bpf.c

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#include <errno.h>
#include <stdio.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <util/util.h>
#include <util/bpf-loader.h>
#include <util/evlist.h>
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/kernel.h>
#include <api/fs/fs.h>
#include <bpf/bpf.h>
#include "tests.h"
#include "llvm.h"
#include "debug.h"
#define NR_ITERS       111
#define PERF_TEST_BPF_PATH "/sys/fs/bpf/perf_test"

#ifdef HAVE_LIBBPF_SUPPORT

static int epoll_pwait_loop(void)
{
    int i;

    /* Should fail NR_ITERS times */
    for (i = 0; i < NR_ITERS; i++)
        epoll_pwait(-(i + 1), NULL, 0, 0, NULL);
    return 0;
}

#ifdef HAVE_BPF_PROLOGUE

static int llseek_loop(void)
{
    int fds[2], i;

    fds[0] = open("/dev/null", O_RDONLY);
    fds[1] = open("/dev/null", O_RDWR);

    if (fds[0] < 0 || fds[1] < 0)
        return -1;

    for (i = 0; i < NR_ITERS; i++) {
        lseek(fds[i % 2], i, (i / 2) % 2 ? SEEK_CUR : SEEK_SET);
        lseek(fds[(i + 1) % 2], i, (i / 2) % 2 ? SEEK_CUR : SEEK_SET);
    }
    close(fds[0]);
    close(fds[1]);
    return 0;
}

#endif

static struct {
    enum test_llvm__testcase prog_id;
    const char *desc;
    const char *name;
    const char *msg_compile_fail;
    const char *msg_load_fail;
    int (*target_func)(void);
    int expect_result;
    bool    pin;
} bpf_testcase_table[] = {
    {
        .prog_id      = LLVM_TESTCASE_BASE,
        .desc         = "Basic BPF filtering",
        .name         = "[basic_bpf_test]",
        .msg_compile_fail = "fix 'perf test LLVM' first",
        .msg_load_fail    = "load bpf object failed",
        .target_func      = &epoll_pwait_loop,
        .expect_result    = (NR_ITERS + 1) / 2,
    },
    {
        .prog_id      = LLVM_TESTCASE_BASE,
        .desc         = "BPF pinning",
        .name         = "[bpf_pinning]",
        .msg_compile_fail = "fix kbuild first",
        .msg_load_fail    = "check your vmlinux setting?",
        .target_func      = &epoll_pwait_loop,
        .expect_result    = (NR_ITERS + 1) / 2,
        .pin          = true,
    },
#ifdef HAVE_BPF_PROLOGUE
    {
        .prog_id      = LLVM_TESTCASE_BPF_PROLOGUE,
        .desc         = "BPF prologue generation",
        .name         = "[bpf_prologue_test]",
        .msg_compile_fail = "fix kbuild first",
        .msg_load_fail    = "check your vmlinux setting?",
        .target_func      = &llseek_loop,
        .expect_result    = (NR_ITERS + 1) / 4,
    },
#endif
    {
        .prog_id      = LLVM_TESTCASE_BPF_RELOCATION,
        .desc         = "BPF relocation checker",
        .name         = "[bpf_relocation_test]",
        .msg_compile_fail = "fix 'perf test LLVM' first",
        .msg_load_fail    = "libbpf error when dealing with relocation",
    },
};

static int do_test(struct bpf_object *obj, int (*func)(void),
           int expect)
{
    struct record_opts opts = {
        .target = {
            .uid = UINT_MAX,
            .uses_mmap = true,
        },
        .freq         = 0,
        .mmap_pages   = 256,
        .default_interval = 1,
    };

    char pid[16];
    char sbuf[STRERR_BUFSIZE];
    struct perf_evlist *evlist;
    int i, ret = TEST_FAIL, err = 0, count = 0;

    struct parse_events_state parse_state;
    struct parse_events_error parse_error;

    bzero(&parse_error, sizeof(parse_error));
    bzero(&parse_state, sizeof(parse_state));
    parse_state.error = &parse_error;
    INIT_LIST_HEAD(&parse_state.list);

    err = parse_events_load_bpf_obj(&parse_state, &parse_state.list, obj, NULL);
    if (err || list_empty(&parse_state.list)) {
        pr_debug("Failed to add events selected by BPF\n");
        return TEST_FAIL;
    }

    snprintf(pid, sizeof(pid), "%d", getpid());
    pid[sizeof(pid) - 1] = '\0';
    opts.target.tid = opts.target.pid = pid;

    /* Instead of perf_evlist__new_default, don't add default events */
    evlist = perf_evlist__new();
    if (!evlist) {
        pr_debug("Not enough memory to create evlist\n");
        return TEST_FAIL;
    }

    err = perf_evlist__create_maps(evlist, &opts.target);
    if (err < 0) {
        pr_debug("Not enough memory to create thread/cpu maps\n");
        goto out_delete_evlist;
    }

    perf_evlist__splice_list_tail(evlist, &parse_state.list);
    evlist->nr_groups = parse_state.nr_groups;

    perf_evlist__config(evlist, &opts, NULL);

    err = perf_evlist__open(evlist);
    if (err < 0) {
        pr_debug("perf_evlist__open: %s\n",
             str_error_r(errno, sbuf, sizeof(sbuf)));
        goto out_delete_evlist;
    }

    err = perf_evlist__mmap(evlist, opts.mmap_pages);
    if (err < 0) {
        pr_debug("perf_evlist__mmap: %s\n",
             str_error_r(errno, sbuf, sizeof(sbuf)));
        goto out_delete_evlist;
    }

    perf_evlist__enable(evlist);
    (*func)();
    perf_evlist__disable(evlist);

    for (i = 0; i < evlist->nr_mmaps; i++) {
        union perf_event *event;
        struct perf_mmap *md;

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

        while ((event = perf_mmap__read_event(md)) != NULL) {
            const u32 type = event->header.type;

            if (type == PERF_RECORD_SAMPLE)
                count ++;
        }
        perf_mmap__read_done(md);
    }

    if (count != expect) {
        pr_debug("BPF filter result incorrect, expected %d, got %d samples\n", expect, count);
        goto out_delete_evlist;
    }

    ret = TEST_OK;

out_delete_evlist:
    perf_evlist__delete(evlist);
    return ret;
}

static struct bpf_object *
prepare_bpf(void *obj_buf, size_t obj_buf_sz, const char *name)
{
    struct bpf_object *obj;

    obj = bpf__prepare_load_buffer(obj_buf, obj_buf_sz, name);
    if (IS_ERR(obj)) {
        pr_debug("Compile BPF program failed.\n");
        return NULL;
    }
    return obj;
}

static int __test__bpf(int idx)
{
    int ret;
    void *obj_buf;
    size_t obj_buf_sz;
    struct bpf_object *obj;

    ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
                       bpf_testcase_table[idx].prog_id,
                       true, NULL);
    if (ret != TEST_OK || !obj_buf || !obj_buf_sz) {
        pr_debug("Unable to get BPF object, %s\n",
             bpf_testcase_table[idx].msg_compile_fail);
        if (idx == 0)
            return TEST_SKIP;
        else
            return TEST_FAIL;
    }

    obj = prepare_bpf(obj_buf, obj_buf_sz,
              bpf_testcase_table[idx].name);
    if ((!!bpf_testcase_table[idx].target_func) != (!!obj)) {
        if (!obj)
            pr_debug("Fail to load BPF object: %s\n",
                 bpf_testcase_table[idx].msg_load_fail);
        else
            pr_debug("Success unexpectedly: %s\n",
                 bpf_testcase_table[idx].msg_load_fail);
        ret = TEST_FAIL;
        goto out;
    }

    if (obj) {
        ret = do_test(obj,
                  bpf_testcase_table[idx].target_func,
                  bpf_testcase_table[idx].expect_result);
        if (ret != TEST_OK)
            goto out;
        if (bpf_testcase_table[idx].pin) {
            int err;

            if (!bpf_fs__mount()) {
                pr_debug("BPF filesystem not mounted\n");
                ret = TEST_FAIL;
                goto out;
            }
            err = mkdir(PERF_TEST_BPF_PATH, 0777);
            if (err && errno != EEXIST) {
                pr_debug("Failed to make perf_test dir: %s\n",
                     strerror(errno));
                ret = TEST_FAIL;
                goto out;
            }
            if (bpf_object__pin(obj, PERF_TEST_BPF_PATH))
                ret = TEST_FAIL;
            if (rm_rf(PERF_TEST_BPF_PATH))
                ret = TEST_FAIL;
        }
    }

out:
    bpf__clear();
    return ret;
}

int test__bpf_subtest_get_nr(void)
{
    return (int)ARRAY_SIZE(bpf_testcase_table);
}

const char *test__bpf_subtest_get_desc(int i)
{
    if (i < 0 || i >= (int)ARRAY_SIZE(bpf_testcase_table))
        return NULL;
    return bpf_testcase_table[i].desc;
}

static int check_env(void)
{
    int err;
    unsigned int kver_int;
    char license[] = "GPL";

    struct bpf_insn insns[] = {
        BPF_MOV64_IMM(BPF_REG_0, 1),
        BPF_EXIT_INSN(),
    };

    err = fetch_kernel_version(&kver_int, NULL, 0);
    if (err) {
        pr_debug("Unable to get kernel version\n");
        return err;
    }

    err = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
                   sizeof(insns) / sizeof(insns[0]),
                   license, kver_int, NULL, 0);
    if (err < 0) {
        pr_err("Missing basic BPF support, skip this test: %s\n",
               strerror(errno));
        return err;
    }
    close(err);

    return 0;
}

int test__bpf(struct test *test __maybe_unused, int i)
{
    int err;

    if (i < 0 || i >= (int)ARRAY_SIZE(bpf_testcase_table))
        return TEST_FAIL;

    if (geteuid() != 0) {
        pr_debug("Only root can run BPF test\n");
        return TEST_SKIP;
    }

    if (check_env())
        return TEST_SKIP;

    err = __test__bpf(i);
    return err;
}

#else
int test__bpf_subtest_get_nr(void)
{
    return 0;
}

const char *test__bpf_subtest_get_desc(int i __maybe_unused)
{
    return NULL;
}

int test__bpf(struct test *test __maybe_unused, int i __maybe_unused)
{
    pr_debug("Skip BPF test because BPF support is not compiled\n");
    return TEST_SKIP;
}
#endif