1  /* Copyright (C) 2011-2023 Free Software Foundation, Inc.
       2     Contributed by Richard Henderson <rth@redhat.com>.
       3  
       4     This file is part of the GNU Transactional Memory Library (libitm).
       5  
       6     Libitm is free software; you can redistribute it and/or modify it
       7     under the terms of the GNU General Public License as published by
       8     the Free Software Foundation; either version 3 of the License, or
       9     (at your option) any later version.
      10  
      11     Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
      12     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      13     FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
      14     more details.
      15  
      16     Under Section 7 of GPL version 3, you are granted additional
      17     permissions described in the GCC Runtime Library Exception, version
      18     3.1, as published by the Free Software Foundation.
      19  
      20     You should have received a copy of the GNU General Public License and
      21     a copy of the GCC Runtime Library Exception along with this program;
      22     see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      23     <http://www.gnu.org/licenses/>.  */
      24  
      25  /* Provide target-independant access to the futex system call.  */
      26  
      27  /* Note for ARM:
      28     There are two styles of syscall, and in the eabi style the syscall
      29     number goes into the thumb frame pointer.  We need to either write
      30     this in pure assembler or just defer entirely to libc.  */
      31  
      32  #include <unistd.h>
      33  #include <sys/syscall.h>
      34  #include <errno.h>
      35  
      36  static inline long
      37  sys_futex0 (std::atomic<int> *addr, int op, int val)
      38  {
      39    long res = syscall (SYS_futex, (int*) addr, op, val, 0);
      40    if (__builtin_expect (res == -1, 0))
      41      return -errno;
      42    return res;
      43  }