Commit 5d8d6634 authored by Dave Marchevsky's avatar Dave Marchevsky Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add local kptr stashing test 



Add a new selftest, local_kptr_stash, which uses bpf_kptr_xchg to stash
a bpf_obj_new-allocated object in a map. Test the following scenarios:

  * Stash two rb_nodes in an arraymap, don't unstash them, rely on map
    free to destruct them
  * Stash two rb_nodes in an arraymap, unstash the second one in a
    separate program, rely on map free to destruct first

Signed-off-by: default avatarDave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230310230743.2320707-4-davemarchevsky@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 738c96d5

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include <test_progs.h>

#include <network_helpers.h>



#include "local_kptr_stash.skel.h"

static void test_local_kptr_stash_simple(void)

{

	LIBBPF_OPTS(bpf_test_run_opts, opts,

		    .data_in = &pkt_v4,

		    .data_size_in = sizeof(pkt_v4),

		    .repeat = 1,

	);

	struct local_kptr_stash *skel;

	int ret;



	skel = local_kptr_stash__open_and_load();

	if (!ASSERT_OK_PTR(skel, "local_kptr_stash__open_and_load"))

		return;



	ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.stash_rb_nodes), &opts);

	ASSERT_OK(ret, "local_kptr_stash_add_nodes run");

	ASSERT_OK(opts.retval, "local_kptr_stash_add_nodes retval");



	local_kptr_stash__destroy(skel);

}



static void test_local_kptr_stash_unstash(void)

{

	LIBBPF_OPTS(bpf_test_run_opts, opts,

		    .data_in = &pkt_v4,

		    .data_size_in = sizeof(pkt_v4),

		    .repeat = 1,

	);

	struct local_kptr_stash *skel;

	int ret;



	skel = local_kptr_stash__open_and_load();

	if (!ASSERT_OK_PTR(skel, "local_kptr_stash__open_and_load"))

		return;



	ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.stash_rb_nodes), &opts);

	ASSERT_OK(ret, "local_kptr_stash_add_nodes run");

	ASSERT_OK(opts.retval, "local_kptr_stash_add_nodes retval");



	ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.unstash_rb_node), &opts);

	ASSERT_OK(ret, "local_kptr_stash_add_nodes run");

	ASSERT_EQ(opts.retval, 42, "local_kptr_stash_add_nodes retval");



	local_kptr_stash__destroy(skel);

}



void test_local_kptr_stash_success(void)

{

	if (test__start_subtest("local_kptr_stash_simple"))

		test_local_kptr_stash_simple();

	if (test__start_subtest("local_kptr_stash_unstash"))

		test_local_kptr_stash_unstash();

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_core_read.h>

#include "bpf_experimental.h"



struct node_data {

	long key;

	long data;

	struct bpf_rb_node node;

};



struct map_value {

	struct prog_test_ref_kfunc *not_kptr;

	struct prog_test_ref_kfunc __kptr *val;

	struct node_data __kptr *node;

};



/* This is necessary so that LLVM generates BTF for node_data struct

 * If it's not included, a fwd reference for node_data will be generated but

 * no struct. Example BTF of "node" field in map_value when not included:

 *

 * [10] PTR '(anon)' type_id=35

 * [34] FWD 'node_data' fwd_kind=struct

 * [35] TYPE_TAG 'kptr_ref' type_id=34

 *

 * (with no node_data struct defined)

 * Had to do the same w/ bpf_kfunc_call_test_release below

 */

struct node_data *just_here_because_btf_bug;



extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, int);

	__type(value, struct map_value);

	__uint(max_entries, 2);

} some_nodes SEC(".maps");



static int create_and_stash(int idx, int val)

{

	struct map_value *mapval;

	struct node_data *res;



	mapval = bpf_map_lookup_elem(&some_nodes, &idx);

	if (!mapval)

		return 1;



	res = bpf_obj_new(typeof(*res));

	if (!res)

		return 1;

	res->key = val;



	res = bpf_kptr_xchg(&mapval->node, res);

	if (res)

		bpf_obj_drop(res);

	return 0;

}



SEC("tc")

long stash_rb_nodes(void *ctx)

{

	return create_and_stash(0, 41) ?: create_and_stash(1, 42);

}



SEC("tc")

long unstash_rb_node(void *ctx)

{

	struct map_value *mapval;

	struct node_data *res;

	long retval;

	int key = 1;



	mapval = bpf_map_lookup_elem(&some_nodes, &key);

	if (!mapval)

		return 1;



	res = bpf_kptr_xchg(&mapval->node, NULL);

	if (res) {

		retval = res->key;

		bpf_obj_drop(res);

		return retval;

	}

	return 1;

}



SEC("tc")

long stash_test_ref_kfunc(void *ctx)

{

	struct prog_test_ref_kfunc *res;

	struct map_value *mapval;

	int key = 0;



	mapval = bpf_map_lookup_elem(&some_nodes, &key);

	if (!mapval)

		return 1;



	res = bpf_kptr_xchg(&mapval->val, NULL);

	if (res)

		bpf_kfunc_call_test_release(res);

	return 0;

}



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