libgomp/config/linux/powerpc/futex.h

   1 /* Copyright (C) 2005-2016 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@redhat.com>.
   3
   4    This file is part of the GNU Offloading and Multi Processing Library
   5    (libgomp).
   6
   7    Libgomp is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  13    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  14    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15    more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 /* Provide target-specific access to the futex system call.  */
  27
  28 #include <sys/syscall.h>
  29
  30 static inline long
  31 sys_futex0 (int *addr, int op, int val)
  32 {
  33   register long int r0  __asm__ ("r0");
  34   register long int r3  __asm__ ("r3");
  35   register long int r4  __asm__ ("r4");
  36   register long int r5  __asm__ ("r5");
  37   register long int r6  __asm__ ("r6");
  38
  39   r0 = SYS_futex;
  40   r3 = (long) addr;
  41   r4 = op;
  42   r5 = val;
  43   r6 = 0;
  44
  45   /* ??? The powerpc64 sysdep.h file clobbers ctr; the powerpc32 sysdep.h
  46      doesn't.  It doesn't much matter for us.  In the interest of unity,
  47      go ahead and clobber it always.  */
  48
  49   __asm volatile ("sc; mfcr %0"
  50                   : "=r"(r0), "=r"(r3), "=r"(r4), "=r"(r5), "=r"(r6)
  51                   : "r"(r0), "r"(r3), "r"(r4), "r"(r5), "r"(r6)
  52                   : "r7", "r8", "r9", "r10", "r11", "r12",
  53                     "cr0", "ctr", "memory");
  54   if (__builtin_expect (r0 & (1 << 28), 0))
  55     return r3;
  56   return 0;
  57 }
  58
  59 static inline void
  60 futex_wait (int *addr, int val)
  61 {
  62   long err = sys_futex0 (addr, gomp_futex_wait, val);
  63   if (__builtin_expect (err == ENOSYS, 0))
  64     {
  65       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  66       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  67       sys_futex0 (addr, gomp_futex_wait, val);
  68     }
  69 }
  70
  71 static inline void
  72 futex_wake (int *addr, int count)
  73 {
  74   long err = sys_futex0 (addr, gomp_futex_wake, count);
  75   if (__builtin_expect (err == ENOSYS, 0))
  76     {
  77       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  78       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  79       sys_futex0 (addr, gomp_futex_wake, count);
  80     }
  81 }
  82
  83 static inline void
  84 cpu_relax (void)
  85 {
  86   __asm volatile ("" : : : "memory");
  87 }