sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/fe_nomask.c

   1 /* Procedure definition for FE_NOMASK_ENV for Linux/ppc.
   2    Copyright (C) 2000, 2006, 2008 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 <fenv_libc.h>
  20 #include <errno.h>
  21 #include <signal.h>
  22 #include <unistd.h>
  23 #include <sysdep.h>
  24 #include <sys/prctl.h>
  25 #include <kernel-features.h>
  26
  27 #if __ASSUME_NEW_PRCTL_SYSCALL == 0
  28 /* This is rather fiddly under Linux.  We don't have direct access,
  29    and there is no system call, but we can change the bits
  30    in a signal handler's context...  */
  31
  32 static struct sigaction oact;
  33
  34 static void
  35 fe_nomask_handler (int signum, struct sigcontext *sc)
  36 {
  37   sc->regs->msr |= 0x900ul;  /* FE0 | FE1 */
  38   sigaction (SIGUSR1, &oact, NULL);
  39 }
  40 #endif
  41
  42 const fenv_t *
  43 __fe_nomask_env (void)
  44 {
  45 #if __ASSUME_NEW_PRCTL_SYSCALL == 0
  46 # if defined PR_SET_FPEXC && defined PR_FP_EXC_PRECISE
  47   int result = INLINE_SYSCALL (prctl, 2, PR_SET_FPEXC, PR_FP_EXC_PRECISE);
  48
  49   if (result == -1 && errno == EINVAL)
  50 # endif
  51     {
  52       struct sigaction act;
  53
  54       act.sa_handler = (sighandler_t) fe_nomask_handler;
  55       sigemptyset (&act.sa_mask);
  56       act.sa_flags = 0;
  57
  58       sigaction (SIGUSR1, &act, &oact);
  59       raise (SIGUSR1);
  60     }
  61 #else
  62   INTERNAL_SYSCALL_DECL (err);
  63   INTERNAL_SYSCALL (prctl, err, 2, PR_SET_FPEXC, PR_FP_EXC_PRECISE);
  64 #endif
  65
  66   return FE_ENABLED_ENV;
  67 }
  68 libm_hidden_def (__fe_nomask_env)