vdso/gettimeofday: Prepare do_coarse() for introduction of struct vdso_clock

To support multiple PTP clocks, the VDSO data structure needs to be
reworked. All clock specific data will end up in struct vdso_clock and in
struct vdso_time_data there will be array of VDSO clocks. At the moment,
vdso_clock is simply a define which maps vdso_clock to vdso_time_data.

Prepare for the rework of these structures by adding a struct vdso_clock
pointer argument to do_coarse(), and replace the struct vdso_time_data
pointer with the new pointer argument where applicable.

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-v1-9-c1b5c69a166f@linutronix.de

Author: anna-marialx

lib/vdso/gettimeofday.c

@@ -229,28 +229,29 @@ static __always_inline int do_coarse_timens(const struct vdso_time_data *vdns, c
 }
 #endif
 
-static __always_inline int do_coarse(const struct vdso_time_data *vd, clockid_t clk,
-				     struct __kernel_timespec *ts)
+static __always_inline
+int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,
+	      clockid_t clk, struct __kernel_timespec *ts)
 {
-	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
+	const struct vdso_timestamp *vdso_ts = &vc->basetime[clk];
 	u32 seq;
 
 	do {
 		/*
 		 * Open coded function vdso_read_begin() to handle
 		 * VDSO_CLOCK_TIMENS. See comment in do_hres().
 		 */
-		while ((seq = READ_ONCE(vd->seq)) & 1) {
+		while ((seq = READ_ONCE(vc->seq)) & 1) {
 			if (IS_ENABLED(CONFIG_TIME_NS) &&
-			    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
-				return do_coarse_timens(vd, clk, ts);
+			    vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
+				return do_coarse_timens(vc, clk, ts);
 			cpu_relax();
 		}
 		smp_rmb();
 
 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
-	} while (unlikely(vdso_read_retry(vd, seq)));
+	} while (unlikely(vdso_read_retry(vc, seq)));
 
 	return 0;
 }
@@ -274,7 +275,7 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
 	if (likely(msk & VDSO_HRES))
 		vc = &vc[CS_HRES_COARSE];
 	else if (msk & VDSO_COARSE)
-		return do_coarse(&vc[CS_HRES_COARSE], clock, ts);
+		return do_coarse(vd, &vc[CS_HRES_COARSE], clock, ts);
 	else if (msk & VDSO_RAW)
 		vc = &vc[CS_RAW];
 	else