x86: Fix alternatives and kprobes to remap write-protected kernel text
[linux-2.6.git] / include / asm-i386 / alternative.h
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
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) {}
31 static inline void alternatives_smp_module_del(struct module *mod) {}
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
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 */