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 38 extern unsigned int orc_lookup[]; 39 extern 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