summaryrefslogtreecommitdiffstats
path: root/include/asm-x86/alternative.h
blob: d8bacf3c4b08765f674791b39603d900f5983f80 (plain)
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
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
#ifndef _ASM_X86_ALTERNATIVE_H
#define _ASM_X86_ALTERNATIVE_H

#include <linux/types.h>
#include <linux/stddef.h>
#include <asm/asm.h>

/*
 * Alternative inline assembly for SMP.
 *
 * The LOCK_PREFIX macro defined here replaces the LOCK and
 * LOCK_PREFIX macros used everywhere in the source tree.
 *
 * SMP alternatives use the same data structures as the other
 * alternatives and the X86_FEATURE_UP flag to indicate the case of a
 * UP system running a SMP kernel.  The existing apply_alternatives()
 * works fine for patching a SMP kernel for UP.
 *
 * The SMP alternative tables can be kept after boot and contain both
 * UP and SMP versions of the instructions to allow switching back to
 * SMP at runtime, when hotplugging in a new CPU, which is especially
 * useful in virtualized environments.
 *
 * The very common lock prefix is handled as special case in a
 * separate table which is a pure address list without replacement ptr
 * and size information.  That keeps the table sizes small.
 */

#ifdef CONFIG_SMP
#define LOCK_PREFIX \
		".section .smp_locks,\"a\"\n"	\
		_ASM_ALIGN "\n"			\
		_ASM_PTR "661f\n" /* address */	\
		".previous\n"			\
		"661:\n\tlock; "

#else /* ! CONFIG_SMP */
#define LOCK_PREFIX ""
#endif

/* This must be included *after* the definition of LOCK_PREFIX */
#include <asm/cpufeature.h>

struct alt_instr {
	u8 *instr;		/* original instruction */
	u8 *replacement;
	u8  cpuid;		/* cpuid bit set for replacement */
	u8  instrlen;		/* length of original instruction */
	u8  replacementlen;	/* length of new instruction, <= instrlen */
	u8  pad1;
#ifdef CONFIG_X86_64
	u32 pad2;
#endif
};

extern void alternative_instructions(void);
extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);

struct module;

#ifdef CONFIG_SMP
extern void alternatives_smp_module_add(struct module *mod, char *name,
					void *locks, void *locks_end,
					void *text, void *text_end);
extern void alternatives_smp_module_del(struct module *mod);
extern void alternatives_smp_switch(int smp);
#else
static inline void alternatives_smp_module_add(struct module *mod, char *name,
					void *locks, void *locks_end,
					void *text, void *text_end) {}
static inline void alternatives_smp_module_del(struct module *mod) {}
static inline void alternatives_smp_switch(int smp) {}
#endif	/* CONFIG_SMP */

/*
 * 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 ("661:\n\t" oldinstr "\n662:\n"			\
		      ".section .altinstructions,\"a\"\n"		\
		      _ASM_ALIGN "\n"					\
		      _ASM_PTR "661b\n"		/* label */		\
		      _ASM_PTR "663f\n"		/* new instruction */	\
		      "	 .byte %c0\n"		/* feature bit */	\
		      "	 .byte 662b-661b\n"	/* sourcelen */		\
		      "	 .byte 664f-663f\n"	/* replacementlen */	\
		      ".previous\n"					\
		      ".section .altinstr_replacement,\"ax\"\n"		\
		      "663:\n\t" newinstr "\n664:\n"  /* replacement */	\
		      ".previous" :: "i" (feature) : "memory")

/*
 * Alternative inline assembly with input.
 *
 * Pecularities:
 * No memory clobber here.
 * Argument numbers start with 1.
 * Best is to use constraints that are fixed size (like (%1) ... "r")
 * If you use variable sized constraints like "m" or "g" in the
 * replacement make sure to pad to the worst case length.
 */
#define alternative_input(oldinstr, newinstr, feature, input...)	\
	asm volatile ("661:\n\t" oldinstr "\n662:\n"			\
		      ".section .altinstructions,\"a\"\n"		\
		      _ASM_ALIGN "\n"					\
		      _ASM_PTR "661b\n"		/* label */		\
		      _ASM_PTR "663f\n"		/* new instruction */	\
		      "	 .byte %c0\n"		/* feature bit */	\
		      "	 .byte 662b-661b\n"	/* sourcelen */		\
		      "	 .byte 664f-663f\n"	/* replacementlen */	\
		      ".previous\n"					\
		      ".section .altinstr_replacement,\"ax\"\n"		\
		      "663:\n\t" newinstr "\n664:\n"  /* replacement */	\
		      ".previous" :: "i" (feature), ##input)

/* Like alternative_input, but with a single output argument */
#define alternative_io(oldinstr, newinstr, feature, output, input...)	\
	asm volatile ("661:\n\t" oldinstr "\n662:\n"			\
		      ".section .altinstructions,\"a\"\n"		\
		      _ASM_ALIGN "\n"					\
		      _ASM_PTR "661b\n"		/* label */		\
		      _ASM_PTR "663f\n"		/* new instruction */	\
		      "	 .byte %c[feat]\n"	/* feature bit */	\
		      "	 .byte 662b-661b\n"	/* sourcelen */		\
		      "	 .byte 664f-663f\n"	/* replacementlen */	\
		      ".previous\n"					\
		      ".section .altinstr_replacement,\"ax\"\n"		\
		      "663:\n\t" newinstr "\n664:\n"  /* replacement */ \
		      ".previous" : output : [feat] "i" (feature), ##input)

/*
 * use this macro(s) if you need more than one output parameter
 * in alternative_io
 */
#define ASM_OUTPUT2(a, b) a, b

struct paravirt_patch_site;
#ifdef CONFIG_PARAVIRT
void apply_paravirt(struct paravirt_patch_site *start,
		    struct paravirt_patch_site *end);
#else
static inline void
apply_paravirt(struct paravirt_patch_site *start,
	       struct paravirt_patch_site *end)
{}
#define __parainstructions	NULL
#define __parainstructions_end	NULL
#endif

extern void text_poke(void *addr, unsigned char *opcode, int len);

#endif /* _ASM_X86_ALTERNATIVE_H */
OpenPOWER on IntegriCloud