diff options
Diffstat (limited to 'kernel/time/vsyscall.c')
| -rw-r--r-- | kernel/time/vsyscall.c | 170 |
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); +} |