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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cpufreq.c (2680B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Scheduler code and data structures related to cpufreq.
      4 *
      5 * Copyright (C) 2016, Intel Corporation
      6 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
      7 */
      8
      9DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
     10
     11/**
     12 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
     13 * @cpu: The CPU to set the pointer for.
     14 * @data: New pointer value.
     15 * @func: Callback function to set for the CPU.
     16 *
     17 * Set and publish the update_util_data pointer for the given CPU.
     18 *
     19 * The update_util_data pointer of @cpu is set to @data and the callback
     20 * function pointer in the target struct update_util_data is set to @func.
     21 * That function will be called by cpufreq_update_util() from RCU-sched
     22 * read-side critical sections, so it must not sleep.  @data will always be
     23 * passed to it as the first argument which allows the function to get to the
     24 * target update_util_data structure and its container.
     25 *
     26 * The update_util_data pointer of @cpu must be NULL when this function is
     27 * called or it will WARN() and return with no effect.
     28 */
     29void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
     30			void (*func)(struct update_util_data *data, u64 time,
     31				     unsigned int flags))
     32{
     33	if (WARN_ON(!data || !func))
     34		return;
     35
     36	if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
     37		return;
     38
     39	data->func = func;
     40	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
     41}
     42EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
     43
     44/**
     45 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
     46 * @cpu: The CPU to clear the pointer for.
     47 *
     48 * Clear the update_util_data pointer for the given CPU.
     49 *
     50 * Callers must use RCU callbacks to free any memory that might be
     51 * accessed via the old update_util_data pointer or invoke synchronize_rcu()
     52 * right after this function to avoid use-after-free.
     53 */
     54void cpufreq_remove_update_util_hook(int cpu)
     55{
     56	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
     57}
     58EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
     59
     60/**
     61 * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
     62 * @policy: cpufreq policy to check.
     63 *
     64 * Return 'true' if:
     65 * - the local and remote CPUs share @policy,
     66 * - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going
     67 *   offline (in which case it is not expected to run cpufreq updates any more).
     68 */
     69bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
     70{
     71	return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
     72		(policy->dvfs_possible_from_any_cpu &&
     73		 rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));
     74}