orc_lookup.h

 1/* SPDX-License-Identifier: GPL-2.0-or-later */
 2#ifndef _ORC_LOOKUP_H
 3#define _ORC_LOOKUP_H
 4
 5/*
 6 * This is a lookup table for speeding up access to the .orc_unwind table.
 7 * Given an input address offset, the corresponding lookup table entry
 8 * specifies a subset of the .orc_unwind table to search.
 9 *
10 * Each block represents the end of the previous range and the start of the
11 * next range.  An extra block is added to give the last range an end.
12 *
13 * The block size should be a power of 2 to avoid a costly 'div' instruction.
14 *
15 * A block size of 256 was chosen because it roughly doubles unwinder
16 * performance while only adding ~5% to the ORC data footprint.
17 */
18#define LOOKUP_BLOCK_ORDER	8
19#define LOOKUP_BLOCK_SIZE	(1 << LOOKUP_BLOCK_ORDER)
20
21#ifndef LINKER_SCRIPT
22
23extern unsigned int orc_lookup[];
24extern unsigned int orc_lookup_end[];
25
26#define LOOKUP_START_IP		(unsigned long)_stext
27#define LOOKUP_STOP_IP		(unsigned long)_etext
28
29#endif /* LINKER_SCRIPT */
30
31#endif /* _ORC_LOOKUP_H */