drivers/gator/gator_events_irq.c

/**
 * Copyright (C) Arm Limited 2010-2016. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include "gator.h"
#include <trace/events/irq.h>

#define HARDIRQ     0
#define SOFTIRQ     1
#define TOTALIRQ    (SOFTIRQ+1)

static ulong hardirq_enabled[GATOR_CLUSTER_COUNT];
static bool hardirq_enabled_any;
static ulong softirq_enabled[GATOR_CLUSTER_COUNT];
static bool softirq_enabled_any;
static ulong hardirq_key[GATOR_CLUSTER_COUNT];
static ulong softirq_key[GATOR_CLUSTER_COUNT];
static DEFINE_PER_CPU(atomic_t[TOTALIRQ], irqCnt);
static DEFINE_PER_CPU(int[TOTALIRQ * 2], irqGet);

GATOR_DEFINE_PROBE(irq_handler_exit,
           TP_PROTO(int irq, struct irqaction *action, int ret))
{
    atomic_inc(&per_cpu(irqCnt, get_physical_cpu())[HARDIRQ]);
}

GATOR_DEFINE_PROBE(softirq_exit, TP_PROTO(unsigned int vec_nr))
{
    atomic_inc(&per_cpu(irqCnt, get_physical_cpu())[SOFTIRQ]);
}

static int gator_events_irq_create_files(struct super_block *sb, struct dentry *root)
{
    struct dentry *dir;
    int i;
    char buf[40];

    /* irq */
    for (i = 0; i < gator_cluster_count; i++) {
        snprintf(buf, sizeof(buf), "%s_irq", gator_clusters[i]->pmnc_name);
        dir = gatorfs_mkdir(sb, root, buf);
        if (!dir)
            return -1;
        gatorfs_create_ulong(sb, dir, "enabled", &hardirq_enabled[i]);
        gatorfs_create_ro_ulong(sb, dir, "key", &hardirq_key[i]);
    }

    /* soft irq */
    for (i = 0; i < gator_cluster_count; i++) {
        snprintf(buf, sizeof(buf), "%s_softirq", gator_clusters[i]->pmnc_name);
        dir = gatorfs_mkdir(sb, root, buf);
        if (!dir)
            return -1;
        gatorfs_create_ulong(sb, dir, "enabled", &softirq_enabled[i]);
        gatorfs_create_ro_ulong(sb, dir, "key", &softirq_key[i]);
    }

    return 0;
}

static int gator_events_irq_online(int **buffer, bool migrate)
{
    int len = 0, cpu = get_physical_cpu();
    int cluster = gator_clusterids[cpu];

    /* synchronization with the irq_exit functions is not necessary as the values are being reset */
    if (hardirq_enabled[cluster]) {
        atomic_set(&per_cpu(irqCnt, cpu)[HARDIRQ], 0);
        per_cpu(irqGet, cpu)[len++] = hardirq_key[cluster];
        per_cpu(irqGet, cpu)[len++] = 0;
    }

    if (softirq_enabled[cluster]) {
        atomic_set(&per_cpu(irqCnt, cpu)[SOFTIRQ], 0);
        per_cpu(irqGet, cpu)[len++] = softirq_key[cluster];
        per_cpu(irqGet, cpu)[len++] = 0;
    }

    if (buffer)
        *buffer = per_cpu(irqGet, cpu);

    return len;
}

static int gator_events_irq_start(void)
{
    int i;

    hardirq_enabled_any = false;
    softirq_enabled_any = false;
    for (i = 0; i < gator_cluster_count; i++) {
        if (hardirq_enabled[i])
            hardirq_enabled_any = true;
        if (softirq_enabled[i])
            softirq_enabled_any = true;
    }

    /* register tracepoints */
    if (hardirq_enabled_any)
        if (GATOR_REGISTER_TRACE(irq_handler_exit))
            goto fail_hardirq_exit;
    if (softirq_enabled_any)
        if (GATOR_REGISTER_TRACE(softirq_exit))
            goto fail_softirq_exit;
    pr_debug("gator: registered irq tracepoints\n");

    return 0;

    /* unregister tracepoints on error */
fail_softirq_exit:
    if (hardirq_enabled_any)
        GATOR_UNREGISTER_TRACE(irq_handler_exit);
fail_hardirq_exit:
    pr_err("gator: irq tracepoints failed to activate, please verify that tracepoints are enabled in the linux kernel\n");

    return -1;
}

static void gator_events_irq_stop(void)
{
    if (hardirq_enabled_any)
        GATOR_UNREGISTER_TRACE(irq_handler_exit);
    if (softirq_enabled_any)
        GATOR_UNREGISTER_TRACE(softirq_exit);
    pr_debug("gator: unregistered irq tracepoints\n");

    hardirq_enabled_any = false;
    memset(hardirq_enabled, 0, sizeof(hardirq_enabled));
    softirq_enabled_any = false;
    memset(softirq_enabled, 0, sizeof(softirq_enabled));
}

static int gator_events_irq_read(int **buffer, bool sched_switch)
{
    int len, value;
    int cpu = get_physical_cpu();
    int cluster = gator_clusterids[cpu];

    len = 0;
    if (hardirq_enabled[cluster]) {
        value = atomic_read(&per_cpu(irqCnt, cpu)[HARDIRQ]);
        atomic_sub(value, &per_cpu(irqCnt, cpu)[HARDIRQ]);

        per_cpu(irqGet, cpu)[len++] = hardirq_key[cluster];
        per_cpu(irqGet, cpu)[len++] = value;
    }

    if (softirq_enabled[cluster]) {
        value = atomic_read(&per_cpu(irqCnt, cpu)[SOFTIRQ]);
        atomic_sub(value, &per_cpu(irqCnt, cpu)[SOFTIRQ]);

        per_cpu(irqGet, cpu)[len++] = softirq_key[cluster];
        per_cpu(irqGet, cpu)[len++] = value;
    }

    if (buffer)
        *buffer = per_cpu(irqGet, cpu);

    return len;
}

static struct gator_interface gator_events_irq_interface = {
    .name = "irq",
    .create_files = gator_events_irq_create_files,
    .online = gator_events_irq_online,
    .start = gator_events_irq_start,
    .stop = gator_events_irq_stop,
    .read = gator_events_irq_read,
};

int gator_events_irq_init(void)
{
    int i;

    for (i = 0; i < gator_cluster_count; i++) {
        hardirq_key[i] = gator_events_get_key();
        softirq_key[i] = gator_events_get_key();

        hardirq_enabled[i] = 0;
        softirq_enabled[i] = 0;
    }

    return gator_events_install(&gator_events_irq_interface);
}