gcc/libgcc/config/i386/shadow-stack-unwind.h
H.J. Lu 5707be3c7d libgcc/CET: Skip signal frames when unwinding shadow stack
When -fcf-protection -mcet is used, I got

FAIL: g++.dg/eh/sighandle.C

(gdb) bt
 #0  _Unwind_RaiseException (exc=exc@entry=0x416ed0)
    at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:140
 #1  0x00007ffff7d9936b in __cxxabiv1::__cxa_throw (obj=<optimized out>,
    tinfo=0x403dd0 <typeinfo for int@@CXXABI_1.3>, dest=0x0)
    at /export/gnu/import/git/sources/gcc/libstdc++-v3/libsupc++/eh_throw.cc:90
 #2  0x0000000000401255 in sighandler (signo=11, si=0x7fffffffd6f8,
    uc=0x7fffffffd5c0)
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:9
 #3  <signal handler called> <<<< Signal frame which isn't on shadow stack
 #4  dosegv ()
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:14
 #5  0x00000000004012e3 in main ()
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:30
(gdb) p frames
$6 = 5
(gdb)

frame count should be 4, not 5.  This patch skips signal frames when
unwinding shadow stack.

gcc/testsuite/

	PR libgcc/85334
	* g++.dg/torture/pr85334.C: New test.

libgcc/

	PR libgcc/85334
	* unwind-generic.h (_Unwind_Frames_Increment): New.
	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
	Likewise.
	* unwind.inc (_Unwind_RaiseException_Phase2): Increment frame
	count with _Unwind_Frames_Increment.
	(_Unwind_ForcedUnwind_Phase2): Likewise.

From-SVN: r259502
2018-04-19 10:05:39 -07:00

57 lines
2.0 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)
/* Increment frame count. Skip signal frames. */
#undef _Unwind_Frames_Increment
#define _Unwind_Frames_Increment(context, frames) \
if (!_Unwind_IsSignalFrame (context)) frames++