1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_ALTERNATIVE_ASM_H
3 #define _ASM_X86_ALTERNATIVE_ASM_H
10 .macro LOCK_PREFIX_HERE
11 .pushsection .smp_locks,"a"
13 .long 671f - . # offset
18 .macro LOCK_PREFIX insn:vararg
23 .macro LOCK_PREFIX_HERE
26 .macro LOCK_PREFIX insn:vararg
31 * Issue one struct alt_instr descriptor entry (need to put it into
32 * the section .altinstructions, see below). This entry contains
33 * enough information for the alternatives patching code to patch an
34 * instruction. See apply_alternatives().
36 .macro altinstruction_entry orig alt feature orig_len alt_len pad_len
46 * Define an alternative between two instructions. If @feature is
47 * present, early code in apply_alternatives() replaces @oldinstr with
48 * @newinstr. ".skip" directive takes care of proper instruction padding
49 * in case @newinstr is longer than @oldinstr.
51 .macro ALTERNATIVE oldinstr, newinstr, feature
55 .skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
58 .pushsection .altinstructions,"a"
59 altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b
62 .pushsection .altinstr_replacement,"ax"
69 #define old_len 141b-140b
70 #define new_len1 144f-143f
71 #define new_len2 145f-144f
74 * gas compatible max based on the idea from:
75 * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
77 * The additional "-" is needed because gas uses a "true" value of -1.
79 #define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
83 * Same as ALTERNATIVE macro above but for two alternatives. If CPU
84 * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
85 * @feature2, it replaces @oldinstr with @feature2.
87 .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
91 .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
92 (alt_max_short(new_len1, new_len2) - (old_len)),0x90
95 .pushsection .altinstructions,"a"
96 altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b
97 altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b
100 .pushsection .altinstr_replacement,"ax"
109 #endif /* __ASSEMBLY__ */
111 #endif /* _ASM_X86_ALTERNATIVE_ASM_H */