libgomp/config/linux/x86/futex.h

   1 /* Copyright (C) 2005-2020 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   long res;
  37
  38   register long r10 __asm__("%r10") = 0;
  39   __asm volatile ("syscall"
  40                   : "=a" (res)
  41                   : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),
  42                     "d" (val), "r" (r10)
  43                   : "r11", "rcx", "memory");
  44   if (__builtin_expect (res == -ENOSYS, 0))
  45     {
  46       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  47       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  48       __asm volatile ("syscall"
  49                       : "=a" (res)
  50                       : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),
  51                         "d" (val), "r" (r10)
  52                       : "r11", "rcx", "memory");
  53     }
  54 }
  55
  56 static inline void
  57 futex_wake (int *addr, int count)
  58 {
  59   long res;
  60
  61   __asm volatile ("syscall"
  62                   : "=a" (res)
  63                   : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),
  64                     "d" (count)
  65                   : "r11", "rcx", "memory");
  66   if (__builtin_expect (res == -ENOSYS, 0))
  67     {
  68       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  69       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  70       __asm volatile ("syscall"
  71                       : "=a" (res)
  72                       : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),
  73                         "d" (count)
  74                       : "r11", "rcx", "memory");
  75     }
  76 }
  77 #else
  78 # ifndef SYS_futex
  79 #  define SYS_futex     240
  80 # endif
  81
  82 static inline void
  83 futex_wait (int *addr, int val)
  84 {
  85   long res;
  86
  87   __asm volatile ("int $0x80"
  88                   : "=a" (res)
  89                   : "0" (SYS_futex), "b" (addr), "c" (gomp_futex_wait),
  90                     "d" (val), "S" (0)
  91                   : "memory");
  92   if (__builtin_expect (res == -ENOSYS, 0))
  93     {
  94       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
  95       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
  96       __asm volatile ("int $0x80"
  97                       : "=a" (res)
  98                       : "0" (SYS_futex), "b" (addr), "c" (gomp_futex_wait),
  99                         "d" (val), "S" (0)
 100                       : "memory");
 101     }
 102 }
 103
 104 static inline void
 105 futex_wake (int *addr, int count)
 106 {
 107   long res;
 108
 109   __asm volatile ("int $0x80"
 110                   : "=a" (res)
 111                   : "0" (SYS_futex), "b" (addr), "c" (gomp_futex_wake),
 112                     "d" (count)
 113                   : "memory");
 114   if (__builtin_expect (res == -ENOSYS, 0))
 115     {
 116       gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
 117       gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
 118       __asm volatile ("int $0x80"
 119                       : "=a" (res)
 120                       : "0" (SYS_futex), "b" (addr), "c" (gomp_futex_wake),
 121                         "d" (count)
 122                       : "memory");
 123     }
 124 }
 125 #endif /* __x86_64__ */
 126
 127 static inline void
 128 cpu_relax (void)
 129 {
 130   __builtin_ia32_pause ();
 131 }