vdso/gettimeofday: Prepare 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 all functions which need the pointer to the vdso_clock array to
work correctly after introducing the new struct. Where applicable, replace
the struct vdso_time_data pointer by a struct vdso_clock pointer.

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-v1-6-c1b5c69a166f@linutronix.de

Author: anna-marialx

lib/vdso/gettimeofday.c

@@ -257,6 +257,7 @@ static __always_inline int
 __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
 			     struct __kernel_timespec *ts)
 {
+	const struct vdso_clock *vc = vd;
 	u32 msk;
 
 	/* Check for negative values or invalid clocks */
@@ -269,15 +270,15 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
 	 */
 	msk = 1U << clock;
 	if (likely(msk & VDSO_HRES))
-		vd = &vd[CS_HRES_COARSE];
+		vc = &vc[CS_HRES_COARSE];
 	else if (msk & VDSO_COARSE)
-		return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
+		return do_coarse(&vc[CS_HRES_COARSE], clock, ts);
 	else if (msk & VDSO_RAW)
-		vd = &vd[CS_RAW];
+		vc = &vc[CS_RAW];
 	else
 		return -1;
 
-	return do_hres(vd, clock, ts);
+	return do_hres(vc, clock, ts);
 }
 
 static __maybe_unused int
@@ -328,11 +329,12 @@ static __maybe_unused int
 __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 			  struct __kernel_old_timeval *tv, struct timezone *tz)
 {
+	const struct vdso_clock *vc = vd;
 
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
 
-		if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
+		if (do_hres(&vc[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
 			return gettimeofday_fallback(tv, tz);
 
 		tv->tv_sec = ts.tv_sec;
@@ -341,7 +343,7 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 
 	if (unlikely(tz != NULL)) {
 		if (IS_ENABLED(CONFIG_TIME_NS) &&
-		    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		    vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
 			vd = __arch_get_vdso_u_timens_data(vd);
 
 		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
@@ -361,13 +363,16 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 static __maybe_unused __kernel_old_time_t
 __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time)
 {
+	const struct vdso_clock *vc = vd;
 	__kernel_old_time_t t;
 
 	if (IS_ENABLED(CONFIG_TIME_NS) &&
-	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+	    vc->clock_mode == VDSO_CLOCKMODE_TIMENS) {
 		vd = __arch_get_vdso_u_timens_data(vd);
+		vc = vd;
+	}
 
-	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
+	t = READ_ONCE(vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
 
 	if (time)
 		*time = t;
@@ -386,6 +391,7 @@ static __maybe_unused
 int __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock,
 				struct __kernel_timespec *res)
 {
+	const struct vdso_clock *vc = vd;
 	u32 msk;
 	u64 ns;
 
@@ -394,7 +400,7 @@ int __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock
 		return -1;
 
 	if (IS_ENABLED(CONFIG_TIME_NS) &&
-	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+	    vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
 		vd = __arch_get_vdso_u_timens_data(vd);
 
 	/*