1#ifndef _ASM_X86_ALTERNATIVE_ASM_H
  2#define _ASM_X86_ALTERNATIVE_ASM_H
  3
  4#ifdef __ASSEMBLY__
  5
  6#include <asm/asm.h>
  7
  8#ifdef CONFIG_SMP
  9	.macro LOCK_PREFIX
 10672:	lock
 11	.pushsection .smp_locks,"a"
 12	.balign 4
 13	.long 672b - .
 14	.popsection
 15	.endm
 16#else
 17	.macro LOCK_PREFIX
 18	.endm
 19#endif
 20
 21/*
 22 * Issue one struct alt_instr descriptor entry (need to put it into
 23 * the section .altinstructions, see below). This entry contains
 24 * enough information for the alternatives patching code to patch an
 25 * instruction. See apply_alternatives().
 26 */
 27.macro altinstruction_entry orig alt feature orig_len alt_len pad_len
 28	.long \orig - .
 29	.long \alt - .
 30	.word \feature
 31	.byte \orig_len
 32	.byte \alt_len
 33	.byte \pad_len
 34.endm
 35
 36/*
 37 * Define an alternative between two instructions. If @feature is
 38 * present, early code in apply_alternatives() replaces @oldinstr with
 39 * @newinstr. ".skip" directive takes care of proper instruction padding
 40 * in case @newinstr is longer than @oldinstr.
 41 */
 42.macro ALTERNATIVE oldinstr, newinstr, feature
 43140:
 44	\oldinstr
 45141:
 46	.skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
 47142:
 48
 49	.pushsection .altinstructions,"a"
 50	altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b
 51	.popsection
 52
 53	.pushsection .altinstr_replacement,"ax"
 54143:
 55	\newinstr
 56144:
 57	.popsection
 58.endm
 59
 60#define old_len			141b-140b
 61#define new_len1		144f-143f
 62#define new_len2		145f-144f
 63
 64/*
 65 * max without conditionals. Idea adapted from:
 66 * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
 67 */
 68#define alt_max_short(a, b)	((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
 69
 70
 71/*
 72 * Same as ALTERNATIVE macro above but for two alternatives. If CPU
 73 * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
 74 * @feature2, it replaces @oldinstr with @feature2.
 75 */
 76.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
 77140:
 78	\oldinstr
 79141:
 80	.skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
 81		(alt_max_short(new_len1, new_len2) - (old_len)),0x90
 82142:
 83
 84	.pushsection .altinstructions,"a"
 85	altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b
 86	altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b
 87	.popsection
 88
 89	.pushsection .altinstr_replacement,"ax"
 90143:
 91	\newinstr1
 92144:
 93	\newinstr2
 94145:
 95	.popsection
 96.endm
 97
 98#endif  /*  __ASSEMBLY__  */
 99
100#endif /* _ASM_X86_ALTERNATIVE_ASM_H */