1#ifndef __ASM_ALTERNATIVE_H
2#define __ASM_ALTERNATIVE_H
3
4#include <linux/types.h>
5#include <linux/stddef.h>
6#include <linux/stringify.h>
7
8struct alt_instr {
9	s32 orig_offset;	/* offset to original instruction */
10	s32 alt_offset;		/* offset to replacement instruction */
11	u16 cpufeature;		/* cpufeature bit set for replacement */
12	u8  orig_len;		/* size of original instruction(s) */
13	u8  alt_len;		/* size of new instruction(s), <= orig_len */
14};
15
16void apply_alternatives_all(void);
17void apply_alternatives(void *start, size_t length);
18void free_alternatives_memory(void);
19
20#define ALTINSTR_ENTRY(feature)						      \
21	" .word 661b - .\n"				/* label           */ \
22	" .word 663f - .\n"				/* new instruction */ \
23	" .hword " __stringify(feature) "\n"		/* feature bit     */ \
24	" .byte 662b-661b\n"				/* source len      */ \
25	" .byte 664f-663f\n"				/* replacement len */
26
27/* alternative assembly primitive: */
28#define ALTERNATIVE(oldinstr, newinstr, feature)			\
29	"661:\n\t"							\
30	oldinstr "\n"							\
31	"662:\n"							\
32	".pushsection .altinstructions,\"a\"\n"				\
33	ALTINSTR_ENTRY(feature)						\
34	".popsection\n"							\
35	".pushsection .altinstr_replacement, \"a\"\n"			\
36	"663:\n\t"							\
37	newinstr "\n"							\
38	"664:\n\t"							\
39	".popsection\n\t"						\
40	".if ((664b-663b) != (662b-661b))\n\t"				\
41	"	.error \"Alternatives instruction length mismatch\"\n\t"\
42	".endif\n"
43
44#endif /* __ASM_ALTERNATIVE_H */
45