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/*
* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#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 */
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