[PATCH bpf-next 2/2] selftests/bpf: Test bpf_for_each_map_elem on BPF_MAP_TYPE_HASH_OF_MAPS

David Vernet
2023-06-05T20:05:24Z

Now that we support using the bpf_for_each_map_elem() on the
BPF_MAP_TYPE_HASH_OF_MAPS map type, we should add selftests that
verify expected behavior.

This patch addds those selftests. Included in this is a new
test_btf_map_in_map_failure.c BPF prog that can be used to verify
expected map-in-map failures in the verifier.

Signed-off-by: David Vernet <void@manifault.com>
---
.../selftests/bpf/prog_tests/btf_map_in_map.c | 44 +++++++++++
.../selftests/bpf/progs/test_btf_map_in_map.c | 73 ++++++++++++++++++-
.../bpf/progs/test_btf_map_in_map_failure.c | 39 ++++++++++
3 files changed, 155 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/progs/test_btf_map_in_map_failure.c

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c b/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
index a8b53b8736f0..257b5b5a08ba 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
@@ -4,6 +4,7 @@
#include <test_progs.h>

#include "test_btf_map_in_map.skel.h"
+#include "test_btf_map_in_map_failure.skel.h"

static int duration;

@@ -154,6 +155,43 @@ static void test_diff_size(void)
test_btf_map_in_map__destroy(skel);
}

+static void test_hash_iter(const char *prog_name)
+{
+ struct test_btf_map_in_map *skel;
+ struct bpf_program *prog;
+ struct bpf_link *link = NULL;
+ int err, child_pid, status;
+
+ skel = test_btf_map_in_map__open();
+ if (!ASSERT_OK_PTR(skel, "test_btf_map_in_map__open\n"))
+ return;
+
+ skel->bss->pid = getpid();
+ err = test_btf_map_in_map__load(skel);
+ if (!ASSERT_OK(err, "test_btf_map_in_map__load"))
+ goto cleanup;
+
+ prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+ if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+ goto cleanup;
+
+ link = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+ goto cleanup;
+
+ child_pid = fork();
+ if (!ASSERT_GT(child_pid, -1, "child_pid"))
+ goto cleanup;
+ if (child_pid == 0)
+ _exit(0);
+ waitpid(child_pid, &status, 0);
+ ASSERT_OK(skel->bss->err, "post_wait_err");
+
+cleanup:
+ bpf_link__destroy(link);
+ test_btf_map_in_map__destroy(skel);
+}
+
void test_btf_map_in_map(void)
{
if (test__start_subtest("lookup_update"))
@@ -161,4 +199,10 @@ void test_btf_map_in_map(void)

if (test__start_subtest("diff_size"))
test_diff_size();
+
+ if (test__start_subtest("hash_iter"))
+ test_hash_iter("test_iter_hash_of_maps");
+
+ RUN_TESTS(test_btf_map_in_map);
+ RUN_TESTS(test_btf_map_in_map_failure);
}
diff --git a/tools/testing/selftests/bpf/progs/test_btf_map_in_map.c b/tools/testing/selftests/bpf/progs/test_btf_map_in_map.c
index c218cf8989a9..905392de6a3b 100644
--- a/tools/testing/selftests/bpf/progs/test_btf_map_in_map.c
+++ b/tools/testing/selftests/bpf/progs/test_btf_map_in_map.c
@@ -1,7 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2020 Facebook */
-#include <linux/bpf.h>
+#include <linux/types.h>
#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <vmlinux.h>
+
+#include "bpf_misc.h"
+
+int err, pid;

struct inner_map {
__uint(type, BPF_MAP_TYPE_ARRAY);
@@ -120,6 +126,13 @@ struct outer_sockarr_sz1 {

int input = 0;

+static bool is_test_task(void)
+{
+ int cur_pid = bpf_get_current_pid_tgid() >> 32;
+
+ return pid == cur_pid;
+}
+
SEC("raw_tp/sys_enter")
int handle__sys_enter(void *ctx)
{
@@ -147,4 +160,62 @@ int handle__sys_enter(void *ctx)
return 0;
}

+struct callback_ctx {
+ bool invoked;
+ bool failed;
+};
+
+static __u64 set_invoked(struct bpf_map *map, __u64 *key, __u64 *val, struct callback_ctx *ctx)
+{
+ struct bpf_map *inner_map;
+
+ ctx->invoked = true;
+ inner_map = bpf_map_lookup_elem(map, key);
+ if (!inner_map) {
+ ctx->failed = true;
+ return 1;
+ }
+
+ return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_iter_hash_of_maps, struct task_struct *task, u64 clone_flags)
+{
+ long ret;
+ struct callback_ctx callback_ctx = {
+ .invoked = false,
+ .failed = false,
+ };
+
+ if (!is_test_task())
+ return 0;
+
+ ret = bpf_for_each_map_elem(&outer_hash, set_invoked, &callback_ctx, 0);
+ if (ret < 1)
+ err = 1;
+
+ if (!callback_ctx.invoked)
+ err = 2;
+
+ if (callback_ctx.failed)
+ err = 3;
+
+ return 0;
+}
+
+static __u64 empty_cb(struct bpf_map *map, __u64 *key, __u64 *val, void *ctx)
+{
+ return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__success
+int BPF_PROG(test_iter_hash_of_maps_no_ctx, struct task_struct *task, u64 clone_flags)
+{
+ /* Should be able to iterate with no context as well. */
+ bpf_for_each_map_elem(&outer_hash, empty_cb, NULL, 0);
+ return 0;
+}
+
char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/test_btf_map_in_map_failure.c b/tools/testing/selftests/bpf/progs/test_btf_map_in_map_failure.c
new file mode 100644
index 000000000000..6b7a94fe15c7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_btf_map_in_map_failure.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/types.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <vmlinux.h>
+
+#include "bpf_misc.h"
+
+struct inner_map {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, int);
+ __type(value, int);
+} inner_map1 SEC(".maps"),
+ inner_map2 SEC(".maps");
+
+struct outer_hash {
+ __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
+ __uint(max_entries, 2);
+ __type(key, int);
+ __array(values, struct inner_map);
+} outer_hash SEC(".maps") = {
+ .values = {
+ [0] = &inner_map2,
+ [1] = &inner_map1,
+ },
+};
+
+SEC("tp_btf/task_newtask")
+__failure
+__msg("R2 type=scalar expected=func")
+int BPF_PROG(test_iter_hash_of_maps_null_cb, struct task_struct *task, u64 clone_flags)
+{
+ /* Can't iterate over a NULL callback. */
+ bpf_for_each_map_elem(&outer_hash, NULL, NULL, 0);
+ return 0;
+}
--
2.40.1