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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stop_task.c (3283B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * stop-task scheduling class.
      4 *
      5 * The stop task is the highest priority task in the system, it preempts
      6 * everything and will be preempted by nothing.
      7 *
      8 * See kernel/stop_machine.c
      9 */
     10
     11#ifdef CONFIG_SMP
     12static int
     13select_task_rq_stop(struct task_struct *p, int cpu, int flags)
     14{
     15	return task_cpu(p); /* stop tasks as never migrate */
     16}
     17
     18static int
     19balance_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
     20{
     21	return sched_stop_runnable(rq);
     22}
     23#endif /* CONFIG_SMP */
     24
     25static void
     26check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
     27{
     28	/* we're never preempted */
     29}
     30
     31static void set_next_task_stop(struct rq *rq, struct task_struct *stop, bool first)
     32{
     33	stop->se.exec_start = rq_clock_task(rq);
     34}
     35
     36static struct task_struct *pick_task_stop(struct rq *rq)
     37{
     38	if (!sched_stop_runnable(rq))
     39		return NULL;
     40
     41	return rq->stop;
     42}
     43
     44static struct task_struct *pick_next_task_stop(struct rq *rq)
     45{
     46	struct task_struct *p = pick_task_stop(rq);
     47
     48	if (p)
     49		set_next_task_stop(rq, p, true);
     50
     51	return p;
     52}
     53
     54static void
     55enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
     56{
     57	add_nr_running(rq, 1);
     58}
     59
     60static void
     61dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
     62{
     63	sub_nr_running(rq, 1);
     64}
     65
     66static void yield_task_stop(struct rq *rq)
     67{
     68	BUG(); /* the stop task should never yield, its pointless. */
     69}
     70
     71static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
     72{
     73	struct task_struct *curr = rq->curr;
     74	u64 delta_exec;
     75
     76	delta_exec = rq_clock_task(rq) - curr->se.exec_start;
     77	if (unlikely((s64)delta_exec < 0))
     78		delta_exec = 0;
     79
     80	schedstat_set(curr->stats.exec_max,
     81		      max(curr->stats.exec_max, delta_exec));
     82
     83	curr->se.sum_exec_runtime += delta_exec;
     84	account_group_exec_runtime(curr, delta_exec);
     85
     86	curr->se.exec_start = rq_clock_task(rq);
     87	cgroup_account_cputime(curr, delta_exec);
     88}
     89
     90/*
     91 * scheduler tick hitting a task of our scheduling class.
     92 *
     93 * NOTE: This function can be called remotely by the tick offload that
     94 * goes along full dynticks. Therefore no local assumption can be made
     95 * and everything must be accessed through the @rq and @curr passed in
     96 * parameters.
     97 */
     98static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
     99{
    100}
    101
    102static void switched_to_stop(struct rq *rq, struct task_struct *p)
    103{
    104	BUG(); /* its impossible to change to this class */
    105}
    106
    107static void
    108prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
    109{
    110	BUG(); /* how!?, what priority? */
    111}
    112
    113static void update_curr_stop(struct rq *rq)
    114{
    115}
    116
    117/*
    118 * Simple, special scheduling class for the per-CPU stop tasks:
    119 */
    120DEFINE_SCHED_CLASS(stop) = {
    121
    122	.enqueue_task		= enqueue_task_stop,
    123	.dequeue_task		= dequeue_task_stop,
    124	.yield_task		= yield_task_stop,
    125
    126	.check_preempt_curr	= check_preempt_curr_stop,
    127
    128	.pick_next_task		= pick_next_task_stop,
    129	.put_prev_task		= put_prev_task_stop,
    130	.set_next_task          = set_next_task_stop,
    131
    132#ifdef CONFIG_SMP
    133	.balance		= balance_stop,
    134	.pick_task		= pick_task_stop,
    135	.select_task_rq		= select_task_rq_stop,
    136	.set_cpus_allowed	= set_cpus_allowed_common,
    137#endif
    138
    139	.task_tick		= task_tick_stop,
    140
    141	.prio_changed		= prio_changed_stop,
    142	.switched_to		= switched_to_stop,
    143	.update_curr		= update_curr_stop,
    144};