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

   1 /* Procedure definition for FE_MASK_ENV for Linux/ppc.
   2    Copyright (C) 2007 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <fenv.h>
  21 #include <errno.h>
  22 #include <signal.h>
  23 #include <unistd.h>
  24 #include <sysdep.h>
  25 #include <sys/prctl.h>
  26 #include <kernel-features.h>
  27
  28 #if __ASSUME_NEW_PRCTL_SYSCALL == 0
  29 /* This is rather fiddly under Linux.  We don't have direct access,
  30    and there is no system call, but we can change the bits
  31    in a signal handler's context...  */
  32
  33 static struct sigaction oact;
  34
  35 static void
  36 fe_mask_handler (int signum, struct sigcontext *sc)
  37 {
  38   sc->regs->msr &= ~0x900ul;  /* FE0 | FE1 */
  39   sigaction (SIGUSR1, &oact, NULL);
  40 }
  41 #endif
  42
  43 const fenv_t *
  44 __fe_mask_env (void)
  45 {
  46 #if __ASSUME_NEW_PRCTL_SYSCALL == 0
  47 # if defined PR_SET_FPEXC && defined PR_FP_EXC_DISABLED
  48   int result = INLINE_SYSCALL (prctl, 2, PR_SET_FPEXC, PR_FP_EXC_DISABLED);
  49
  50   if (result == -1 && errno == EINVAL)
  51 # endif
  52     {
  53       struct sigaction act;
  54
  55       act.sa_handler = (sighandler_t) fe_mask_handler;
  56       sigemptyset (&act.sa_mask);
  57       act.sa_flags = 0;
  58
  59       sigaction (SIGUSR1, &act, &oact);
  60       raise (SIGUSR1);
  61     }
  62 #else
  63   INTERNAL_SYSCALL_DECL (err);
  64   INTERNAL_SYSCALL (prctl, err, 2, PR_SET_FPEXC, PR_FP_EXC_DISABLED);
  65 #endif
  66
  67   return FE_DFL_ENV;
  68 }