GCC Middle and Back End API Reference
asan.h
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1 /* AddressSanitizer, a fast memory error detector.
2  Copyright (C) 2011-2013 Free Software Foundation, Inc.
3  Contributed by Kostya Serebryany <kcc@google.com>
4 
5 This file is part of GCC.
6 
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11 
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16 
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20 
21 #ifndef TREE_ASAN
22 #define TREE_ASAN
23 
24 extern void asan_finish_file (void);
25 extern rtx asan_emit_stack_protection (rtx, HOST_WIDE_INT *, tree *, int);
26 extern bool asan_protect_global (tree);
27 extern void initialize_sanitizer_builtins (void);
28 
29 /* Alias set for accessing the shadow memory. */
30 extern alias_set_type asan_shadow_set;
31 
32 /* Shadow memory is found at
33  (address >> ASAN_SHADOW_SHIFT) + targetm.asan_shadow_offset (). */
34 #define ASAN_SHADOW_SHIFT 3
35 
36 /* Red zone size, stack and global variables are padded by ASAN_RED_ZONE_SIZE
37  up to 2 * ASAN_RED_ZONE_SIZE - 1 bytes. */
38 #define ASAN_RED_ZONE_SIZE 32
39 
40 /* Shadow memory values for stack protection. Left is below protected vars,
41  the first pointer in stack corresponding to that offset contains
42  ASAN_STACK_FRAME_MAGIC word, the second pointer to a string describing
43  the frame. Middle is for padding in between variables, right is
44  above the last protected variable and partial immediately after variables
45  up to ASAN_RED_ZONE_SIZE alignment. */
46 #define ASAN_STACK_MAGIC_LEFT 0xf1
47 #define ASAN_STACK_MAGIC_MIDDLE 0xf2
48 #define ASAN_STACK_MAGIC_RIGHT 0xf3
49 #define ASAN_STACK_MAGIC_PARTIAL 0xf4
50 
51 #define ASAN_STACK_FRAME_MAGIC 0x41b58ab3
52 
53 /* Return true if DECL should be guarded on the stack. */
54 
55 static inline bool
56 asan_protect_stack_decl (tree decl)
57 {
58  return DECL_P (decl) && !DECL_ARTIFICIAL (decl);
59 }
60 
61 /* Return the size of padding needed to insert after a protected
62  decl of SIZE. */
63 
64 static inline unsigned int
65 asan_red_zone_size (unsigned int size)
66 {
67  unsigned int c = size & (ASAN_RED_ZONE_SIZE - 1);
68  return c ? 2 * ASAN_RED_ZONE_SIZE - c : ASAN_RED_ZONE_SIZE;
69 }
70 
71 #endif /* TREE_ASAN */