linux/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)
{ … }

void update_vsyscall(struct timekeeper *tk)
{ … }

void update_vsyscall_tz(void)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }