// 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 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;

        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];
        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         = &vc[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         = &vc[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
        vdso_ts->sec    = tk->raw_sec;
        vdso_ts->nsec   = tk->tkr_raw.xtime_nsec;

        /* CLOCK_TAI */
        vdso_ts         = &vc[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_time_data *vdata = vdso_k_time_data;
        struct vdso_clock *vc = vdata->clock_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;
        vc[CS_HRES_COARSE].clock_mode   = clock_mode;
        vc[CS_RAW].clock_mode           = clock_mode;

        /* CLOCK_REALTIME also required for time() */
        vdso_ts         = &vc[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         = &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
        vdso_ts->sec    = tk->xtime_sec;
        vdso_ts->nsec   = tk->coarse_nsec;

        /* CLOCK_MONOTONIC_COARSE */
        vdso_ts         = &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
        vdso_ts->sec    = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
        nsec            = tk->coarse_nsec;
        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().
         */
        WRITE_ONCE(vdata->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_time_data(vdata, tk);

        __arch_update_vdso_clock(&vc[CS_HRES_COARSE]);
        __arch_update_vdso_clock(&vc[CS_RAW]);

        vdso_write_end(vdata);

        __arch_sync_vdso_time_data(vdata);
}

void update_vsyscall_tz(void)
{
        struct vdso_time_data *vdata = vdso_k_time_data;

        vdata->tz_minuteswest = sys_tz.tz_minuteswest;
        vdata->tz_dsttime = sys_tz.tz_dsttime;

        __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 + tk->monotonic_to_aux.tv_sec;

                nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
                nsec += tk->monotonic_to_aux.tv_nsec;
                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
 *
 * 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_time_data *vdata = vdso_k_time_data;
        unsigned long flags = timekeeper_lock_irqsave();

        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_time_data *vdata = vdso_k_time_data;

        vdso_write_end(vdata);
        __arch_sync_vdso_time_data(vdata);
        timekeeper_unlock_irqrestore(flags);
}