x64程序集反向字符串函数[重复]

我正在学习组装,并面临以下问题:

在函数中

asm_func4:
        push rbp                ; preserve rbp
        call _strlen            ; get rdi strlen
        mov rdx, rax            ; copy strlen to reverse counter 
        sub rdx, 2              ; remove \n and 0h 
        xor rcx, rcx            ; clear counter        

_reverse_str:
        mov al, [rdi+rdx]       ; copy last char to al
        mov byte [rsi+rcx], al  ; copy al to rsi 
        inc rcx                 ; increment destination counter
        dec rdx                 ; decrement reverse counter 
        jnz  _reverse_str       ; not zero? do it again

_reverse_end:
        mov byte [rsi+rcx], 0h  ; null-terminate the string
        mov rax,rsi             ; copy to rax to return the func
        pop rbp                 ; must be preserved
        ret

我得到了一个 SIGSEGV 同时执行行`mov byte[rsi+rcx],al;将al复制到rsi。 我在这里做错了什么?

这是“gdb”信息:

0x0000555555555317 in _reverse_str ()
1: (char *) $rdi = 0x555555556086 "Hello from asm_func4\n"
2: (char *) $rsi = 0x55555555609b ""
3: (char *) $rax = 0x34 <error: Cannot access memory at address 0x34>
4: (char) $al = 52 '4'
5: (int) $rcx = 0
6: (int) $rdx = 19
(gdb) x/i $pc
=> 0x555555555317 <_reverse_str+3>: mov    %al,(%rsi,%rcx,1)
(gdb) stepi

Program received signal SIGSEGV, Segmentation fault.

函数是从C:

#include <stdio.h>
#include "prog.h"


int main(void)
{

    printf("%s", asm_func4("Hello from asm_func4\n"));

    return 0;
}

程序h是:

#pragma once
 char* asm_func4(char *);