glibc/sysdeps/s390/fpu/fesetenv.c
Stefan Liebler 5d96fe8c0d S390: Fix handling of DXC-byte in FPC-register.
On s390, the DXC(data-exception-code)-byte in FPC(floating-point-control)-
register contains a code of the last occured exception.
If bits 6 and 7 of DXC-byte are zero, the bits 0-5 correspond to the
ieee-exception flag bits.
The current implementation always uses these bits as ieee-exception flag bits.
fetestexcept() reports any exception after the first usage of a
vector-instruction in a process, because it raises an "vector instruction
exception" with DXC-code 0xFE.
This patch fixes the handling of the DXC-byte. The DXC-Byte is only handled
if bits 6 and 7 are zero.

The #define _FPU_RESERVED is extended by the DXC-Byte.
Otherwise the tests math/test-fpucw-static and math/test-fpucw-ieee-static
fails, because DXC-Byte contains the vector instruction exception when reaching
main(). This exception was triggered by strrchr() call in __init_misc().
__init_misc() is called after __setfpucw () in __libc_init_first().

The field __ieee_instruction_pointer in struct fenv_t is renamed to __unused
because it is a relict from commit "Remove PTRACE_PEEKUSER"
(87b9b50f0d) and isn´t used anymore.

ChangeLog:

	[BZ #18610]
	* sysdeps/s390/fpu/bits/fenv.h (fenv_t): Rename
	__ieee_instruction_pointer to __unused.
	* sysdeps/s390/fpu/fesetenv.c (__fesetenv): Remove usage of
	__ieee_instruction_pointer.
	* sysdeps/s390/fpu/fclrexcpt.c (feclearexcept): Fix dxc-field handling.
	* sysdeps/s390/fpu/fgetexcptflg.c (fegetexceptflag): Likewise.
	* sysdeps/s390/fpu/fsetexcptflg.c (fesetexceptflag): Likewise.
	* sysdeps/s390/fpu/ftestexcept.c (fetestexcept): Likewise.
	* sysdeps/s390/fpu/fpu_control.h (_FPU_RESERVED):
	Mark dxc-field as reserved.
2015-08-26 10:26:18 +02:00

51 lines
1.4 KiB
C

/* Install given floating-point environment.
Copyright (C) 2000-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Denis Joseph Barrow (djbarrow@de.ibm.com).
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 <fenv_libc.h>
#include <fpu_control.h>
#include <stddef.h>
#include <asm/ptrace.h>
#include <sys/ptrace.h>
#include <unistd.h>
int
__fesetenv (const fenv_t *envp)
{
fenv_t env;
if (envp == FE_DFL_ENV)
{
env.__fpc = _FPU_DEFAULT;
}
else if (envp == FE_NOMASK_ENV)
{
env.__fpc = FPC_EXCEPTION_MASK;
}
else
env = (*envp);
_FPU_SETCW (env.__fpc);
/* Success. */
return 0;
}
libm_hidden_def (__fesetenv)
weak_alias (__fesetenv, fesetenv)
libm_hidden_weak (fesetenv)