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1965aae3 PA |
1 | #ifndef _ASM_X86_ALTERNATIVE_H |
2 | #define _ASM_X86_ALTERNATIVE_H | |
6b592570 | 3 | |
f005f5d8 AL |
4 | #ifndef __ASSEMBLY__ |
5 | ||
6b592570 PA |
6 | #include <linux/types.h> |
7 | #include <linux/stddef.h> | |
edc953fa | 8 | #include <linux/stringify.h> |
6b592570 PA |
9 | #include <asm/asm.h> |
10 | ||
11 | /* | |
12 | * Alternative inline assembly for SMP. | |
13 | * | |
14 | * The LOCK_PREFIX macro defined here replaces the LOCK and | |
15 | * LOCK_PREFIX macros used everywhere in the source tree. | |
16 | * | |
17 | * SMP alternatives use the same data structures as the other | |
18 | * alternatives and the X86_FEATURE_UP flag to indicate the case of a | |
19 | * UP system running a SMP kernel. The existing apply_alternatives() | |
20 | * works fine for patching a SMP kernel for UP. | |
21 | * | |
22 | * The SMP alternative tables can be kept after boot and contain both | |
23 | * UP and SMP versions of the instructions to allow switching back to | |
24 | * SMP at runtime, when hotplugging in a new CPU, which is especially | |
25 | * useful in virtualized environments. | |
26 | * | |
27 | * The very common lock prefix is handled as special case in a | |
28 | * separate table which is a pure address list without replacement ptr | |
29 | * and size information. That keeps the table sizes small. | |
30 | */ | |
31 | ||
32 | #ifdef CONFIG_SMP | |
b3ac891b | 33 | #define LOCK_PREFIX_HERE \ |
9cebed42 PA |
34 | ".pushsection .smp_locks,\"a\"\n" \ |
35 | ".balign 4\n" \ | |
36 | ".long 671f - .\n" /* offset */ \ | |
37 | ".popsection\n" \ | |
b3ac891b LB |
38 | "671:" |
39 | ||
40 | #define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; " | |
6b592570 PA |
41 | |
42 | #else /* ! CONFIG_SMP */ | |
b701a47b | 43 | #define LOCK_PREFIX_HERE "" |
6b592570 PA |
44 | #define LOCK_PREFIX "" |
45 | #endif | |
46 | ||
6b592570 | 47 | struct alt_instr { |
59e97e4d AL |
48 | s32 instr_offset; /* original instruction */ |
49 | s32 repl_offset; /* offset to replacement instruction */ | |
83a7a2ad | 50 | u16 cpuid; /* cpuid bit set for replacement */ |
6b592570 | 51 | u8 instrlen; /* length of original instruction */ |
4332195c BP |
52 | u8 replacementlen; /* length of new instruction */ |
53 | u8 padlen; /* length of build-time padding */ | |
54 | } __packed; | |
6b592570 | 55 | |
5e907bb0 IM |
56 | /* |
57 | * Debug flag that can be tested to see whether alternative | |
58 | * instructions were patched in already: | |
59 | */ | |
60 | extern int alternatives_patched; | |
61 | ||
6b592570 PA |
62 | extern void alternative_instructions(void); |
63 | extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); | |
64 | ||
65 | struct module; | |
66 | ||
67 | #ifdef CONFIG_SMP | |
68 | extern void alternatives_smp_module_add(struct module *mod, char *name, | |
69 | void *locks, void *locks_end, | |
70 | void *text, void *text_end); | |
71 | extern void alternatives_smp_module_del(struct module *mod); | |
816afe4f | 72 | extern void alternatives_enable_smp(void); |
2cfa1978 | 73 | extern int alternatives_text_reserved(void *start, void *end); |
3fb82d56 | 74 | extern bool skip_smp_alternatives; |
6b592570 PA |
75 | #else |
76 | static inline void alternatives_smp_module_add(struct module *mod, char *name, | |
2ac1ea7c JP |
77 | void *locks, void *locks_end, |
78 | void *text, void *text_end) {} | |
6b592570 | 79 | static inline void alternatives_smp_module_del(struct module *mod) {} |
816afe4f | 80 | static inline void alternatives_enable_smp(void) {} |
2cfa1978 MH |
81 | static inline int alternatives_text_reserved(void *start, void *end) |
82 | { | |
83 | return 0; | |
84 | } | |
6b592570 PA |
85 | #endif /* CONFIG_SMP */ |
86 | ||
4332195c BP |
87 | #define b_replacement(num) "664"#num |
88 | #define e_replacement(num) "665"#num | |
954e482b | 89 | |
4332195c BP |
90 | #define alt_end_marker "663" |
91 | #define alt_slen "662b-661b" | |
92 | #define alt_pad_len alt_end_marker"b-662b" | |
93 | #define alt_total_slen alt_end_marker"b-661b" | |
94 | #define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f" | |
954e482b | 95 | |
4332195c BP |
96 | #define __OLDINSTR(oldinstr, num) \ |
97 | "661:\n\t" oldinstr "\n662:\n" \ | |
98 | ".skip -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \ | |
99 | "((" alt_rlen(num) ")-(" alt_slen ")),0x90\n" | |
954e482b | 100 | |
4332195c BP |
101 | #define OLDINSTR(oldinstr, num) \ |
102 | __OLDINSTR(oldinstr, num) \ | |
103 | alt_end_marker ":\n" | |
104 | ||
dbe4058a BP |
105 | /* |
106 | * max without conditionals. Idea adapted from: | |
107 | * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax | |
108 | * | |
109 | * The additional "-" is needed because gas works with s32s. | |
110 | */ | |
111 | #define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") - (" b ")))))" | |
112 | ||
4332195c BP |
113 | /* |
114 | * Pad the second replacement alternative with additional NOPs if it is | |
115 | * additionally longer than the first replacement alternative. | |
116 | */ | |
dbe4058a BP |
117 | #define OLDINSTR_2(oldinstr, num1, num2) \ |
118 | "661:\n\t" oldinstr "\n662:\n" \ | |
119 | ".skip -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \ | |
120 | "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n" \ | |
4332195c BP |
121 | alt_end_marker ":\n" |
122 | ||
123 | #define ALTINSTR_ENTRY(feature, num) \ | |
954e482b | 124 | " .long 661b - .\n" /* label */ \ |
4332195c | 125 | " .long " b_replacement(num)"f - .\n" /* new instruction */ \ |
954e482b | 126 | " .word " __stringify(feature) "\n" /* feature bit */ \ |
4332195c BP |
127 | " .byte " alt_total_slen "\n" /* source len */ \ |
128 | " .byte " alt_rlen(num) "\n" /* replacement len */ \ | |
129 | " .byte " alt_pad_len "\n" /* pad len */ | |
954e482b | 130 | |
4332195c BP |
131 | #define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \ |
132 | b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t" | |
954e482b | 133 | |
edc953fa MD |
134 | /* alternative assembly primitive: */ |
135 | #define ALTERNATIVE(oldinstr, newinstr, feature) \ | |
4332195c | 136 | OLDINSTR(oldinstr, 1) \ |
9cebed42 | 137 | ".pushsection .altinstructions,\"a\"\n" \ |
954e482b | 138 | ALTINSTR_ENTRY(feature, 1) \ |
9cebed42 | 139 | ".popsection\n" \ |
9cebed42 | 140 | ".pushsection .altinstr_replacement, \"ax\"\n" \ |
954e482b | 141 | ALTINSTR_REPLACEMENT(newinstr, feature, 1) \ |
9cebed42 | 142 | ".popsection" |
954e482b FY |
143 | |
144 | #define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\ | |
4332195c | 145 | OLDINSTR_2(oldinstr, 1, 2) \ |
9cebed42 | 146 | ".pushsection .altinstructions,\"a\"\n" \ |
954e482b FY |
147 | ALTINSTR_ENTRY(feature1, 1) \ |
148 | ALTINSTR_ENTRY(feature2, 2) \ | |
9cebed42 | 149 | ".popsection\n" \ |
9cebed42 | 150 | ".pushsection .altinstr_replacement, \"ax\"\n" \ |
954e482b FY |
151 | ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \ |
152 | ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ | |
9cebed42 | 153 | ".popsection" |
edc953fa | 154 | |
6b592570 PA |
155 | /* |
156 | * Alternative instructions for different CPU types or capabilities. | |
157 | * | |
158 | * This allows to use optimized instructions even on generic binary | |
159 | * kernels. | |
160 | * | |
161 | * length of oldinstr must be longer or equal the length of newinstr | |
162 | * It can be padded with nops as needed. | |
163 | * | |
164 | * For non barrier like inlines please define new variants | |
165 | * without volatile and memory clobber. | |
166 | */ | |
167 | #define alternative(oldinstr, newinstr, feature) \ | |
edc953fa | 168 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory") |
6b592570 | 169 | |
4332195c BP |
170 | #define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \ |
171 | asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory") | |
172 | ||
6b592570 PA |
173 | /* |
174 | * Alternative inline assembly with input. | |
175 | * | |
176 | * Pecularities: | |
177 | * No memory clobber here. | |
178 | * Argument numbers start with 1. | |
179 | * Best is to use constraints that are fixed size (like (%1) ... "r") | |
180 | * If you use variable sized constraints like "m" or "g" in the | |
181 | * replacement make sure to pad to the worst case length. | |
edc953fa | 182 | * Leaving an unused argument 0 to keep API compatibility. |
6b592570 PA |
183 | */ |
184 | #define alternative_input(oldinstr, newinstr, feature, input...) \ | |
edc953fa MD |
185 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ |
186 | : : "i" (0), ## input) | |
6b592570 | 187 | |
5b3e83f4 FY |
188 | /* |
189 | * This is similar to alternative_input. But it has two features and | |
190 | * respective instructions. | |
191 | * | |
192 | * If CPU has feature2, newinstr2 is used. | |
193 | * Otherwise, if CPU has feature1, newinstr1 is used. | |
194 | * Otherwise, oldinstr is used. | |
195 | */ | |
196 | #define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2, \ | |
197 | feature2, input...) \ | |
198 | asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \ | |
199 | newinstr2, feature2) \ | |
200 | : : "i" (0), ## input) | |
201 | ||
6b592570 PA |
202 | /* Like alternative_input, but with a single output argument */ |
203 | #define alternative_io(oldinstr, newinstr, feature, output, input...) \ | |
edc953fa MD |
204 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ |
205 | : output : "i" (0), ## input) | |
6b592570 | 206 | |
1b1d9258 JB |
207 | /* Like alternative_io, but for replacing a direct call with another one. */ |
208 | #define alternative_call(oldfunc, newfunc, feature, output, input...) \ | |
209 | asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \ | |
210 | : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input) | |
211 | ||
954e482b FY |
212 | /* |
213 | * Like alternative_call, but there are two features and respective functions. | |
214 | * If CPU has feature2, function2 is used. | |
215 | * Otherwise, if CPU has feature1, function1 is used. | |
216 | * Otherwise, old function is used. | |
217 | */ | |
218 | #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \ | |
219 | output, input...) \ | |
317c2ce7 JP |
220 | { \ |
221 | register void *__sp asm(_ASM_SP); \ | |
954e482b FY |
222 | asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\ |
223 | "call %P[new2]", feature2) \ | |
317c2ce7 JP |
224 | : output, "+r" (__sp) \ |
225 | : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ | |
226 | [new2] "i" (newfunc2), ## input); \ | |
227 | } | |
954e482b | 228 | |
6b592570 PA |
229 | /* |
230 | * use this macro(s) if you need more than one output parameter | |
231 | * in alternative_io | |
232 | */ | |
1b1d9258 | 233 | #define ASM_OUTPUT2(a...) a |
6b592570 | 234 | |
819165fb JB |
235 | /* |
236 | * use this macro if you need clobbers but no inputs in | |
237 | * alternative_{input,io,call}() | |
238 | */ | |
239 | #define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr | |
240 | ||
f005f5d8 AL |
241 | #endif /* __ASSEMBLY__ */ |
242 | ||
1965aae3 | 243 | #endif /* _ASM_X86_ALTERNATIVE_H */ |