linux-kernel - [tip: timers/vdso] vdso: Make vdso_time

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Message-ID: <174099858620.10177.4119971334794072658.tip-bot2@tip-bot2>
Date: Mon, 03 Mar 2025 10:43:06 -0000
From: "tip-bot2 for Anna-Maria Behnsen" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Anna-Maria Behnsen" <anna-maria@...utronix.de>,
 Nam Cao <namcao@...utronix.de>, thomas.weissschuh@...utronix.de,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/vdso] vdso: Make vdso_time_data cacheline aligned

The following commit has been merged into the timers/vdso branch of tip:

Commit-ID:     48313da79b19fc4943be7507473a3501cf73906c
Gitweb:        https://git.kernel.org/tip/48313da79b19fc4943be7507473a3501cf73906c
Author:        Anna-Maria Behnsen <anna-maria@...utronix.de>
AuthorDate:    Tue, 25 Feb 2025 13:36:35 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Mon, 03 Mar 2025 10:24:33 +01:00

vdso: Make vdso_time_data cacheline aligned

vdso_time_data is not cacheline aligned at the moment. When instantiating
an array, the start of the second array member is not cache line aligned.

This increases the number of the required cache lines which needs to be
read when handling e.g. CLOCK_MONOTONIC_RAW, because the data spawns an
extra cache line if the previous data does not end at a cache line
boundary.

Therefore make struct vdso_time_data cacheline aligned.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Signed-off-by: Nam Cao <namcao@...utronix.de>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 include/vdso/datapage.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index ed4fb4c..dfd98f9 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -11,6 +11,7 @@
 
 #include <vdso/align.h>
 #include <vdso/bits.h>
+#include <vdso/cache.h>
 #include <vdso/clocksource.h>
 #include <vdso/ktime.h>
 #include <vdso/limits.h>
@@ -126,7 +127,7 @@ struct vdso_time_data {
 	u32			__unused;
 
 	struct arch_vdso_time_data arch_data;
-};
+} ____cacheline_aligned;
 
 /**
  * struct vdso_rng_data - vdso RNG state information