1 files changed, 170 insertions, 0 deletions
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
new file mode 100644
index 000000000..f0d5062d9
--- /dev/null
+++ b/kernel/time/vsyscall.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 ARM Ltd.
+ *
+ * Generic implementation of update_vsyscall and update_vsyscall_tz.
+ *
+ * Based on the x86 specific implementation.
+ */
+
+#include <linux/hrtimer.h>
+#include <linux/timekeeper_internal.h>
+#include <vdso/datapage.h>
+#include <vdso/helpers.h>
+#include <vdso/vsyscall.h>
+
+#include "timekeeping_internal.h"
+
+static inline void update_vdso_data(struct vdso_data *vdata,
+				    struct timekeeper *tk)
+{
+	struct vdso_timestamp *vdso_ts;
+	u64 nsec, sec;
+
+	vdata[CS_HRES_COARSE].cycle_last	= tk->tkr_mono.cycle_last;
+	vdata[CS_HRES_COARSE].mask		= tk->tkr_mono.mask;
+	vdata[CS_HRES_COARSE].mult		= tk->tkr_mono.mult;
+	vdata[CS_HRES_COARSE].shift		= tk->tkr_mono.shift;
+	vdata[CS_RAW].cycle_last		= tk->tkr_raw.cycle_last;
+	vdata[CS_RAW].mask			= tk->tkr_raw.mask;
+	vdata[CS_RAW].mult			= tk->tkr_raw.mult;
+	vdata[CS_RAW].shift			= tk->tkr_raw.shift;
+
+	/* CLOCK_MONOTONIC */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
+	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
+
+	nsec = tk->tkr_mono.xtime_nsec;
+	nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
+	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
+		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
+		vdso_ts->sec++;
+	}
+	vdso_ts->nsec	= nsec;
+
+	/* Copy MONOTONIC time for BOOTTIME */
+	sec	= vdso_ts->sec;
+	/* Add the boot offset */
+	sec	+= tk->monotonic_to_boot.tv_sec;
+	nsec	+= (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;
+
+	/* CLOCK_BOOTTIME */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
+	vdso_ts->sec	= sec;
+
+	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
+		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
+		vdso_ts->sec++;
+	}
+	vdso_ts->nsec	= nsec;
+
+	/* CLOCK_MONOTONIC_RAW */
+	vdso_ts		= &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
+	vdso_ts->sec	= tk->raw_sec;
+	vdso_ts->nsec	= tk->tkr_raw.xtime_nsec;
+
+	/* CLOCK_TAI */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
+	vdso_ts->sec	= tk->xtime_sec + (s64)tk->tai_offset;
+	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;
+}
+
+void update_vsyscall(struct timekeeper *tk)
+{
+	struct vdso_data *vdata = __arch_get_k_vdso_data();
+	struct vdso_timestamp *vdso_ts;
+	s32 clock_mode;
+	u64 nsec;
+
+	/* copy vsyscall data */
+	vdso_write_begin(vdata);
+
+	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
+	vdata[CS_HRES_COARSE].clock_mode	= clock_mode;
+	vdata[CS_RAW].clock_mode		= clock_mode;
+
+	/* CLOCK_REALTIME also required for time() */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
+	vdso_ts->sec	= tk->xtime_sec;
+	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;
+
+	/* CLOCK_REALTIME_COARSE */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
+	vdso_ts->sec	= tk->xtime_sec;
+	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
+
+	/* CLOCK_MONOTONIC_COARSE */
+	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
+	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
+	nsec		= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
+	nsec		= nsec + tk->wall_to_monotonic.tv_nsec;
+	vdso_ts->sec	+= __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
+
+	/*
+	 * Read without the seqlock held by clock_getres().
+	 * Note: No need to have a second copy.
+	 */
+	WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
+
+	/*
+	 * If the current clocksource is not VDSO capable, then spare the
+	 * update of the high resolution parts.
+	 */
+	if (clock_mode != VDSO_CLOCKMODE_NONE)
+		update_vdso_data(vdata, tk);
+
+	__arch_update_vsyscall(vdata, tk);
+
+	vdso_write_end(vdata);
+
+	__arch_sync_vdso_data(vdata);
+}
+
+void update_vsyscall_tz(void)
+{
+	struct vdso_data *vdata = __arch_get_k_vdso_data();
+
+	vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
+	vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
+
+	__arch_sync_vdso_data(vdata);
+}
+
+/**
+ * vdso_update_begin - Start of a VDSO update section
+ *
+ * Allows architecture code to safely update the architecture specific VDSO
+ * data. Disables interrupts, acquires timekeeper lock to serialize against
+ * concurrent updates from timekeeping and invalidates the VDSO data
+ * sequence counter to prevent concurrent readers from accessing
+ * inconsistent data.
+ *
+ * Returns: Saved interrupt flags which need to be handed in to
+ * vdso_update_end().
+ */
+unsigned long vdso_update_begin(void)
+{
+	struct vdso_data *vdata = __arch_get_k_vdso_data();
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&timekeeper_lock, flags);
+	vdso_write_begin(vdata);
+	return flags;
+}
+
+/**
+ * vdso_update_end - End of a VDSO update section
+ * @flags:	Interrupt flags as returned from vdso_update_begin()
+ *
+ * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
+ * synchronization if the architecture requires it, drops timekeeper lock
+ * and restores interrupt flags.
+ */
+void vdso_update_end(unsigned long flags)
+{
+	struct vdso_data *vdata = __arch_get_k_vdso_data();
+
+	vdso_write_end(vdata);
+	__arch_sync_vdso_data(vdata);
+	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+}