1 #ifndef _I386_ALTERNATIVE_H
2 #define _I386_ALTERNATIVE_H
3
4 #include <asm/types.h>
5 #include <linux/stddef.h>
6 #include <linux/types.h>
7
8 struct alt_instr {
9 u8 *instr; /* original instruction */
10 u8 *replacement;
11 u8 cpuid; /* cpuid bit set for replacement */
12 u8 instrlen; /* length of original instruction */
13 u8 replacementlen; /* length of new instruction, <= instrlen */
14 u8 pad;
15 };
16
17 extern void alternative_instructions(void);
18 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
19
20 struct module;
21 #ifdef CONFIG_SMP
22 extern void alternatives_smp_module_add(struct module *mod, char *name,
23 void *locks, void *locks_end,
24 void *text, void *text_end);
25 extern void alternatives_smp_module_del(struct module *mod);
26 extern void alternatives_smp_switch(int smp);
27 #else
alternatives_smp_module_add(struct module * mod,char * name,void * locks,void * locks_end,void * text,void * text_end)28 static inline void alternatives_smp_module_add(struct module *mod, char *name,
29 void *locks, void *locks_end,
30 void *text, void *text_end) {}
alternatives_smp_module_del(struct module * mod)31 static inline void alternatives_smp_module_del(struct module *mod) {}
alternatives_smp_switch(int smp)32 static inline void alternatives_smp_switch(int smp) {}
33 #endif /* CONFIG_SMP */
34
35 /*
36 * Alternative instructions for different CPU types or capabilities.
37 *
38 * This allows to use optimized instructions even on generic binary
39 * kernels.
40 *
41 * length of oldinstr must be longer or equal the length of newinstr
42 * It can be padded with nops as needed.
43 *
44 * For non barrier like inlines please define new variants
45 * without volatile and memory clobber.
46 */
47 #define alternative(oldinstr, newinstr, feature) \
48 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
49 ".section .altinstructions,\"a\"\n" \
50 " .align 4\n" \
51 " .long 661b\n" /* label */ \
52 " .long 663f\n" /* new instruction */ \
53 " .byte %c0\n" /* feature bit */ \
54 " .byte 662b-661b\n" /* sourcelen */ \
55 " .byte 664f-663f\n" /* replacementlen */ \
56 ".previous\n" \
57 ".section .altinstr_replacement,\"ax\"\n" \
58 "663:\n\t" newinstr "\n664:\n" /* replacement */\
59 ".previous" :: "i" (feature) : "memory")
60
61 /*
62 * Alternative inline assembly with input.
63 *
64 * Pecularities:
65 * No memory clobber here.
66 * Argument numbers start with 1.
67 * Best is to use constraints that are fixed size (like (%1) ... "r")
68 * If you use variable sized constraints like "m" or "g" in the
69 * replacement maake sure to pad to the worst case length.
70 */
71 #define alternative_input(oldinstr, newinstr, feature, input...) \
72 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
73 ".section .altinstructions,\"a\"\n" \
74 " .align 4\n" \
75 " .long 661b\n" /* label */ \
76 " .long 663f\n" /* new instruction */ \
77 " .byte %c0\n" /* feature bit */ \
78 " .byte 662b-661b\n" /* sourcelen */ \
79 " .byte 664f-663f\n" /* replacementlen */ \
80 ".previous\n" \
81 ".section .altinstr_replacement,\"ax\"\n" \
82 "663:\n\t" newinstr "\n664:\n" /* replacement */\
83 ".previous" :: "i" (feature), ##input)
84
85 /* Like alternative_input, but with a single output argument */
86 #define alternative_io(oldinstr, newinstr, feature, output, input...) \
87 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
88 ".section .altinstructions,\"a\"\n" \
89 " .align 4\n" \
90 " .long 661b\n" /* label */ \
91 " .long 663f\n" /* new instruction */ \
92 " .byte %c[feat]\n" /* feature bit */ \
93 " .byte 662b-661b\n" /* sourcelen */ \
94 " .byte 664f-663f\n" /* replacementlen */ \
95 ".previous\n" \
96 ".section .altinstr_replacement,\"ax\"\n" \
97 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
98 ".previous" : output : [feat] "i" (feature), ##input)
99
100 /*
101 * use this macro(s) if you need more than one output parameter
102 * in alternative_io
103 */
104 #define ASM_OUTPUT2(a, b) a, b
105
106 /*
107 * Alternative inline assembly for SMP.
108 *
109 * The LOCK_PREFIX macro defined here replaces the LOCK and
110 * LOCK_PREFIX macros used everywhere in the source tree.
111 *
112 * SMP alternatives use the same data structures as the other
113 * alternatives and the X86_FEATURE_UP flag to indicate the case of a
114 * UP system running a SMP kernel. The existing apply_alternatives()
115 * works fine for patching a SMP kernel for UP.
116 *
117 * The SMP alternative tables can be kept after boot and contain both
118 * UP and SMP versions of the instructions to allow switching back to
119 * SMP at runtime, when hotplugging in a new CPU, which is especially
120 * useful in virtualized environments.
121 *
122 * The very common lock prefix is handled as special case in a
123 * separate table which is a pure address list without replacement ptr
124 * and size information. That keeps the table sizes small.
125 */
126
127 #ifdef CONFIG_SMP
128 #define LOCK_PREFIX \
129 ".section .smp_locks,\"a\"\n" \
130 " .align 4\n" \
131 " .long 661f\n" /* address */ \
132 ".previous\n" \
133 "661:\n\tlock; "
134
135 #else /* ! CONFIG_SMP */
136 #define LOCK_PREFIX ""
137 #endif
138
139 struct paravirt_patch_site;
140 #ifdef CONFIG_PARAVIRT
141 void apply_paravirt(struct paravirt_patch_site *start,
142 struct paravirt_patch_site *end);
143 #else
144 static inline void
apply_paravirt(struct paravirt_patch_site * start,struct paravirt_patch_site * end)145 apply_paravirt(struct paravirt_patch_site *start,
146 struct paravirt_patch_site *end)
147 {}
148 #define __parainstructions NULL
149 #define __parainstructions_end NULL
150 #endif
151
152 extern void text_poke(void *addr, unsigned char *opcode, int len);
153
154 #endif /* _I386_ALTERNATIVE_H */
155