What is the correct constant to call the exit system?

Question

I am trying to learn the x86_64 assembly and am using GCC as my assembler. The exact command I use is:

gcc -nostdlib tapydn.S -D__ASSEMBLY__

I mainly use gcc for my preprocessor. Here tapydn.S:

.global _start

#include <asm-generic/unistd.h>

syscall=0x80

.text
_start:
    movl $__NR_exit, %eax
    movl $0x00, %ebx
    int  $syscall

This results in a segmentation error. I believe the problem is with the following line:

 movl $__NR_exit, %eax

I used __NR_exitbecause it was more visual than some magic number. However, it seems that its use is incorrect. I believe this is so, because when I change the corresponding line to the following, it works fine:

movl $0x01, %eax

Further support for this trace of thought is content usr/include/asm-generic/unistd.h:

#define __NR_exit 93
__SYSCALL(__NR_exit, sys_exit)

, __NR_exit 1, 93! , , , . , $0x01 ( undefined ++), ...

sys_exit. . ( $):

movl $sys_exit, %eax

:

/tmp/cc7tEUtC.o: In function `_start':
(.text+0x1): undefined reference to `sys_exit'
collect2: error: ld returned 1 exit status

, , - -nostdlib GCC. , .

Jester 32 64 0x3C, :

movq $0x3C, %eax
movq $0x00, %ebx

. eax ebx rax rbx:

movq $0x3C, %rax
movq $0x00, %rbx

.

Jester , syscall, int $0x80:

.global _start

#include <asm-generic/unistd.h>

.text
_start:
    movq $0x3C, %rax
    movq $0x00, %rbx
    syscall

, , rdi rbx System V AMD64 ABI:

movq $0x00, %rdi

, , 0x3C .

, :

• __NR_exit?
• exit?

Answer 1

sys/syscall.h. SYS_###, ### - . __NR_### . , , , , . rdi, rsi, rdx, r10, r8 r9. Linux:

#include <sys/syscall.h>

    .globl _start
_start:
    mov $SYS_exit,%eax
    xor %edi,%edi
    syscall

UNIX- .