1/*
2 * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
16 */
17#ifndef _ORC_LOOKUP_H
18#define _ORC_LOOKUP_H
19
20/*
21 * This is a lookup table for speeding up access to the .orc_unwind table.
22 * Given an input address offset, the corresponding lookup table entry
23 * specifies a subset of the .orc_unwind table to search.
24 *
25 * Each block represents the end of the previous range and the start of the
26 * next range. An extra block is added to give the last range an end.
27 *
28 * The block size should be a power of 2 to avoid a costly 'div' instruction.
29 *
30 * A block size of 256 was chosen because it roughly doubles unwinder
31 * performance while only adding ~5% to the ORC data footprint.
32 */
33#define LOOKUP_BLOCK_ORDER 8
34#define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER)
35
36#ifndef LINKER_SCRIPT
37
38extern unsigned int orc_lookup[];
39extern unsigned int orc_lookup_end[];
40
41#define LOOKUP_START_IP (unsigned long)_stext
42#define LOOKUP_STOP_IP (unsigned long)_etext
43
44#endif /* LINKER_SCRIPT */
45
46#endif /* _ORC_LOOKUP_H */
47