main/libitm/config/linux/futex_bits.h

   1 /* Copyright (C) 2011-2014 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, long op, long 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 }