gcc/libgcc/config/i386/shadow-stack-unwind.h
H.J. Lu b72e71a39c i386: Remove _Unwind_Frames_Increment
CET kernel has been changed to place a restore token on shadow stack for
signal handler to enhance security.  It is usually transparent to user
programs since kernel will pop the restore token when signal handler
returns.  But when an exception is thrown from a signal handler, now
we need to remove _Unwind_Frames_Increment to pop the the restore token
from shadow stack.  Otherwise, we get

FAIL: g++.dg/torture/pr85334.C   -O0  execution test
FAIL: g++.dg/torture/pr85334.C   -O1  execution test
FAIL: g++.dg/torture/pr85334.C   -O2  execution test
FAIL: g++.dg/torture/pr85334.C   -O3 -g  execution test
FAIL: g++.dg/torture/pr85334.C   -Os  execution test
FAIL: g++.dg/torture/pr85334.C   -O2 -flto -fno-use-linker-plugin -flto-partition=none  execution test

	PR libgcc/85334
	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
	Removed.

From-SVN: r263030
2018-07-27 07:40:47 -07:00

52 lines
1.8 KiB
C

/* _Unwind_Frames_Extra with shadow stack for x86-64 and x86.
Copyright (C) 2017-2018 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC 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 General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* NB: We need _get_ssp and _inc_ssp from <cetintrin.h>. But we can't
include <x86intrin.h> which ends up including <mm_malloc.h>, which
includes <stdlib.h> and <errno.h> unconditionally. But we can't
include any libc system headers unconditionally from libgcc. Avoid
including <mm_malloc.h> here by defining _IMMINTRIN_H_INCLUDED. */
#define _IMMINTRIN_H_INCLUDED
#include <cetintrin.h>
#undef _IMMINTRIN_H_INCLUDED
/* Unwind the shadow stack for EH. */
#undef _Unwind_Frames_Extra
#define _Unwind_Frames_Extra(x) \
do \
{ \
_Unwind_Word ssp = _get_ssp (); \
if (ssp != 0) \
{ \
_Unwind_Word tmp = (x); \
while (tmp > 255) \
{ \
_inc_ssp (255); \
tmp -= 255; \
} \
_inc_ssp (tmp); \
} \
} \
while (0)