nptl/sysdeps/unix/sysv/linux/x86_64/libc-lowlevellock.S

   1 /* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 /* In libc.so we do not unconditionally use the lock prefix.  Only if
  21    the application is using threads.  */
  22 #ifndef UP
  23 # define LOCK \
  24         cmpl    $0, __libc_multiple_threads(%rip);                            \
  25         je      0f;                                                           \
  26         lock;                                                                 \
  27 0:
  28 #endif
  29
  30 #include "lowlevellock.S"