Commit 52354973 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/asm: Provide ALTERNATIVE_3 



Fairly straight forward adaptation/extention of ALTERNATIVE_2.

Required for call depth tracking.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111147.787711192@infradead.org
parent 770ae1b7

arch/x86/include/asm/alternative.h

+30 −3
Original line number Diff line number Diff line
@@ -364,6 +364,7 @@ static inline int alternatives_text_reserved(void *start, void *end) 
#define old_len			141b-140b

#define new_len1		144f-143f

#define new_len2		145f-144f

#define new_len3		146f-145f



/*

 * gas compatible max based on the idea from:
@@ -371,7 +372,8 @@ static inline int alternatives_text_reserved(void *start, void *end) 
 *

 * The additional "-" is needed because gas uses a "true" value of -1.

 */

#define alt_max_short(a, b)	((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))

#define alt_max_2(a, b)		((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))

#define alt_max_3(a, b, c)	(alt_max_2(alt_max_2(a, b), c))





/*
@@ -383,8 +385,8 @@ static inline int alternatives_text_reserved(void *start, void *end) 
140:

	\oldinstr

141:

	.skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \

		(alt_max_short(new_len1, new_len2) - (old_len)),0x90

	.skip -((alt_max_2(new_len1, new_len2) - (old_len)) > 0) * \

		(alt_max_2(new_len1, new_len2) - (old_len)),0x90

142:



	.pushsection .altinstructions,"a"
@@ -401,6 +403,31 @@ static inline int alternatives_text_reserved(void *start, void *end) 
	.popsection

.endm



.macro ALTERNATIVE_3 oldinstr, newinstr1, feature1, newinstr2, feature2, newinstr3, feature3

140:

	\oldinstr

141:

	.skip -((alt_max_3(new_len1, new_len2, new_len3) - (old_len)) > 0) * \

		(alt_max_3(new_len1, new_len2, new_len3) - (old_len)),0x90

142:



	.pushsection .altinstructions,"a"

	altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f

	altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f

	altinstruction_entry 140b,145f,\feature3,142b-140b,146f-145f

	.popsection



	.pushsection .altinstr_replacement,"ax"

143:

	\newinstr1

144:

	\newinstr2

145:

	\newinstr3

146:

	.popsection

.endm



/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */

#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) \

	ALTERNATIVE_2 oldinstr, newinstr_no, X86_FEATURE_ALWAYS,	\