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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - include/asm-i386/alternative.h
1 #ifndef _I386_ALTERNATIVE_H
2 #define _I386_ALTERNATIVE_H
7 #include <linux/stddef.h>
8 #include <linux/types.h>
11 u8
*instr
; /* original instruction */
13 u8 cpuid
; /* cpuid bit set for replacement */
14 u8 instrlen
; /* length of original instruction */
15 u8 replacementlen
; /* length of new instruction, <= instrlen */
19 extern void apply_alternatives(struct alt_instr
*start
, struct alt_instr
*end
);
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
);
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
) {}
39 * Alternative instructions for different CPU types or capabilities.
41 * This allows to use optimized instructions even on generic binary
44 * length of oldinstr must be longer or equal the length of newinstr
45 * It can be padded with nops as needed.
47 * For non barrier like inlines please define new variants
48 * without volatile and memory clobber.
50 #define alternative(oldinstr, newinstr, feature) \
51 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
52 ".section .altinstructions,\"a\"\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 */ \
60 ".section .altinstr_replacement,\"ax\"\n" \
61 "663:\n\t" newinstr "\n664:\n" /* replacement */\
62 ".previous" :: "i" (feature) : "memory")
65 * Alternative inline assembly with input.
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.
74 #define alternative_input(oldinstr, newinstr, feature, input...) \
75 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
76 ".section .altinstructions,\"a\"\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 */ \
84 ".section .altinstr_replacement,\"ax\"\n" \
85 "663:\n\t" newinstr "\n664:\n" /* replacement */\
86 ".previous" :: "i" (feature), ##input)
89 * Alternative inline assembly for SMP.
91 * The LOCK_PREFIX macro defined here replaces the LOCK and
92 * LOCK_PREFIX macros used everywhere in the source tree.
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.
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.
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.
110 #define LOCK_PREFIX \
111 ".section .smp_locks,\"a\"\n" \
113 " .long 661f\n" /* address */ \
117 #else /* ! CONFIG_SMP */
118 #define LOCK_PREFIX ""
121 struct paravirt_patch
;
122 #ifdef CONFIG_PARAVIRT
123 void apply_paravirt(struct paravirt_patch
*start
, struct paravirt_patch
*end
);
126 apply_paravirt(struct paravirt_patch
*start
, struct paravirt_patch
*end
)
128 #define __start_parainstructions NULL
129 #define __stop_parainstructions NULL
132 #endif /* _I386_ALTERNATIVE_H */