openat-syscall-all-cpus.c

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

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <api/fs/fs.h>
#include <linux/err.h>
#include <api/fs/tracing_path.h>
#include "evsel.h"
#include "tests.h"
#include "thread_map.h"
#include "cpumap.h"
#include "debug.h"
#include "stat.h"

int test__openat_syscall_event_on_all_cpus(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    int err = -1, fd, cpu;
    struct cpu_map *cpus;
    struct perf_evsel *evsel;
    unsigned int nr_openat_calls = 111, i;
    cpu_set_t cpu_set;
    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;
    }

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

    CPU_ZERO(&cpu_set);

    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(evsel, 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_evsel_delete;
    }

    for (cpu = 0; cpu < cpus->nr; ++cpu) {
        unsigned int ncalls = nr_openat_calls + cpu;
        /*
         * XXX eventually lift this restriction in a way that
         * keeps perf building on older glibc installations
         * without CPU_ALLOC. 1024 cpus in 2010 still seems
         * a reasonable upper limit tho :-)
         */
        if (cpus->map[cpu] >= CPU_SETSIZE) {
            pr_debug("Ignoring CPU %d\n", cpus->map[cpu]);
            continue;
        }

        CPU_SET(cpus->map[cpu], &cpu_set);
        if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0) {
            pr_debug("sched_setaffinity() failed on CPU %d: %s ",
                 cpus->map[cpu],
                 str_error_r(errno, sbuf, sizeof(sbuf)));
            goto out_close_fd;
        }
        for (i = 0; i < ncalls; ++i) {
            fd = openat(0, "/etc/passwd", O_RDONLY);
            close(fd);
        }
        CPU_CLR(cpus->map[cpu], &cpu_set);
    }

    /*
     * Here we need to explicitly preallocate the counts, as if
     * we use the auto allocation it will allocate just for 1 cpu,
     * as we start by cpu 0.
     */
    if (perf_evsel__alloc_counts(evsel, cpus->nr, 1) < 0) {
        pr_debug("perf_evsel__alloc_counts(ncpus=%d)\n", cpus->nr);
        goto out_close_fd;
    }

    err = 0;

    for (cpu = 0; cpu < cpus->nr; ++cpu) {
        unsigned int expected;

        if (cpus->map[cpu] >= CPU_SETSIZE)
            continue;

        if (perf_evsel__read_on_cpu(evsel, cpu, 0) < 0) {
            pr_debug("perf_evsel__read_on_cpu\n");
            err = -1;
            break;
        }

        expected = nr_openat_calls + cpu;
        if (perf_counts(evsel->counts, cpu, 0)->val != expected) {
            pr_debug("perf_evsel__read_on_cpu: expected to intercept %d calls on cpu %d, got %" PRIu64 "\n",
                 expected, cpus->map[cpu], perf_counts(evsel->counts, cpu, 0)->val);
            err = -1;
        }
    }

    perf_evsel__free_counts(evsel);
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;
}