1 #ifndef _X86_64_ALTERNATIVE_H
2 #define _X86_64_ALTERNATIVE_H
6 #include <linux/types.h>
7 #include <linux/stddef.h>
10 * Alternative inline assembly for SMP.
12 * The LOCK_PREFIX macro defined here replaces the LOCK and
13 * LOCK_PREFIX macros used everywhere in the source tree.
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.
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.
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.
32 ".section .smp_locks,\"a\"\n" \
34 " .quad 661f\n" /* address */ \
38 #else /* ! CONFIG_SMP */
39 #define LOCK_PREFIX ""
42 /* This must be included *after* the definition of LOCK_PREFIX */
43 #include <asm/cpufeature.h>
46 u8
*instr
; /* original instruction */
48 u8 cpuid
; /* cpuid bit set for replacement */
49 u8 instrlen
; /* length of original instruction */
50 u8 replacementlen
; /* length of new instruction, <= instrlen */
54 extern void alternative_instructions(void);
55 extern void apply_alternatives(struct alt_instr
*start
, struct alt_instr
*end
);
60 extern void alternatives_smp_module_add(struct module
*mod
, char *name
,
61 void *locks
, void *locks_end
,
62 void *text
, void *text_end
);
63 extern void alternatives_smp_module_del(struct module
*mod
);
64 extern void alternatives_smp_switch(int smp
);
66 static inline void alternatives_smp_module_add(struct module
*mod
, char *name
,
67 void *locks
, void *locks_end
,
68 void *text
, void *text_end
) {}
69 static inline void alternatives_smp_module_del(struct module
*mod
) {}
70 static inline void alternatives_smp_switch(int smp
) {}
76 * Alternative instructions for different CPU types or capabilities.
78 * This allows to use optimized instructions even on generic binary
81 * length of oldinstr must be longer or equal the length of newinstr
82 * It can be padded with nops as needed.
84 * For non barrier like inlines please define new variants
85 * without volatile and memory clobber.
87 #define alternative(oldinstr, newinstr, feature) \
88 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
89 ".section .altinstructions,\"a\"\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 */ \
97 ".section .altinstr_replacement,\"ax\"\n" \
98 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
99 ".previous" :: "i" (feature) : "memory")
102 * Alternative inline assembly with input.
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.
111 #define alternative_input(oldinstr, newinstr, feature, input...) \
112 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
113 ".section .altinstructions,\"a\"\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 */ \
121 ".section .altinstr_replacement,\"ax\"\n" \
122 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
123 ".previous" :: "i" (feature), ##input)
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" \
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 */ \
136 ".section .altinstr_replacement,\"ax\"\n" \
137 "663:\n\t" newinstr "\n664:\n" /* replacement */ \
138 ".previous" : output : [feat] "i" (feature), ##input)
141 * use this macro(s) if you need more than one output parameter
144 #define ASM_OUTPUT2(a, b) a, b
146 struct paravirt_patch
;
147 #ifdef CONFIG_PARAVIRT
148 void apply_paravirt(struct paravirt_patch
*start
, struct paravirt_patch
*end
);
151 apply_paravirt(struct paravirt_patch
*start
, struct paravirt_patch
*end
)
153 #define __parainstructions NULL
154 #define __parainstructions_end NULL
157 extern void text_poke(void *addr
, unsigned char *opcode
, int len
);
159 #endif /* _X86_64_ALTERNATIVE_H */