[PATCH] paravirt: Patch inline replacements for paravirt intercepts
[linux-2.6.git] / include / asm-i386 / alternative.h
1 #ifndef _I386_ALTERNATIVE_H
2 #define _I386_ALTERNATIVE_H
3
4 #ifdef __KERNEL__
5
6 #include <asm/types.h>
7 #include <linux/stddef.h>
8 #include <linux/types.h>
9
10 struct alt_instr {
11         u8 *instr;              /* original instruction */
12         u8 *replacement;
13         u8  cpuid;              /* cpuid bit set for replacement */
14         u8  instrlen;           /* length of original instruction */
15         u8  replacementlen;     /* length of new instruction, <= instrlen */
16         u8  pad;
17 };
18
19 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
20
21 struct module;
22 #ifdef CONFIG_SMP
23 extern void alternatives_smp_module_add(struct module *mod, char *name,
24                                         void *locks, void *locks_end,
25                                         void *text, void *text_end);
26 extern void alternatives_smp_module_del(struct module *mod);
27 extern void alternatives_smp_switch(int smp);
28 #else
29 static inline void alternatives_smp_module_add(struct module *mod, char *name,
30                                         void *locks, void *locks_end,
31                                         void *text, void *text_end) {}
32 static inline void alternatives_smp_module_del(struct module *mod) {}
33 static inline void alternatives_smp_switch(int smp) {}
34 #endif
35
36 #endif
37
38 /*
39  * Alternative instructions for different CPU types or capabilities.
40  *
41  * This allows to use optimized instructions even on generic binary
42  * kernels.
43  *
44  * length of oldinstr must be longer or equal the length of newinstr
45  * It can be padded with nops as needed.
46  *
47  * For non barrier like inlines please define new variants
48  * without volatile and memory clobber.
49  */
50 #define alternative(oldinstr, newinstr, feature)                        \
51         asm volatile ("661:\n\t" oldinstr "\n662:\n"                    \
52                       ".section .altinstructions,\"a\"\n"               \
53                       "  .align 4\n"                                    \
54                       "  .long 661b\n"            /* label */           \
55                       "  .long 663f\n"            /* new instruction */ \
56                       "  .byte %c0\n"             /* feature bit */     \
57                       "  .byte 662b-661b\n"       /* sourcelen */       \
58                       "  .byte 664f-663f\n"       /* replacementlen */  \
59                       ".previous\n"                                     \
60                       ".section .altinstr_replacement,\"ax\"\n"         \
61                       "663:\n\t" newinstr "\n664:\n"   /* replacement */\
62                       ".previous" :: "i" (feature) : "memory")
63
64 /*
65  * Alternative inline assembly with input.
66  *
67  * Pecularities:
68  * No memory clobber here.
69  * Argument numbers start with 1.
70  * Best is to use constraints that are fixed size (like (%1) ... "r")
71  * If you use variable sized constraints like "m" or "g" in the
72  * replacement maake sure to pad to the worst case length.
73  */
74 #define alternative_input(oldinstr, newinstr, feature, input...)        \
75         asm volatile ("661:\n\t" oldinstr "\n662:\n"                    \
76                       ".section .altinstructions,\"a\"\n"               \
77                       "  .align 4\n"                                    \
78                       "  .long 661b\n"            /* label */           \
79                       "  .long 663f\n"            /* new instruction */ \
80                       "  .byte %c0\n"             /* feature bit */     \
81                       "  .byte 662b-661b\n"       /* sourcelen */       \
82                       "  .byte 664f-663f\n"       /* replacementlen */  \
83                       ".previous\n"                                     \
84                       ".section .altinstr_replacement,\"ax\"\n"         \
85                       "663:\n\t" newinstr "\n664:\n"   /* replacement */\
86                       ".previous" :: "i" (feature), ##input)
87
88 /*
89  * Alternative inline assembly for SMP.
90  *
91  * The LOCK_PREFIX macro defined here replaces the LOCK and
92  * LOCK_PREFIX macros used everywhere in the source tree.
93  *
94  * SMP alternatives use the same data structures as the other
95  * alternatives and the X86_FEATURE_UP flag to indicate the case of a
96  * UP system running a SMP kernel.  The existing apply_alternatives()
97  * works fine for patching a SMP kernel for UP.
98  *
99  * The SMP alternative tables can be kept after boot and contain both
100  * UP and SMP versions of the instructions to allow switching back to
101  * SMP at runtime, when hotplugging in a new CPU, which is especially
102  * useful in virtualized environments.
103  *
104  * The very common lock prefix is handled as special case in a
105  * separate table which is a pure address list without replacement ptr
106  * and size information.  That keeps the table sizes small.
107  */
108
109 #ifdef CONFIG_SMP
110 #define LOCK_PREFIX \
111                 ".section .smp_locks,\"a\"\n"   \
112                 "  .align 4\n"                  \
113                 "  .long 661f\n" /* address */  \
114                 ".previous\n"                   \
115                 "661:\n\tlock; "
116
117 #else /* ! CONFIG_SMP */
118 #define LOCK_PREFIX ""
119 #endif
120
121 struct paravirt_patch;
122 #ifdef CONFIG_PARAVIRT
123 void apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end);
124 #else
125 static inline void
126 apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end)
127 {}
128 #define __start_parainstructions NULL
129 #define __stop_parainstructions NULL
130 #endif
131
132 #endif /* _I386_ALTERNATIVE_H */