Re: [PATCH bpf-next 5/5] selftests/bpf: test return value handling for struct_ops prog

Hi,

On 9/29/2021 7:19 AM, Andrii Nakryiko wrote:

On Mon, Sep 27, 2021 at 7:38 PM Hou Tao [off-list ref] wrote:

quoted

Running a BPF_PROG_TYPE_STRUCT_OPS prog for dummy_st_ops::init()
through bpf_prog_test_run(). Three test cases are added:
(1) attach dummy_st_ops should fail
(2) function return value of bpf_dummy_ops::init() is expected
(3) pointer argument of bpf_dummy_ops::init() works as expected

Signed-off-by: Hou Tao <redacted>
---
 .../selftests/bpf/prog_tests/dummy_st_ops.c   | 81 +++++++++++++++++++
 .../selftests/bpf/progs/dummy_st_ops.c        | 33 ++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops.c

diff --git a/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c b/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
new file mode 100644
index 000000000000..4b1b52b847e6
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <test_progs.h>
+#include "dummy_st_ops.skel.h"
+
+/* Need to keep consistent with definitions in include/linux/bpf_dummy_ops.h */
+struct bpf_dummy_ops_state {
+       int val;
+};
+
+static void test_dummy_st_ops_attach(void)
+{
+       struct dummy_st_ops *skel;
+       struct bpf_link *link;
+
+       skel = dummy_st_ops__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
+               goto out;

no need for __destroy() as we haven't created skeleton, so this could
be just a return

Will do.

quoted

+
+       link = bpf_map__attach_struct_ops(skel->maps.dummy_1);
+       if (!ASSERT_EQ(libbpf_get_error(link), -EOPNOTSUPP,
+                      "dummy_st_ops_attach"))
+               goto out;

nit: unless you expect to add something here soon, probably doing
ASSERT_EQ() and let it fall through to out: and destroy would be a bit
more readable

Make sense. Will do.

quoted

+out:
+       dummy_st_ops__destroy(skel);
+}
+
+static void test_dummy_init_ret_value(void)
+{
+       struct dummy_st_ops *skel;
+       int err, fd;
+       __u32 duration = 0, retval = 0;
+
+       skel = dummy_st_ops__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
+               goto out;

same, just return is fine and no need for out: label

OK. Will do in v2.

quoted

+
+       fd = bpf_program__fd(skel->progs.init_1);
+       err = bpf_prog_test_run(fd, 1, NULL, 0,
+                               NULL, NULL, &retval, &duration);
+       ASSERT_OK(err, "test_run");
+       ASSERT_EQ(retval, 0xf2f3f4f5, "test_ret");
+out:
+       dummy_st_ops__destroy(skel);
+}
+
+static void test_dummy_init_ptr_arg(void)
+{
+       struct dummy_st_ops *skel;
+       int err, fd;
+       __u32 duration = 0, retval = 0;
+       struct bpf_dummy_ops_state in_state, out_state;
+       __u32 state_size;
+
+       skel = dummy_st_ops__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
+               goto out;

here as well

OK. Will do.

quoted

+
+       fd = bpf_program__fd(skel->progs.init_1);
+       memset(&in_state, 0, sizeof(in_state));
+       in_state.val = 0xbeef;
+       memset(&out_state, 0, sizeof(out_state));
+       err = bpf_prog_test_run(fd, 1, &in_state, sizeof(in_state),
+                               &out_state, &state_size, &retval, &duration);
+       ASSERT_OK(err, "test_run");
+       ASSERT_EQ(state_size, sizeof(out_state), "test_data_out");
+       ASSERT_EQ(out_state.val, 0x5a, "test_ptr_ret");
+       ASSERT_EQ(retval, in_state.val, "test_ret");
+out:
+       dummy_st_ops__destroy(skel);
+}
+
+void test_dummy_st_ops(void)
+{
+       if (test__start_subtest("dummy_st_ops_attach"))
+               test_dummy_st_ops_attach();
+       if (test__start_subtest("dummy_init_ret_value"))
+               test_dummy_init_ret_value();
+       if (test__start_subtest("dummy_init_ptr_arg"))
+               test_dummy_init_ptr_arg();
+}

diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops.c b/tools/testing/selftests/bpf/progs/dummy_st_ops.c
new file mode 100644
index 000000000000..133c328f082a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/dummy_st_ops.c

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct bpf_dummy_ops_state {
+       int val;
+} __attribute__((preserve_access_index));
+
+struct bpf_dummy_ops {
+       int (*init)(struct bpf_dummy_ops_state *state);
+};
+
+char _liencse[] SEC("license") = "GPL";

typo: _license (but it doesn't matter to libbpf, it looks at the
section name only

Will fix.

quoted

+
+SEC("struct_ops/init_1")
+int BPF_PROG(init_1, struct bpf_dummy_ops_state *state)
+{
+       int ret;
+
+       if (!state)
+               return 0xf2f3f4f5;
+
+       ret = state->val;
+       state->val = 0x5a;
+       return ret;
+}
+
+SEC(".struct_ops")
+struct bpf_dummy_ops dummy_1 = {
+       .init = (void *)init_1,
+};
--
2.29.2

.