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
8struct 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
17extern void alternative_instructions(void);
18extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
19
20struct module;
21#ifdef CONFIG_SMP
22extern void alternatives_smp_module_add(struct module *mod, char *name,
23					void *locks, void *locks_end,
24					void *text, void *text_end);
25extern void alternatives_smp_module_del(struct module *mod);
26extern void alternatives_smp_switch(int smp);
27#else
28static inline void alternatives_smp_module_add(struct module *mod, char *name,
29					void *locks, void *locks_end,
30					void *text, void *text_end) {}
31static inline void alternatives_smp_module_del(struct module *mod) {}
32static 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
139struct paravirt_patch_site;
140#ifdef CONFIG_PARAVIRT
141void apply_paravirt(struct paravirt_patch_site *start,
142		    struct paravirt_patch_site *end);
143#else
144static inline void
145apply_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
152extern void text_poke(void *addr, unsigned char *opcode, int len);
153
154#endif /* _I386_ALTERNATIVE_H */
155