialized data

SECTION .data   ; Section containing initialized data

  text db "hello world",10 ; 

SECTION .text   ; Section containing code


global main

extern printf

;-------------
;MAIN PROGRAM BEGINS HERE
;-------------

main:



      push rbp

      mov rbp,rsp

      push rbx

      push rsi

      push rdi ;preserve registers

      ****************


      ;code i wish to execute

      push text ;pushing address of text on to the stack
      ;x86-64 uses registers for first 6 args, thus should have been:
      ;mov rdi,text (place address of text in rdi)
      ;mov rax,0 (place a terminating byte at end of rdi)

      call printf ;calling printf from c-libraries

      add rsp,8 ;reseting the stack to pre "push text"

      **************  

      pop rdi ;preserve registers

      pop rsi

      pop rbx

      mov rsp,rbp

      pop rbp

      ret

推荐答案

x86_64的前6个参数不使用堆栈.您需要将它们加载到适当的寄存器中.这些是:

x86_64 does not use the stack for the first 6 args. You need to load them in the proper registers. Those are:

rdi, rsi, rdx, rcx, r8, r9

我用来记住前两个的技巧是想象功能是memcpy实现为rep movsb，

The trick I use to remember the first two is to imagine the function is memcpy implemented as rep movsb,

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