| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 | /* |
| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 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 | /* |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 */ |