20 files changed, 950 insertions, 236 deletions

diff --git a/Documentation/ABI/stable/sysfs-kernel-time-aux-clocks b/Documentation/ABI/stable/sysfs-kernel-time-aux-clocks
new file mode 100644
index 000000000000..825508f42af6
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-kernel-time-aux-clocks
@@ -0,0 +1,5 @@
+What:		/sys/kernel/time/aux_clocks/<ID>/enable
+Date:		May 2025
+Contact:	Thomas Gleixner <tglx@linutronix.de>
+Description:
+		Controls the enablement of auxiliary clock timekeepers.
diff --git a/arch/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h
index de58951b8df6..417aae5763a8 100644
--- a/arch/arm64/include/asm/vdso/vsyscall.h
+++ b/arch/arm64/include/asm/vdso/vsyscall.h
@@ -13,12 +13,11 @@
  * Update the vDSO data page to keep in sync with kernel timekeeping.
  */
 static __always_inline
-void __arm64_update_vsyscall(struct vdso_time_data *vdata)
+void __arch_update_vdso_clock(struct vdso_clock *vc)
 {
-	vdata->clock_data[CS_HRES_COARSE].mask	= VDSO_PRECISION_MASK;
-	vdata->clock_data[CS_RAW].mask		= VDSO_PRECISION_MASK;
+	vc->mask	= VDSO_PRECISION_MASK;
 }
-#define __arch_update_vsyscall __arm64_update_vsyscall
+#define __arch_update_vdso_clock __arch_update_vdso_clock
 
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>
diff --git a/include/asm-generic/vdso/vsyscall.h b/include/asm-generic/vdso/vsyscall.h
index b550afa15ecd..7fc0b560007d 100644
--- a/include/asm-generic/vdso/vsyscall.h
+++ b/include/asm-generic/vdso/vsyscall.h
@@ -22,11 +22,11 @@ static __always_inline const struct vdso_rng_data *__arch_get_vdso_u_rng_data(vo
 
 #endif /* CONFIG_GENERIC_VDSO_DATA_STORE */
 
-#ifndef __arch_update_vsyscall
-static __always_inline void __arch_update_vsyscall(struct vdso_time_data *vdata)
+#ifndef __arch_update_vdso_clock
+static __always_inline void __arch_update_vdso_clock(struct vdso_clock *vc)
 {
 }
-#endif /* __arch_update_vsyscall */
+#endif /* __arch_update_vdso_clock */
 
 #ifndef __arch_sync_vdso_time_data
 static __always_inline void __arch_sync_vdso_time_data(struct vdso_time_data *vdata)
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index dd48c64b605e..4d3dbcef379e 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -37,6 +37,11 @@ static inline int clockid_to_fd(const clockid_t clk)
 	return ~(clk >> 3);
 }
 
+static inline bool clockid_aux_valid(clockid_t id)
+{
+	return IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS) && id >= CLOCK_AUX && id <= CLOCK_AUX_LAST;
+}
+
 #ifdef CONFIG_POSIX_TIMERS
 
 #include <linux/signal_types.h>
diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 785048a3b3e6..c27aac67cb3f 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -12,6 +12,22 @@
 #include <linux/time.h>
 
 /**
+ * timekeeper_ids - IDs for various time keepers in the kernel
+ * @TIMEKEEPER_CORE:		The central core timekeeper managing system time
+ * @TIMEKEEPER_AUX_FIRST:	The first AUX timekeeper
+ * @TIMEKEEPER_AUX_LAST:	The last AUX timekeeper
+ * @TIMEKEEPERS_MAX:		The maximum number of timekeepers managed
+ */
+enum timekeeper_ids {
+	TIMEKEEPER_CORE,
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+	TIMEKEEPER_AUX_FIRST,
+	TIMEKEEPER_AUX_LAST = TIMEKEEPER_AUX_FIRST + MAX_AUX_CLOCKS - 1,
+#endif
+	TIMEKEEPERS_MAX,
+};
+
+/**
  * struct tk_read_base - base structure for timekeeping readout
  * @clock:	Current clocksource used for timekeeping.
  * @mask:	Bitmask for two's complement subtraction of non 64bit clocks
@@ -51,11 +67,14 @@ struct tk_read_base {
  * @offs_real:			Offset clock monotonic -> clock realtime
  * @offs_boot:			Offset clock monotonic -> clock boottime
  * @offs_tai:			Offset clock monotonic -> clock tai
+ * @offs_aux:			Offset clock monotonic -> clock AUX
  * @coarse_nsec:		The nanoseconds part for coarse time getters
+ * @id:				The timekeeper ID
  * @tkr_raw:			The readout base structure for CLOCK_MONOTONIC_RAW
  * @raw_sec:			CLOCK_MONOTONIC_RAW  time in seconds
  * @clock_was_set_seq:		The sequence number of clock was set events
  * @cs_was_changed_seq:		The sequence number of clocksource change events
+ * @clock_valid:		Indicator for valid clock
  * @monotonic_to_boot:		CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
  * @cycle_interval:		Number of clock cycles in one NTP interval
  * @xtime_interval:		Number of clock shifted nano seconds in one NTP
@@ -95,13 +114,16 @@ struct tk_read_base {
  * @monotonic_to_boottime is a timespec64 representation of @offs_boot to
  * accelerate the VDSO update for CLOCK_BOOTTIME.
  *
+ * @offs_aux is used by the auxiliary timekeepers which do not utilize any
+ * of the regular timekeeper offset fields.
+ *
  * The cacheline ordering of the structure is optimized for in kernel usage of
  * the ktime_get() and ktime_get_ts64() family of time accessors. Struct
  * timekeeper is prepended in the core timekeeping code with a sequence count,
  * which results in the following cacheline layout:
  *
  * 0:	seqcount, tkr_mono
- * 1:	xtime_sec ... coarse_nsec
+ * 1:	xtime_sec ... id
  * 2:	tkr_raw, raw_sec
  * 3,4: Internal variables
  *
@@ -121,8 +143,12 @@ struct timekeeper {
 	struct timespec64	wall_to_monotonic;
 	ktime_t			offs_real;
 	ktime_t			offs_boot;
-	ktime_t			offs_tai;
+	union {
+		ktime_t		offs_tai;
+		ktime_t		offs_aux;
+	};
 	u32			coarse_nsec;
+	enum timekeeper_ids	id;
 
 	/* Cacheline 2: */
 	struct tk_read_base	tkr_raw;
@@ -131,6 +157,7 @@ struct timekeeper {
 	/* Cachline 3 and 4 (timekeeping internal variables): */
 	unsigned int		clock_was_set_seq;
 	u8			cs_was_changed_seq;
+	u8			clock_valid;
 
 	struct timespec64	monotonic_to_boot;
 
@@ -163,4 +190,10 @@ static inline void update_vsyscall_tz(void)
 }
 #endif
 
+#if defined(CONFIG_GENERIC_GETTIMEOFDAY) && defined(CONFIG_POSIX_AUX_CLOCKS)
+extern void vdso_time_update_aux(struct timekeeper *tk);
+#else
+static inline void vdso_time_update_aux(struct timekeeper *tk) { }
+#endif
+
 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 542773650200..aee2c1a46e47 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -44,6 +44,7 @@ extern void ktime_get_ts64(struct timespec64 *ts);
 extern void ktime_get_real_ts64(struct timespec64 *tv);
 extern void ktime_get_coarse_ts64(struct timespec64 *ts);
 extern void ktime_get_coarse_real_ts64(struct timespec64 *ts);
+extern void ktime_get_clock_ts64(clockid_t id, struct timespec64 *ts);
 
 /* Multigrain timestamp interfaces */
 extern void ktime_get_coarse_real_ts64_mg(struct timespec64 *ts);
@@ -263,6 +264,17 @@ extern bool timekeeping_rtc_skipresume(void);
 
 extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta);
 
+/*
+ * Auxiliary clock interfaces
+ */
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+extern bool ktime_get_aux(clockid_t id, ktime_t *kt);
+extern bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt);
+#else
+static inline bool ktime_get_aux(clockid_t id, ktime_t *kt) { return false; }
+static inline bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt) { return false; }
+#endif
+
 /**
  * struct system_time_snapshot - simultaneous raw/real time capture with
  *				 counter value
diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
index 4f4b6e48e01c..16ca1ac206fd 100644
--- a/include/uapi/linux/time.h
+++ b/include/uapi/linux/time.h
@@ -64,6 +64,17 @@ struct timezone {
 #define CLOCK_TAI			11
 
 #define MAX_CLOCKS			16
+
+/*
+ * AUX clock support. AUXiliary clocks are dynamically configured by
+ * enabling a clock ID. These clock can be steered independently of the
+ * core timekeeper. The kernel can support up to 8 auxiliary clocks, but
+ * the actual limit depends on eventual architecture constraints vs. VDSO.
+ */
+#define CLOCK_AUX			MAX_CLOCKS
+#define MAX_AUX_CLOCKS			8
+#define CLOCK_AUX_LAST			(CLOCK_AUX + MAX_AUX_CLOCKS - 1)
+
 #define CLOCKS_MASK			(CLOCK_REALTIME | CLOCK_MONOTONIC)
 #define CLOCKS_MONO			CLOCK_MONOTONIC
 
diff --git a/include/vdso/auxclock.h b/include/vdso/auxclock.h
new file mode 100644
index 000000000000..6d6e74cbc400
--- /dev/null
+++ b/include/vdso/auxclock.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _VDSO_AUXCLOCK_H
+#define _VDSO_AUXCLOCK_H
+
+#include <uapi/linux/time.h>
+#include <uapi/linux/types.h>
+
+static __always_inline u64 aux_clock_resolution_ns(void)
+{
+	return 1;
+}
+
+#endif /* _VDSO_AUXCLOCK_H */
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 1864e76e8f69..02533038640e 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -5,6 +5,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/compiler.h>
+#include <uapi/linux/bits.h>
 #include <uapi/linux/time.h>
 #include <uapi/linux/types.h>
 #include <uapi/asm-generic/errno-base.h>
@@ -38,6 +39,7 @@ struct vdso_arch_data {
 #endif
 
 #define VDSO_BASES	(CLOCK_TAI + 1)
+#define VDSO_BASE_AUX	0
 #define VDSO_HRES	(BIT(CLOCK_REALTIME)		| \
 			 BIT(CLOCK_MONOTONIC)		| \
 			 BIT(CLOCK_BOOTTIME)		| \
@@ -45,6 +47,7 @@ struct vdso_arch_data {
 #define VDSO_COARSE	(BIT(CLOCK_REALTIME_COARSE)	| \
 			 BIT(CLOCK_MONOTONIC_COARSE))
 #define VDSO_RAW	(BIT(CLOCK_MONOTONIC_RAW))
+#define VDSO_AUX	__GENMASK(CLOCK_AUX_LAST, CLOCK_AUX)
 
 #define CS_HRES_COARSE	0
 #define CS_RAW		1
@@ -117,6 +120,7 @@ struct vdso_clock {
  * @arch_data:		architecture specific data (optional, defaults
  *			to an empty struct)
  * @clock_data:		clocksource related data (array)
+ * @aux_clock_data:	auxiliary clocksource related data (array)
  * @tz_minuteswest:	minutes west of Greenwich
  * @tz_dsttime:		type of DST correction
  * @hrtimer_res:	hrtimer resolution
@@ -133,6 +137,7 @@ struct vdso_time_data {
 	struct arch_vdso_time_data	arch_data;
 
 	struct vdso_clock		clock_data[CS_BASES];
+	struct vdso_clock		aux_clock_data[MAX_AUX_CLOCKS];
 
 	s32				tz_minuteswest;
 	s32				tz_dsttime;
diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
index 0a98fed550ba..1a5ee9d9052c 100644
--- a/include/vdso/helpers.h
+++ b/include/vdso/helpers.h
@@ -28,17 +28,47 @@ static __always_inline u32 vdso_read_retry(const struct vdso_clock *vc,
 	return seq != start;
 }
 
-static __always_inline void vdso_write_begin(struct vdso_time_data *vd)
+static __always_inline void vdso_write_seq_begin(struct vdso_clock *vc)
 {
-	struct vdso_clock *vc = vd->clock_data;
+	/*
+	 * WRITE_ONCE() is required otherwise the compiler can validly tear
+	 * updates to vc->seq and it is possible that the value seen by the
+	 * reader is inconsistent.
+	 */
+	WRITE_ONCE(vc->seq, vc->seq + 1);
+}
 
+static __always_inline void vdso_write_seq_end(struct vdso_clock *vc)
+{
 	/*
 	 * WRITE_ONCE() is required otherwise the compiler can validly tear
-	 * updates to vd[x].seq and it is possible that the value seen by the
+	 * updates to vc->seq and it is possible that the value seen by the
 	 * reader is inconsistent.
 	 */
-	WRITE_ONCE(vc[CS_HRES_COARSE].seq, vc[CS_HRES_COARSE].seq + 1);
-	WRITE_ONCE(vc[CS_RAW].seq, vc[CS_RAW].seq + 1);
+	WRITE_ONCE(vc->seq, vc->seq + 1);
+}
+
+static __always_inline void vdso_write_begin_clock(struct vdso_clock *vc)
+{
+	vdso_write_seq_begin(vc);
+	/* Ensure the sequence invalidation is visible before data is modified */
+	smp_wmb();
+}
+
+static __always_inline void vdso_write_end_clock(struct vdso_clock *vc)
+{
+	/* Ensure the data update is visible before the sequence is set valid again */
+	smp_wmb();
+	vdso_write_seq_end(vc);
+}
+
+static __always_inline void vdso_write_begin(struct vdso_time_data *vd)
+{
+	struct vdso_clock *vc = vd->clock_data;
+
+	vdso_write_seq_begin(&vc[CS_HRES_COARSE]);
+	vdso_write_seq_begin(&vc[CS_RAW]);
+	/* Ensure the sequence invalidation is visible before data is modified */
 	smp_wmb();
 }
 
@@ -46,14 +76,10 @@ static __always_inline void vdso_write_end(struct vdso_time_data *vd)
 {
 	struct vdso_clock *vc = vd->clock_data;
 
+	/* Ensure the data update is visible before the sequence is set valid again */
 	smp_wmb();
-	/*
-	 * WRITE_ONCE() is required otherwise the compiler can validly tear
-	 * updates to vd[x].seq and it is possible that the value seen by the
-	 * reader is inconsistent.
-	 */
-	WRITE_ONCE(vc[CS_HRES_COARSE].seq, vc[CS_HRES_COARSE].seq + 1);
-	WRITE_ONCE(vc[CS_RAW].seq, vc[CS_RAW].seq + 1);
+	vdso_write_seq_end(&vc[CS_HRES_COARSE]);
+	vdso_write_seq_end(&vc[CS_RAW]);
 }
 
 #endif /* !__ASSEMBLY__ */
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index b0b97a60aaa6..7c6a52f7836c 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -82,9 +82,9 @@ config CONTEXT_TRACKING_IDLE
 	help
 	  Tracks idle state on behalf of RCU.
 
-if GENERIC_CLOCKEVENTS
 menu "Timers subsystem"
 
+if GENERIC_CLOCKEVENTS
 # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
 # only related to the tick functionality. Oneshot clockevent devices
 # are supported independent of this.
@@ -208,6 +208,17 @@ config CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
 	  interval and NTP's maximum frequency drift of 500 parts
 	  per million.	If the clocksource is good enough for NTP,
 	  it is good enough for the clocksource watchdog!
+endif
+
+config POSIX_AUX_CLOCKS
+	bool "Enable auxiliary POSIX clocks"
+	depends on POSIX_TIMERS
+	help
+	  Auxiliary POSIX clocks are clocks which can be steered
+	  independently of the core timekeeper, which controls the
+	  MONOTONIC, REALTIME, BOOTTIME and TAI clocks.  They are useful to
+	  provide e.g. lockless time accessors to independent PTP clocks
+	  and other clock domains, which are not correlated to the TAI/NTP
+	  notion of time.
 
 endmenu
-endif
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index e3642278df43..667452768ed3 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -242,6 +242,11 @@ static void timens_set_vvar_page(struct task_struct *task,
 	for (i = 0; i < CS_BASES; i++)
 		timens_setup_vdso_clock_data(&vc[i], ns);
 
+	if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS)) {
+		for (i = 0; i < ARRAY_SIZE(vdata->aux_clock_data); i++)
+			timens_setup_vdso_clock_data(&vdata->aux_clock_data[i], ns);
+	}
+
 out:
 	mutex_unlock(&offset_lock);
 }
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index b837d3d9d325..97fa99b96dd0 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/audit.h>
+#include <linux/timekeeper_internal.h>
 
 #include "ntp_internal.h"
 #include "timekeeping_internal.h"
@@ -86,14 +87,16 @@ struct ntp_data {
 #endif
 };
 
-static struct ntp_data tk_ntp_data = {
-	.tick_usec		= USER_TICK_USEC,
-	.time_state		= TIME_OK,
-	.time_status		= STA_UNSYNC,
-	.time_constant		= 2,
-	.time_maxerror		= NTP_PHASE_LIMIT,
-	.time_esterror		= NTP_PHASE_LIMIT,
-	.ntp_next_leap_sec	= TIME64_MAX,
+static struct ntp_data tk_ntp_data[TIMEKEEPERS_MAX] = {
+	[ 0 ... TIMEKEEPERS_MAX - 1 ] = {
+		.tick_usec		= USER_TICK_USEC,
+		.time_state		= TIME_OK,
+		.time_status		= STA_UNSYNC,
+		.time_constant		= 2,
+		.time_maxerror		= NTP_PHASE_LIMIT,
+		.time_esterror		= NTP_PHASE_LIMIT,
+		.ntp_next_leap_sec	= TIME64_MAX,
+	},
 };
 
 #define SECS_PER_DAY		86400
@@ -300,7 +303,7 @@ static void ntp_update_offset(struct ntp_data *ntpdata, long offset)
 	 * Select how the frequency is to be controlled
 	 * and in which mode (PLL or FLL).
 	 */
-	real_secs = __ktime_get_real_seconds();
+	real_secs = ktime_get_ntp_seconds(ntpdata - tk_ntp_data);
 	secs = (long)(real_secs - ntpdata->time_reftime);
 	if (unlikely(ntpdata->time_status & STA_FREQHOLD))
 		secs = 0;
@@ -348,33 +351,38 @@ static void __ntp_clear(struct ntp_data *ntpdata)
 
 /**
  * ntp_clear - Clears the NTP state variables
+ * @tkid:	Timekeeper ID to be able to select proper ntp data array member
  */
-void ntp_clear(void)
+void ntp_clear(unsigned int tkid)
 {
-	__ntp_clear(&tk_ntp_data);
+	__ntp_clear(&tk_ntp_data[tkid]);
 }
 
 
-u64 ntp_tick_length(void)
+u64 ntp_tick_length(unsigned int tkid)
 {
-	return tk_ntp_data.tick_length;
+	return tk_ntp_data[tkid].tick_length;
 }
 
 /**
  * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
+ * @tkid:	Timekeeper ID
  *
- * Provides the time of the next leapsecond against CLOCK_REALTIME in
- * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
+ * Returns: For @tkid == TIMEKEEPER_CORE this provides the time of the next
+ *	    leap second against CLOCK_REALTIME in a ktime_t format if a
+ *	    leap second is pending. KTIME_MAX otherwise.
  */
-ktime_t ntp_get_next_leap(void)
+ktime_t ntp_get_next_leap(unsigned int tkid)
 {
-	struct ntp_data *ntpdata = &tk_ntp_data;
-	ktime_t ret;
+	struct ntp_data *ntpdata = &tk_ntp_data[TIMEKEEPER_CORE];
+
+	if (tkid != TIMEKEEPER_CORE)
+		return KTIME_MAX;
 
 	if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS))
 		return ktime_set(ntpdata->ntp_next_leap_sec, 0);
-	ret = KTIME_MAX;
-	return ret;
+
+	return KTIME_MAX;
 }
 
 /*
@@ -387,9 +395,9 @@ ktime_t ntp_get_next_leap(void)
  *
  * Also handles leap second processing, and returns leap offset
  */
-int second_overflow(time64_t secs)
+int second_overflow(unsigned int tkid, time64_t secs)
 {
-	struct ntp_data *ntpdata = &tk_ntp_data;
+	struct ntp_data *ntpdata = &tk_ntp_data[tkid];
 	s64 delta;
 	int leap = 0;
 	s32 rem;
@@ -605,7 +613,7 @@ static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_ns
  */
 static inline bool ntp_synced(void)
 {
-	return !(tk_ntp_data.time_status & STA_UNSYNC);
+	return !(tk_ntp_data[TIMEKEEPER_CORE].time_status & STA_UNSYNC);
 }
 
 /*
@@ -702,7 +710,7 @@ static inline void process_adj_status(struct ntp_data *ntpdata, const struct __k
 	 * reference time to current time.
 	 */
 	if (!(ntpdata->time_status & STA_PLL) && (txc->status & STA_PLL))
-		ntpdata->time_reftime = __ktime_get_real_seconds();
+		ntpdata->time_reftime = ktime_get_ntp_seconds(ntpdata - tk_ntp_data);
 
 	/* only set allowed bits */
 	ntpdata->time_status &= STA_RONLY;
@@ -759,10 +767,10 @@ static inline void process_adjtimex_modes(struct ntp_data *ntpdata, const struct
  * adjtimex() mainly allows reading (and writing, if superuser) of
  * kernel time-keeping variables. used by xntpd.
  */
-int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
-		  s32 *time_tai, struct audit_ntp_data *ad)
+int ntp_adjtimex(unsigned int tkid, struct __kernel_timex *txc, const struct timespec64 *ts,
+		 s32 *time_tai, struct audit_ntp_data *ad)
 {
-	struct ntp_data *ntpdata = &tk_ntp_data;
+	struct ntp_data *ntpdata = &tk_ntp_data[tkid];
 	int result;
 
 	if (txc->modes & ADJ_ADJTIME) {
@@ -1031,8 +1039,8 @@ static void hardpps_update_phase(struct ntp_data *ntpdata, long error)
  */
 void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
 {
+	struct ntp_data *ntpdata = &tk_ntp_data[TIMEKEEPER_CORE];
 	struct pps_normtime pts_norm, freq_norm;
-	struct ntp_data *ntpdata = &tk_ntp_data;
 
 	pts_norm = pps_normalize_ts(*phase_ts);
 
@@ -1083,18 +1091,18 @@ void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_t
 
 static int __init ntp_tick_adj_setup(char *str)
 {
-	int rc = kstrtos64(str, 0, &tk_ntp_data.ntp_tick_adj);
+	int rc = kstrtos64(str, 0, &tk_ntp_data[TIMEKEEPER_CORE].ntp_tick_adj);
 	if (rc)
 		return rc;
 
-	tk_ntp_data.ntp_tick_adj <<= NTP_SCALE_SHIFT;
+	tk_ntp_data[TIMEKEEPER_CORE].ntp_tick_adj <<= NTP_SCALE_SHIFT;
 	return 1;
 }
-
 __setup("ntp_tick_adj=", ntp_tick_adj_setup);
 
 void __init ntp_init(void)
 {
-	ntp_clear();
+	for (int id = 0; id < TIMEKEEPERS_MAX; id++)
+		__ntp_clear(tk_ntp_data + id);
 	ntp_init_cmos_sync();
 }
diff --git a/kernel/time/ntp_internal.h b/kernel/time/ntp_internal.h
index 5a633dce9057..7084d839c207 100644
--- a/kernel/time/ntp_internal.h
+++ b/kernel/time/ntp_internal.h
@@ -3,14 +3,13 @@
 #define _LINUX_NTP_INTERNAL_H
 
 extern void ntp_init(void);
-extern void ntp_clear(void);
+extern void ntp_clear(unsigned int tkid);
 /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
-extern u64 ntp_tick_length(void);
-extern ktime_t ntp_get_next_leap(void);
-extern int second_overflow(time64_t secs);
-extern int __do_adjtimex(struct __kernel_timex *txc,
-			 const struct timespec64 *ts,
-			 s32 *time_tai, struct audit_ntp_data *ad);
+extern u64 ntp_tick_length(unsigned int tkid);
+extern ktime_t ntp_get_next_leap(unsigned int tkid);
+extern int second_overflow(unsigned int tkid, time64_t secs);
+extern int ntp_adjtimex(unsigned int tkid, struct __kernel_timex *txc, const struct timespec64 *ts,
+			s32 *time_tai, struct audit_ntp_data *ad);
 extern void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts);
 
 #if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 2053b1a4c9e4..8b582174b1f9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1526,6 +1526,9 @@ static const struct k_clock * const posix_clocks[] = {
 	[CLOCK_REALTIME_ALARM]		= &alarm_clock,
 	[CLOCK_BOOTTIME_ALARM]		= &alarm_clock,
 	[CLOCK_TAI]			= &clock_tai,
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+	[CLOCK_AUX ... CLOCK_AUX_LAST]	= &clock_aux,
+#endif
 };
 
 static const struct k_clock *clockid_to_kclock(const clockid_t id)
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index 61906f0688c1..7f259e845d24 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -41,6 +41,7 @@ extern const struct k_clock clock_posix_dynamic;
 extern const struct k_clock clock_process;
 extern const struct k_clock clock_thread;
 extern const struct k_clock alarm_clock;
+extern const struct k_clock clock_aux;
 
 void posix_timer_queue_signal(struct k_itimer *timr);
 
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 83c65f3afcca..059fa8b79be6 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -6,6 +6,7 @@
 #include <linux/timekeeper_internal.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
+#include <linux/kobject.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
 #include <linux/mm.h>
@@ -25,6 +26,8 @@
 #include <linux/audit.h>
 #include <linux/random.h>
 
+#include <vdso/auxclock.h>
+
 #include "tick-internal.h"
 #include "ntp_internal.h"
 #include "timekeeping_internal.h"
@@ -53,7 +56,32 @@ struct tk_data {
 	raw_spinlock_t		lock;
 } ____cacheline_aligned;
 
-static struct tk_data tk_core;
+static struct tk_data timekeeper_data[TIMEKEEPERS_MAX];
+
+/* The core timekeeper */
+#define tk_core		(timekeeper_data[TIMEKEEPER_CORE])
+
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+static inline bool tk_get_aux_ts64(unsigned int tkid, struct timespec64 *ts)
+{
+	return ktime_get_aux_ts64(CLOCK_AUX + tkid - TIMEKEEPER_AUX_FIRST, ts);
+}
+
+static inline bool tk_is_aux(const struct timekeeper *tk)
+{
+	return tk->id >= TIMEKEEPER_AUX_FIRST && tk->id <= TIMEKEEPER_AUX_LAST;
+}
+#else
+static inline bool tk_get_aux_ts64(unsigned int tkid, struct timespec64 *ts)
+{
+	return false;
+}
+
+static inline bool tk_is_aux(const struct timekeeper *tk)
+{
+	return false;
+}
+#endif
 
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
@@ -113,6 +141,16 @@ static struct tk_fast tk_fast_raw  ____cacheline_aligned = {
 	.base[1] = FAST_TK_INIT,
 };
 
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+static __init void tk_aux_setup(void);
+static void tk_aux_update_clocksource(void);
+static void tk_aux_advance(void);
+#else
+static inline void tk_aux_setup(void) { }
+static inline void tk_aux_update_clocksource(void) { }
+static inline void tk_aux_advance(void) { }
+#endif
+
 unsigned long timekeeper_lock_irqsave(void)
 {
 	unsigned long flags;
@@ -601,7 +639,7 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
  */
 static inline void tk_update_leap_state(struct timekeeper *tk)
 {
-	tk->next_leap_ktime = ntp_get_next_leap();
+	tk->next_leap_ktime = ntp_get_next_leap(tk->id);
 	if (tk->next_leap_ktime != KTIME_MAX)
 		/* Convert to monotonic time */
 		tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
@@ -663,7 +701,7 @@ static void timekeeping_restore_shadow(struct tk_data *tkd)
 
 static void timekeeping_update_from_shadow(struct tk_data *tkd, unsigned int action)
 {
-	struct timekeeper *tk = &tk_core.shadow_timekeeper;
+	struct timekeeper *tk = &tkd->shadow_timekeeper;
 
 	lockdep_assert_held(&tkd->lock);
 
@@ -678,18 +716,22 @@ static void timekeeping_update_from_shadow(struct tk_data *tkd, unsigned int act
 
 	if (action & TK_CLEAR_NTP) {
 		tk->ntp_error = 0;
-		ntp_clear();
+		ntp_clear(tk->id);
 	}
 
 	tk_update_leap_state(tk);
 	tk_update_ktime_data(tk);
+	tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
 
-	update_vsyscall(tk);
-	update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
+	if (tk->id == TIMEKEEPER_CORE) {
+		update_vsyscall(tk);
+		update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
 
-	tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
-	update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
-	update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
+		update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
+		update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
+	} else if (tk_is_aux(tk)) {
+		vdso_time_update_aux(tk);
+	}
 
 	if (action & TK_CLOCK_WAS_SET)
 		tk->clock_was_set_seq++;
@@ -975,9 +1017,14 @@ time64_t ktime_get_real_seconds(void)
 EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
 
 /**
- * __ktime_get_real_seconds - The same as ktime_get_real_seconds
- * but without the sequence counter protect. This internal function
- * is called just when timekeeping lock is already held.
+ * __ktime_get_real_seconds - Unprotected access to CLOCK_REALTIME seconds
+ *
+ * The same as ktime_get_real_seconds() but without the sequence counter
+ * protection. This function is used in restricted contexts like the x86 MCE
+ * handler and in KGDB. It's unprotected on 32-bit vs. concurrent half
+ * completed modification and only to be used for such critical contexts.
+ *
+ * Returns: Racy snapshot of the CLOCK_REALTIME seconds value
  */
 noinstr time64_t __ktime_get_real_seconds(void)
 {
@@ -1412,41 +1459,73 @@ int do_settimeofday64(const struct timespec64 *ts)
 }
 EXPORT_SYMBOL(do_settimeofday64);
 
+static inline bool timekeeper_is_core_tk(struct timekeeper *tk)
+{
+	return !IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS) || tk->id == TIMEKEEPER_CORE;
+}
+
 /**
- * timekeeping_inject_offset - Adds or subtracts from the current time.
+ * __timekeeping_inject_offset - Adds or subtracts from the current time.
+ * @tkd:	Pointer to the timekeeper to modify
  * @ts:		Pointer to the timespec variable containing the offset
  *
  * Adds or subtracts an offset value from the current time.
  */
-static int timekeeping_inject_offset(const struct timespec64 *ts)
+static int __timekeeping_inject_offset(struct tk_data *tkd, const struct timespec64 *ts)
 {
+	struct timekeeper *tks = &tkd->shadow_timekeeper;
+	struct timespec64 tmp;
+
 	if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
 		return -EINVAL;
 
-	scoped_guard (raw_spinlock_irqsave, &tk_core.lock) {
-		struct timekeeper *tks = &tk_core.shadow_timekeeper;
-		struct timespec64 tmp;
-
-		timekeeping_forward_now(tks);
+	timekeeping_forward_now(tks);
 
+	if (timekeeper_is_core_tk(tks)) {
 		/* Make sure the proposed value is valid */
 		tmp = timespec64_add(tk_xtime(tks), *ts);
 		if (timespec64_compare(&tks->wall_to_monotonic, ts) > 0 ||
 		    !timespec64_valid_settod(&tmp)) {
-			timekeeping_restore_shadow(&tk_core);
+			timekeeping_restore_shadow(tkd);
 			return -EINVAL;
 		}
 
 		tk_xtime_add(tks, ts);
 		tk_set_wall_to_mono(tks, timespec64_sub(tks->wall_to_monotonic, *ts));
-		timekeeping_update_from_shadow(&tk_core, TK_UPDATE_ALL);
+	} else {
+		struct tk_read_base *tkr_mono = &tks->tkr_mono;
+		ktime_t now, offs;
+
+		/* Get the current time */
+		now = ktime_add_ns(tkr_mono->base, timekeeping_get_ns(tkr_mono));
+		/* Add the relative offset change */
+		offs = ktime_add(tks->offs_aux, timespec64_to_ktime(*ts));
+
+		/* Prevent that the resulting time becomes negative */
+		if (ktime_add(now, offs) < 0) {
+			timekeeping_restore_shadow(tkd);
+			return -EINVAL;
+		}
+		tks->offs_aux = offs;
 	}
 
-	/* Signal hrtimers about time change */
-	clock_was_set(CLOCK_SET_WALL);
+	timekeeping_update_from_shadow(tkd, TK_UPDATE_ALL);
 	return 0;
 }
 
+static int timekeeping_inject_offset(const struct timespec64 *ts)
+{
+	int ret;
+
+	scoped_guard (raw_spinlock_irqsave, &tk_core.lock)
+		ret = __timekeeping_inject_offset(&tk_core, ts);
+
+	/* Signal hrtimers about time change */
+	if (!ret)
+		clock_was_set(CLOCK_SET_WALL);
+	return ret;
+}
+
 /*
  * Indicates if there is an offset between the system clock and the hardware
  * clock/persistent clock/rtc.
@@ -1522,6 +1601,8 @@ static int change_clocksource(void *data)
 		timekeeping_update_from_shadow(&tk_core, TK_UPDATE_ALL);
 	}
 
+	tk_aux_update_clocksource();
+
 	if (old) {
 		if (old->disable)
 			old->disable(old);
@@ -1573,6 +1654,39 @@ void ktime_get_raw_ts64(struct timespec64 *ts)
 }
 EXPORT_SYMBOL(ktime_get_raw_ts64);
 
+/**
+ * ktime_get_clock_ts64 - Returns time of a clock in a timespec
+ * @id:		POSIX clock ID of the clock to read
+ * @ts:		Pointer to the timespec64 to be set
+ *
+ * The timestamp is invalidated (@ts->sec is set to -1) if the
+ * clock @id is not available.
+ */
+void ktime_get_clock_ts64(clockid_t id, struct timespec64 *ts)
+{
+	/* Invalidate time stamp */
+	ts->tv_sec = -1;
+	ts->tv_nsec = 0;
+
+	switch (id) {
+	case CLOCK_REALTIME:
+		ktime_get_real_ts64(ts);
+		return;
+	case CLOCK_MONOTONIC:
+		ktime_get_ts64(ts);
+		return;
+	case CLOCK_MONOTONIC_RAW:
+		ktime_get_raw_ts64(ts);
+		return;
+	case CLOCK_AUX ... CLOCK_AUX_LAST:
+		if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS))
+			ktime_get_aux_ts64(id, ts);
+		return;
+	default:
+		WARN_ON_ONCE(1);
+	}
+}
+EXPORT_SYMBOL_GPL(ktime_get_clock_ts64);
 
 /**
  * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
@@ -1649,10 +1763,12 @@ read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
 	*boot_offset = ns_to_timespec64(local_clock());
 }
 
-static __init void tkd_basic_setup(struct tk_data *tkd)
+static __init void tkd_basic_setup(struct tk_data *tkd, enum timekeeper_ids tk_id, bool valid)
 {
 	raw_spin_lock_init(&tkd->lock);
 	seqcount_raw_spinlock_init(&tkd->seq, &tkd->lock);
+	tkd->timekeeper.id = tkd->shadow_timekeeper.id = tk_id;
+	tkd->timekeeper.clock_valid = tkd->shadow_timekeeper.clock_valid = valid;
 }
 
 /*
@@ -1682,7 +1798,8 @@ void __init timekeeping_init(void)
 	struct timekeeper *tks = &tk_core.shadow_timekeeper;
 	struct clocksource *clock;
 
-	tkd_basic_setup(&tk_core);
+	tkd_basic_setup(&tk_core, TIMEKEEPER_CORE, true);
+	tk_aux_setup();
 
 	read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
 	if (timespec64_valid_settod(&wall_time) &&
@@ -2034,7 +2151,7 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
  */
 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 {
-	u64 ntp_tl = ntp_tick_length();
+	u64 ntp_tl = ntp_tick_length(tk->id);
 	u32 mult;
 
 	/*
@@ -2115,7 +2232,7 @@ static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
 		}
 
 		/* Figure out if its a leap sec and apply if needed */
-		leap = second_overflow(tk->xtime_sec);
+		leap = second_overflow(tk->id, tk->xtime_sec);
 		if (unlikely(leap)) {
 			struct timespec64 ts;
 
@@ -2181,16 +2298,14 @@ static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
  * timekeeping_advance - Updates the timekeeper to the current time and
  * current NTP tick length
  */
-static bool timekeeping_advance(enum timekeeping_adv_mode mode)
+static bool __timekeeping_advance(struct tk_data *tkd, enum timekeeping_adv_mode mode)
 {
-	struct timekeeper *tk = &tk_core.shadow_timekeeper;
-	struct timekeeper *real_tk = &tk_core.timekeeper;
+	struct timekeeper *tk = &tkd->shadow_timekeeper;
+	struct timekeeper *real_tk = &tkd->timekeeper;
 	unsigned int clock_set = 0;
 	int shift = 0, maxshift;
 	u64 offset, orig_offset;
 
-	guard(raw_spinlock_irqsave)(&tk_core.lock);
-
 	/* Make sure we're fully resumed: */
 	if (unlikely(timekeeping_suspended))
 		return false;
@@ -2214,7 +2329,7 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 	shift = ilog2(offset) - ilog2(tk->cycle_interval);
 	shift = max(0, shift);
 	/* Bound shift to one less than what overflows tick_length */
-	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
+	maxshift = (64 - (ilog2(ntp_tick_length(tk->id)) + 1)) - 1;
 	shift = min(shift, maxshift);
 	while (offset >= tk->cycle_interval) {
 		offset = logarithmic_accumulation(tk, offset, shift, &clock_set);
@@ -2239,19 +2354,27 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 	if (orig_offset != offset)
 		tk_update_coarse_nsecs(tk);
 
-	timekeeping_update_from_shadow(&tk_core, clock_set);
+	timekeeping_update_from_shadow(tkd, clock_set);
 
 	return !!clock_set;
 }
 
+static bool timekeeping_advance(enum timekeeping_adv_mode mode)
+{
+	guard(raw_spinlock_irqsave)(&tk_core.lock);
+	return __timekeeping_advance(&tk_core, mode);
+}
+
 /**
  * update_wall_time - Uses the current clocksource to increment the wall time
  *
+ * It also updates the enabled auxiliary clock timekeepers
  */
 void update_wall_time(void)
 {
 	if (timekeeping_advance(TK_ADV_TICK))
 		clock_was_set_delayed();
+	tk_aux_advance();
 }
 
 /**
@@ -2449,7 +2572,7 @@ ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
 /*
  * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
  */
-static int timekeeping_validate_timex(const struct __kernel_timex *txc)
+static int timekeeping_validate_timex(const struct __kernel_timex *txc, bool aux_clock)
 {
 	if (txc->modes & ADJ_ADJTIME) {
 		/* singleshot must not be used with any other mode bits */
@@ -2508,6 +2631,20 @@ static int timekeeping_validate_timex(const struct __kernel_timex *txc)
 			return -EINVAL;
 	}
 
+	if (aux_clock) {
+		/* Auxiliary clocks are similar to TAI and do not have leap seconds */
+		if (txc->status & (STA_INS | STA_DEL))
+			return -EINVAL;
+
+		/* No TAI offset setting */
+		if (txc->modes & ADJ_TAI)
+			return -EINVAL;
+
+		/* No PPS support either */
+		if (txc->status & (STA_PPSFREQ | STA_PPSTIME))
+			return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -2526,74 +2663,103 @@ unsigned long random_get_entropy_fallback(void)
 }
 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)
+struct adjtimex_result {
+	struct audit_ntp_data	ad;
+	struct timespec64	delta;
+	bool			clock_set;
+};
+
+static int __do_adjtimex(struct tk_data *tkd, struct __kernel_timex *txc,
+			 struct adjtimex_result *result)
 {
-	struct audit_ntp_data ad;
-	bool offset_set = false;
-	bool clock_set = false;
+	struct timekeeper *tks = &tkd->shadow_timekeeper;
+	bool aux_clock = !timekeeper_is_core_tk(tks);
 	struct timespec64 ts;
+	s32 orig_tai, tai;
 	int ret;
 
 	/* Validate the data before disabling interrupts */
-	ret = timekeeping_validate_timex(txc);
+	ret = timekeeping_validate_timex(txc, aux_clock);
 	if (ret)
 		return ret;
 	add_device_randomness(txc, sizeof(*txc));
 
-	if (txc->modes & ADJ_SETOFFSET) {
-		struct timespec64 delta;
+	if (!aux_clock)
+		ktime_get_real_ts64(&ts);
+	else
+		tk_get_aux_ts64(tkd->timekeeper.id, &ts);
 
-		delta.tv_sec  = txc->time.tv_sec;
-		delta.tv_nsec = txc->time.tv_usec;
+	add_device_randomness(&ts, sizeof(ts));
+
+	guard(raw_spinlock_irqsave)(&tkd->lock);
+
+	if (!tks->clock_valid)
+		return -ENODEV;
+
+	if (txc->modes & ADJ_SETOFFSET) {
+		result->delta.tv_sec  = txc->time.tv_sec;
+		result->delta.tv_nsec = txc->time.tv_usec;
 		if (!(txc->modes & ADJ_NANO))
-			delta.tv_nsec *= 1000;
-		ret = timekeeping_inject_offset(&delta);
+			result->delta.tv_nsec *= 1000;
+		ret = __timekeeping_inject_offset(tkd, &result->delta);
 		if (ret)
 			return ret;
-
-		offset_set = delta.tv_sec != 0;
-		audit_tk_injoffset(delta);
+		result->clock_set = true;
 	}
 
-	audit_ntp_init(&ad);
+	orig_tai = tai = tks->tai_offset;
+	ret = ntp_adjtimex(tks->id, txc, &ts, &tai, &result->ad);
 
-	ktime_get_real_ts64(&ts);
-	add_device_randomness(&ts, sizeof(ts));
+	if (tai != orig_tai) {
+		__timekeeping_set_tai_offset(tks, tai);
+		timekeeping_update_from_shadow(tkd, TK_CLOCK_WAS_SET);
+		result->clock_set = true;
+	} else {
+		tk_update_leap_state_all(&tk_core);
+	}
 
-	scoped_guard (raw_spinlock_irqsave, &tk_core.lock) {
-		struct timekeeper *tks = &tk_core.shadow_timekeeper;
-		s32 orig_tai, tai;
+	/* Update the multiplier immediately if frequency was set directly */
+	if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
+		result->clock_set |= __timekeeping_advance(tkd, TK_ADV_FREQ);
 
-		orig_tai = tai = tks->tai_offset;
-		ret = __do_adjtimex(txc, &ts, &tai, &ad);
+	return ret;
+}
 
-		if (tai != orig_tai) {
-			__timekeeping_set_tai_offset(tks, tai);
-			timekeeping_update_from_shadow(&tk_core, TK_CLOCK_WAS_SET);
-			clock_set = true;
-		} else {
-			tk_update_leap_state_all(&tk_core);
-		}
-	}
+/**
+ * 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)
+{
+	struct adjtimex_result result = { };
+	int ret;
 
-	audit_ntp_log(&ad);
+	ret = __do_adjtimex(&tk_core, txc, &result);
+	if (ret < 0)
+		return ret;
 
-	/* Update the multiplier immediately if frequency was set directly */
-	if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
-		clock_set |= timekeeping_advance(TK_ADV_FREQ);
+	if (txc->modes & ADJ_SETOFFSET)
+		audit_tk_injoffset(result.delta);
 
-	if (clock_set)
+	audit_ntp_log(&result.ad);
+
+	if (result.clock_set)
 		clock_was_set(CLOCK_SET_WALL);
 
-	ntp_notify_cmos_timer(offset_set);
+	ntp_notify_cmos_timer(result.delta.tv_sec != 0);
 
 	return ret;
 }
 
+/*
+ * Invoked from NTP with the time keeper lock held, so lockless access is
+ * fine.
+ */
+long ktime_get_ntp_seconds(unsigned int id)
+{
+	return timekeeper_data[id].timekeeper.xtime_sec;
+}
+
 #ifdef CONFIG_NTP_PPS
 /**
  * hardpps() - Accessor function to NTP __hardpps function
@@ -2607,3 +2773,316 @@ void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
 }
 EXPORT_SYMBOL(hardpps);
 #endif /* CONFIG_NTP_PPS */
+
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+#include "posix-timers.h"
+
+/*
+ * Bitmap for the activated auxiliary timekeepers to allow lockless quick
+ * checks in the hot paths without touching extra cache lines. If set, then
+ * the state of the corresponding timekeeper has to be re-checked under
+ * timekeeper::lock.
+ */
+static unsigned long aux_timekeepers;
+
+static inline unsigned int clockid_to_tkid(unsigned int id)
+{
+	return TIMEKEEPER_AUX_FIRST + id - CLOCK_AUX;
+}
+
+static inline struct tk_data *aux_get_tk_data(clockid_t id)
+{
+	if (!clockid_aux_valid(id))
+		return NULL;
+	return &timekeeper_data[clockid_to_tkid(id)];
+}
+
+/* Invoked from timekeeping after a clocksource change */
+static void tk_aux_update_clocksource(void)
+{
+	unsigned long active = READ_ONCE(aux_timekeepers);
+	unsigned int id;
+
+	for_each_set_bit(id, &active, BITS_PER_LONG) {
+		struct tk_data *tkd = &timekeeper_data[id + TIMEKEEPER_AUX_FIRST];
+		struct timekeeper *tks = &tkd->shadow_timekeeper;
+
+		guard(raw_spinlock_irqsave)(&tkd->lock);
+		if (!tks->clock_valid)
+			continue;
+
+		timekeeping_forward_now(tks);
+		tk_setup_internals(tks, tk_core.timekeeper.tkr_mono.clock);
+		timekeeping_update_from_shadow(tkd, TK_UPDATE_ALL);
+	}
+}
+
+static void tk_aux_advance(void)
+{
+	unsigned long active = READ_ONCE(aux_timekeepers);
+	unsigned int id;
+
+	/* Lockless quick check to avoid extra cache lines */
+	for_each_set_bit(id, &active, BITS_PER_LONG) {
+		struct tk_data *aux_tkd = &timekeeper_data[id + TIMEKEEPER_AUX_FIRST];
+
+		guard(raw_spinlock)(&aux_tkd->lock);
+		if (aux_tkd->shadow_timekeeper.clock_valid)
+			__timekeeping_advance(aux_tkd, TK_ADV_TICK);
+	}
+}
+
+/**
+ * ktime_get_aux - Get time for a AUX clock
+ * @id:	ID of the clock to read (CLOCK_AUX...)
+ * @kt:	Pointer to ktime_t to store the time stamp
+ *
+ * Returns: True if the timestamp is valid, false otherwise
+ */
+bool ktime_get_aux(clockid_t id, ktime_t *kt)
+{
+	struct tk_data *aux_tkd = aux_get_tk_data(id);
+	struct timekeeper *aux_tk;
+	unsigned int seq;
+	ktime_t base;
+	u64 nsecs;
+
+	WARN_ON(timekeeping_suspended);
+
+	if (!aux_tkd)
+		return false;
+
+	aux_tk = &aux_tkd->timekeeper;
+	do {
+		seq = read_seqcount_begin(&aux_tkd->seq);
+		if (!aux_tk->clock_valid)
+			return false;
+
+		base = ktime_add(aux_tk->tkr_mono.base, aux_tk->offs_aux);
+		nsecs = timekeeping_get_ns(&aux_tk->tkr_mono);
+	} while (read_seqcount_retry(&aux_tkd->seq, seq));
+
+	*kt = ktime_add_ns(base, nsecs);
+	return true;
+}
+EXPORT_SYMBOL_GPL(ktime_get_aux);
+
+/**
+ * ktime_get_aux_ts64 - Get time for a AUX clock
+ * @id:	ID of the clock to read (CLOCK_AUX...)
+ * @ts:	Pointer to timespec64 to store the time stamp
+ *
+ * Returns: True if the timestamp is valid, false otherwise
+ */
+bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *ts)
+{
+	ktime_t now;
+
+	if (!ktime_get_aux(id, &now))
+		return false;
+	*ts = ktime_to_timespec64(now);
+	return true;
+}
+EXPORT_SYMBOL_GPL(ktime_get_aux_ts64);
+
+static int aux_get_res(clockid_t id, struct timespec64 *tp)
+{
+	if (!clockid_aux_valid(id))
+		return -ENODEV;
+
+	tp->tv_sec = aux_clock_resolution_ns() / NSEC_PER_SEC;
+	tp->tv_nsec = aux_clock_resolution_ns() % NSEC_PER_SEC;
+	return 0;
+}
+
+static int aux_get_timespec(clockid_t id, struct timespec64 *tp)
+{
+	return ktime_get_aux_ts64(id, tp) ? 0 : -ENODEV;
+}
+
+static int aux_clock_set(const clockid_t id, const struct timespec64 *tnew)
+{
+	struct tk_data *aux_tkd = aux_get_tk_data(id);
+	struct timekeeper *aux_tks;
+	ktime_t tnow, nsecs;
+
+	if (!timespec64_valid_settod(tnew))
+		return -EINVAL;
+	if (!aux_tkd)
+		return -ENODEV;
+
+	aux_tks = &aux_tkd->shadow_timekeeper;
+
+	guard(raw_spinlock_irq)(&aux_tkd->lock);
+	if (!aux_tks->clock_valid)
+		return -ENODEV;
+
+	/* Forward the timekeeper base time */
+	timekeeping_forward_now(aux_tks);
+	/*
+	 * Get the updated base time. tkr_mono.base has not been
+	 * updated yet, so do that first. That makes the update
+	 * in timekeeping_update_from_shadow() redundant, but
+	 * that's harmless. After that @tnow can be calculated
+	 * by using tkr_mono::cycle_last, which has been set
+	 * by timekeeping_forward_now().
+	 */
+	tk_update_ktime_data(aux_tks);
+	nsecs = timekeeping_cycles_to_ns(&aux_tks->tkr_mono, aux_tks->tkr_mono.cycle_last);
+	tnow = ktime_add(aux_tks->tkr_mono.base, nsecs);
+
+	/*
+	 * Calculate the new AUX offset as delta to @tnow ("monotonic").
+	 * That avoids all the tk::xtime back and forth conversions as
+	 * xtime ("realtime") is not applicable for auxiliary clocks and
+	 * kept in sync with "monotonic".
+	 */
+	aux_tks->offs_aux = ktime_sub(timespec64_to_ktime(*tnew), tnow);
+
+	timekeeping_update_from_shadow(aux_tkd, TK_UPDATE_ALL);
+	return 0;
+}
+
+static int aux_clock_adj(const clockid_t id, struct __kernel_timex *txc)
+{
+	struct tk_data *aux_tkd = aux_get_tk_data(id);
+	struct adjtimex_result result = { };
+
+	if (!aux_tkd)
+		return -ENODEV;
+
+	/*
+	 * @result is ignored for now as there are neither hrtimers nor a
+	 * RTC related to auxiliary clocks for now.
+	 */
+	return __do_adjtimex(aux_tkd, txc, &result);
+}
+
+const struct k_clock clock_aux = {
+	.clock_getres		= aux_get_res,
+	.clock_get_timespec	= aux_get_timespec,
+	.clock_set		= aux_clock_set,
+	.clock_adj		= aux_clock_adj,
+};
+
+static void aux_clock_enable(clockid_t id)
+{
+	struct tk_read_base *tkr_raw = &tk_core.timekeeper.tkr_raw;
+	struct tk_data *aux_tkd = aux_get_tk_data(id);
+	struct timekeeper *aux_tks = &aux_tkd->shadow_timekeeper;
+
+	/* Prevent the core timekeeper from changing. */
+	guard(raw_spinlock_irq)(&tk_core.lock);
+
+	/*
+	 * Setup the auxiliary clock assuming that the raw core timekeeper
+	 * clock frequency conversion is close enough. Userspace has to
+	 * adjust for the deviation via clock_adjtime(2).
+	 */
+	guard(raw_spinlock_nested)(&aux_tkd->lock);
+
+	/* Remove leftovers of a previous registration */
+	memset(aux_tks, 0, sizeof(*aux_tks));
+	/* Restore the timekeeper id */
+	aux_tks->id = aux_tkd->timekeeper.id;
+	/* Setup the timekeeper based on the current system clocksource */
+	tk_setup_internals(aux_tks, tkr_raw->clock);
+
+	/* Mark it valid and set it live */
+	aux_tks->clock_valid = true;
+	timekeeping_update_from_shadow(aux_tkd, TK_UPDATE_ALL);
+}
+
+static void aux_clock_disable(clockid_t id)
+{
+	struct tk_data *aux_tkd = aux_get_tk_data(id);
+
+	guard(raw_spinlock_irq)(&aux_tkd->lock);
+	aux_tkd->shadow_timekeeper.clock_valid = false;
+	timekeeping_update_from_shadow(aux_tkd, TK_UPDATE_ALL);
+}
+
+static DEFINE_MUTEX(aux_clock_mutex);
+
+static ssize_t aux_clock_enable_store(struct kobject *kobj, struct kobj_attribute *attr,
+				      const char *buf, size_t count)
+{
+	/* Lazy atoi() as name is "0..7" */
+	int id = kobj->name[0] & 0x7;
+	bool enable;
+
+	if (!capable(CAP_SYS_TIME))
+		return -EPERM;
+
+	if (kstrtobool(buf, &enable) < 0)
+		return -EINVAL;
+
+	guard(mutex)(&aux_clock_mutex);
+	if (enable == test_bit(id, &aux_timekeepers))
+		return count;
+
+	if (enable) {
+		aux_clock_enable(CLOCK_AUX + id);
+		set_bit(id, &aux_timekeepers);
+	} else {
+		aux_clock_disable(CLOCK_AUX + id);
+		clear_bit(id, &aux_timekeepers);
+	}
+	return count;
+}
+
+static ssize_t aux_clock_enable_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	unsigned long active = READ_ONCE(aux_timekeepers);
+	/* Lazy atoi() as name is "0..7" */
+	int id = kobj->name[0] & 0x7;
+
+	return sysfs_emit(buf, "%d\n", test_bit(id, &active));
+}
+
+static struct kobj_attribute aux_clock_enable_attr = __ATTR_RW(aux_clock_enable);
+
+static struct attribute *aux_clock_enable_attrs[] = {
+	&aux_clock_enable_attr.attr,
+	NULL
+};
+
+static const struct attribute_group aux_clock_enable_attr_group = {
+	.attrs = aux_clock_enable_attrs,
+};
+
+static int __init tk_aux_sysfs_init(void)
+{
+	struct kobject *auxo, *tko = kobject_create_and_add("time", kernel_kobj);
+
+	if (!tko)
+		return -ENOMEM;
+
+	auxo = kobject_create_and_add("aux_clocks", tko);
+	if (!auxo) {
+		kobject_put(tko);
+		return -ENOMEM;
+	}
+
+	for (int i = 0; i <= MAX_AUX_CLOCKS; i++) {
+		char id[2] = { [0] = '0' + i, };
+		struct kobject *clk = kobject_create_and_add(id, auxo);
+
+		if (!clk)
+			return -ENOMEM;
+
+		int ret = sysfs_create_group(clk, &aux_clock_enable_attr_group);
+
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+late_initcall(tk_aux_sysfs_init);
+
+static __init void tk_aux_setup(void)
+{
+	for (int i = TIMEKEEPER_AUX_FIRST; i <= TIMEKEEPER_AUX_LAST; i++)
+		tkd_basic_setup(&timekeeper_data[i], i, false);
+}
+#endif /* CONFIG_POSIX_AUX_CLOCKS */
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h
index 8c9079108ffb..973ede670a36 100644
--- a/kernel/time/timekeeping_internal.h
+++ b/kernel/time/timekeeping_internal.h
@@ -45,4 +45,7 @@ static inline u64 clocksource_delta(u64 now, u64 last, u64 mask, u64 max_delta)
 unsigned long timekeeper_lock_irqsave(void);
 void timekeeper_unlock_irqrestore(unsigned long flags);
 
+/* NTP specific interface to access the current seconds value */
+long ktime_get_ntp_seconds(unsigned int id);
+
 #endif /* _TIMEKEEPING_INTERNAL_H */
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 32ef27c71b57..8ba8b0d8a387 100644
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -15,26 +15,25 @@
 
 #include "timekeeping_internal.h"
 
+static inline void fill_clock_configuration(struct vdso_clock *vc, const struct tk_read_base *base)
+{
+	vc->cycle_last	= base->cycle_last;
+#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
+	vc->max_cycles	= base->clock->max_cycles;
+#endif
+	vc->mask	= base->mask;
+	vc->mult	= base->mult;
+	vc->shift	= base->shift;
+}
+
 static inline void update_vdso_time_data(struct vdso_time_data *vdata, struct timekeeper *tk)
 {
 	struct vdso_clock *vc = vdata->clock_data;
 	struct vdso_timestamp *vdso_ts;
 	u64 nsec, sec;
 
-	vc[CS_HRES_COARSE].cycle_last	= tk->tkr_mono.cycle_last;
-#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
-	vc[CS_HRES_COARSE].max_cycles	= tk->tkr_mono.clock->max_cycles;
-#endif
-	vc[CS_HRES_COARSE].mask		= tk->tkr_mono.mask;
-	vc[CS_HRES_COARSE].mult		= tk->tkr_mono.mult;
-	vc[CS_HRES_COARSE].shift	= tk->tkr_mono.shift;
-	vc[CS_RAW].cycle_last		= tk->tkr_raw.cycle_last;
-#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
-	vc[CS_RAW].max_cycles		= tk->tkr_raw.clock->max_cycles;
-#endif
-	vc[CS_RAW].mask			= tk->tkr_raw.mask;
-	vc[CS_RAW].mult			= tk->tkr_raw.mult;
-	vc[CS_RAW].shift		= tk->tkr_raw.shift;
+	fill_clock_configuration(&vc[CS_HRES_COARSE],	&tk->tkr_mono);
+	fill_clock_configuration(&vc[CS_RAW],		&tk->tkr_raw);
 
 	/* CLOCK_MONOTONIC */
 	vdso_ts		= &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
@@ -119,7 +118,8 @@ void update_vsyscall(struct timekeeper *tk)
 	if (clock_mode != VDSO_CLOCKMODE_NONE)
 		update_vdso_time_data(vdata, tk);
 
-	__arch_update_vsyscall(vdata);
+	__arch_update_vdso_clock(&vc[CS_HRES_COARSE]);
+	__arch_update_vdso_clock(&vc[CS_RAW]);
 
 	vdso_write_end(vdata);
 
@@ -136,6 +136,46 @@ void update_vsyscall_tz(void)
 	__arch_sync_vdso_time_data(vdata);
 }
 
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+void vdso_time_update_aux(struct timekeeper *tk)
+{
+	struct vdso_time_data *vdata = vdso_k_time_data;
+	struct vdso_timestamp *vdso_ts;
+	struct vdso_clock *vc;
+	s32 clock_mode;
+	u64 nsec;
+
+	vc = &vdata->aux_clock_data[tk->id - TIMEKEEPER_AUX_FIRST];
+	vdso_ts = &vc->basetime[VDSO_BASE_AUX];
+	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
+	if (!tk->clock_valid)
+		clock_mode = VDSO_CLOCKMODE_NONE;
+
+	/* copy vsyscall data */
+	vdso_write_begin_clock(vc);
+
+	vc->clock_mode = clock_mode;
+
+	if (clock_mode != VDSO_CLOCKMODE_NONE) {
+		fill_clock_configuration(vc, &tk->tkr_mono);
+
+		vdso_ts->sec	= tk->xtime_sec;
+
+		nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
+		nsec += tk->offs_aux;
+		vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
+		nsec = nsec << tk->tkr_mono.shift;
+		vdso_ts->nsec = nsec;
+	}
+
+	__arch_update_vdso_clock(vc);
+
+	vdso_write_end_clock(vc);
+
+	__arch_sync_vdso_time_data(vdata);
+}
+#endif
+
 /**
  * vdso_update_begin - Start of a VDSO update section
  *
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 93ef801a97ef..02ea19f67164 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -2,6 +2,7 @@
 /*
  * Generic userspace implementations of gettimeofday() and similar.
  */
+#include <vdso/auxclock.h>
 #include <vdso/datapage.h>
 #include <vdso/helpers.h>
 
@@ -71,6 +72,42 @@ static inline bool vdso_cycles_ok(u64 cycles)
 }
 #endif
 
+static __always_inline bool vdso_clockid_valid(clockid_t clock)
+{
+	/* Check for negative values or invalid clocks */
+	return likely((u32) clock <= CLOCK_AUX_LAST);
+}
+
+/*
+ * Must not be invoked within the sequence read section as a race inside
+ * that loop could result in __iter_div_u64_rem() being extremely slow.
+ */
+static __always_inline void vdso_set_timespec(struct __kernel_timespec *ts, u64 sec, u64 ns)
+{
+	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+}
+
+static __always_inline
+bool vdso_get_timestamp(const struct vdso_time_data *vd, const struct vdso_clock *vc,
+			unsigned int clkidx, u64 *sec, u64 *ns)
+{
+	const struct vdso_timestamp *vdso_ts = &vc->basetime[clkidx];
+	u64 cycles;
+
+	if (unlikely(!vdso_clocksource_ok(vc)))
+		return false;
+
+	cycles = __arch_get_hw_counter(vc->clock_mode, vd);
+	if (unlikely(!vdso_cycles_ok(cycles)))
+		return false;
+
+	*ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);
+	*sec = vdso_ts->sec;
+
+	return true;
+}
+
 #ifdef CONFIG_TIME_NS
 
 #ifdef CONFIG_GENERIC_VDSO_DATA_STORE
@@ -82,48 +119,35 @@ const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_tim
 #endif /* CONFIG_GENERIC_VDSO_DATA_STORE */
 
 static __always_inline
-int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
-		   clockid_t clk, struct __kernel_timespec *ts)
+bool do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
+		    clockid_t clk, struct __kernel_timespec *ts)
 {
 	const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns);
 	const struct timens_offset *offs = &vcns->offset[clk];
 	const struct vdso_clock *vc = vd->clock_data;
-	const struct vdso_timestamp *vdso_ts;
-	u64 cycles, ns;
 	u32 seq;
 	s64 sec;
+	u64 ns;
 
 	if (clk != CLOCK_MONOTONIC_RAW)
 		vc = &vc[CS_HRES_COARSE];
 	else
 		vc = &vc[CS_RAW];
-	vdso_ts = &vc->basetime[clk];
 
 	do {
 		seq = vdso_read_begin(vc);
 
-		if (unlikely(!vdso_clocksource_ok(vc)))
-			return -1;
-
-		cycles = __arch_get_hw_counter(vc->clock_mode, vd);
-		if (unlikely(!vdso_cycles_ok(cycles)))
-			return -1;
-		ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);
-		sec = vdso_ts->sec;
+		if (!vdso_get_timestamp(vd, vc, clk, &sec, &ns))
+			return false;
 	} while (unlikely(vdso_read_retry(vc, seq)));
 
 	/* Add the namespace offset */
 	sec += offs->sec;
 	ns += offs->nsec;
 
-	/*
-	 * Do this outside the loop: a race inside the loop could result
-	 * in __iter_div_u64_rem() being extremely slow.
-	 */
-	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
-	ts->tv_nsec = ns;
+	vdso_set_timespec(ts, sec, ns);
 
-	return 0;
+	return true;
 }
 #else
 static __always_inline
@@ -133,24 +157,23 @@ const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_tim
 }
 
 static __always_inline
-int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
-		   clockid_t clk, struct __kernel_timespec *ts)
+bool do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
+		    clockid_t clk, struct __kernel_timespec *ts)
 {
-	return -EINVAL;
+	return false;
 }
 #endif
 
 static __always_inline
-int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc,
-	    clockid_t clk, struct __kernel_timespec *ts)
+bool 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 = &vc->basetime[clk];
-	u64 cycles, sec, ns;
+	u64 sec, ns;
 	u32 seq;
 
 	/* Allows to compile the high resolution parts out */
 	if (!__arch_vdso_hres_capable())
-		return -1;
+		return false;
 
 	do {
 		/*
@@ -172,30 +195,19 @@ int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc,
 		}
 		smp_rmb();
 
-		if (unlikely(!vdso_clocksource_ok(vc)))
-			return -1;
-
-		cycles = __arch_get_hw_counter(vc->clock_mode, vd);
-		if (unlikely(!vdso_cycles_ok(cycles)))
-			return -1;
-		ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);
-		sec = vdso_ts->sec;
+		if (!vdso_get_timestamp(vd, vc, clk, &sec, &ns))
+			return false;
 	} while (unlikely(vdso_read_retry(vc, seq)));
 
-	/*
-	 * Do this outside the loop: a race inside the loop could result
-	 * in __iter_div_u64_rem() being extremely slow.
-	 */
-	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
-	ts->tv_nsec = ns;
+	vdso_set_timespec(ts, sec, ns);
 
-	return 0;
+	return true;
 }
 
 #ifdef CONFIG_TIME_NS
 static __always_inline
-int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
-		     clockid_t clk, struct __kernel_timespec *ts)
+bool do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
+		      clockid_t clk, struct __kernel_timespec *ts)
 {
 	const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns);
 	const struct timens_offset *offs = &vcns->offset[clk];
@@ -217,26 +229,22 @@ int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock
 	sec += offs->sec;
 	nsec += offs->nsec;
 
-	/*
-	 * Do this outside the loop: a race inside the loop could result
-	 * in __iter_div_u64_rem() being extremely slow.
-	 */
-	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
-	ts->tv_nsec = nsec;
-	return 0;
+	vdso_set_timespec(ts, sec, nsec);
+
+	return true;
 }
 #else
 static __always_inline
-int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
-		     clockid_t clk, struct __kernel_timespec *ts)
+bool do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
+		      clockid_t clk, struct __kernel_timespec *ts)
 {
-	return -1;
+	return false;
 }
 #endif
 
 static __always_inline
-int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,
-	      clockid_t clk, struct __kernel_timespec *ts)
+bool 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 = &vc->basetime[clk];
 	u32 seq;
@@ -258,19 +266,60 @@ int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vc, seq)));
 
-	return 0;
+	return true;
+}
+
+static __always_inline
+bool do_aux(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_timespec *ts)
+{
+	const struct vdso_clock *vc;
+	u32 seq, idx;
+	u64 sec, ns;
+
+	if (!IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS))
+		return false;
+
+	idx = clock - CLOCK_AUX;
+	vc = &vd->aux_clock_data[idx];
+
+	do {
+		/*
+		 * Open coded function vdso_read_begin() to handle
+		 * VDSO_CLOCK_TIMENS. See comment in do_hres().
+		 */
+		while ((seq = READ_ONCE(vc->seq)) & 1) {
+			if (IS_ENABLED(CONFIG_TIME_NS) && vc->clock_mode == VDSO_CLOCKMODE_TIMENS) {
+				vd = __arch_get_vdso_u_timens_data(vd);
+				vc = &vd->aux_clock_data[idx];
+				/* Re-read from the real time data page */
+				continue;
+			}
+			cpu_relax();
+		}
+		smp_rmb();
+
+		/* Auxclock disabled? */
+		if (vc->clock_mode == VDSO_CLOCKMODE_NONE)
+			return false;
+
+		if (!vdso_get_timestamp(vd, vc, VDSO_BASE_AUX, &sec, &ns))
+			return false;
+	} while (unlikely(vdso_read_retry(vc, seq)));
+
+	vdso_set_timespec(ts, sec, ns);
+
+	return true;
 }
 
-static __always_inline int
+static __always_inline bool
 __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
 			     struct __kernel_timespec *ts)
 {
 	const struct vdso_clock *vc = vd->clock_data;
 	u32 msk;
 
-	/* Check for negative values or invalid clocks */
-	if (unlikely((u32) clock >= MAX_CLOCKS))
-		return -1;
+	if (!vdso_clockid_valid(clock))
+		return false;
 
 	/*
 	 * Convert the clockid to a bitmask and use it to check which
@@ -283,8 +332,10 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
 		return do_coarse(vd, &vc[CS_HRES_COARSE], clock, ts);
 	else if (msk & VDSO_RAW)
 		vc = &vc[CS_RAW];
+	else if (msk & VDSO_AUX)
+		return do_aux(vd, clock, ts);
 	else
-		return -1;
+		return false;
 
 	return do_hres(vd, vc, clock, ts);
 }
@@ -293,9 +344,11 @@ static __maybe_unused int
 __cvdso_clock_gettime_data(const struct vdso_time_data *vd, clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime_common(vd, clock, ts);
+	bool ok;
+
+	ok = __cvdso_clock_gettime_common(vd, clock, ts);
 
-	if (unlikely(ret))
+	if (unlikely(!ok))
 		return clock_gettime_fallback(clock, ts);
 	return 0;
 }
@@ -312,18 +365,18 @@ __cvdso_clock_gettime32_data(const struct vdso_time_data *vd, clockid_t clock,
 			     struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
-	int ret;
+	bool ok;
 
-	ret = __cvdso_clock_gettime_common(vd, clock, &ts);
+	ok = __cvdso_clock_gettime_common(vd, clock, &ts);
 
-	if (unlikely(ret))
+	if (unlikely(!ok))
 		return clock_gettime32_fallback(clock, res);
 
-	/* For ret == 0 */
+	/* For ok == true */
 	res->tv_sec = ts.tv_sec;
 	res->tv_nsec = ts.tv_nsec;
 
-	return ret;
+	return 0;
 }
 
 static __maybe_unused int
@@ -342,7 +395,7 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
 
-		if (do_hres(vd, &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;
@@ -396,16 +449,15 @@ static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time
 
 #ifdef VDSO_HAS_CLOCK_GETRES
 static __maybe_unused
-int __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock,
-				struct __kernel_timespec *res)
+bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock,
+				 struct __kernel_timespec *res)
 {
 	const struct vdso_clock *vc = vd->clock_data;
 	u32 msk;
 	u64 ns;
 
-	/* Check for negative values or invalid clocks */
-	if (unlikely((u32) clock >= MAX_CLOCKS))
-		return -1;
+	if (!vdso_clockid_valid(clock))
+		return false;
 
 	if (IS_ENABLED(CONFIG_TIME_NS) &&
 	    vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
@@ -426,24 +478,28 @@ int __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock
 		 * Preserves the behaviour of posix_get_coarse_res().
 		 */
 		ns = LOW_RES_NSEC;
+	} else if (msk & VDSO_AUX) {
+		ns = aux_clock_resolution_ns();
 	} else {
-		return -1;
+		return false;
 	}
 
 	if (likely(res)) {
 		res->tv_sec = 0;
 		res->tv_nsec = ns;
 	}
-	return 0;
+	return true;
 }
 
 static __maybe_unused
 int __cvdso_clock_getres_data(const struct vdso_time_data *vd, clockid_t clock,
 			      struct __kernel_timespec *res)
 {
-	int ret = __cvdso_clock_getres_common(vd, clock, res);
+	bool ok;
 
-	if (unlikely(ret))
+	ok =  __cvdso_clock_getres_common(vd, clock, res);
+
+	if (unlikely(!ok))
 		return clock_getres_fallback(clock, res);
 	return 0;
 }
@@ -460,18 +516,18 @@ __cvdso_clock_getres_time32_data(const struct vdso_time_data *vd, clockid_t cloc
 				 struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
-	int ret;
+	bool ok;
 
-	ret = __cvdso_clock_getres_common(vd, clock, &ts);
+	ok = __cvdso_clock_getres_common(vd, clock, &ts);
 
-	if (unlikely(ret))
+	if (unlikely(!ok))
 		return clock_getres32_fallback(clock, res);
 
 	if (likely(res)) {
 		res->tv_sec = ts.tv_sec;
 		res->tv_nsec = ts.tv_nsec;
 	}
-	return ret;
+	return 0;
 }
 
 static __maybe_unused int