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1#ifndef _X86_64_ALTERNATIVE_H
2#define _X86_64_ALTERNATIVE_H
3
4#ifdef __KERNEL__
5
6#include <linux/types.h>
7#include <linux/stddef.h>
8
9/*
10 * Alternative inline assembly for SMP.
11 *
12 * The LOCK_PREFIX macro defined here replaces the LOCK and
13 * LOCK_PREFIX macros used everywhere in the source tree.
14 *
15 * SMP alternatives use the same data structures as the other
16 * alternatives and the X86_FEATURE_UP flag to indicate the case of a
17 * UP system running a SMP kernel. The existing apply_alternatives()
18 * works fine for patching a SMP kernel for UP.
19 *
20 * The SMP alternative tables can be kept after boot and contain both
21 * UP and SMP versions of the instructions to allow switching back to
22 * SMP at runtime, when hotplugging in a new CPU, which is especially
23 * useful in virtualized environments.
24 *
25 * The very common lock prefix is handled as special case in a
26 * separate table which is a pure address list without replacement ptr
27 * and size information. That keeps the table sizes small.
28 */
29
30#ifdef CONFIG_SMP
31#define LOCK_PREFIX \
32 ".section .smp_locks,\"a\"\n" \
33 " .align 8\n" \
34 " .quad 661f\n" /* address */ \
35 ".previous\n" \
36 "661:\n\tlock; "
37
38#else /* ! CONFIG_SMP */
39#define LOCK_PREFIX ""
40#endif
41
42/* This must be included *after* the definition of LOCK_PREFIX */
43#include <asm/cpufeature.h>
44
45struct alt_instr {
46 u8 *instr; /* original instruction */
47 u8 *replacement;
48 u8 cpuid; /* cpuid bit set for replacement */
49 u8 instrlen; /* length of original instruction */
50 u8 replacementlen; /* length of new instruction, <= instrlen */
51 u8 pad[5];
52};
53
54extern void alternative_instructions(void);
55extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
56
57struct module;
58
59#ifdef CONFIG_SMP
60extern void alternatives_smp_module_add(struct module *mod, char *name,
61 void *locks, void *locks_end,
62 void *text, void *text_end);
63extern void alternatives_smp_module_del(struct module *mod);
64extern void alternatives_smp_switch(int smp);
65#else
66static inline void alternatives_smp_module_add(struct module *mod, char *name,
67 void *locks, void *locks_end,
68 void *text, void *text_end) {}
69static inline void alternatives_smp_module_del(struct module *mod) {}
70static inline void alternatives_smp_switch(int smp) {}
71#endif
72
73#endif
74
75/*
76 * Alternative instructions for different CPU types or capabilities.
77 *
78 * This allows to use optimized instructions even on generic binary
79 * kernels.
80 *
81 * length of oldinstr must be longer or equal the length of newinstr
82 * It can be padded with nops as needed.
83 *
84 * For non barrier like inlines please define new variants
85 * without volatile and memory clobber.
86 */
87#define alternative(oldinstr, newinstr, feature) \
88 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
89 ".section .altinstructions,\"a\"\n" \
90 " .align 8\n" \
91 " .quad 661b\n" /* label */ \
92 " .quad 663f\n" /* new instruction */ \
93 " .byte %c0\n" /* feature bit */ \
94 " .byte 662b-661b\n" /* sourcelen */ \
95 " .byte 664f-663f\n" /* replacementlen */ \
96 ".previous\n" \
97 ".section .altinstr_replacement,\"ax\"\n" \
98 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
99 ".previous" :: "i" (feature) : "memory")
100
101/*
102 * Alternative inline assembly with input.
103 *
104 * Pecularities:
105 * No memory clobber here.
106 * Argument numbers start with 1.
107 * Best is to use constraints that are fixed size (like (%1) ... "r")
108 * If you use variable sized constraints like "m" or "g" in the
109 * replacement make sure to pad to the worst case length.
110 */
111#define alternative_input(oldinstr, newinstr, feature, input...) \
112 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
113 ".section .altinstructions,\"a\"\n" \
114 " .align 8\n" \
115 " .quad 661b\n" /* label */ \
116 " .quad 663f\n" /* new instruction */ \
117 " .byte %c0\n" /* feature bit */ \
118 " .byte 662b-661b\n" /* sourcelen */ \
119 " .byte 664f-663f\n" /* replacementlen */ \
120 ".previous\n" \
121 ".section .altinstr_replacement,\"ax\"\n" \
122 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
123 ".previous" :: "i" (feature), ##input)
124
125/* Like alternative_input, but with a single output argument */
126#define alternative_io(oldinstr, newinstr, feature, output, input...) \
127 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
128 ".section .altinstructions,\"a\"\n" \
129 " .align 8\n" \
130 " .quad 661b\n" /* label */ \
131 " .quad 663f\n" /* new instruction */ \
132 " .byte %c[feat]\n" /* feature bit */ \
133 " .byte 662b-661b\n" /* sourcelen */ \
134 " .byte 664f-663f\n" /* replacementlen */ \
135 ".previous\n" \
136 ".section .altinstr_replacement,\"ax\"\n" \
137 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
138 ".previous" : output : [feat] "i" (feature), ##input)
139
140/*
141 * use this macro(s) if you need more than one output parameter
142 * in alternative_io
143 */
144#define ASM_OUTPUT2(a, b) a, b
145
146struct paravirt_patch;
147#ifdef CONFIG_PARAVIRT
148void apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end);
149#else
150static inline void
151apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end)
152{}
153#define __parainstructions NULL
154#define __parainstructions_end NULL
155#endif
156
157extern void text_poke(void *addr, unsigned char *opcode, int len);
158
159#endif /* _X86_64_ALTERNATIVE_H */
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