google3/third_party/grte/v5_src/glibc-2.27/sysdeps/unix/sysv/linux/sched_getcpu.c

/* Copyright (C) 2007-2018 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <sched.h>
#include <sysdep.h>

#ifdef HAVE_GETCPU_VSYSCALL
# define HAVE_VSYSCALL
#endif
#include <sysdep-vdso.h>

#if defined __clang__ && defined __powerpc64__
/* On ppc, sched_getcpu's body eventually expands into asm code
   that does a bctrl, but clang does not recognize the need to save
   the link register, so calls loop infinitely instead of returning.
   As workaround, make a dummy function call that forces a link
   register save.  */
volatile int sched_getcpu_dummy_glob;

void __attribute__((noinline)) sched_getcpu_dummy ()
{
  sched_getcpu_dummy_glob = 45;
}
#endif

int
sched_getcpu (void)
{
#ifdef __NR_getcpu
  unsigned int cpu;
#if defined __clang__ && defined __powerpc64__
  sched_getcpu_dummy ();
#endif
  int r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);

  return r == -1 ? r : cpu;
#else
  __set_errno (ENOSYS);
  return -1;
#endif
}