我试图弄清楚一个字符串在汇编中是否是回文。实际上我试图将字符串'my_string'的字节反向复制到'tmp_str'。然后我试图使用repe和cmpsb来比较这两个字符串。
我面临的问题是，在GDB中设置断点时，程序随机挂起或抛出SIGILL或SIGSEV。这种行为是真正随机的，或者足够随机，以至于我无法将错误的来源归结到一行。我非常困惑，希望能了解导致这些错误的原因。注意，如果我没有设置断点或设置其他断点，如第25、27、28行，它工作得很好。
我已经检查过了，for循环的迭代次数和值都是正确的，初始字符串的格式也是我所期望的。
错误示例：

• 挂起 *〈-如果断点设置为第30行

Program received signal SIGILL, Illegal instruction. _start.for_1.end () at 4.asm:32 32 jmp .for_1.start〈-当断点设置为第28行时（错误不可重现，但确实发生了）
Program received signal SIGSEGV, Segmentation fault. 0x0000000000400feb in ?? ()〈-当断点设置为第31行时

;; Write an assembly program to determine if a string stored in memory is a palindrome
;; (A palindrome is a string which is the same after being reversed, like "refer")
;; Use at least one repeat instruction

                segment .data
my_string       db              "bob", 0

                segment .bss
tmp_str         resb            4

                segment .text
                global _start

_start:
                ;/* Copy initial string BACKWARDS */
                xor             rcx, rcx                        ; have to use manual for loop
.for_1.start:
                cmp             ecx, 4
                je              .for_1.end
                mov             al, byte [my_string+ecx]        ; get character from original string from i'th place
                mov             rbx, tmp_str+2                  ; go to end of tmp_str (writing my_string to tmp_str backwards)
                sub             rbx, rcx                        ; we can't minus from address expression thingy, so just deduct from register stored above
                mov             [rbx], byte al                  ; copy byte in ebx into mem address stored atueax
                inc             ecx                             ; increment counter     
                jmp             .for_1.start                    ; unconditional start to stop (for loops check and do conditional jumps at top)
.for_1.end:
                ;/* Compare strings */
                mov             rsi, my_string                  ; now we want to compare strings (remember, pointer in reg moves in movsb)
                mov             rdi, tmp_str                    ; rdi, set to tmp_str address 
                mov             rcx, 2                          ; since rcx was modified by rep, we need to reset that though
                repe            cmpsb                           ; compare strings whilst each val (byte) is equal
                                                                ; now, if rcx is NOT 0, the bytes do not match and is not a palindrome!
                ;/* EOP */
                mov             eax, 1
                xor             ebx, ebx
                int 0x80

如果有人能提供一些建议，我将不胜感激。
编译命令：yasm -f elf64 -g dwarf2 <file>.asm ; ld <file>.o -o <file>