sdt.c

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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <stdio.h>
#include <sys/epoll.h>
#include <util/evlist.h>
#include <linux/filter.h>
#include "tests.h"
#include "debug.h"
#include "probe-file.h"
#include "build-id.h"

/* To test SDT event, we need libelf support to scan elf binary */
#if defined(HAVE_SDT_EVENT) && defined(HAVE_LIBELF_SUPPORT)

#include <sys/sdt.h>

static int target_function(void)
{
    DTRACE_PROBE(perf, test_target);
    return TEST_OK;
}

/* Copied from builtin-buildid-cache.c */
static int build_id_cache__add_file(const char *filename)
{
    char sbuild_id[SBUILD_ID_SIZE];
    u8 build_id[BUILD_ID_SIZE];
    int err;

    err = filename__read_build_id(filename, &build_id, sizeof(build_id));
    if (err < 0) {
        pr_debug("Failed to read build id of %s\n", filename);
        return err;
    }

    build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
    err = build_id_cache__add_s(sbuild_id, filename, NULL, false, false);
    if (err < 0)
        pr_debug("Failed to add build id cache of %s\n", filename);
    return err;
}

static char *get_self_path(void)
{
    char *buf = calloc(PATH_MAX, sizeof(char));

    if (buf && readlink("/proc/self/exe", buf, PATH_MAX - 1) < 0) {
        pr_debug("Failed to get correct path of perf\n");
        free(buf);
        return NULL;
    }
    return buf;
}

static int search_cached_probe(const char *target,
                   const char *group, const char *event)
{
    struct probe_cache *cache = probe_cache__new(target, NULL);
    int ret = 0;

    if (!cache) {
        pr_debug("Failed to open probe cache of %s\n", target);
        return -EINVAL;
    }

    if (!probe_cache__find_by_name(cache, group, event)) {
        pr_debug("Failed to find %s:%s in the cache\n", group, event);
        ret = -ENOENT;
    }
    probe_cache__delete(cache);

    return ret;
}

int test__sdt_event(struct test *test __maybe_unused, int subtests __maybe_unused)
{
    int ret = TEST_FAIL;
    char __tempdir[] = "./test-buildid-XXXXXX";
    char *tempdir = NULL, *myself = get_self_path();

    if (myself == NULL || mkdtemp(__tempdir) == NULL) {
        pr_debug("Failed to make a tempdir for build-id cache\n");
        goto error;
    }
    /* Note that buildid_dir must be an absolute path */
    tempdir = realpath(__tempdir, NULL);
    if (tempdir == NULL)
        goto error_rmdir;

    /* At first, scan itself */
    set_buildid_dir(tempdir);
    if (build_id_cache__add_file(myself) < 0)
        goto error_rmdir;

    /* Open a cache and make sure the SDT is stored */
    if (search_cached_probe(myself, "sdt_perf", "test_target") < 0)
        goto error_rmdir;

    /* TBD: probing on the SDT event and collect logs */

    /* Call the target and get an event */
    ret = target_function();

error_rmdir:
    /* Cleanup temporary buildid dir */
    rm_rf(__tempdir);
error:
    free(tempdir);
    free(myself);
    return ret;
}
#else
int test__sdt_event(struct test *test __maybe_unused, int subtests __maybe_unused)
{
    pr_debug("Skip SDT event test because SDT support is not compiled\n");
    return TEST_SKIP;
}
#endif