22 files changed, 242 insertions, 120 deletions

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 405efb3e4996..94408a784c8e 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -28,9 +28,6 @@ static inline cycles_t get_cycles(void)
 }
 #define get_cycles get_cycles
 
-extern struct system_counterval_t convert_art_to_tsc(u64 art);
-extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns);
-
 extern void tsc_early_init(void);
 extern void tsc_init(void);
 extern void mark_tsc_unstable(char *reason);
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index 0ef36190abe6..b2d2df026f6e 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -328,9 +328,8 @@ static __always_inline u64 vdso_calc_ns(const struct vdso_data *vd, u64 cycles,
 	 * due to unsigned comparison.
 	 *
 	 * Due to the MSB/Sign-bit being used as invalid marker (see
-	 * arch_vdso_cycles_valid() above), the effective mask is S64_MAX,
-	 * but that case is also unlikely and will also take the unlikely path
-	 * here.
+	 * arch_vdso_cycles_ok() above), the effective mask is S64_MAX, but that
+	 * case is also unlikely and will also take the unlikely path here.
 	 */
 	if (unlikely(delta > vd->max_cycles)) {
 		/*
diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h
index be199a9b2676..93226281b450 100644
--- a/arch/x86/include/asm/vdso/vsyscall.h
+++ b/arch/x86/include/asm/vdso/vsyscall.h
@@ -4,7 +4,6 @@
 
 #ifndef __ASSEMBLY__
 
-#include <linux/hrtimer.h>
 #include <linux/timekeeper_internal.h>
 #include <vdso/datapage.h>
 #include <asm/vgtod.h>
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index 7aa38b2ad8a9..a0ce291abcae 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -14,11 +14,6 @@
 
 #include <uapi/linux/time.h>
 
-#ifdef BUILD_VDSO32_64
-typedef u64 gtod_long_t;
-#else
-typedef unsigned long gtod_long_t;
-#endif
 #endif /* CONFIG_GENERIC_GETTIMEOFDAY */
 
 #endif /* _ASM_X86_VGTOD_H */
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 06b170759e5b..d4462fb26299 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -50,9 +50,9 @@ int tsc_clocksource_reliable;
 
 static int __read_mostly tsc_force_recalibrate;
 
-static u32 art_to_tsc_numerator;
-static u32 art_to_tsc_denominator;
-static u64 art_to_tsc_offset;
+static struct clocksource_base art_base_clk = {
+	.id    = CSID_X86_ART,
+};
 static bool have_art;
 
 struct cyc2ns {
@@ -1074,7 +1074,7 @@ core_initcall(cpufreq_register_tsc_scaling);
  */
 static void __init detect_art(void)
 {
-	unsigned int unused[2];
+	unsigned int unused;
 
 	if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF)
 		return;
@@ -1089,13 +1089,14 @@ static void __init detect_art(void)
 	    tsc_async_resets)
 		return;
 
-	cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator,
-	      &art_to_tsc_numerator, unused, unused+1);
+	cpuid(ART_CPUID_LEAF, &art_base_clk.denominator,
+	      &art_base_clk.numerator, &art_base_clk.freq_khz, &unused);
 
-	if (art_to_tsc_denominator < ART_MIN_DENOMINATOR)
+	art_base_clk.freq_khz /= KHZ;
+	if (art_base_clk.denominator < ART_MIN_DENOMINATOR)
 		return;
 
-	rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset);
+	rdmsrl(MSR_IA32_TSC_ADJUST, art_base_clk.offset);
 
 	/* Make this sticky over multiple CPU init calls */
 	setup_force_cpu_cap(X86_FEATURE_ART);
@@ -1296,67 +1297,6 @@ int unsynchronized_tsc(void)
 	return 0;
 }
 
-/*
- * Convert ART to TSC given numerator/denominator found in detect_art()
- */
-struct system_counterval_t convert_art_to_tsc(u64 art)
-{
-	u64 tmp, res, rem;
-
-	rem = do_div(art, art_to_tsc_denominator);
-
-	res = art * art_to_tsc_numerator;
-	tmp = rem * art_to_tsc_numerator;
-
-	do_div(tmp, art_to_tsc_denominator);
-	res += tmp + art_to_tsc_offset;
-
-	return (struct system_counterval_t) {
-		.cs_id	= have_art ? CSID_X86_TSC : CSID_GENERIC,
-		.cycles	= res,
-	};
-}
-EXPORT_SYMBOL(convert_art_to_tsc);
-
-/**
- * convert_art_ns_to_tsc() - Convert ART in nanoseconds to TSC.
- * @art_ns: ART (Always Running Timer) in unit of nanoseconds
- *
- * PTM requires all timestamps to be in units of nanoseconds. When user
- * software requests a cross-timestamp, this function converts system timestamp
- * to TSC.
- *
- * This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set
- * indicating the tsc_khz is derived from CPUID[15H]. Drivers should check
- * that this flag is set before conversion to TSC is attempted.
- *
- * Return:
- * struct system_counterval_t - system counter value with the ID of the
- *	corresponding clocksource:
- *	cycles:		System counter value
- *	cs_id:		The clocksource ID for validating comparability
- */
-
-struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
-{
-	u64 tmp, res, rem;
-
-	rem = do_div(art_ns, USEC_PER_SEC);
-
-	res = art_ns * tsc_khz;
-	tmp = rem * tsc_khz;
-
-	do_div(tmp, USEC_PER_SEC);
-	res += tmp;
-
-	return (struct system_counterval_t) {
-		.cs_id	= have_art ? CSID_X86_TSC : CSID_GENERIC,
-		.cycles	= res,
-	};
-}
-EXPORT_SYMBOL(convert_art_ns_to_tsc);
-
-
 static void tsc_refine_calibration_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
 /**
@@ -1458,8 +1398,10 @@ out:
 	if (tsc_unstable)
 		goto unreg;
 
-	if (boot_cpu_has(X86_FEATURE_ART))
+	if (boot_cpu_has(X86_FEATURE_ART)) {
 		have_art = true;
+		clocksource_tsc.base = &art_base_clk;
+	}
 	clocksource_register_khz(&clocksource_tsc, tsc_khz);
 unreg:
 	clocksource_unregister(&clocksource_tsc_early);
@@ -1484,8 +1426,10 @@ static int __init init_tsc_clocksource(void)
 	 * the refined calibration and directly register it as a clocksource.
 	 */
 	if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
-		if (boot_cpu_has(X86_FEATURE_ART))
+		if (boot_cpu_has(X86_FEATURE_ART)) {
 			have_art = true;
+			clocksource_tsc.base = &art_base_clk;
+		}
 		clocksource_register_khz(&clocksource_tsc, tsc_khz);
 		clocksource_unregister(&clocksource_tsc_early);
 
@@ -1509,10 +1453,12 @@ static bool __init determine_cpu_tsc_frequencies(bool early)
 
 	if (early) {
 		cpu_khz = x86_platform.calibrate_cpu();
-		if (tsc_early_khz)
+		if (tsc_early_khz) {
 			tsc_khz = tsc_early_khz;
-		else
+		} else {
 			tsc_khz = x86_platform.calibrate_tsc();
+			clocksource_tsc.freq_khz = tsc_khz;
+		}
 	} else {
 		/* We should not be here with non-native cpu calibration */
 		WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);
diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index bbcfd529399b..89d57dd911dc 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -124,7 +124,8 @@ static int e1000e_phc_get_syncdevicetime(ktime_t *device,
 	sys_cycles = er32(PLTSTMPH);
 	sys_cycles <<= 32;
 	sys_cycles |= er32(PLTSTMPL);
-	*system = convert_art_to_tsc(sys_cycles);
+	system->cycles = sys_cycles;
+	system->cs_id = CSID_X86_ART;
 
 	return 0;
 }
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
index fefaf52fd677..927b623cedd5 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -2156,7 +2156,8 @@ ice_ptp_get_syncdevicetime(ktime_t *device,
 			hh_ts_lo = rd32(hw, GLHH_ART_TIME_L);
 			hh_ts_hi = rd32(hw, GLHH_ART_TIME_H);
 			hh_ts = ((u64)hh_ts_hi << 32) | hh_ts_lo;
-			*system = convert_art_ns_to_tsc(hh_ts);
+			system->cycles = hh_ts;
+			system->cs_id = CSID_X86_ART;
 			/* Read Device source clock time */
 			hh_ts_lo = rd32(hw, GLTSYN_HHTIME_L(tmr_idx));
 			hh_ts_hi = rd32(hw, GLTSYN_HHTIME_H(tmr_idx));
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 1bb026232efc..946edbad4302 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -938,7 +938,11 @@ static bool igc_is_crosststamp_supported(struct igc_adapter *adapter)
 static struct system_counterval_t igc_device_tstamp_to_system(u64 tstamp)
 {
 #if IS_ENABLED(CONFIG_X86_TSC) && !defined(CONFIG_UML)
-	return convert_art_ns_to_tsc(tstamp);
+	return (struct system_counterval_t) {
+		.cs_id		= CSID_X86_ART,
+		.cycles		= tstamp,
+		.use_nsecs	= true,
+	};
 #else
 	return (struct system_counterval_t) { };
 #endif
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c
index 60283543ffc8..e73fa34237d3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c
@@ -390,10 +390,11 @@ static int intel_crosststamp(ktime_t *device,
 		*device = ns_to_ktime(ptp_time);
 		read_unlock_irqrestore(&priv->ptp_lock, flags);
 		get_arttime(priv->mii, intel_priv->mdio_adhoc_addr, &art_time);
-		*system = convert_art_to_tsc(art_time);
+		system->cycles = art_time;
 	}
 
 	system->cycles *= intel_priv->crossts_adj;
+	system->cs_id = CSID_X86_ART;
 	priv->plat->flags &= ~STMMAC_FLAG_INT_SNAPSHOT_EN;
 
 	return 0;
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 0ad8b550bb4b..d35b677b08fe 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -21,6 +21,7 @@
 #include <asm/div64.h>
 #include <asm/io.h>
 
+struct clocksource_base;
 struct clocksource;
 struct module;
 
@@ -50,6 +51,7 @@ struct module;
  *			multiplication
  * @name:		Pointer to clocksource name
  * @list:		List head for registration (internal)
+ * @freq_khz:		Clocksource frequency in khz.
  * @rating:		Rating value for selection (higher is better)
  *			To avoid rating inflation the following
  *			list should give you a guide as to how
@@ -70,6 +72,8 @@ struct module;
  *			validate the clocksource from which the snapshot was
  *			taken.
  * @flags:		Flags describing special properties
+ * @base:		Hardware abstraction for clock on which a clocksource
+ *			is based
  * @enable:		Optional function to enable the clocksource
  * @disable:		Optional function to disable the clocksource
  * @suspend:		Optional suspend function for the clocksource
@@ -107,10 +111,12 @@ struct clocksource {
 	u64			max_cycles;
 	const char		*name;
 	struct list_head	list;
+	u32			freq_khz;
 	int			rating;
 	enum clocksource_ids	id;
 	enum vdso_clock_mode	vdso_clock_mode;
 	unsigned long		flags;
+	struct clocksource_base *base;
 
 	int			(*enable)(struct clocksource *cs);
 	void			(*disable)(struct clocksource *cs);
@@ -306,4 +312,25 @@ static inline unsigned int clocksource_get_max_watchdog_retry(void)
 
 void clocksource_verify_percpu(struct clocksource *cs);
 
+/**
+ * struct clocksource_base - hardware abstraction for clock on which a clocksource
+ *			is based
+ * @id:			Defaults to CSID_GENERIC. The id value is used for conversion
+ *			functions which require that the current clocksource is based
+ *			on a clocksource_base with a particular ID in certain snapshot
+ *			functions to allow callers to validate the clocksource from
+ *			which the snapshot was taken.
+ * @freq_khz:		Nominal frequency of the base clock in kHz
+ * @offset:		Offset between the base clock and the clocksource
+ * @numerator:		Numerator of the clock ratio between base clock and the clocksource
+ * @denominator:	Denominator of the clock ratio between base clock and the clocksource
+ */
+struct clocksource_base {
+	enum clocksource_ids	id;
+	u32			freq_khz;
+	u64			offset;
+	u32			numerator;
+	u32			denominator;
+};
+
 #endif /* _LINUX_CLOCKSOURCE_H */
diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h
index a4fa3436940c..2bb4d8c2f1b0 100644
--- a/include/linux/clocksource_ids.h
+++ b/include/linux/clocksource_ids.h
@@ -9,6 +9,7 @@ enum clocksource_ids {
 	CSID_X86_TSC_EARLY,
 	CSID_X86_TSC,
 	CSID_X86_KVM_CLK,
+	CSID_X86_ART,
 	CSID_MAX,
 };
 
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 4924a33700b7..72744638c5b0 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -139,7 +139,6 @@ extern void tick_nohz_irq_exit(void);
 extern bool tick_nohz_idle_got_tick(void);
 extern ktime_t tick_nohz_get_next_hrtimer(void);
 extern ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next);
-extern unsigned long tick_nohz_get_idle_calls(void);
 extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
 extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 0ea7823b7f31..fc12a9ba2c88 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -310,12 +310,18 @@ struct system_device_crosststamp {
  *		timekeeping code to verify comparability of two cycle values.
  *		The default ID, CSID_GENERIC, does not identify a specific
  *		clocksource.
+ * @use_nsecs:	@cycles is in nanoseconds.
  */
 struct system_counterval_t {
 	u64			cycles;
 	enum clocksource_ids	cs_id;
+	bool			use_nsecs;
 };
 
+extern bool ktime_real_to_base_clock(ktime_t treal,
+				     enum clocksource_ids base_id, u64 *cycles);
+extern bool timekeeping_clocksource_has_base(enum clocksource_ids id);
+
 /*
  * Get cross timestamp between system clock and device clock
  */
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index d04d394db064..7647e0946f50 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -77,6 +77,10 @@ struct vdso_timestamp {
  * vdso_data will be accessed by 64 bit and compat code at the same time
  * so we should be careful before modifying this structure.
  *
+ * The ordering of the struct members is optimized to have fast access to the
+ * often required struct members which are related to CLOCK_REALTIME and
+ * CLOCK_MONOTONIC. This information is stored in the first cache lines.
+ *
  * @basetime is used to store the base time for the system wide time getter
  * VVAR page.
  *
diff --git a/kernel/time/clocksource-wdtest.c b/kernel/time/clocksource-wdtest.c
index d06185e054ea..62e73444ffe4 100644
--- a/kernel/time/clocksource-wdtest.c
+++ b/kernel/time/clocksource-wdtest.c
@@ -22,6 +22,7 @@
 #include "tick-internal.h"
 
 MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Clocksource watchdog unit test");
 MODULE_AUTHOR("Paul E. McKenney <[email protected]>");
 
 static int holdoff = IS_BUILTIN(CONFIG_TEST_CLOCKSOURCE_WATCHDOG) ? 10 : 0;
diff --git a/kernel/time/test_udelay.c b/kernel/time/test_udelay.c
index 20d5df631570..783f2297111b 100644
--- a/kernel/time/test_udelay.c
+++ b/kernel/time/test_udelay.c
@@ -155,5 +155,6 @@ static void __exit udelay_test_exit(void)
 
 module_exit(udelay_test_exit);
 
+MODULE_DESCRIPTION("udelay test module");
 MODULE_AUTHOR("David Riley <[email protected]>");
 MODULE_LICENSE("GPL");
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 771d1e040303..b4843099a8da 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -1141,6 +1141,7 @@ void tick_broadcast_switch_to_oneshot(void)
 #ifdef CONFIG_HOTPLUG_CPU
 void hotplug_cpu__broadcast_tick_pull(int deadcpu)
 {
+	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
 	struct clock_event_device *bc;
 	unsigned long flags;
 
@@ -1148,6 +1149,28 @@ void hotplug_cpu__broadcast_tick_pull(int deadcpu)
 	bc = tick_broadcast_device.evtdev;
 
 	if (bc && broadcast_needs_cpu(bc, deadcpu)) {
+		/*
+		 * If the broadcast force bit of the current CPU is set,
+		 * then the current CPU has not yet reprogrammed the local
+		 * timer device to avoid a ping-pong race. See
+		 * ___tick_broadcast_oneshot_control().
+		 *
+		 * If the broadcast device is hrtimer based then
+		 * programming the broadcast event below does not have any
+		 * effect because the local clockevent device is not
+		 * running and not programmed because the broadcast event
+		 * is not earlier than the pending event of the local clock
+		 * event device. As a consequence all CPUs waiting for a
+		 * broadcast event are stuck forever.
+		 *
+		 * Detect this condition and reprogram the cpu local timer
+		 * device to avoid the starvation.
+		 */
+		if (tick_check_broadcast_expired()) {
+			cpumask_clear_cpu(smp_processor_id(), tick_broadcast_force_mask);
+			tick_program_event(td->evtdev->next_event, 1);
+		}
+
 		/* This moves the broadcast assignment to this CPU: */
 		clockevents_program_event(bc, bc->next_event, 1);
 	}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 71a792cd8936..753a184c7090 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1026,10 +1026,10 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu)
 		if (expires == KTIME_MAX || ts->next_tick == hrtimer_get_expires(&ts->sched_timer))
 			return;
 
-		WARN_ON_ONCE(1);
-		printk_once("basemono: %llu ts->next_tick: %llu dev->next_event: %llu timer->active: %d timer->expires: %llu\n",
-			    basemono, ts->next_tick, dev->next_event,
-			    hrtimer_active(&ts->sched_timer), hrtimer_get_expires(&ts->sched_timer));
+		WARN_ONCE(1, "basemono: %llu ts->next_tick: %llu dev->next_event: %llu "
+			  "timer->active: %d timer->expires: %llu\n", basemono, ts->next_tick,
+			  dev->next_event, hrtimer_active(&ts->sched_timer),
+			  hrtimer_get_expires(&ts->sched_timer));
 	}
 
 	/*
@@ -1385,20 +1385,6 @@ unsigned long tick_nohz_get_idle_calls_cpu(int cpu)
 	return ts->idle_calls;
 }
 
-/**
- * tick_nohz_get_idle_calls - return the current idle calls counter value
- *
- * Called from the schedutil frequency scaling governor in scheduler context.
- *
- * Return: the current idle calls counter value for the current CPU
- */
-unsigned long tick_nohz_get_idle_calls(void)
-{
-	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
-
-	return ts->idle_calls;
-}
-
 static void tick_nohz_account_idle_time(struct tick_sched *ts,
 					ktime_t now)
 {
diff --git a/kernel/time/time_test.c b/kernel/time/time_test.c
index 3e5d422dd15c..2889763165e5 100644
--- a/kernel/time/time_test.c
+++ b/kernel/time/time_test.c
@@ -96,4 +96,5 @@ static struct kunit_suite time_test_suite = {
 };
 
 kunit_test_suite(time_test_suite);
+MODULE_DESCRIPTION("time unit test suite");
 MODULE_LICENSE("GPL");
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4e18db1819f8..2fa87dcfeda9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1195,6 +1195,108 @@ static bool timestamp_in_interval(u64 start, u64 end, u64 ts)
 	return false;
 }
 
+static bool convert_clock(u64 *val, u32 numerator, u32 denominator)
+{
+	u64 rem, res;
+
+	if (!numerator || !denominator)
+		return false;
+
+	res = div64_u64_rem(*val, denominator, &rem) * numerator;
+	*val = res + div_u64(rem * numerator, denominator);
+	return true;
+}
+
+static bool convert_base_to_cs(struct system_counterval_t *scv)
+{
+	struct clocksource *cs = tk_core.timekeeper.tkr_mono.clock;
+	struct clocksource_base *base;
+	u32 num, den;
+
+	/* The timestamp was taken from the time keeper clock source */
+	if (cs->id == scv->cs_id)
+		return true;
+
+	/*
+	 * Check whether cs_id matches the base clock. Prevent the compiler from
+	 * re-evaluating @base as the clocksource might change concurrently.
+	 */
+	base = READ_ONCE(cs->base);
+	if (!base || base->id != scv->cs_id)
+		return false;
+
+	num = scv->use_nsecs ? cs->freq_khz : base->numerator;
+	den = scv->use_nsecs ? USEC_PER_SEC : base->denominator;
+
+	if (!convert_clock(&scv->cycles, num, den))
+		return false;
+
+	scv->cycles += base->offset;
+	return true;
+}
+
+static bool convert_cs_to_base(u64 *cycles, enum clocksource_ids base_id)
+{
+	struct clocksource *cs = tk_core.timekeeper.tkr_mono.clock;
+	struct clocksource_base *base;
+
+	/*
+	 * Check whether base_id matches the base clock. Prevent the compiler from
+	 * re-evaluating @base as the clocksource might change concurrently.
+	 */
+	base = READ_ONCE(cs->base);
+	if (!base || base->id != base_id)
+		return false;
+
+	*cycles -= base->offset;
+	if (!convert_clock(cycles, base->denominator, base->numerator))
+		return false;
+	return true;
+}
+
+static bool convert_ns_to_cs(u64 *delta)
+{
+	struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
+
+	if (BITS_TO_BYTES(fls64(*delta) + tkr->shift) >= sizeof(*delta))
+		return false;
+
+	*delta = div_u64((*delta << tkr->shift) - tkr->xtime_nsec, tkr->mult);
+	return true;
+}
+
+/**
+ * ktime_real_to_base_clock() - Convert CLOCK_REALTIME timestamp to a base clock timestamp
+ * @treal:	CLOCK_REALTIME timestamp to convert
+ * @base_id:	base clocksource id
+ * @cycles:	pointer to store the converted base clock timestamp
+ *
+ * Converts a supplied, future realtime clock value to the corresponding base clock value.
+ *
+ * Return:  true if the conversion is successful, false otherwise.
+ */
+bool ktime_real_to_base_clock(ktime_t treal, enum clocksource_ids base_id, u64 *cycles)
+{
+	struct timekeeper *tk = &tk_core.timekeeper;
+	unsigned int seq;
+	u64 delta;
+
+	do {
+		seq = read_seqcount_begin(&tk_core.seq);
+		if ((u64)treal < tk->tkr_mono.base_real)
+			return false;
+		delta = (u64)treal - tk->tkr_mono.base_real;
+		if (!convert_ns_to_cs(&delta))
+			return false;
+		*cycles = tk->tkr_mono.cycle_last + delta;
+		if (!convert_cs_to_base(cycles, base_id))
+			return false;
+	} while (read_seqcount_retry(&tk_core.seq, seq));
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(ktime_real_to_base_clock);
+
 /**
  * get_device_system_crosststamp - Synchronously capture system/device timestamp
  * @get_time_fn:	Callback to get simultaneous device time and
@@ -1241,7 +1343,7 @@ int get_device_system_crosststamp(int (*get_time_fn)
 		 * installed timekeeper clocksource
 		 */
 		if (system_counterval.cs_id == CSID_GENERIC ||
-		    tk->tkr_mono.clock->id != system_counterval.cs_id)
+		    !convert_base_to_cs(&system_counterval))
 			return -ENODEV;
 		cycles = system_counterval.cycles;
 
@@ -1307,6 +1409,30 @@ int get_device_system_crosststamp(int (*get_time_fn)
 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
 
 /**
+ * timekeeping_clocksource_has_base - Check whether the current clocksource
+ *				      is based on given a base clock
+ * @id:		base clocksource ID
+ *
+ * Note:	The return value is a snapshot which can become invalid right
+ *		after the function returns.
+ *
+ * Return:	true if the timekeeper clocksource has a base clock with @id,
+ *		false otherwise
+ */
+bool timekeeping_clocksource_has_base(enum clocksource_ids id)
+{
+	/*
+	 * This is a snapshot, so no point in using the sequence
+	 * count. Just prevent the compiler from re-evaluating @base as the
+	 * clocksource might change concurrently.
+	 */
+	struct clocksource_base *base = READ_ONCE(tk_core.timekeeper.tkr_mono.clock->base);
+
+	return base ? base->id == id : false;
+}
+EXPORT_SYMBOL_GPL(timekeeping_clocksource_has_base);
+
+/**
  * do_settimeofday64 - Sets the time of day.
  * @ts:     pointer to the timespec64 variable containing the new time
  *
@@ -2421,6 +2547,7 @@ EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
 
 /**
  * do_adjtimex() - Accessor function to NTP __do_adjtimex function
+ * @txc:	Pointer to kernel_timex structure containing NTP parameters
  */
 int do_adjtimex(struct __kernel_timex *txc)
 {
@@ -2489,6 +2616,8 @@ int do_adjtimex(struct __kernel_timex *txc)
 #ifdef CONFIG_NTP_PPS
 /**
  * hardpps() - Accessor function to NTP __hardpps function
+ * @phase_ts:	Pointer to timespec64 structure representing phase timestamp
+ * @raw_ts:	Pointer to timespec64 structure representing raw timestamp
  */
 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
 {
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 899850bd6f0b..c01eaafd8041 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -140,14 +140,14 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 
 	do {
 		/*
-		 * Open coded 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 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
+		 * 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
+		 * 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
 		 * even again.
 		 */
 		while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
@@ -223,8 +223,8 @@ static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
 
 	do {
 		/*
-		 * Open coded to handle VDSO_CLOCK_TIMENS. See comment in
-		 * do_hres().
+		 * Open coded function vdso_read_begin() to handle
+		 * VDSO_CLOCK_TIMENS. See comment in do_hres().
 		 */
 		while ((seq = READ_ONCE(vd->seq)) & 1) {
 			if (IS_ENABLED(CONFIG_TIME_NS) &&
diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index 766734dc5be2..5d86e5a9c814 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -463,7 +463,8 @@ static int azx_get_sync_time(ktime_t *device,
 	*device = ktime_add_ns(*device, (wallclk_cycles * NSEC_PER_SEC) /
 			       ((HDA_MAX_CYCLE_VALUE + 1) * runtime->rate));
 
-	*system = convert_art_to_tsc(tsc_counter);
+	system->cycles = tsc_counter;
+	system->cs_id = CSID_X86_ART;
 
 	return 0;
 }