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Subject[patch 27/38] x86/asm: Provide ALTERNATIVE_3
Date
From: Peter Zijlstra <peterz@infradead.org>

Fairly straight forward adaptation/extention of ALTERNATIVE_2.

Required for call depth tracking.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/alternative.h | 33 ++++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)

--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -367,6 +367,7 @@ static inline int alternatives_text_rese
#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:
@@ -374,7 +375,8 @@ static inline int alternatives_text_rese
*
* 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))


/*
@@ -386,8 +388,8 @@ static inline int alternatives_text_rese
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"
@@ -404,6 +406,31 @@ static inline int alternatives_text_rese
.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, \
\
 
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