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_spudemand.c (3336B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * spu aware cpufreq governor for the cell processor
      4 *
      5 * © Copyright IBM Corporation 2006-2008
      6 *
      7 * Author: Christian Krafft <krafft@de.ibm.com>
      8 */
      9
     10#include <linux/cpufreq.h>
     11#include <linux/sched.h>
     12#include <linux/sched/loadavg.h>
     13#include <linux/module.h>
     14#include <linux/timer.h>
     15#include <linux/workqueue.h>
     16#include <linux/atomic.h>
     17#include <asm/machdep.h>
     18#include <asm/spu.h>
     19
     20#define POLL_TIME	100000		/* in µs */
     21#define EXP		753		/* exp(-1) in fixed-point */
     22
     23struct spu_gov_info_struct {
     24	unsigned long busy_spus;	/* fixed-point */
     25	struct cpufreq_policy *policy;
     26	struct delayed_work work;
     27	unsigned int poll_int;		/* µs */
     28};
     29static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
     30
     31static int calc_freq(struct spu_gov_info_struct *info)
     32{
     33	int cpu;
     34	int busy_spus;
     35
     36	cpu = info->policy->cpu;
     37	busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
     38
     39	info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1);
     40	pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
     41			cpu, busy_spus, info->busy_spus);
     42
     43	return info->policy->max * info->busy_spus / FIXED_1;
     44}
     45
     46static void spu_gov_work(struct work_struct *work)
     47{
     48	struct spu_gov_info_struct *info;
     49	int delay;
     50	unsigned long target_freq;
     51
     52	info = container_of(work, struct spu_gov_info_struct, work.work);
     53
     54	/* after cancel_delayed_work_sync we unset info->policy */
     55	BUG_ON(info->policy == NULL);
     56
     57	target_freq = calc_freq(info);
     58	__cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
     59
     60	delay = usecs_to_jiffies(info->poll_int);
     61	schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
     62}
     63
     64static void spu_gov_init_work(struct spu_gov_info_struct *info)
     65{
     66	int delay = usecs_to_jiffies(info->poll_int);
     67	INIT_DEFERRABLE_WORK(&info->work, spu_gov_work);
     68	schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
     69}
     70
     71static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
     72{
     73	cancel_delayed_work_sync(&info->work);
     74}
     75
     76static int spu_gov_start(struct cpufreq_policy *policy)
     77{
     78	unsigned int cpu = policy->cpu;
     79	struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
     80	struct spu_gov_info_struct *affected_info;
     81	int i;
     82
     83	if (!cpu_online(cpu)) {
     84		printk(KERN_ERR "cpu %d is not online\n", cpu);
     85		return -EINVAL;
     86	}
     87
     88	if (!policy->cur) {
     89		printk(KERN_ERR "no cpu specified in policy\n");
     90		return -EINVAL;
     91	}
     92
     93	/* initialize spu_gov_info for all affected cpus */
     94	for_each_cpu(i, policy->cpus) {
     95		affected_info = &per_cpu(spu_gov_info, i);
     96		affected_info->policy = policy;
     97	}
     98
     99	info->poll_int = POLL_TIME;
    100
    101	/* setup timer */
    102	spu_gov_init_work(info);
    103
    104	return 0;
    105}
    106
    107static void spu_gov_stop(struct cpufreq_policy *policy)
    108{
    109	unsigned int cpu = policy->cpu;
    110	struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
    111	int i;
    112
    113	/* cancel timer */
    114	spu_gov_cancel_work(info);
    115
    116	/* clean spu_gov_info for all affected cpus */
    117	for_each_cpu (i, policy->cpus) {
    118		info = &per_cpu(spu_gov_info, i);
    119		info->policy = NULL;
    120	}
    121}
    122
    123static struct cpufreq_governor spu_governor = {
    124	.name = "spudemand",
    125	.start = spu_gov_start,
    126	.stop = spu_gov_stop,
    127	.owner = THIS_MODULE,
    128};
    129cpufreq_governor_init(spu_governor);
    130cpufreq_governor_exit(spu_governor);
    131
    132MODULE_LICENSE("GPL");
    133MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");