gcc/config/i386/cet.c

   1 /* Functions for CET/x86.
   2    Copyright (C) 2017-2019 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 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "output.h"
  25 #include "linux-common.h"
  26
  27 void
  28 file_end_indicate_exec_stack_and_cet (void)
  29 {
  30   file_end_indicate_exec_stack ();
  31
  32   if (flag_cf_protection == CF_NONE)
  33     return;
  34
  35   unsigned int feature_1 = 0;
  36
  37   if (flag_cf_protection & CF_BRANCH)
  38     /* GNU_PROPERTY_X86_FEATURE_1_IBT.  */
  39     feature_1 |= 0x1;
  40
  41   if (flag_cf_protection & CF_RETURN)
  42     /* GNU_PROPERTY_X86_FEATURE_1_SHSTK.  */
  43     feature_1 |= 0x2;
  44
  45   if (feature_1)
  46     {
  47       int p2align = ptr_mode == SImode ? 2 : 3;
  48
  49       /* Generate GNU_PROPERTY_X86_FEATURE_1_XXX.  */
  50       switch_to_section (get_section (".note.gnu.property",
  51                                       SECTION_NOTYPE, NULL));
  52
  53       ASM_OUTPUT_ALIGN (asm_out_file, p2align);
  54       /* name length.  */
  55       fprintf (asm_out_file, ASM_LONG " 1f - 0f\n");
  56       /* data length.  */
  57       fprintf (asm_out_file, ASM_LONG " 4f - 1f\n");
  58       /* note type: NT_GNU_PROPERTY_TYPE_0.  */
  59       fprintf (asm_out_file, ASM_LONG " 5\n");
  60       fprintf (asm_out_file, "0:\n");
  61       /* vendor name: "GNU".  */
  62       fprintf (asm_out_file, STRING_ASM_OP " \"GNU\"\n");
  63       fprintf (asm_out_file, "1:\n");
  64       ASM_OUTPUT_ALIGN (asm_out_file, p2align);
  65       /* pr_type: GNU_PROPERTY_X86_FEATURE_1_AND.  */
  66       fprintf (asm_out_file, ASM_LONG " 0xc0000002\n");
  67       /* pr_datasz.  */\
  68       fprintf (asm_out_file, ASM_LONG " 3f - 2f\n");
  69       fprintf (asm_out_file, "2:\n");
  70       /* GNU_PROPERTY_X86_FEATURE_1_XXX.  */
  71       fprintf (asm_out_file, ASM_LONG " 0x%x\n", feature_1);
  72       fprintf (asm_out_file, "3:\n");
  73       ASM_OUTPUT_ALIGN (asm_out_file, p2align);
  74       fprintf (asm_out_file, "4:\n");
  75     }
  76 }