openat-syscall.c

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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
#include <api/fs/tracing_path.h>
#include <linux/err.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "thread_map.h"
#include "evsel.h"
#include "debug.h"
#include "tests.h"

int test__openat_syscall_event(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    int err = -1, fd;
    struct perf_evsel *evsel;
    unsigned int nr_openat_calls = 111, i;
    struct thread_map *threads = thread_map__new(-1, getpid(), UINT_MAX);
    char sbuf[STRERR_BUFSIZE];
    char errbuf[BUFSIZ];

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

    evsel = perf_evsel__newtp("syscalls", "sys_enter_openat");
    if (IS_ERR(evsel)) {
        tracing_path__strerror_open_tp(errno, errbuf, sizeof(errbuf), "syscalls", "sys_enter_openat");
        pr_debug("%s\n", errbuf);
        goto out_thread_map_delete;
    }

    if (perf_evsel__open_per_thread(evsel, 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_evsel_delete;
    }

    for (i = 0; i < nr_openat_calls; ++i) {
        fd = openat(0, "/etc/passwd", O_RDONLY);
        close(fd);
    }

    if (perf_evsel__read_on_cpu(evsel, 0, 0) < 0) {
        pr_debug("perf_evsel__read_on_cpu\n");
        goto out_close_fd;
    }

    if (perf_counts(evsel->counts, 0, 0)->val != nr_openat_calls) {
        pr_debug("perf_evsel__read_on_cpu: expected to intercept %d calls, got %" PRIu64 "\n",
             nr_openat_calls, perf_counts(evsel->counts, 0, 0)->val);
        goto out_close_fd;
    }

    err = 0;
out_close_fd:
    perf_evsel__close_fd(evsel);
out_evsel_delete:
    perf_evsel__delete(evsel);
out_thread_map_delete:
    thread_map__put(threads);
    return err;
}