cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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tick-oneshot.c (3227B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * This file contains functions which manage high resolution tick
      4 * related events.
      5 *
      6 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
      7 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
      8 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
      9 */
     10#include <linux/cpu.h>
     11#include <linux/err.h>
     12#include <linux/hrtimer.h>
     13#include <linux/interrupt.h>
     14#include <linux/percpu.h>
     15#include <linux/profile.h>
     16#include <linux/sched.h>
     17
     18#include "tick-internal.h"
     19
     20/**
     21 * tick_program_event
     22 */
     23int tick_program_event(ktime_t expires, int force)
     24{
     25	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
     26
     27	if (unlikely(expires == KTIME_MAX)) {
     28		/*
     29		 * We don't need the clock event device any more, stop it.
     30		 */
     31		clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
     32		dev->next_event = KTIME_MAX;
     33		return 0;
     34	}
     35
     36	if (unlikely(clockevent_state_oneshot_stopped(dev))) {
     37		/*
     38		 * We need the clock event again, configure it in ONESHOT mode
     39		 * before using it.
     40		 */
     41		clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
     42	}
     43
     44	return clockevents_program_event(dev, expires, force);
     45}
     46
     47/**
     48 * tick_resume_oneshot - resume oneshot mode
     49 */
     50void tick_resume_oneshot(void)
     51{
     52	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
     53
     54	clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
     55	clockevents_program_event(dev, ktime_get(), true);
     56}
     57
     58/**
     59 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
     60 */
     61void tick_setup_oneshot(struct clock_event_device *newdev,
     62			void (*handler)(struct clock_event_device *),
     63			ktime_t next_event)
     64{
     65	newdev->event_handler = handler;
     66	clockevents_switch_state(newdev, CLOCK_EVT_STATE_ONESHOT);
     67	clockevents_program_event(newdev, next_event, true);
     68}
     69
     70/**
     71 * tick_switch_to_oneshot - switch to oneshot mode
     72 */
     73int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
     74{
     75	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
     76	struct clock_event_device *dev = td->evtdev;
     77
     78	if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
     79		    !tick_device_is_functional(dev)) {
     80
     81		pr_info("Clockevents: could not switch to one-shot mode:");
     82		if (!dev) {
     83			pr_cont(" no tick device\n");
     84		} else {
     85			if (!tick_device_is_functional(dev))
     86				pr_cont(" %s is not functional.\n", dev->name);
     87			else
     88				pr_cont(" %s does not support one-shot mode.\n",
     89					dev->name);
     90		}
     91		return -EINVAL;
     92	}
     93
     94	td->mode = TICKDEV_MODE_ONESHOT;
     95	dev->event_handler = handler;
     96	clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
     97	tick_broadcast_switch_to_oneshot();
     98	return 0;
     99}
    100
    101/**
    102 * tick_check_oneshot_mode - check whether the system is in oneshot mode
    103 *
    104 * returns 1 when either nohz or highres are enabled. otherwise 0.
    105 */
    106int tick_oneshot_mode_active(void)
    107{
    108	unsigned long flags;
    109	int ret;
    110
    111	local_irq_save(flags);
    112	ret = __this_cpu_read(tick_cpu_device.mode) == TICKDEV_MODE_ONESHOT;
    113	local_irq_restore(flags);
    114
    115	return ret;
    116}
    117
    118#ifdef CONFIG_HIGH_RES_TIMERS
    119/**
    120 * tick_init_highres - switch to high resolution mode
    121 *
    122 * Called with interrupts disabled.
    123 */
    124int tick_init_highres(void)
    125{
    126	return tick_switch_to_oneshot(hrtimer_interrupt);
    127}
    128#endif