glibc/sysdeps/unix/syscall.S

/* Copyright (C) 1993-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>

#ifndef SYS_syscall
#define SYS_syscall	0
#endif

/* This works if the kernel does an "indirect system call" for system call 0,
   taking the first argument word off the stack as the system call number.  */

SYSCALL (syscall, 1)
	ret
PSEUDO_END(syscall)