Commit d6b42068 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for BPF_F_PRESERVE_ELEMS 



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: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200930224927.1936644-3-songliubraving@fb.com
parent 792caccc

tools/testing/selftests/bpf/prog_tests/pe_preserve_elems.c

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// 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);

}

tools/testing/selftests/bpf/progs/test_pe_preserve_elems.c

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// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2020 Facebook

#include <linux/bpf.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;



	return bpf_perf_event_read_value(&array_1, 0, &val, sizeof(val));

}



SEC("raw_tp/task_rename")

int BPF_PROG(read_array_2)

{

	struct bpf_perf_event_value val;



	return bpf_perf_event_read_value(&array_2, 0, &val, sizeof(val));

}



char LICENSE[] SEC("license") = "GPL";