> On Sep 30, 2020, at 2:28 PM, Song Liu <songliubraving@xxxxxx> wrote:
>
> Add tests for perf event array with and without BPF_F_PRESERVE_ELEMS.
>
> Add a perf event to array via fd mfd. Without BPF_F_PRESERVE_ELEMS, the
> perf event is removed when mfd is closed. With BPF_F_PRESERVE_ELEMS, the
> perf event is removed when the map is freed.
>
> Signed-off-by: Song Liu <songliubraving@xxxxxx>
> ---
> .../bpf/prog_tests/pe_preserve_elems.c | 66 +++++++++++++++++++
> .../bpf/progs/test_pe_preserve_elems.c | 44 +++++++++++++
> 2 files changed, 110 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/pe_preserve_elems.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_pe_preserve_elems.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/pe_preserve_elems.c b/tools/testing/selftests/bpf/prog_tests/pe_preserve_elems.c
> new file mode 100644
> index 0000000000000..673d38395253b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/pe_preserve_elems.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2019 Facebook */
> +#include <test_progs.h>
> +#include <linux/bpf.h>
> +#include "test_pe_preserve_elems.skel.h"
> +
> +static int duration;
> +
> +static void test_one_map(struct bpf_map *map, struct bpf_program *prog,
> + bool has_share_pe)
> +{
> + int err, key = 0, pfd = -1, mfd = bpf_map__fd(map);
> + DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts);
> + struct perf_event_attr attr = {
> + .size = sizeof(struct perf_event_attr),
> + .type = PERF_TYPE_SOFTWARE,
> + .config = PERF_COUNT_SW_CPU_CLOCK,
> + };
> +
> + pfd = syscall(__NR_perf_event_open, &attr, 0 /* pid */,
> + -1 /* cpu 0 */, -1 /* group id */, 0 /* flags */);
> + if (CHECK(pfd < 0, "perf_event_open", "failed\n"))
> + return;
> +
> + err = bpf_map_update_elem(mfd, &key, &pfd, BPF_ANY);
> + close(pfd);
> + if (CHECK(err < 0, "bpf_map_update_elem", "failed\n"))
> + return;
> +
> + err = bpf_prog_test_run_opts(bpf_program__fd(prog), &opts);
> + if (CHECK(err < 0, "bpf_prog_test_run_opts", "failed\n"))
> + return;
> + if (CHECK(opts.retval != 0, "bpf_perf_event_read_value",
> + "failed with %d\n", opts.retval))
> + return;
> +
> + /* closing mfd, prog still holds a reference on map */
> + close(mfd);
> +
> + err = bpf_prog_test_run_opts(bpf_program__fd(prog), &opts);
> + if (CHECK(err < 0, "bpf_prog_test_run_opts", "failed\n"))
> + return;
> +
> + if (has_share_pe) {
> + CHECK(opts.retval != 0, "bpf_perf_event_read_value",
> + "failed with %d\n", opts.retval);
> + } else {
> + CHECK(opts.retval != -ENOENT, "bpf_perf_event_read_value",
> + "should have failed with %d, but got %d\n", -ENOENT,
> + opts.retval);
> + }
> +}
> +
> +void test_pe_preserve_elems(void)
> +{
> + struct test_pe_preserve_elems *skel;
> +
> + skel = test_pe_preserve_elems__open_and_load();
> + if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
> + return;
> +
> + test_one_map(skel->maps.array_1, skel->progs.read_array_1, false);
> + test_one_map(skel->maps.array_2, skel->progs.read_array_2, true);
> +
> + test_pe_preserve_elems__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_pe_preserve_elems.c b/tools/testing/selftests/bpf/progs/test_pe_preserve_elems.c
> new file mode 100644
> index 0000000000000..dc77e406de41f
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_pe_preserve_elems.c
> @@ -0,0 +1,44 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2020 Facebook
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(max_entries, 1);
> + __uint(key_size, sizeof(int));
> + __uint(value_size, sizeof(int));
> +} array_1 SEC(".maps");
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(max_entries, 1);
> + __uint(key_size, sizeof(int));
> + __uint(value_size, sizeof(int));
> + __uint(map_flags, BPF_F_PRESERVE_ELEMS);
> +} array_2 SEC(".maps");
> +
> +SEC("raw_tp/sched_switch")
> +int BPF_PROG(read_array_1)
> +{
> + struct bpf_perf_event_value val;
> + long ret;
> +
> + ret = bpf_perf_event_read_value(&array_1, 0, &val, sizeof(val));
> + bpf_printk("read_array_1 returns %ld", ret);
Oops, I didn't do amend... Please ignore this version..
I am so sorry for the problem...
Song
> + return ret;
> +}
> +
> +SEC("raw_tp/task_rename")
> +int BPF_PROG(read_array_2)
> +{
> + struct bpf_perf_event_value val;
> + long ret;
> +
> + ret = bpf_perf_event_read_value(&array_2, 0, &val, sizeof(val));
> + bpf_printk("read_array_2 returns %ld", ret);
> + return ret;
> +}
> +
> +char LICENSE[] SEC("license") = "GPL";
> --
> 2.24.1
>
