1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> |
4 | */ |
5 | #ifndef _ORC_LOOKUP_H |
6 | #define _ORC_LOOKUP_H |
7 | |
8 | /* |
9 | * This is a lookup table for speeding up access to the .orc_unwind table. |
10 | * Given an input address offset, the corresponding lookup table entry |
11 | * specifies a subset of the .orc_unwind table to search. |
12 | * |
13 | * Each block represents the end of the previous range and the start of the |
14 | * next range. An extra block is added to give the last range an end. |
15 | * |
16 | * The block size should be a power of 2 to avoid a costly 'div' instruction. |
17 | * |
18 | * A block size of 256 was chosen because it roughly doubles unwinder |
19 | * performance while only adding ~5% to the ORC data footprint. |
20 | */ |
21 | #define LOOKUP_BLOCK_ORDER 8 |
22 | #define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER) |
23 | |
24 | #ifndef LINKER_SCRIPT |
25 | |
26 | extern unsigned int orc_lookup[]; |
27 | extern unsigned int orc_lookup_end[]; |
28 | |
29 | #define LOOKUP_START_IP (unsigned long)_stext |
30 | #define LOOKUP_STOP_IP (unsigned long)_etext |
31 | |
32 | #endif /* LINKER_SCRIPT */ |
33 | |
34 | #endif /* _ORC_LOOKUP_H */ |
35 | |