mmap-basic.c

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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
/* For the CLR_() macros */
#include <pthread.h>

#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
#include "cpumap.h"
#include "tests.h"
#include <linux/err.h>
#include <linux/kernel.h>

/*
 * This test will generate random numbers of calls to some getpid syscalls,
 * then establish an mmap for a group of events that are created to monitor
 * the syscalls.
 *
 * It will receive the events, using mmap, use its PERF_SAMPLE_ID generated
 * sample.id field to map back to its respective perf_evsel instance.
 *
 * Then it checks if the number of syscalls reported as perf events by
 * the kernel corresponds to the number of syscalls made.
 */
int test__basic_mmap(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    int err = -1;
    union perf_event *event;
    struct thread_map *threads;
    struct cpu_map *cpus;
    struct perf_evlist *evlist;
    cpu_set_t cpu_set;
    const char *syscall_names[] = { "getsid", "getppid", "getpgid", };
    pid_t (*syscalls[])(void) = { (void *)getsid, getppid, (void*)getpgid };
#define nsyscalls ARRAY_SIZE(syscall_names)
    unsigned int nr_events[nsyscalls],
             expected_nr_events[nsyscalls], i, j;
    struct perf_evsel *evsels[nsyscalls], *evsel;
    char sbuf[STRERR_BUFSIZE];
    struct perf_mmap *md;

    threads = thread_map__new(-1, getpid(), UINT_MAX);
    if (threads == NULL) {
        pr_debug("thread_map__new\n");
        return -1;
    }

    cpus = cpu_map__new(NULL);
    if (cpus == NULL) {
        pr_debug("cpu_map__new\n");
        goto out_free_threads;
    }

    CPU_ZERO(&cpu_set);
    CPU_SET(cpus->map[0], &cpu_set);
    sched_setaffinity(0, sizeof(cpu_set), &cpu_set);
    if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0) {
        pr_debug("sched_setaffinity() failed on CPU %d: %s ",
             cpus->map[0], str_error_r(errno, sbuf, sizeof(sbuf)));
        goto out_free_cpus;
    }

    evlist = perf_evlist__new();
    if (evlist == NULL) {
        pr_debug("perf_evlist__new\n");
        goto out_free_cpus;
    }

    perf_evlist__set_maps(evlist, cpus, threads);

    for (i = 0; i < nsyscalls; ++i) {
        char name[64];

        snprintf(name, sizeof(name), "sys_enter_%s", syscall_names[i]);
        evsels[i] = perf_evsel__newtp("syscalls", name);
        if (IS_ERR(evsels[i])) {
            pr_debug("perf_evsel__new(%s)\n", name);
            goto out_delete_evlist;
        }

        evsels[i]->attr.wakeup_events = 1;
        perf_evsel__set_sample_id(evsels[i], false);

        perf_evlist__add(evlist, evsels[i]);

        if (perf_evsel__open(evsels[i], cpus, threads) < 0) {
            pr_debug("failed to open counter: %s, "
                 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
                 str_error_r(errno, sbuf, sizeof(sbuf)));
            goto out_delete_evlist;
        }

        nr_events[i] = 0;
        expected_nr_events[i] = 1 + rand() % 127;
    }

    if (perf_evlist__mmap(evlist, 128) < 0) {
        pr_debug("failed to mmap events: %d (%s)\n", errno,
             str_error_r(errno, sbuf, sizeof(sbuf)));
        goto out_delete_evlist;
    }

    for (i = 0; i < nsyscalls; ++i)
        for (j = 0; j < expected_nr_events[i]; ++j) {
            int foo = syscalls[i]();
            ++foo;
        }

    md = &evlist->mmap[0];
    if (perf_mmap__read_init(md) < 0)
        goto out_init;

    while ((event = perf_mmap__read_event(md)) != NULL) {
        struct perf_sample sample;

        if (event->header.type != PERF_RECORD_SAMPLE) {
            pr_debug("unexpected %s event\n",
                 perf_event__name(event->header.type));
            goto out_delete_evlist;
        }

        err = perf_evlist__parse_sample(evlist, event, &sample);
        if (err) {
            pr_err("Can't parse sample, err = %d\n", err);
            goto out_delete_evlist;
        }

        err = -1;
        evsel = perf_evlist__id2evsel(evlist, sample.id);
        if (evsel == NULL) {
            pr_debug("event with id %" PRIu64
                 " doesn't map to an evsel\n", sample.id);
            goto out_delete_evlist;
        }
        nr_events[evsel->idx]++;
        perf_mmap__consume(md);
    }
    perf_mmap__read_done(md);

out_init:
    err = 0;
    evlist__for_each_entry(evlist, evsel) {
        if (nr_events[evsel->idx] != expected_nr_events[evsel->idx]) {
            pr_debug("expected %d %s events, got %d\n",
                 expected_nr_events[evsel->idx],
                 perf_evsel__name(evsel), nr_events[evsel->idx]);
            err = -1;
            goto out_delete_evlist;
        }
    }

out_delete_evlist:
    perf_evlist__delete(evlist);
    cpus    = NULL;
    threads = NULL;
out_free_cpus:
    cpu_map__put(cpus);
out_free_threads:
    thread_map__put(threads);
    return err;
}