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Commit ba72a7b4 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
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selftests/bpf: test for BPF_F_LOCK 



Add C based test that runs 4 bpf programs in parallel
that update the same hash and array maps.
And another 2 threads that read from these two maps
via lookup(key, value, BPF_F_LOCK) api
to make sure the user space sees consistent value in both
hash and array elements while user space races with kernel bpf progs.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent df5d22fa

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ BPF_OBJ_FILES = \ 
	sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \

	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \

	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_xdp_vlan.o \

	xdp_dummy.o test_map_in_map.o test_spin_lock.o

	xdp_dummy.o test_map_in_map.o test_spin_lock.o test_map_lock.o



# Objects are built with default compilation flags and with sub-register

# code-gen enabled.

tools/testing/selftests/bpf/test_map_lock.c

0 → 100644
+66 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2019 Facebook

#include <linux/bpf.h>

#include <linux/version.h>

#include "bpf_helpers.h"



#define VAR_NUM 16



struct hmap_elem {

	struct bpf_spin_lock lock;

	int var[VAR_NUM];

};



struct bpf_map_def SEC("maps") hash_map = {

	.type = BPF_MAP_TYPE_HASH,

	.key_size = sizeof(int),

	.value_size = sizeof(struct hmap_elem),

	.max_entries = 1,

};



BPF_ANNOTATE_KV_PAIR(hash_map, int, struct hmap_elem);



struct array_elem {

	struct bpf_spin_lock lock;

	int var[VAR_NUM];

};



struct bpf_map_def SEC("maps") array_map = {

	.type = BPF_MAP_TYPE_ARRAY,

	.key_size = sizeof(int),

	.value_size = sizeof(struct array_elem),

	.max_entries = 1,

};



BPF_ANNOTATE_KV_PAIR(array_map, int, struct array_elem);



SEC("map_lock_demo")

int bpf_map_lock_test(struct __sk_buff *skb)

{

	struct hmap_elem zero = {}, *val;

	int rnd = bpf_get_prandom_u32();

	int key = 0, err = 1, i;

	struct array_elem *q;



	val = bpf_map_lookup_elem(&hash_map, &key);

	if (!val)

		goto err;

	/* spin_lock in hash map */

	bpf_spin_lock(&val->lock);

	for (i = 0; i < VAR_NUM; i++)

		val->var[i] = rnd;

	bpf_spin_unlock(&val->lock);



	/* spin_lock in array */

	q = bpf_map_lookup_elem(&array_map, &key);

	if (!q)

		goto err;

	bpf_spin_lock(&q->lock);

	for (i = 0; i < VAR_NUM; i++)

		q->var[i] = rnd;

	bpf_spin_unlock(&q->lock);

	err = 0;

err:

	return err;

}

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

tools/testing/selftests/bpf/test_progs.c

+74 −0
Original line number Diff line number Diff line
@@ -2025,6 +2025,79 @@ static void test_spinlock(void) 
	bpf_object__close(obj);

}



static void *parallel_map_access(void *arg)

{

	int err, map_fd = *(u32 *) arg;

	int vars[17], i, j, rnd, key = 0;



	for (i = 0; i < 10000; i++) {

		err = bpf_map_lookup_elem_flags(map_fd, &key, vars, BPF_F_LOCK);

		if (err) {

			printf("lookup failed\n");

			error_cnt++;

			goto out;

		}

		if (vars[0] != 0) {

			printf("lookup #%d var[0]=%d\n", i, vars[0]);

			error_cnt++;

			goto out;

		}

		rnd = vars[1];

		for (j = 2; j < 17; j++) {

			if (vars[j] == rnd)

				continue;

			printf("lookup #%d var[1]=%d var[%d]=%d\n",

			       i, rnd, j, vars[j]);

			error_cnt++;

			goto out;

		}

	}

out:

	pthread_exit(arg);

}



static void test_map_lock(void)

{

	const char *file = "./test_map_lock.o";

	int prog_fd, map_fd[2], vars[17] = {};

	pthread_t thread_id[6];

	struct bpf_object *obj;

	int err = 0, key = 0, i;

	void *ret;



	err = bpf_prog_load(file, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd);

	if (err) {

		printf("test_map_lock:bpf_prog_load errno %d\n", errno);

		goto close_prog;

	}

	map_fd[0] = bpf_find_map(__func__, obj, "hash_map");

	if (map_fd[0] < 0)

		goto close_prog;

	map_fd[1] = bpf_find_map(__func__, obj, "array_map");

	if (map_fd[1] < 0)

		goto close_prog;



	bpf_map_update_elem(map_fd[0], &key, vars, BPF_F_LOCK);



	for (i = 0; i < 4; i++)

		assert(pthread_create(&thread_id[i], NULL,

				      &test_spin_lock, &prog_fd) == 0);

	for (i = 4; i < 6; i++)

		assert(pthread_create(&thread_id[i], NULL,

				      &parallel_map_access, &map_fd[i - 4]) == 0);

	for (i = 0; i < 4; i++)

		assert(pthread_join(thread_id[i], &ret) == 0 &&

		       ret == (void *)&prog_fd);

	for (i = 4; i < 6; i++)

		assert(pthread_join(thread_id[i], &ret) == 0 &&

		       ret == (void *)&map_fd[i - 4]);

	goto close_prog_noerr;

close_prog:

	error_cnt++;

close_prog_noerr:

	bpf_object__close(obj);

}



int main(void)

{

	srand(time(NULL));
@@ -2054,6 +2127,7 @@ int main(void) 
	test_queue_stack_map(STACK);

	test_flow_dissector();

	test_spinlock();

	test_map_lock();



	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);

	return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;