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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 | /* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_ALTERNATIVE_H #define _ASM_ALTERNATIVE_H #ifndef __ASSEMBLY__ #include <linux/types.h> #include <linux/stddef.h> #include <linux/stringify.h> #include <asm/asm.h> struct alt_instr { s32 instr_offset; /* offset to original instruction */ s32 replace_offset; /* offset to replacement instruction */ u16 feature; /* feature bit set for replacement */ u8 instrlen; /* length of original instruction */ u8 replacementlen; /* length of new instruction */ } __packed; /* * Debug flag that can be tested to see whether alternative * instructions were patched in already: */ extern int alternatives_patched; extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; extern void alternative_instructions(void); extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); #define b_replacement(num) "664"#num #define e_replacement(num) "665"#num #define alt_end_marker "663" #define alt_slen "662b-661b" #define alt_total_slen alt_end_marker"b-661b" #define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f" #define __OLDINSTR(oldinstr, num) \ "661:\n\t" oldinstr "\n662:\n" \ ".fill -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \ "((" alt_rlen(num) ")-(" alt_slen ")) / 4, 4, 0x03400000\n" #define OLDINSTR(oldinstr, num) \ __OLDINSTR(oldinstr, num) \ alt_end_marker ":\n" #define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") < (" b ")))))" /* * Pad the second replacement alternative with additional NOPs if it is * additionally longer than the first replacement alternative. */ #define OLDINSTR_2(oldinstr, num1, num2) \ "661:\n\t" oldinstr "\n662:\n" \ ".fill -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \ "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) / 4, " \ "4, 0x03400000\n" \ alt_end_marker ":\n" #define ALTINSTR_ENTRY(feature, num) \ " .long 661b - .\n" /* label */ \ " .long " b_replacement(num)"f - .\n" /* new instruction */ \ " .short " __stringify(feature) "\n" /* feature bit */ \ " .byte " alt_total_slen "\n" /* source len */ \ " .byte " alt_rlen(num) "\n" /* replacement len */ #define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \ b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t" /* alternative assembly primitive: */ #define ALTERNATIVE(oldinstr, newinstr, feature) \ OLDINSTR(oldinstr, 1) \ ".pushsection .altinstructions,\"a\"\n" \ ALTINSTR_ENTRY(feature, 1) \ ".popsection\n" \ ".subsection 1\n" \ ALTINSTR_REPLACEMENT(newinstr, feature, 1) \ ".previous\n" #define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\ OLDINSTR_2(oldinstr, 1, 2) \ ".pushsection .altinstructions,\"a\"\n" \ ALTINSTR_ENTRY(feature1, 1) \ ALTINSTR_ENTRY(feature2, 2) \ ".popsection\n" \ ".subsection 1\n" \ ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \ ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ ".previous\n" /* * Alternative instructions for different CPU types or capabilities. * * This allows to use optimized instructions even on generic binary * kernels. * * length of oldinstr must be longer or equal the length of newinstr * It can be padded with nops as needed. * * For non barrier like inlines please define new variants * without volatile and memory clobber. */ #define alternative(oldinstr, newinstr, feature) \ (asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")) #define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \ (asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")) #endif /* __ASSEMBLY__ */ #endif /* _ASM_ALTERNATIVE_H */ |