arm-spe.c

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// SPDX-License-Identifier: GPL-2.0
/*
 * Arm Statistical Profiling Extensions (SPE) support
 * Copyright (c) 2017-2018, Arm Ltd.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/log2.h>
#include <time.h>

#include "../../util/cpumap.h"
#include "../../util/evsel.h"
#include "../../util/evlist.h"
#include "../../util/session.h"
#include "../../util/util.h"
#include "../../util/pmu.h"
#include "../../util/debug.h"
#include "../../util/auxtrace.h"
#include "../../util/arm-spe.h"

#define KiB(x) ((x) * 1024)
#define MiB(x) ((x) * 1024 * 1024)

struct arm_spe_recording {
    struct auxtrace_record      itr;
    struct perf_pmu         *arm_spe_pmu;
    struct perf_evlist      *evlist;
};

static size_t
arm_spe_info_priv_size(struct auxtrace_record *itr __maybe_unused,
               struct perf_evlist *evlist __maybe_unused)
{
    return ARM_SPE_AUXTRACE_PRIV_SIZE;
}

static int arm_spe_info_fill(struct auxtrace_record *itr,
                 struct perf_session *session,
                 struct auxtrace_info_event *auxtrace_info,
                 size_t priv_size)
{
    struct arm_spe_recording *sper =
            container_of(itr, struct arm_spe_recording, itr);
    struct perf_pmu *arm_spe_pmu = sper->arm_spe_pmu;

    if (priv_size != ARM_SPE_AUXTRACE_PRIV_SIZE)
        return -EINVAL;

    if (!session->evlist->nr_mmaps)
        return -EINVAL;

    auxtrace_info->type = PERF_AUXTRACE_ARM_SPE;
    auxtrace_info->priv[ARM_SPE_PMU_TYPE] = arm_spe_pmu->type;

    return 0;
}

static int arm_spe_recording_options(struct auxtrace_record *itr,
                     struct perf_evlist *evlist,
                     struct record_opts *opts)
{
    struct arm_spe_recording *sper =
            container_of(itr, struct arm_spe_recording, itr);
    struct perf_pmu *arm_spe_pmu = sper->arm_spe_pmu;
    struct perf_evsel *evsel, *arm_spe_evsel = NULL;
    bool privileged = geteuid() == 0 || perf_event_paranoid() < 0;
    struct perf_evsel *tracking_evsel;
    int err;

    sper->evlist = evlist;

    evlist__for_each_entry(evlist, evsel) {
        if (evsel->attr.type == arm_spe_pmu->type) {
            if (arm_spe_evsel) {
                pr_err("There may be only one " ARM_SPE_PMU_NAME "x event\n");
                return -EINVAL;
            }
            evsel->attr.freq = 0;
            evsel->attr.sample_period = 1;
            arm_spe_evsel = evsel;
            opts->full_auxtrace = true;
        }
    }

    if (!opts->full_auxtrace)
        return 0;

    /* We are in full trace mode but '-m,xyz' wasn't specified */
    if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) {
        if (privileged) {
            opts->auxtrace_mmap_pages = MiB(4) / page_size;
        } else {
            opts->auxtrace_mmap_pages = KiB(128) / page_size;
            if (opts->mmap_pages == UINT_MAX)
                opts->mmap_pages = KiB(256) / page_size;
        }
    }

    /* Validate auxtrace_mmap_pages */
    if (opts->auxtrace_mmap_pages) {
        size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
        size_t min_sz = KiB(8);

        if (sz < min_sz || !is_power_of_2(sz)) {
            pr_err("Invalid mmap size for ARM SPE: must be at least %zuKiB and a power of 2\n",
                   min_sz / 1024);
            return -EINVAL;
        }
    }


    /*
     * To obtain the auxtrace buffer file descriptor, the auxtrace event
     * must come first.
     */
    perf_evlist__to_front(evlist, arm_spe_evsel);

    perf_evsel__set_sample_bit(arm_spe_evsel, CPU);
    perf_evsel__set_sample_bit(arm_spe_evsel, TIME);
    perf_evsel__set_sample_bit(arm_spe_evsel, TID);

    /* Add dummy event to keep tracking */
    err = parse_events(evlist, "dummy:u", NULL);
    if (err)
        return err;

    tracking_evsel = perf_evlist__last(evlist);
    perf_evlist__set_tracking_event(evlist, tracking_evsel);

    tracking_evsel->attr.freq = 0;
    tracking_evsel->attr.sample_period = 1;
    perf_evsel__set_sample_bit(tracking_evsel, TIME);
    perf_evsel__set_sample_bit(tracking_evsel, CPU);
    perf_evsel__reset_sample_bit(tracking_evsel, BRANCH_STACK);

    return 0;
}

static u64 arm_spe_reference(struct auxtrace_record *itr __maybe_unused)
{
    struct timespec ts;

    clock_gettime(CLOCK_MONOTONIC_RAW, &ts);

    return ts.tv_sec ^ ts.tv_nsec;
}

static void arm_spe_recording_free(struct auxtrace_record *itr)
{
    struct arm_spe_recording *sper =
            container_of(itr, struct arm_spe_recording, itr);

    free(sper);
}

static int arm_spe_read_finish(struct auxtrace_record *itr, int idx)
{
    struct arm_spe_recording *sper =
            container_of(itr, struct arm_spe_recording, itr);
    struct perf_evsel *evsel;

    evlist__for_each_entry(sper->evlist, evsel) {
        if (evsel->attr.type == sper->arm_spe_pmu->type)
            return perf_evlist__enable_event_idx(sper->evlist,
                                 evsel, idx);
    }
    return -EINVAL;
}

struct auxtrace_record *arm_spe_recording_init(int *err,
                           struct perf_pmu *arm_spe_pmu)
{
    struct arm_spe_recording *sper;

    if (!arm_spe_pmu) {
        *err = -ENODEV;
        return NULL;
    }

    sper = zalloc(sizeof(struct arm_spe_recording));
    if (!sper) {
        *err = -ENOMEM;
        return NULL;
    }

    sper->arm_spe_pmu = arm_spe_pmu;
    sper->itr.recording_options = arm_spe_recording_options;
    sper->itr.info_priv_size = arm_spe_info_priv_size;
    sper->itr.info_fill = arm_spe_info_fill;
    sper->itr.free = arm_spe_recording_free;
    sper->itr.reference = arm_spe_reference;
    sper->itr.read_finish = arm_spe_read_finish;
    sper->itr.alignment = 0;

    return &sper->itr;
}

struct perf_event_attr
*arm_spe_pmu_default_config(struct perf_pmu *arm_spe_pmu)
{
    struct perf_event_attr *attr;

    attr = zalloc(sizeof(struct perf_event_attr));
    if (!attr) {
        pr_err("arm_spe default config cannot allocate a perf_event_attr\n");
        return NULL;
    }

    /*
     * If kernel driver doesn't advertise a minimum,
     * use max allowable by PMSIDR_EL1.INTERVAL
     */
    if (perf_pmu__scan_file(arm_spe_pmu, "caps/min_interval", "%llu",
                  &attr->sample_period) != 1) {
        pr_debug("arm_spe driver doesn't advertise a min. interval. Using 4096\n");
        attr->sample_period = 4096;
    }

    arm_spe_pmu->selectable = true;
    arm_spe_pmu->is_uncore = false;

    return attr;
}