1  /*
       2   * Copyright (c) 2015-2021 The strace developers.
       3   * All rights reserved.
       4   *
       5   * SPDX-License-Identifier: LGPL-2.1-or-later
       6   */
       7  
       8  /* Return codes: 1 - ok, 0 - ignore, other - error. */
       9  static int
      10  arch_get_scno(struct tcb *tcp)
      11  {
      12  	kernel_ulong_t scno = 0;
      13  
      14  	if (upeek(tcp, REG_A3, &alpha_a3) < 0)
      15  		return -1;
      16  	if (upeek(tcp, REG_R0, &scno) < 0)
      17  		return -1;
      18  
      19  	/*
      20  	 * Do some sanity checks to figure out if it's
      21  	 * really a syscall entry
      22  	 */
      23  	if (!scno_in_range(scno)) {
      24  		if (alpha_a3 == 0 || alpha_a3 == -1UL) {
      25  			debug_msg("stray syscall exit: r0 = %lu", scno);
      26  			return 0;
      27  		}
      28  	}
      29  
      30  	tcp->scno = scno;
      31  	return 1;
      32  }