vdso/datapage: Define vdso_clock to prepare for multiple PTP clocks

Multiple PTP clocks, which are independent of timekeeping, are required for
systems, which utilize PTP for synchronizing e.g. automation systems
independent of clock TAI.

PTP clocks are slow to access, but applications require fast access to the
relevant time similar to the regular timekeeping relevant clocks.

To prepare for that the VDSO data representation must be reworked. For
transition to the new structure of the vdso, add a define which maps
vdso_clock to vdso_data. This will be removed when all users are updated
step by step.

No functional change.

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-v1-4-c1b5c69a166f@linutronix.de

diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index dfd98f969f151eca3c551c3e90f69af9ee8f22bb..1df22e8bb9b31153546b72b1e8b8c8aeaed7d9e3 100644 (file)
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -129,6 +129,8 @@ struct vdso_time_data {
        struct arch_vdso_time_data arch_data;
 } ____cacheline_aligned;
 
+#define vdso_clock vdso_time_data
+
 /**
  * struct vdso_rng_data - vdso RNG state information
  * @generation:        counter representing the number of RNG reseeds