[linux.git] / kernel / time / vsyscall.c

// 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 reolution 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);
}
Commit	Line	Data
44f57d78 VF	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Copyright 2019 ARM Ltd.
	4	*
	5	* Generic implementation of update_vsyscall and update_vsyscall_tz.
	6	*
	7	* Based on the x86 specific implementation.
	8	*/
	9
	10	#include <linux/hrtimer.h>
	11	#include <linux/timekeeper_internal.h>
	12	#include <vdso/datapage.h>
	13	#include <vdso/helpers.h>
	14	#include <vdso/vsyscall.h>
	15
19d0070a TG	16	#include "timekeeping_internal.h"
19d0070a TG	17
44f57d78 VF	18	static inline void update_vdso_data(struct vdso_data *vdata,
	19	struct timekeeper *tk)
	20	{
	21	struct vdso_timestamp *vdso_ts;
b99328a6	22	u64 nsec, sec;
44f57d78 VF	23
	24	vdata[CS_HRES_COARSE].cycle_last = tk->tkr_mono.cycle_last;
	25	vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask;
	26	vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult;
	27	vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift;
	28	vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last;
	29	vdata[CS_RAW].mask = tk->tkr_raw.mask;
	30	vdata[CS_RAW].mult = tk->tkr_raw.mult;
	31	vdata[CS_RAW].shift = tk->tkr_raw.shift;
	32
44f57d78 VF	33	/* CLOCK_MONOTONIC */
	34	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
	35	vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
	36
	37	nsec = tk->tkr_mono.xtime_nsec;
	38	nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
	39	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
	40	nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
	41	vdso_ts->sec++;
	42	}
	43	vdso_ts->nsec = nsec;
	44
b99328a6 TG	45	/* Copy MONOTONIC time for BOOTTIME */
	46	sec = vdso_ts->sec;
	47	/* Add the boot offset */
	48	sec += tk->monotonic_to_boot.tv_sec;
	49	nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;
44f57d78 VF	50
	51	/* CLOCK_BOOTTIME */
	52	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
b99328a6 TG	53	vdso_ts->sec = sec;
b99328a6 TG	54
44f57d78 VF	55	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
	56	nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
	57	vdso_ts->sec++;
	58	}
	59	vdso_ts->nsec = nsec;
	60
b99328a6 TG	61	/* CLOCK_MONOTONIC_RAW */
	62	vdso_ts = &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
	63	vdso_ts->sec = tk->raw_sec;
	64	vdso_ts->nsec = tk->tkr_raw.xtime_nsec;
	65
44f57d78 VF	66	/* CLOCK_TAI */
	67	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
	68	vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset;
	69	vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
44f57d78 VF	70	}
	71
	72	void update_vsyscall(struct timekeeper *tk)
	73	{
	74	struct vdso_data *vdata = __arch_get_k_vdso_data();
	75	struct vdso_timestamp *vdso_ts;
5d51bee7	76	s32 clock_mode;
44f57d78 VF	77	u64 nsec;
44f57d78 VF	78
44f57d78 VF	79	/* copy vsyscall data */
	80	vdso_write_begin(vdata);
	81
5d51bee7	82	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
5d51bee7 TG	83	vdata[CS_HRES_COARSE].clock_mode = clock_mode;
5d51bee7 TG	84	vdata[CS_RAW].clock_mode = clock_mode;
44f57d78	85
9f24c540 TG	86	/* CLOCK_REALTIME also required for time() */
	87	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
	88	vdso_ts->sec = tk->xtime_sec;
	89	vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
	90
44f57d78 VF	91	/* CLOCK_REALTIME_COARSE */
	92	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
	93	vdso_ts->sec = tk->xtime_sec;
	94	vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
	95
	96	/* CLOCK_MONOTONIC_COARSE */
	97	vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
	98	vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
	99	nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
	100	nsec = nsec + tk->wall_to_monotonic.tv_nsec;
0df1c986	101	vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
44f57d78	102
9f24c540 TG	103	/*
	104	* Read without the seqlock held by clock_getres().
	105	* Note: No need to have a second copy.
	106	*/
	107	WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
	108
	109	/*
c7a18100 TG	110	* If the current clocksource is not VDSO capable, then spare the
c7a18100 TG	111	* update of the high reolution parts.
9f24c540	112	*/
c7a18100	113	if (clock_mode != VDSO_CLOCKMODE_NONE)
9f24c540	114	update_vdso_data(vdata, tk);
44f57d78 VF	115
	116	__arch_update_vsyscall(vdata, tk);
	117
	118	vdso_write_end(vdata);
	119
	120	__arch_sync_vdso_data(vdata);
	121	}
	122
	123	void update_vsyscall_tz(void)
	124	{
	125	struct vdso_data *vdata = __arch_get_k_vdso_data();
	126
52338415 HC	127	vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
52338415 HC	128	vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
44f57d78 VF	129
	130	__arch_sync_vdso_data(vdata);
	131	}
19d0070a TG	132
	133	/**
	134	* vdso_update_begin - Start of a VDSO update section
	135	*
	136	* Allows architecture code to safely update the architecture specific VDSO
	137	* data. Disables interrupts, acquires timekeeper lock to serialize against
	138	* concurrent updates from timekeeping and invalidates the VDSO data
	139	* sequence counter to prevent concurrent readers from accessing
	140	* inconsistent data.
	141	*
	142	* Returns: Saved interrupt flags which need to be handed in to
	143	* vdso_update_end().
	144	*/
	145	unsigned long vdso_update_begin(void)
	146	{
	147	struct vdso_data *vdata = __arch_get_k_vdso_data();
	148	unsigned long flags;
	149
	150	raw_spin_lock_irqsave(&timekeeper_lock, flags);
	151	vdso_write_begin(vdata);
	152	return flags;
	153	}
	154
	155	/**
	156	* vdso_update_end - End of a VDSO update section
	157	* @flags: Interrupt flags as returned from vdso_update_begin()
	158	*
	159	* Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
	160	* synchronization if the architecture requires it, drops timekeeper lock
	161	* and restores interrupt flags.
	162	*/
	163	void vdso_update_end(unsigned long flags)
	164	{
	165	struct vdso_data *vdata = __arch_get_k_vdso_data();
	166
	167	vdso_write_end(vdata);
	168	__arch_sync_vdso_data(vdata);
	169	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
	170	}