83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_ALTERNATIVE_ASM_H
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#define _ASM_ALTERNATIVE_ASM_H
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#ifdef __ASSEMBLY__
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#include <asm/asm.h>
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/*
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* Issue one struct alt_instr descriptor entry (need to put it into
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* the section .altinstructions, see below). This entry contains
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* enough information for the alternatives patching code to patch an
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* instruction. See apply_alternatives().
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*/
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.macro altinstruction_entry orig alt feature orig_len alt_len
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.long \orig - .
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.long \alt - .
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.short \feature
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.byte \orig_len
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.byte \alt_len
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.endm
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/*
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* Define an alternative between two instructions. If @feature is
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* present, early code in apply_alternatives() replaces @oldinstr with
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* @newinstr. ".fill" directive takes care of proper instruction padding
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* in case @newinstr is longer than @oldinstr.
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*/
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.macro ALTERNATIVE oldinstr, newinstr, feature
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140 :
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\oldinstr
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141 :
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.fill - (((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)) / 4, 4, 0x03400000
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142 :
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.pushsection .altinstructions, "a"
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altinstruction_entry 140b, 143f, \feature, 142b-140b, 144f-143f
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.popsection
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.subsection 1
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143 :
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\newinstr
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144 :
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.previous
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.endm
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#define old_len (141b-140b)
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#define new_len1 (144f-143f)
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#define new_len2 (145f-144f)
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#define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
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/*
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* Same as ALTERNATIVE macro above but for two alternatives. If CPU
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* has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
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* @feature2, it replaces @oldinstr with @feature2.
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*/
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.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
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140 :
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\oldinstr
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141 :
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.fill - ((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
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(alt_max_short(new_len1, new_len2) - (old_len)) / 4, 4, 0x03400000
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142 :
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.pushsection .altinstructions, "a"
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altinstruction_entry 140b, 143f, \feature1, 142b-140b, 144f-143f, 142b-141b
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altinstruction_entry 140b, 144f, \feature2, 142b-140b, 145f-144f, 142b-141b
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.popsection
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.subsection 1
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143 :
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\newinstr1
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144 :
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\newinstr2
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145 :
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.previous
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.endm
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_ALTERNATIVE_ASM_H */
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