sysdeps/sparc/sparc64/cpu_relax.c

   1 /* CPU strand yielding for busy loops.  Linux/sparc64 version.
   2    Copyright (C) 2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sparc-ifunc.h>
  20
  21 static void
  22 __cpu_relax_generic (void)
  23 {
  24   asm volatile ("rd %ccr, %g0;"
  25                 "rd %ccr, %g0;"
  26                 "rd %ccr, %g0");
  27 }
  28
  29 static void
  30 __cpu_relax_pause (void)
  31 {
  32   asm volatile ("wr %g0, 128, %asr27");
  33 }
  34
  35 sparc_libc_ifunc (__cpu_relax,
  36                   hwcap & HWCAP_SPARC_PAUSE
  37                   ? __cpu_relax_pause
  38                   : __cpu_relax_generic)