35 lines
1.0 KiB
C
35 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
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*/
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#ifndef _ORC_LOOKUP_H
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#define _ORC_LOOKUP_H
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/*
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* This is a lookup table for speeding up access to the .orc_unwind table.
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* Given an input address offset, the corresponding lookup table entry
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* specifies a subset of the .orc_unwind table to search.
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*
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* Each block represents the end of the previous range and the start of the
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* next range. An extra block is added to give the last range an end.
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*
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* The block size should be a power of 2 to avoid a costly 'div' instruction.
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*
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* A block size of 256 was chosen because it roughly doubles unwinder
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* performance while only adding ~5% to the ORC data footprint.
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*/
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#define LOOKUP_BLOCK_ORDER 8
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#define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER)
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#ifndef LINKER_SCRIPT
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extern unsigned int orc_lookup[];
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extern unsigned int orc_lookup_end[];
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#define LOOKUP_START_IP (unsigned long)_stext
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#define LOOKUP_STOP_IP (unsigned long)_etext
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#endif /* LINKER_SCRIPT */
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#endif /* _ORC_LOOKUP_H */
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