libgcc/config/i386/shadow-stack-unwind.h

   1 /* _Unwind_Frames_Extra with shadow stack for x86-64 and x86.
   2    Copyright (C) 2017-2018 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC 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
  14 GNU General Public License for more details.
  15
  16 Under Section 7 of GPL version 3, you are granted additional
  17 permissions described in the GCC Runtime Library Exception, version
  18 3.1, as published by the Free Software Foundation.
  19
  20 You should have received a copy of the GNU General Public License and
  21 a copy of the GCC Runtime Library Exception along with this program;
  22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 <http://www.gnu.org/licenses/>.  */
  24
  25 /* NB: We need _get_ssp and _inc_ssp from <cetintrin.h>.  But we can't
  26    include <x86intrin.h> which ends up including <mm_malloc.h>, which
  27    includes <stdlib.h> and <errno.h> unconditionally.  But we can't
  28    include any libc system headers unconditionally from libgcc.  Avoid
  29    including <mm_malloc.h> here by defining _IMMINTRIN_H_INCLUDED.  */
  30 #define _IMMINTRIN_H_INCLUDED
  31 #include <cetintrin.h>
  32 #undef _IMMINTRIN_H_INCLUDED
  33
  34 /* Unwind the shadow stack for EH.  */
  35 #undef _Unwind_Frames_Extra
  36 #define _Unwind_Frames_Extra(x)                 \
  37   do                                            \
  38     {                                           \
  39       _Unwind_Word ssp = _get_ssp ();           \
  40       if (ssp != 0)                             \
  41         {                                       \
  42           _Unwind_Word tmp = (x);               \
  43           while (tmp > 255)                     \
  44             {                                   \
  45               _inc_ssp (255);                   \
  46               tmp -= 255;                       \
  47             }                                   \
  48           _inc_ssp (tmp);                       \
  49         }                                       \
  50     }                                           \
  51     while (0)
  52
  53 /* Increment frame count.  Skip signal frames.  */
  54 #undef _Unwind_Frames_Increment
  55 #define _Unwind_Frames_Increment(context, frames) \
  56   if (!_Unwind_IsSignalFrame (context)) frames++