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9f24c540f7
The low resolution parts of the VDSO, i.e.:
clock_gettime(CLOCK_*_COARSE), clock_getres(), time()
can be used even if there is no VDSO capable clocksource.
But if an architecture opts out of the VDSO data update then this
information becomes stale. This affects ARM when there is no architected
timer available. The lack of update causes userspace to use stale data
forever.
Make the update of the low resolution parts unconditional and only skip
the update of the high resolution parts if the architecture requests it.
Fixes: 44f57d788e ("timekeeping: Provide a generic update_vsyscall() implementation")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200114185946.765577901@linutronix.de
128 lines
3.7 KiB
C
128 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright 2019 ARM Ltd.
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*
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* Generic implementation of update_vsyscall and update_vsyscall_tz.
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*
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* Based on the x86 specific implementation.
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*/
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#include <linux/hrtimer.h>
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#include <linux/timekeeper_internal.h>
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#include <vdso/datapage.h>
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#include <vdso/helpers.h>
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#include <vdso/vsyscall.h>
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static inline void update_vdso_data(struct vdso_data *vdata,
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struct timekeeper *tk)
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{
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struct vdso_timestamp *vdso_ts;
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u64 nsec, sec;
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vdata[CS_HRES_COARSE].cycle_last = tk->tkr_mono.cycle_last;
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vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask;
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vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult;
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vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift;
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vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last;
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vdata[CS_RAW].mask = tk->tkr_raw.mask;
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vdata[CS_RAW].mult = tk->tkr_raw.mult;
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vdata[CS_RAW].shift = tk->tkr_raw.shift;
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/* CLOCK_MONOTONIC */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
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vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
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nsec = tk->tkr_mono.xtime_nsec;
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nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
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while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
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nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
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vdso_ts->sec++;
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}
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vdso_ts->nsec = nsec;
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/* Copy MONOTONIC time for BOOTTIME */
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sec = vdso_ts->sec;
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/* Add the boot offset */
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sec += tk->monotonic_to_boot.tv_sec;
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nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;
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/* CLOCK_BOOTTIME */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
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vdso_ts->sec = sec;
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while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
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nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
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vdso_ts->sec++;
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}
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vdso_ts->nsec = nsec;
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/* CLOCK_MONOTONIC_RAW */
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vdso_ts = &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
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vdso_ts->sec = tk->raw_sec;
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vdso_ts->nsec = tk->tkr_raw.xtime_nsec;
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/* CLOCK_TAI */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
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vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset;
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vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
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}
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void update_vsyscall(struct timekeeper *tk)
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{
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struct vdso_data *vdata = __arch_get_k_vdso_data();
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struct vdso_timestamp *vdso_ts;
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u64 nsec;
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/* copy vsyscall data */
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vdso_write_begin(vdata);
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vdata[CS_HRES_COARSE].clock_mode = __arch_get_clock_mode(tk);
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vdata[CS_RAW].clock_mode = __arch_get_clock_mode(tk);
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/* CLOCK_REALTIME also required for time() */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
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vdso_ts->sec = tk->xtime_sec;
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vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
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/* CLOCK_REALTIME_COARSE */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
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vdso_ts->sec = tk->xtime_sec;
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vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
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/* CLOCK_MONOTONIC_COARSE */
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vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
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vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
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nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
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nsec = nsec + tk->wall_to_monotonic.tv_nsec;
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vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
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/*
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* Read without the seqlock held by clock_getres().
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* Note: No need to have a second copy.
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*/
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WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
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/*
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* Architectures can opt out of updating the high resolution part
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* of the VDSO.
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*/
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if (__arch_update_vdso_data())
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update_vdso_data(vdata, tk);
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__arch_update_vsyscall(vdata, tk);
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vdso_write_end(vdata);
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__arch_sync_vdso_data(vdata);
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}
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void update_vsyscall_tz(void)
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{
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struct vdso_data *vdata = __arch_get_k_vdso_data();
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vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
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vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
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__arch_sync_vdso_data(vdata);
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}
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