aarch64_cycle_counter.c

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/* -*- C -*- */
/*
 * Copyright (c) 2021 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */
#ifdef CONFIG_AARCH64

#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_LIB


#include "lib/trace.h"
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>

static void enable_user_space_access_pccnt(void *dt)
{
        uint64_t pmcr_val;

        /* Enables the cycle counter register */
        asm volatile("msr pmcntenset_el0, %0" :: "r" ((u64)(1 << 31)));

        /* Performance Monitors User Enable Register. */
        asm volatile("msr pmuserenr_el0, %0" : : "r"(1 |((u64)(1 << 2))));

        /* Reset cycle counter(0 bit) and start all event(2nd bit) counters */
        asm volatile("mrs %0, pmcr_el0" : "=r" (pmcr_val));
        asm volatile("msr pmcr_el0, %0" : : "r" (pmcr_val | 1 |((u64)(1 << 2))));
}

static void disable_user_space_pccnt_access(void *dt)
{
        /* Enables the cycle counter register */
        asm volatile("msr pmcntenset_el0, %0" :: "r" (0 << 31));

        /* Disable user-mode access to counters. */
        asm volatile("msr pmuserenr_el0, %0" : : "r"((u64)0));
}

int  start_cycle_counter(void)
{
        /* Call the function on each cpu with NULL param and wait for completion*/
        on_each_cpu(enable_user_space_access_pccnt, NULL, 1);
        return 0;
}

void  finish_cycle_counter(void)
{
        /* Call the function on each cpu with NULL param and wait for completion*/
        on_each_cpu(disable_user_space_pccnt_access, NULL, 1);
}
#endif /* CONFIG_AARCH64 */

#undef M0_TRACE_SUBSYSTEM

/*
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/*
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