1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
#ifndef _ORC_LOOKUP_H
#define _ORC_LOOKUP_H
/*
* This is a lookup table for speeding up access to the .orc_unwind table.
* Given an input address offset, the corresponding lookup table entry
* specifies a subset of the .orc_unwind table to search.
*
* Each block represents the end of the previous range and the start of the
* next range. An extra block is added to give the last range an end.
*
* The block size should be a power of 2 to avoid a costly 'div' instruction.
*
* A block size of 256 was chosen because it roughly doubles unwinder
* performance while only adding ~5% to the ORC data footprint.
*/
#define LOOKUP_BLOCK_ORDER 8
#define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER)
#ifndef LINKER_SCRIPT
extern unsigned int orc_lookup[];
extern unsigned int orc_lookup_end[];
#define LOOKUP_START_IP (unsigned long)_stext
#define LOOKUP_STOP_IP (unsigned long)_etext
#endif /* LINKER_SCRIPT */
#endif /* _ORC_LOOKUP_H */
|
