libgomp/config/linux/x86/futex.h

   1 /* Copyright (C) 2005-2015 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 #ifdef __x86_64__
  29 # ifndef SYS_futex
  30 #  define SYS_futex     202
  31 # endif
  32
  33 static inline void
  34 futex_wait (int *addr, int val)
  35 {
  36   register long r10 __asm__("%r10");
  37   long res;
  38
  39   r10 = 0;
  40   __asm volatile ("syscall"
  41                   : "=a" (res)
  42                   : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),
  43                     "d" (val), "r" (r10)
  44                   : "r11", "rcx", "memory");
  45   if (__builtin_expect (res == -ENOSYS, 0))
  46     {
  47       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  48       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  49       r10 = 0;
  50       __asm volatile ("syscall"
  51                       : "=a" (res)
  52                       : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),
  53                         "d" (val), "r" (r10)
  54                       : "r11", "rcx", "memory");
  55     }
  56 }
  57
  58 static inline void
  59 futex_wake (int *addr, int count)
  60 {
  61   long res;
  62
  63   __asm volatile ("syscall"
  64                   : "=a" (res)
  65                   : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),
  66                     "d" (count)
  67                   : "r11", "rcx", "memory");
  68   if (__builtin_expect (res == -ENOSYS, 0))
  69     {
  70       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  71       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  72       __asm volatile ("syscall"
  73                       : "=a" (res)
  74                       : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),
  75                         "d" (count)
  76                       : "r11", "rcx", "memory");
  77     }
  78 }
  79 #else
  80 # ifndef SYS_futex
  81 #  define SYS_futex     240
  82 # endif
  83
  84 static inline long
  85 sys_futex0 (int *addr, int op, int val)
  86 {
  87   long res;
  88
  89   __asm volatile ("int $0x80"
  90                   : "=a" (res)
  91                   : "0"(SYS_futex), "b" (addr), "c"(op),
  92                     "d"(val), "S"(0)
  93                   : "memory");
  94   return res;
  95 }
  96
  97 static inline void
  98 futex_wait (int *addr, int val)
  99 {
 100   long res = sys_futex0 (addr, gomp_futex_wait, val);
 101   if (__builtin_expect (res == -ENOSYS, 0))
 102     {
 103       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
 104       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
 105       sys_futex0 (addr, gomp_futex_wait, val);
 106     }
 107 }
 108
 109 static inline void
 110 futex_wake (int *addr, int count)
 111 {
 112   long res = sys_futex0 (addr, gomp_futex_wake, count);
 113   if (__builtin_expect (res == -ENOSYS, 0))
 114     {
 115       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
 116       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
 117       sys_futex0 (addr, gomp_futex_wake, count);
 118     }
 119 }
 120
 121 #endif /* __x86_64__ */
 122
 123 static inline void
 124 cpu_relax (void)
 125 {
 126   __builtin_ia32_pause ();
 127 }