1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_ALTERNATIVE_ASM_H 3 #define _ASM_X86_ALTERNATIVE_ASM_H 4 5 #ifdef __ASSEMBLY__ 6 7 #include <asm/asm.h> 8 9 #ifdef CONFIG_SMP 10 .macro LOCK_PREFIX 11 672: lock 12 .pushsection .smp_locks,"a" 13 .balign 4 14 .long 672b - . 15 .popsection 16 .endm 17 #else 18 .macro LOCK_PREFIX 19 .endm 20 #endif 21 22 /* 23 * objtool annotation to ignore the alternatives and only consider the original 24 * instruction(s). 25 */ 26 .macro ANNOTATE_IGNORE_ALTERNATIVE 27 .Lannotate_\@: 28 .pushsection .discard.ignore_alts 29 .long .Lannotate_\@ - . 30 .popsection 31 .endm 32 33 /* 34 * Issue one struct alt_instr descriptor entry (need to put it into 35 * the section .altinstructions, see below). This entry contains 36 * enough information for the alternatives patching code to patch an 37 * instruction. See apply_alternatives(). 38 */ 39 .macro altinstruction_entry orig alt feature orig_len alt_len pad_len 40 .long \orig - . 41 .long \alt - . 42 .word \feature 43 .byte \orig_len 44 .byte \alt_len 45 .byte \pad_len 46 .endm 47 48 /* 49 * Define an alternative between two instructions. If @feature is 50 * present, early code in apply_alternatives() replaces @oldinstr with 51 * @newinstr. ".skip" directive takes care of proper instruction padding 52 * in case @newinstr is longer than @oldinstr. 53 */ 54 .macro ALTERNATIVE oldinstr, newinstr, feature 55 140: 56 \oldinstr 57 141: 58 .skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90 59 142: 60 61 .pushsection .altinstructions,"a" 62 altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b 63 .popsection 64 65 .pushsection .altinstr_replacement,"ax" 66 143: 67 \newinstr 68 144: 69 .popsection 70 .endm 71 72 #define old_len 141b-140b 73 #define new_len1 144f-143f 74 #define new_len2 145f-144f 75 76 /* 77 * gas compatible max based on the idea from: 78 * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax 79 * 80 * The additional "-" is needed because gas uses a "true" value of -1. 81 */ 82 #define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b))))) 83 84 85 /* 86 * Same as ALTERNATIVE macro above but for two alternatives. If CPU 87 * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has 88 * @feature2, it replaces @oldinstr with @feature2. 89 */ 90 .macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2 91 140: 92 \oldinstr 93 141: 94 .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \ 95 (alt_max_short(new_len1, new_len2) - (old_len)),0x90 96 142: 97 98 .pushsection .altinstructions,"a" 99 altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b 100 altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b 101 .popsection 102 103 .pushsection .altinstr_replacement,"ax" 104 143: 105 \newinstr1 106 144: 107 \newinstr2 108 145: 109 .popsection 110 .endm 111 112 #endif /* __ASSEMBLY__ */ 113 114 #endif /* _ASM_X86_ALTERNATIVE_ASM_H */ 115