1 files changed, 441 insertions, 0 deletions
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
new file mode 100644
index 000000000000..ce2f69552003
--- /dev/null
+++ b/lib/vdso/gettimeofday.c
@@ -0,0 +1,441 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic userspace implementations of gettimeofday() and similar.
+ */
+#include <vdso/datapage.h>
+#include <vdso/helpers.h>
+
+#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
+
+#ifndef vdso_shift_ns
+static __always_inline u64 vdso_shift_ns(u64 ns, u32 shift)
+{
+	return ns >> shift;
+}
+#endif
+
+#ifndef __arch_vdso_hres_capable
+static inline bool __arch_vdso_hres_capable(void)
+{
+	return true;
+}
+#endif
+
+#ifndef vdso_clocksource_ok
+static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
+{
+	return vd->clock_mode != VDSO_CLOCKMODE_NONE;
+}
+#endif
+
+#ifndef vdso_cycles_ok
+static inline bool vdso_cycles_ok(u64 cycles)
+{
+	return true;
+}
+#endif
+
+#ifdef CONFIG_TIME_NS
+static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
+					  struct __kernel_timespec *ts)
+{
+	const struct vdso_data *vd;
+	const struct timens_offset *offs = &vdns->offset[clk];
+	const struct vdso_timestamp *vdso_ts;
+	u64 cycles, last, ns;
+	u32 seq;
+	s64 sec;
+
+	vd = vdns - (clk == CLOCK_MONOTONIC_RAW ? CS_RAW : CS_HRES_COARSE);
+	vd = __arch_get_timens_vdso_data(vd);
+	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);
+
+		if (unlikely(!vdso_clocksource_ok(vd)))
+			return -1;
+
+		cycles = __arch_get_hw_counter(vd->clock_mode, vd);
+		if (unlikely(!vdso_cycles_ok(cycles)))
+			return -1;
+		ns = vdso_ts->nsec;
+		last = vd->cycle_last;
+		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
+		ns = vdso_shift_ns(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(const struct vdso_data *vd)
+{
+	return NULL;
+}
+
+static __always_inline 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;
+
+	/* Allows to compile the high resolution parts out */
+	if (!__arch_vdso_hres_capable())
+		return -1;
+
+	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
+		 * even again.
+		 */
+		while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
+			if (IS_ENABLED(CONFIG_TIME_NS) &&
+			    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+				return do_hres_timens(vd, clk, ts);
+			cpu_relax();
+		}
+		smp_rmb();
+
+		if (unlikely(!vdso_clocksource_ok(vd)))
+			return -1;
+
+		cycles = __arch_get_hw_counter(vd->clock_mode, vd);
+		if (unlikely(!vdso_cycles_ok(cycles)))
+			return -1;
+		ns = vdso_ts->nsec;
+		last = vd->cycle_last;
+		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
+		ns = vdso_shift_ns(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 __always_inline 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(vdns);
+	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 __always_inline 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 VDSO_CLOCK_TIMENS. See comment in
+		 * do_hres().
+		 */
+		while ((seq = READ_ONCE(vd->seq)) & 1) {
+			if (IS_ENABLED(CONFIG_TIME_NS) &&
+			    vd->clock_mode == VDSO_CLOCKMODE_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 __always_inline int
+__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
+			     struct __kernel_timespec *ts)
+{
+	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_data(const struct vdso_data *vd, clockid_t clock,
+			   struct __kernel_timespec *ts)
+{
+	int ret = __cvdso_clock_gettime_common(vd, clock, ts);
+
+	if (unlikely(ret))
+		return clock_gettime_fallback(clock, ts);
+	return 0;
+}
+
+static __maybe_unused int
+__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+{
+	return __cvdso_clock_gettime_data(__arch_get_vdso_data(), clock, ts);
+}
+
+#ifdef BUILD_VDSO32
+static __maybe_unused int
+__cvdso_clock_gettime32_data(const struct vdso_data *vd, clockid_t clock,
+			     struct old_timespec32 *res)
+{
+	struct __kernel_timespec ts;
+	int ret;
+
+	ret = __cvdso_clock_gettime_common(vd, 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;
+}
+
+static __maybe_unused int
+__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
+{
+	return __cvdso_clock_gettime32_data(__arch_get_vdso_data(), clock, res);
+}
+#endif /* BUILD_VDSO32 */
+
+static __maybe_unused int
+__cvdso_gettimeofday_data(const struct vdso_data *vd,
+			  struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+
+	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 == VDSO_CLOCKMODE_TIMENS)
+			vd = __arch_get_timens_vdso_data(vd);
+
+		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
+		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
+	}
+
+	return 0;
+}
+
+static __maybe_unused int
+__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+	return __cvdso_gettimeofday_data(__arch_get_vdso_data(), tv, tz);
+}
+
+#ifdef VDSO_HAS_TIME
+static __maybe_unused __kernel_old_time_t
+__cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
+{
+	__kernel_old_time_t t;
+
+	if (IS_ENABLED(CONFIG_TIME_NS) &&
+	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		vd = __arch_get_timens_vdso_data(vd);
+
+	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
+
+	if (time)
+		*time = t;
+
+	return t;
+}
+
+static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
+{
+	return __cvdso_time_data(__arch_get_vdso_data(), time);
+}
+#endif /* VDSO_HAS_TIME */
+
+#ifdef VDSO_HAS_CLOCK_GETRES
+static __maybe_unused
+int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
+				struct __kernel_timespec *res)
+{
+	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 == VDSO_CLOCKMODE_TIMENS)
+		vd = __arch_get_timens_vdso_data(vd);
+
+	/*
+	 * 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_data(const struct vdso_data *vd, clockid_t clock,
+			      struct __kernel_timespec *res)
+{
+	int ret = __cvdso_clock_getres_common(vd, clock, res);
+
+	if (unlikely(ret))
+		return clock_getres_fallback(clock, res);
+	return 0;
+}
+
+static __maybe_unused
+int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
+{
+	return __cvdso_clock_getres_data(__arch_get_vdso_data(), clock, res);
+}
+
+#ifdef BUILD_VDSO32
+static __maybe_unused int
+__cvdso_clock_getres_time32_data(const struct vdso_data *vd, clockid_t clock,
+				 struct old_timespec32 *res)
+{
+	struct __kernel_timespec ts;
+	int ret;
+
+	ret = __cvdso_clock_getres_common(vd, 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;
+}
+
+static __maybe_unused int
+__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
+{
+	return __cvdso_clock_getres_time32_data(__arch_get_vdso_data(),
+						clock, res);
+}
+#endif /* BUILD_VDSO32 */
+#endif /* VDSO_HAS_CLOCK_GETRES */