/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_ALTERNATIVE_ASM_H
#define _ASM_X86_ALTERNATIVE_ASM_H
#ifdef __ASSEMBLY__
#include <asm/asm.h>
#ifdef CONFIG_SMP
.macro LOCK_PREFIX
672: lock
.pushsection .smp_locks,"a"
.balign 4
.long 672b - .
.popsection
.endm
#else
.macro LOCK_PREFIX
.endm
#endif
/*
* Issue one struct alt_instr descriptor entry (need to put it into
* the section .altinstructions, see below). This entry contains
* enough information for the alternatives patching code to patch an
* instruction. See apply_alternatives().
*/
.macro altinstruction_entry orig alt feature orig_len alt_len pad_len
.long \orig - .
.long \alt - .
.word \feature
.byte \orig_len
.byte \alt_len
.byte \pad_len
.endm
/*
* Define an alternative between two instructions. If @feature is
* present, early code in apply_alternatives() replaces @oldinstr with
* @newinstr. ".skip" directive takes care of proper instruction padding
* in case @newinstr is longer than @oldinstr.
*/
.macro ALTERNATIVE oldinstr, newinstr, feature
140:
\oldinstr
141:
.skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
142:
.pushsection .altinstructions,"a"
altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b
.popsection
.pushsection .altinstr_replacement,"ax"
143:
\newinstr
144:
.popsection
.endm
#define old_len 141b-140b
#define new_len1 144f-143f
#define new_len2 145f-144f
/*
* gas compatible max based on the idea from:
* http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
*
* The additional "-" is needed because gas uses a "true" value of -1.
*/
#define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
/*
* Same as ALTERNATIVE macro above but for two alternatives. If CPU
* has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
* @feature2, it replaces @oldinstr with @feature2.
*/
.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
140:
\oldinstr
141:
.skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
(alt_max_short(new_len1, new_len2) - (old_len)),0x90
142:
.pushsection .altinstructions,"a"
altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b
altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b
.popsection
.pushsection .altinstr_replacement,"ax"
143:
\newinstr1
144:
\newinstr2
145:
.popsection
.endm
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_ALTERNATIVE_ASM_H */
