lib/vdso/gettimeofday.c - linux/kernel/git/bpf/bpf - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Generic userspace implementations of gettimeofday() and similar.
  */
 #include <linux/compiler.h>
 #include <linux/math64.h>
 #include <linux/time.h>
 #include <linux/kernel.h>
 #include <linux/hrtimer_defs.h>
 #include <vdso/datapage.h>
 #include <vdso/helpers.h>

 /*
  * The generic vDSO implementation requires that gettimeofday.h
  * provides:
  * - __arch_get_vdso_data(): to get the vdso datapage.
  * - __arch_get_hw_counter(): to get the hw counter based on the
  *   clock_mode.
  * - gettimeofday_fallback(): fallback for gettimeofday.
  * - clock_gettime_fallback(): fallback for clock_gettime.
  * - clock_getres_fallback(): fallback for clock_getres.
  */
 #ifdef ENABLE_COMPAT_VDSO
 #include <asm/vdso/compat_gettimeofday.h>
 #else
 #include <asm/vdso/gettimeofday.h>
 #endif /* ENABLE_COMPAT_VDSO */

 #ifndef vdso_calc_delta
 /*
  * Default implementation which works for all sane clocksources. That
  * obviously excludes x86/TSC.
  */
 static __always_inline
 u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 {
 	return ((cycles - last) & mask) * mult;
 }
 #endif

 #ifdef CONFIG_TIME_NS
 static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
 			  struct __kernel_timespec *ts)
 {
 	const struct vdso_data *vd = __arch_get_timens_vdso_data();
 	const struct timens_offset *offs = &vdns->offset[clk];
 	const struct vdso_timestamp *vdso_ts;
 	u64 cycles, last, ns;
 	u32 seq;
 	s64 sec;

 	if (clk != CLOCK_MONOTONIC_RAW)
 		vd = &vd[CS_HRES_COARSE];
 	else
 		vd = &vd[CS_RAW];
 	vdso_ts = &vd->basetime[clk];

 	do {
 		seq = vdso_read_begin(vd);
 		cycles = __arch_get_hw_counter(vd->clock_mode);
 		ns = vdso_ts->nsec;
 		last = vd->cycle_last;
 		if (unlikely((s64)cycles < 0))
 			return -1;

 		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
 		ns >>= vd->shift;
 		sec = vdso_ts->sec;
 	} while (unlikely(vdso_read_retry(vd, 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;

 	return 0;
 }
 #else
 static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
 {
 	return NULL;
 }

 static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
 			  struct __kernel_timespec *ts)
 {
 	return -EINVAL;
 }
 #endif

 static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 				   struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	u64 cycles, last, sec, ns;
 	u32 seq;

 	do {
 		/*
 		 * Open coded to handle VCLOCK_TIMENS. Time namespace
 		 * enabled tasks have a special VVAR page installed which
 		 * has vd->seq set to 1 and vd->clock_mode set to
 		 * VCLOCK_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)) {
 			if (IS_ENABLED(CONFIG_TIME_NS) &&
 			    vd->clock_mode == VCLOCK_TIMENS)
 				return do_hres_timens(vd, clk, ts);
 			cpu_relax();
 		}
 		smp_rmb();

 		cycles = __arch_get_hw_counter(vd->clock_mode);
 		ns = vdso_ts->nsec;
 		last = vd->cycle_last;
 		if (unlikely((s64)cycles < 0))
 			return -1;

 		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
 		ns >>= vd->shift;
 		sec = vdso_ts->sec;
 	} while (unlikely(vdso_read_retry(vd, 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;

 	return 0;
 }

 #ifdef CONFIG_TIME_NS
 static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
 			    struct __kernel_timespec *ts)
 {
 	const struct vdso_data *vd = __arch_get_timens_vdso_data();
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	const struct timens_offset *offs = &vdns->offset[clk];
 	u64 nsec;
 	s64 sec;
 	s32 seq;

 	do {
 		seq = vdso_read_begin(vd);
 		sec = vdso_ts->sec;
 		nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));

 	/* Add the namespace offset */
 	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;
 }
 #else
 static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
 			    struct __kernel_timespec *ts)
 {
 	return -1;
 }
 #endif

 static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
 				     struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	u32 seq;

 	do {
 		/*
 		 * Open coded to handle VCLOCK_TIMENS. See comment in
 		 * do_hres().
 		 */
 		while ((seq = READ_ONCE(vd->seq)) & 1) {
 			if (IS_ENABLED(CONFIG_TIME_NS) &&
 			    vd->clock_mode == VCLOCK_TIMENS)
 				return do_coarse_timens(vd, clk, ts);
 			cpu_relax();
 		}
 		smp_rmb();

 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));

 	return 0;
 }

 static __maybe_unused int
 __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
 	u32 msk;

 	/* Check for negative values or invalid clocks */
 	if (unlikely((u32) clock >= MAX_CLOCKS))
 		return -1;

 	/*
 	 * Convert the clockid to a bitmask and use it to check which
 	 * clocks are handled in the VDSO directly.
 	 */
 	msk = 1U << clock;
 	if (likely(msk & VDSO_HRES))
 		vd = &vd[CS_HRES_COARSE];
 	else if (msk & VDSO_COARSE)
 		return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
 	else if (msk & VDSO_RAW)
 		vd = &vd[CS_RAW];
 	else
 		return -1;

 	return do_hres(vd, clock, ts);
 }

 static __maybe_unused int
 __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
 {
 	int ret = __cvdso_clock_gettime_common(clock, ts);

 	if (unlikely(ret))
 		return clock_gettime_fallback(clock, ts);
 	return 0;
 }

 #ifdef BUILD_VDSO32
 static __maybe_unused int
 __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
 	int ret;

 	ret = __cvdso_clock_gettime_common(clock, &ts);

 	if (unlikely(ret))
 		return clock_gettime32_fallback(clock, res);

 	/* For ret == 0 */
 	res->tv_sec = ts.tv_sec;
 	res->tv_nsec = ts.tv_nsec;

 	return ret;
 }
 #endif /* BUILD_VDSO32 */

 static __maybe_unused int
 __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();

 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;

 		if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
 			return gettimeofday_fallback(tv, tz);

 		tv->tv_sec = ts.tv_sec;
 		tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
 	}

 	if (unlikely(tz != NULL)) {
 		if (IS_ENABLED(CONFIG_TIME_NS) &&
 		    vd->clock_mode == VCLOCK_TIMENS)
 			vd = __arch_get_timens_vdso_data();

 		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
 		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
 	}

 	return 0;
 }

 #ifdef VDSO_HAS_TIME
 static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
 	__kernel_old_time_t t;

 	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
 		vd = __arch_get_timens_vdso_data();

 	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);

 	if (time)
 		*time = t;

 	return t;
 }
 #endif /* VDSO_HAS_TIME */

 #ifdef VDSO_HAS_CLOCK_GETRES
 static __maybe_unused
 int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
 	u32 msk;
 	u64 ns;

 	/* Check for negative values or invalid clocks */
 	if (unlikely((u32) clock >= MAX_CLOCKS))
 		return -1;

 	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
 		vd = __arch_get_timens_vdso_data();

 	/*
 	 * Convert the clockid to a bitmask and use it to check which
 	 * clocks are handled in the VDSO directly.
 	 */
 	msk = 1U << clock;
 	if (msk & (VDSO_HRES | VDSO_RAW)) {
 		/*
 		 * Preserves the behaviour of posix_get_hrtimer_res().
 		 */
 		ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
 	} else if (msk & VDSO_COARSE) {
 		/*
 		 * Preserves the behaviour of posix_get_coarse_res().
 		 */
 		ns = LOW_RES_NSEC;
 	} else {
 		return -1;
 	}

 	if (likely(res)) {
 		res->tv_sec = 0;
 		res->tv_nsec = ns;
 	}
 	return 0;
 }

 static __maybe_unused
 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 {
 	int ret = __cvdso_clock_getres_common(clock, res);

 	if (unlikely(ret))
 		return clock_getres_fallback(clock, res);
 	return 0;
 }

 #ifdef BUILD_VDSO32
 static __maybe_unused int
 __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
 	int ret;

 	ret = __cvdso_clock_getres_common(clock, &ts);

 	if (unlikely(ret))
 		return clock_getres32_fallback(clock, res);

 	if (likely(res)) {
 		res->tv_sec = ts.tv_sec;
 		res->tv_nsec = ts.tv_nsec;
 	}
 	return ret;
 }
 #endif /* BUILD_VDSO32 */
 #endif /* VDSO_HAS_CLOCK_GETRES */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Generic userspace implementations of gettimeofday() and similar.
	*/
	#include <linux/compiler.h>
	#include <linux/math64.h>
	#include <linux/time.h>
	#include <linux/kernel.h>
	#include <linux/hrtimer_defs.h>
	#include <vdso/datapage.h>
	#include <vdso/helpers.h>

	/*
	* The generic vDSO implementation requires that gettimeofday.h
	* provides:
	* - __arch_get_vdso_data(): to get the vdso datapage.
	* - __arch_get_hw_counter(): to get the hw counter based on the
	* clock_mode.
	* - gettimeofday_fallback(): fallback for gettimeofday.
	* - clock_gettime_fallback(): fallback for clock_gettime.
	* - clock_getres_fallback(): fallback for clock_getres.
	*/
	#ifdef ENABLE_COMPAT_VDSO
	#include <asm/vdso/compat_gettimeofday.h>
	#else
	#include <asm/vdso/gettimeofday.h>
	#endif /* ENABLE_COMPAT_VDSO */

	#ifndef vdso_calc_delta
	/*
	* Default implementation which works for all sane clocksources. That
	* obviously excludes x86/TSC.
	*/
	static __always_inline
	u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
	{
	return ((cycles - last) & mask) * mult;
	}
	#endif

	#ifdef CONFIG_TIME_NS
	static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	const struct vdso_data *vd = __arch_get_timens_vdso_data();
	const struct timens_offset *offs = &vdns->offset[clk];
	const struct vdso_timestamp *vdso_ts;
	u64 cycles, last, ns;
	u32 seq;
	s64 sec;

	if (clk != CLOCK_MONOTONIC_RAW)
	vd = &vd[CS_HRES_COARSE];
	else
	vd = &vd[CS_RAW];
	vdso_ts = &vd->basetime[clk];

	do {
	seq = vdso_read_begin(vd);
	cycles = __arch_get_hw_counter(vd->clock_mode);
	ns = vdso_ts->nsec;
	last = vd->cycle_last;
	if (unlikely((s64)cycles < 0))
	return -1;

	ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
	ns >>= vd->shift;
	sec = vdso_ts->sec;
	} while (unlikely(vdso_read_retry(vd, 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;

	return 0;
	}
	#else
	static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
	{
	return NULL;
	}

	static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	return -EINVAL;
	}
	#endif

	static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	u64 cycles, last, sec, ns;
	u32 seq;

	do {
	/*
	* Open coded to handle VCLOCK_TIMENS. Time namespace
	* enabled tasks have a special VVAR page installed which
	* has vd->seq set to 1 and vd->clock_mode set to
	* VCLOCK_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)) {
	if (IS_ENABLED(CONFIG_TIME_NS) &&
	vd->clock_mode == VCLOCK_TIMENS)
	return do_hres_timens(vd, clk, ts);
	cpu_relax();
	}
	smp_rmb();

	cycles = __arch_get_hw_counter(vd->clock_mode);
	ns = vdso_ts->nsec;
	last = vd->cycle_last;
	if (unlikely((s64)cycles < 0))
	return -1;

	ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
	ns >>= vd->shift;
	sec = vdso_ts->sec;
	} while (unlikely(vdso_read_retry(vd, 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;

	return 0;
	}

	#ifdef CONFIG_TIME_NS
	static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	const struct vdso_data *vd = __arch_get_timens_vdso_data();
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	const struct timens_offset *offs = &vdns->offset[clk];
	u64 nsec;
	s64 sec;
	s32 seq;

	do {
	seq = vdso_read_begin(vd);
	sec = vdso_ts->sec;
	nsec = vdso_ts->nsec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	/* Add the namespace offset */
	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;
	}
	#else
	static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	return -1;
	}
	#endif

	static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
	struct __kernel_timespec *ts)
	{
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	u32 seq;

	do {
	/*
	* Open coded to handle VCLOCK_TIMENS. See comment in
	* do_hres().
	*/
	while ((seq = READ_ONCE(vd->seq)) & 1) {
	if (IS_ENABLED(CONFIG_TIME_NS) &&
	vd->clock_mode == VCLOCK_TIMENS)
	return do_coarse_timens(vd, clk, ts);
	cpu_relax();
	}
	smp_rmb();

	ts->tv_sec = vdso_ts->sec;
	ts->tv_nsec = vdso_ts->nsec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	return 0;
	}

	static __maybe_unused int
	__cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
	{
	const struct vdso_data *vd = __arch_get_vdso_data();
	u32 msk;

	/* Check for negative values or invalid clocks */
	if (unlikely((u32) clock >= MAX_CLOCKS))
	return -1;

	/*
	* Convert the clockid to a bitmask and use it to check which
	* clocks are handled in the VDSO directly.
	*/
	msk = 1U << clock;
	if (likely(msk & VDSO_HRES))
	vd = &vd[CS_HRES_COARSE];
	else if (msk & VDSO_COARSE)
	return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
	else if (msk & VDSO_RAW)
	vd = &vd[CS_RAW];
	else
	return -1;

	return do_hres(vd, clock, ts);
	}

	static __maybe_unused int
	__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
	{
	int ret = __cvdso_clock_gettime_common(clock, ts);

	if (unlikely(ret))
	return clock_gettime_fallback(clock, ts);
	return 0;
	}

	#ifdef BUILD_VDSO32
	static __maybe_unused int
	__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
	{
	struct __kernel_timespec ts;
	int ret;

	ret = __cvdso_clock_gettime_common(clock, &ts);

	if (unlikely(ret))
	return clock_gettime32_fallback(clock, res);

	/* For ret == 0 */
	res->tv_sec = ts.tv_sec;
	res->tv_nsec = ts.tv_nsec;

	return ret;
	}
	#endif /* BUILD_VDSO32 */

	static __maybe_unused int
	__cvdso_gettimeofday(struct __kernel_old_timeval tv, struct timezone tz)
	{
	const struct vdso_data *vd = __arch_get_vdso_data();

	if (likely(tv != NULL)) {
	struct __kernel_timespec ts;

	if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
	return gettimeofday_fallback(tv, tz);

	tv->tv_sec = ts.tv_sec;
	tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
	}

	if (unlikely(tz != NULL)) {
	if (IS_ENABLED(CONFIG_TIME_NS) &&
	vd->clock_mode == VCLOCK_TIMENS)
	vd = __arch_get_timens_vdso_data();

	tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
	tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
	}

	return 0;
	}

	#ifdef VDSO_HAS_TIME
	static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
	{
	const struct vdso_data *vd = __arch_get_vdso_data();
	__kernel_old_time_t t;

	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
	vd = __arch_get_timens_vdso_data();

	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);

	if (time)
	*time = t;

	return t;
	}
	#endif /* VDSO_HAS_TIME */

	#ifdef VDSO_HAS_CLOCK_GETRES
	static __maybe_unused
	int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
	{
	const struct vdso_data *vd = __arch_get_vdso_data();
	u32 msk;
	u64 ns;

	/* Check for negative values or invalid clocks */
	if (unlikely((u32) clock >= MAX_CLOCKS))
	return -1;

	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
	vd = __arch_get_timens_vdso_data();

	/*
	* Convert the clockid to a bitmask and use it to check which
	* clocks are handled in the VDSO directly.
	*/
	msk = 1U << clock;
	if (msk & (VDSO_HRES \| VDSO_RAW)) {
	/*
	* Preserves the behaviour of posix_get_hrtimer_res().
	*/
	ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
	} else if (msk & VDSO_COARSE) {
	/*
	* Preserves the behaviour of posix_get_coarse_res().
	*/
	ns = LOW_RES_NSEC;
	} else {
	return -1;
	}

	if (likely(res)) {
	res->tv_sec = 0;
	res->tv_nsec = ns;
	}
	return 0;
	}

	static __maybe_unused
	int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
	{
	int ret = __cvdso_clock_getres_common(clock, res);

	if (unlikely(ret))
	return clock_getres_fallback(clock, res);
	return 0;
	}

	#ifdef BUILD_VDSO32
	static __maybe_unused int
	__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
	{
	struct __kernel_timespec ts;
	int ret;

	ret = __cvdso_clock_getres_common(clock, &ts);

	if (unlikely(ret))
	return clock_getres32_fallback(clock, res);

	if (likely(res)) {
	res->tv_sec = ts.tv_sec;
	res->tv_nsec = ts.tv_nsec;
	}
	return ret;
	}
	#endif /* BUILD_VDSO32 */
	#endif /* VDSO_HAS_CLOCK_GETRES */