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vdso: Move architecture related data before basetime data

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Architecture related vdso data is required in the fast path when reading
CLOCK_MONOTONIC or CLOCK_REALTIME. At the moment, this information is
located at the end of the vdso_time_data structure, which is a suboptimal
cache layout.

Move the architecture specific VDSO data right before the basetime
information, which is always required. This change does not have an impact
on architectures with CONFIG_ARCH_HAS_VDSO_DATA=n. Architectures, which
have it enabled, gain a better cache layout.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250303-vdso-clock-v1-18-c1b5c69a166f@linutronix.de
This commit is contained in:
Anna-Maria Behnsen 2025-03-03 12:11:20 +01:00 • committed by Thomas Gleixner
parent ed0c10f34f
commit 97a5a90ca2
1 changed files with 4 additions and 4 deletions
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8
include/vdso/datapage.h
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@ -70,6 +70,8 @@ struct vdso_timestamp {
/**
* struct vdso_time_data - vdso datapage representation
* @arch_data: architecture specific data (optional, defaults
* to an empty struct)
* @seq: timebase sequence counter
* @clock_mode: clock mode
* @cycle_last: timebase at clocksource init
@ -83,8 +85,6 @@ struct vdso_timestamp {
* @tz_dsttime: type of DST correction
* @hrtimer_res: hrtimer resolution
* @__unused: unused
* @arch_data: architecture specific data (optional, defaults
* to an empty struct)
*
* vdso_time_data will be accessed by 64 bit and compat code at the same time
* so we should be careful before modifying this structure.
@ -105,6 +105,8 @@ struct vdso_timestamp {
* offset must be zero.
*/
struct vdso_time_data {
struct arch_vdso_time_data arch_data;
u32 seq;
s32 clock_mode;
@ -125,8 +127,6 @@ struct vdso_time_data {
s32 tz_dsttime;
u32 hrtimer_res;
u32 __unused;
struct arch_vdso_time_data arch_data;
} ____cacheline_aligned;
#define vdso_clock vdso_time_data