sysdeps/s390/fpu/fegetenv.c

   1 /* Store current floating-point environment.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Denis Joseph Barrow (djbarrow@de.ibm.com).
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA. */
  20
  21 #include <fenv_libc.h>
  22 #include <fpu_control.h>
  23 #include <stddef.h>
  24 #include <asm/ptrace.h>
  25 #include <sys/ptrace.h>
  26 #include <unistd.h>
  27
  28 int
  29 fegetenv (fenv_t *envp)
  30 {
  31   /* The S/390 IEEE fpu doesn't keep track of the ieee instruction pointer.
  32      To get around that the kernel will store the address of the last
  33      fpu fault to the process structure. This ptrace call reads this value
  34      from the kernel space. That means the ieee_instruction_pointer is
  35      only correct after a fpu fault. That's the best we can do, there is
  36      no way to find out the ieee instruction pointer if there was no fault.  */
  37   _FPU_GETCW (envp->fpc);
  38   envp->ieee_instruction_pointer =
  39     ptrace (PTRACE_PEEKUSER, getpid (), PT_IEEE_IP);
  40
  41   /* Success.  */
  42   return 0;
  43 }