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Diffstat (limited to 'arch/x86/include/asm/alternative.h')
-rw-r--r--arch/x86/include/asm/alternative.h65
1 files changed, 40 insertions, 25 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 473bdbee378a..5aef6a97d80e 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -48,8 +48,9 @@ struct alt_instr {
48 s32 repl_offset; /* offset to replacement instruction */ 48 s32 repl_offset; /* offset to replacement instruction */
49 u16 cpuid; /* cpuid bit set for replacement */ 49 u16 cpuid; /* cpuid bit set for replacement */
50 u8 instrlen; /* length of original instruction */ 50 u8 instrlen; /* length of original instruction */
51 u8 replacementlen; /* length of new instruction, <= instrlen */ 51 u8 replacementlen; /* length of new instruction */
52}; 52 u8 padlen; /* length of build-time padding */
53} __packed;
53 54
54extern void alternative_instructions(void); 55extern void alternative_instructions(void);
55extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); 56extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
@@ -76,50 +77,61 @@ static inline int alternatives_text_reserved(void *start, void *end)
76} 77}
77#endif /* CONFIG_SMP */ 78#endif /* CONFIG_SMP */
78 79
79#define OLDINSTR(oldinstr) "661:\n\t" oldinstr "\n662:\n" 80#define b_replacement(num) "664"#num
81#define e_replacement(num) "665"#num
80 82
81#define b_replacement(number) "663"#number 83#define alt_end_marker "663"
82#define e_replacement(number) "664"#number 84#define alt_slen "662b-661b"
85#define alt_pad_len alt_end_marker"b-662b"
86#define alt_total_slen alt_end_marker"b-661b"
87#define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f"
83 88
84#define alt_slen "662b-661b" 89#define __OLDINSTR(oldinstr, num) \
85#define alt_rlen(number) e_replacement(number)"f-"b_replacement(number)"f" 90 "661:\n\t" oldinstr "\n662:\n" \
91 ".skip -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \
92 "((" alt_rlen(num) ")-(" alt_slen ")),0x90\n"
86 93
87#define ALTINSTR_ENTRY(feature, number) \ 94#define OLDINSTR(oldinstr, num) \
95 __OLDINSTR(oldinstr, num) \
96 alt_end_marker ":\n"
97
98/*
99 * Pad the second replacement alternative with additional NOPs if it is
100 * additionally longer than the first replacement alternative.
101 */
102#define OLDINSTR_2(oldinstr, num1, num2) \
103 __OLDINSTR(oldinstr, num1) \
104 ".skip -(((" alt_rlen(num2) ")-(" alt_rlen(num1) ")-(662b-661b)) > 0) * " \
105 "((" alt_rlen(num2) ")-(" alt_rlen(num1) ")-(662b-661b)),0x90\n" \
106 alt_end_marker ":\n"
107
108#define ALTINSTR_ENTRY(feature, num) \
88 " .long 661b - .\n" /* label */ \ 109 " .long 661b - .\n" /* label */ \
89 " .long " b_replacement(number)"f - .\n" /* new instruction */ \ 110 " .long " b_replacement(num)"f - .\n" /* new instruction */ \
90 " .word " __stringify(feature) "\n" /* feature bit */ \ 111 " .word " __stringify(feature) "\n" /* feature bit */ \
91 " .byte " alt_slen "\n" /* source len */ \ 112 " .byte " alt_total_slen "\n" /* source len */ \
92 " .byte " alt_rlen(number) "\n" /* replacement len */ 113 " .byte " alt_rlen(num) "\n" /* replacement len */ \
114 " .byte " alt_pad_len "\n" /* pad len */
93 115
94#define DISCARD_ENTRY(number) /* rlen <= slen */ \ 116#define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \
95 " .byte 0xff + (" alt_rlen(number) ") - (" alt_slen ")\n" 117 b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
96
97#define ALTINSTR_REPLACEMENT(newinstr, feature, number) /* replacement */ \
98 b_replacement(number)":\n\t" newinstr "\n" e_replacement(number) ":\n\t"
99 118
100/* alternative assembly primitive: */ 119/* alternative assembly primitive: */
101#define ALTERNATIVE(oldinstr, newinstr, feature) \ 120#define ALTERNATIVE(oldinstr, newinstr, feature) \
102 OLDINSTR(oldinstr) \ 121 OLDINSTR(oldinstr, 1) \
103 ".pushsection .altinstructions,\"a\"\n" \ 122 ".pushsection .altinstructions,\"a\"\n" \
104 ALTINSTR_ENTRY(feature, 1) \ 123 ALTINSTR_ENTRY(feature, 1) \
105 ".popsection\n" \ 124 ".popsection\n" \
106 ".pushsection .discard,\"aw\",@progbits\n" \
107 DISCARD_ENTRY(1) \
108 ".popsection\n" \
109 ".pushsection .altinstr_replacement, \"ax\"\n" \ 125 ".pushsection .altinstr_replacement, \"ax\"\n" \
110 ALTINSTR_REPLACEMENT(newinstr, feature, 1) \ 126 ALTINSTR_REPLACEMENT(newinstr, feature, 1) \
111 ".popsection" 127 ".popsection"
112 128
113#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\ 129#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
114 OLDINSTR(oldinstr) \ 130 OLDINSTR_2(oldinstr, 1, 2) \
115 ".pushsection .altinstructions,\"a\"\n" \ 131 ".pushsection .altinstructions,\"a\"\n" \
116 ALTINSTR_ENTRY(feature1, 1) \ 132 ALTINSTR_ENTRY(feature1, 1) \
117 ALTINSTR_ENTRY(feature2, 2) \ 133 ALTINSTR_ENTRY(feature2, 2) \
118 ".popsection\n" \ 134 ".popsection\n" \
119 ".pushsection .discard,\"aw\",@progbits\n" \
120 DISCARD_ENTRY(1) \
121 DISCARD_ENTRY(2) \
122 ".popsection\n" \
123 ".pushsection .altinstr_replacement, \"ax\"\n" \ 135 ".pushsection .altinstr_replacement, \"ax\"\n" \
124 ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \ 136 ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \
125 ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ 137 ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
@@ -146,6 +158,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
146#define alternative(oldinstr, newinstr, feature) \ 158#define alternative(oldinstr, newinstr, feature) \
147 asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory") 159 asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")
148 160
161#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
162 asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")
163
149/* 164/*
150 * Alternative inline assembly with input. 165 * Alternative inline assembly with input.
151 * 166 *
generated by cgit v1.2.2 (git 2.25.0) at 2025-04-25 05:32:50 -0400