Where in the hello world assembly program is the segmentation fault?

Question

I have written my first assembly program

; ----------------------------------------------------------------------------------------
; Writes "Hello, World" to the console using only system calls. Runs on 64-bit Linux only.
; To assemble and run:
;
;   nasm -felf64 hello.asm && ld hello.o && .a.out
; ----------------------------------------------------------------------------------------
            global      _start

            section     .text
_start      mov         rax, 1                      ; system call for write
            mov         rdi, 1                      ; file handle 1 is stdout
            mov         rsi, message                ; address of string to output
            mov         rdx, 13                     ; number of bytes
            syscall                                 ; invoke operating system to do the write
            mov         rax, 60                     ; system all for exit
            xor         rdi, rdi                    ; exit code 0

            section     .data

message:    db          "Hello, world", 10          ; note the newline at the end

using gedit text editor in Ubuntu studio 20.04 64bits system. I ran the program using Xfce terminal using command nasm -felf64 hello.asm && ld hello.o && ./a.out and received the output on two lines:

Hello, world

Segmentation fault (core dumped)

I got the source code from nasm tuitorial webpage. So where in this program is the segmentation fault

The CPU doesn't know when to stop executing code, You've cleared `rdi`, but never `_exit`. — Thomas Jager, Jul 05 '20 at 21:11
You set up the registers for the `_exit` system call but you never actually executed the `syscall` instruction. Add `syscall` after `xor rdi, rdi` and it works. That line is present in the tutorial so I guess you missed copying it. — Nate Eldredge, Jul 05 '20 at 21:21
Ah! Muchas gracias for that, I didn't notice it in the source code. Thanks again. — Hilary Diaz, Jul 05 '20 at 21:35

Where in the hello world assembly program is the segmentation fault?

0 Answers0