Commit 64c3613c authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

vdso/gettimeofday: Prepare do_hres() 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_hres(), and replace the struct vdso_time_data
pointer with the new pointer argument where applicable.

No functional change.

Signed-off-by: default avatarAnna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: default avatarNam Cao <namcao@linutronix.de>
Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250303-vdso-clock-v1-7-c1b5c69a166f@linutronix.de
parent cddb82d1

lib/vdso/gettimeofday.c

+17 −16
Original line number Diff line number Diff line
@@ -139,10 +139,11 @@ static __always_inline int do_hres_timens(const struct vdso_time_data *vdns, clo 
}

#endif



static __always_inline int do_hres(const struct vdso_time_data *vd, clockid_t clk,

				   struct __kernel_timespec *ts)

static __always_inline

int do_hres(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];

	u64 cycles, sec, ns;

	u32 seq;
@@ -154,31 +155,31 @@ static __always_inline int do_hres(const struct vdso_time_data *vd, clockid_t cl 
		/*

		 * Open coded function vdso_read_begin() to handle

		 * VDSO_CLOCKMODE_TIMENS. Time namespace enabled tasks have a

		 * special VVAR page installed which has vd->seq set to 1 and

		 * vd->clock_mode set to VDSO_CLOCKMODE_TIMENS. For non time

		 * special VVAR page installed which has vc->seq set to 1 and

		 * vc->clock_mode set to VDSO_CLOCKMODE_TIMENS. For non time

		 * namespace affected tasks this does not affect performance

		 * because if vd->seq is odd, i.e. a concurrent update is in

		 * progress the extra check for vd->clock_mode is just a few

		 * extra instructions while spin waiting for vd->seq to become

		 * because if vc->seq is odd, i.e. a concurrent update is in

		 * progress the extra check for vc->clock_mode is just a few

		 * extra instructions while spin waiting for vc->seq to become

		 * even again.

		 */

		while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {

		while (unlikely((seq = READ_ONCE(vc->seq)) & 1)) {

			if (IS_ENABLED(CONFIG_TIME_NS) &&

			    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)

			    vc->clock_mode == VDSO_CLOCKMODE_TIMENS)

				return do_hres_timens(vd, clk, ts);

			cpu_relax();

		}

		smp_rmb();



		if (unlikely(!vdso_clocksource_ok(vd)))

		if (unlikely(!vdso_clocksource_ok(vc)))

			return -1;



		cycles = __arch_get_hw_counter(vd->clock_mode, vd);

		cycles = __arch_get_hw_counter(vc->clock_mode, vd);

		if (unlikely(!vdso_cycles_ok(cycles)))

			return -1;

		ns = vdso_calc_ns(vd, cycles, vdso_ts->nsec);

		ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);

		sec = vdso_ts->sec;

	} while (unlikely(vdso_read_retry(vd, seq)));

	} while (unlikely(vdso_read_retry(vc, seq)));



	/*

	 * Do this outside the loop: a race inside the loop could result
@@ -278,7 +279,7 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, 
	else

		return -1;



	return do_hres(vc, clock, ts);

	return do_hres(vd, vc, clock, ts);

}



static __maybe_unused int
@@ -334,7 +335,7 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd, 
	if (likely(tv != NULL)) {

		struct __kernel_timespec ts;



		if (do_hres(&vc[CS_HRES_COARSE], CLOCK_REALTIME, &ts))

		if (do_hres(vd, &vc[CS_HRES_COARSE], CLOCK_REALTIME, &ts))

			return gettimeofday_fallback(tv, tz);



		tv->tv_sec = ts.tv_sec;