[tip: x86/core] x86/asm: Provide ALTERNATIVE_3

tip-bot2 for Peter Zijlstra
2022-10-17T14:56:04Z

The following commit has been merged into the x86/core branch of tip:

Commit-ID: 52354973573cc260ff2fc661cb28ff8eaa7b879b
Gitweb: https://git.kernel.org/tip/52354973573cc260ff2fc661cb28ff8eaa7b879b
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 15 Sep 2022 13:11:26 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 17 Oct 2022 16:41:14 +02:00

x86/asm: Provide ALTERNATIVE_3

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111147.787711192@infradead.org
---
arch/x86/include/asm/alternative.h | 33 ++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index ef007fa..4c416b2 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -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, \