mmap-thread-lookup.c

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// SPDX-License-Identifier: GPL-2.0
#include <inttypes.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include "debug.h"
#include "tests.h"
#include "machine.h"
#include "thread_map.h"
#include "symbol.h"
#include "thread.h"
#include "util.h"

#define THREADS 4

static int go_away;

struct thread_data {
    pthread_t   pt;
    pid_t       tid;
    void        *map;
    int     ready[2];
};

static struct thread_data threads[THREADS];

static int thread_init(struct thread_data *td)
{
    void *map;

    map = mmap(NULL, page_size,
           PROT_READ|PROT_WRITE|PROT_EXEC,
           MAP_SHARED|MAP_ANONYMOUS, -1, 0);

    if (map == MAP_FAILED) {
        perror("mmap failed");
        return -1;
    }

    td->map = map;
    td->tid = syscall(SYS_gettid);

    pr_debug("tid = %d, map = %p\n", td->tid, map);
    return 0;
}

static void *thread_fn(void *arg)
{
    struct thread_data *td = arg;
    ssize_t ret;
    int go;

    if (thread_init(td))
        return NULL;

    /* Signal thread_create thread is initialized. */
    ret = write(td->ready[1], &go, sizeof(int));
    if (ret != sizeof(int)) {
        pr_err("failed to notify\n");
        return NULL;
    }

    while (!go_away) {
        /* Waiting for main thread to kill us. */
        usleep(100);
    }

    munmap(td->map, page_size);
    return NULL;
}

static int thread_create(int i)
{
    struct thread_data *td = &threads[i];
    int err, go;

    if (pipe(td->ready))
        return -1;

    err = pthread_create(&td->pt, NULL, thread_fn, td);
    if (!err) {
        /* Wait for thread initialization. */
        ssize_t ret = read(td->ready[0], &go, sizeof(int));
        err = ret != sizeof(int);
    }

    close(td->ready[0]);
    close(td->ready[1]);
    return err;
}

static int threads_create(void)
{
    struct thread_data *td0 = &threads[0];
    int i, err = 0;

    go_away = 0;

    /* 0 is main thread */
    if (thread_init(td0))
        return -1;

    for (i = 1; !err && i < THREADS; i++)
        err = thread_create(i);

    return err;
}

static int threads_destroy(void)
{
    struct thread_data *td0 = &threads[0];
    int i, err = 0;

    /* cleanup the main thread */
    munmap(td0->map, page_size);

    go_away = 1;

    for (i = 1; !err && i < THREADS; i++)
        err = pthread_join(threads[i].pt, NULL);

    return err;
}

typedef int (*synth_cb)(struct machine *machine);

static int synth_all(struct machine *machine)
{
    return perf_event__synthesize_threads(NULL,
                          perf_event__process,
                          machine, 0, 500, 1);
}

static int synth_process(struct machine *machine)
{
    struct thread_map *map;
    int err;

    map = thread_map__new_by_pid(getpid());

    err = perf_event__synthesize_thread_map(NULL, map,
                        perf_event__process,
                        machine, 0, 500);

    thread_map__put(map);
    return err;
}

static int mmap_events(synth_cb synth)
{
    struct machine *machine;
    int err, i;

    /*
     * The threads_create will not return before all threads
     * are spawned and all created memory map.
     *
     * They will loop until threads_destroy is called, so we
     * can safely run synthesizing function.
     */
    TEST_ASSERT_VAL("failed to create threads", !threads_create());

    machine = machine__new_host();

    dump_trace = verbose > 1 ? 1 : 0;

    err = synth(machine);

    dump_trace = 0;

    TEST_ASSERT_VAL("failed to destroy threads", !threads_destroy());
    TEST_ASSERT_VAL("failed to synthesize maps", !err);

    /*
     * All data is synthesized, try to find map for each
     * thread object.
     */
    for (i = 0; i < THREADS; i++) {
        struct thread_data *td = &threads[i];
        struct addr_location al;
        struct thread *thread;

        thread = machine__findnew_thread(machine, getpid(), td->tid);

        pr_debug("looking for map %p\n", td->map);

        thread__find_map(thread, PERF_RECORD_MISC_USER,
                 (unsigned long) (td->map + 1), &al);

        thread__put(thread);

        if (!al.map) {
            pr_debug("failed, couldn't find map\n");
            err = -1;
            break;
        }

        pr_debug("map %p, addr %" PRIx64 "\n", al.map, al.map->start);
    }

    machine__delete_threads(machine);
    machine__delete(machine);
    return err;
}

/*
 * This test creates 'THREADS' number of threads (including
 * main thread) and each thread creates memory map.
 *
 * When threads are created, we synthesize them with both
 * (separate tests):
 *   perf_event__synthesize_thread_map (process based)
 *   perf_event__synthesize_threads    (global)
 *
 * We test we can find all memory maps via:
 *   thread__find_map
 *
 * by using all thread objects.
 */
int test__mmap_thread_lookup(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    /* perf_event__synthesize_threads synthesize */
    TEST_ASSERT_VAL("failed with sythesizing all",
            !mmap_events(synth_all));

    /* perf_event__synthesize_thread_map synthesize */
    TEST_ASSERT_VAL("failed with sythesizing process",
            !mmap_events(synth_process));

    return 0;
}