[bpf-next,v3,2/2] selftests/bpf: add .BTF.ext line/func info getter tests

Commit Message

Mykyta Yatsenko April 1, 2025, 4:54 p.m. UTC

From: Mykyta Yatsenko <[e-mail]>

Add selftests checking that line and func info retrieved by newly added
libbpf APIs are the same as returned by kernel via bpf_prog_get_info_by_fd.

Signed-off-by: Mykyta Yatsenko <[e-mail]>
---
 .../selftests/bpf/prog_tests/test_btf_ext.c   | 111 ++++++++++++++++++
 .../selftests/bpf/progs/test_btf_ext.c        |  21 ++++
 2 files changed, 132 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_btf_ext.c

Comments

Andrii Nakryiko April 1, 2025, 8:06 p.m. UTC | #1

On Tue, Apr 1, 2025 at 9:54 AM Mykyta Yatsenko
<[e-mail]> wrote:
>
> From: Mykyta Yatsenko <[e-mail]>
>
> Add selftests checking that line and func info retrieved by newly added
> libbpf APIs are the same as returned by kernel via bpf_prog_get_info_by_fd.
>
> Signed-off-by: Mykyta Yatsenko <[e-mail]>
> ---
>  .../selftests/bpf/prog_tests/test_btf_ext.c   | 111 ++++++++++++++++++
>  .../selftests/bpf/progs/test_btf_ext.c        |  21 ++++
>  2 files changed, 132 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_btf_ext.c
>

Seems like s390x isn't happy about this test, please check what's
going on there. See some nits below as well.

API-wise everything looks good, though.

pw-bot: cr

> diff --git a/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
> new file mode 100644
> index 000000000000..00aeebc8f863
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
> @@ -0,0 +1,111 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */

outdated copy/paste

> +#include <test_progs.h>
> +#include "test_btf_ext.skel.h"
> +#include "btf_helpers.h"
> +
> +static void subtest_line_info(void)
> +{
> +       struct test_btf_ext *skel;
> +       struct bpf_prog_info info;
> +       struct bpf_line_info line_info[1024], *libbpf_line_info;
> +       __u32 info_len = sizeof(info), libbbpf_line_info_cnt;
> +       int err, fd, i;
> +
> +       skel = test_btf_ext__open();
> +       if (!ASSERT_OK_PTR(skel, "skel_open"))
> +               return;
> +
> +       bpf_program__set_autoload(skel->progs.global_func, true);

no need to set this explicitly, it will be auto-loaded anyways

> +
> +       err = test_btf_ext__load(skel);
> +       if (!ASSERT_OK(err, "skel_load"))
> +               goto out;

you can actually shorten these two steps to test_btf_ext__open_and_load()

> +
> +       fd = bpf_program__fd(skel->progs.global_func);
> +
> +       memset(&info, 0, sizeof(info));
> +       info.line_info = ptr_to_u64(&line_info);
> +       info.nr_line_info = sizeof(line_info);
> +       info.line_info_rec_size = sizeof(*line_info);
> +       err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
> +       if (!ASSERT_OK(err, "prog_info"))
> +               goto out;
> +
> +       libbpf_line_info = bpf_program__line_info(skel->progs.global_func);
> +       libbbpf_line_info_cnt = bpf_program__line_info_cnt(skel->progs.global_func);
> +
> +       if (!ASSERT_OK_PTR(libbpf_line_info, "bpf_program__line_info"))
> +               goto out;
> +       if (!ASSERT_GT(libbbpf_line_info_cnt, 0, "line_info_cnt>0"))
> +               goto out;
> +       if (!ASSERT_EQ(libbbpf_line_info_cnt, info.nr_line_info, "line_info_cnt"))
> +               goto out;

hm.., why _GT and _EQ?... Shouldn't just ASSERT_EQ be enough?

> +
> +       for (i = 0; i < libbbpf_line_info_cnt; ++i) {
> +               int eq = memcmp(libbpf_line_info + i, line_info + i, sizeof(*line_info));
> +
> +               if (!ASSERT_EQ(eq, 0, "line_info"))
> +                       goto out;
> +       }

seems like we have ASSERT_MEMEQ(), let's use that? I'd probably get
rid of the loop to not spam test output too much. Just one big
ASSERT_MEMEQ() should be good enough (though admittedly would be
harder to debug, if something breaks... but we don't expect that, so
it's probably fine a tradeoff)

> +
> +out:
> +       test_btf_ext__destroy(skel);
> +}
> +
> +static void subtest_func_info(void)
> +{
> +       struct test_btf_ext *skel;
> +       struct bpf_prog_info info;
> +       struct bpf_func_info func_info[1024], *libbpf_func_info;
> +       __u32 info_len = sizeof(info), libbbpf_func_info_cnt;
> +       int err, fd, i;
> +
> +       skel = test_btf_ext__open();
> +       if (!ASSERT_OK_PTR(skel, "skel_open"))
> +               return;
> +
> +       bpf_program__set_autoload(skel->progs.global_func, true);
> +
> +       err = test_btf_ext__load(skel);
> +       if (!ASSERT_OK(err, "skel_load"))
> +               goto out;
> +
> +       fd = bpf_program__fd(skel->progs.global_func);
> +
> +       memset(&info, 0, sizeof(info));
> +       info.func_info = ptr_to_u64(&func_info);
> +       info.nr_func_info = sizeof(func_info);
> +       info.func_info_rec_size = sizeof(*func_info);
> +       err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
> +       if (!ASSERT_OK(err, "prog_info"))
> +               goto out;
> +
> +       libbpf_func_info = bpf_program__func_info(skel->progs.global_func);
> +       libbbpf_func_info_cnt = bpf_program__func_info_cnt(skel->progs.global_func);
> +
> +       if (!ASSERT_OK_PTR(libbpf_func_info, "bpf_program__func_info"))
> +               goto out;
> +       if (!ASSERT_GT(libbbpf_func_info_cnt, 0, "func_info_cnt>0"))
> +               goto out;
> +       if (!ASSERT_EQ(libbbpf_func_info_cnt, info.nr_func_info, "func_info_cnt"))
> +               goto out;
> +
> +       for (i = 0; i < libbbpf_func_info_cnt; ++i) {
> +               int eq = memcmp(libbpf_func_info + i, func_info + i, sizeof(*func_info));
> +
> +               if (!ASSERT_EQ(eq, 0, "func_info"))
> +                       goto out;
> +       }
> +
> +out:
> +       test_btf_ext__destroy(skel);
> +}
> +
> +void test_btf_ext(void)
> +{
> +       if (test__start_subtest("func_info"))
> +               subtest_func_info();
> +       if (test__start_subtest("line_info"))
> +               subtest_line_info();

nit: I'd combine those two subtests into one test, same program, same
logic to get data, two ASSERT_MEMEQ(), not sure subtest is buying us
anything

> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_btf_ext.c b/tools/testing/selftests/bpf/progs/test_btf_ext.c
> new file mode 100644
> index 000000000000..be92e445a988
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_btf_ext.c
> @@ -0,0 +1,21 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2025 Meta Platforms Inc. */
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +const volatile int val = 3;
> +
> +static __attribute__ ((noinline))

use __noinline, it's defined in bpf_helpers.h

> +int f0(int var)
> +{
> +       int retval = var + val;
> +
> +       return retval;
> +}
> +
> +SEC("tc")
> +int global_func(struct __sk_buff *skb)
> +{
> +       return f0(skb->len);
> +}
> --
> 2.49.0
>

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
new file mode 100644
index 000000000000..00aeebc8f863
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_btf_ext.c
@@ -0,0 +1,111 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+#include "test_btf_ext.skel.h"
+#include "btf_helpers.h"
+
+static void subtest_line_info(void)
+{
+	struct test_btf_ext *skel;
+	struct bpf_prog_info info;
+	struct bpf_line_info line_info[1024], *libbpf_line_info;
+	__u32 info_len = sizeof(info), libbbpf_line_info_cnt;
+	int err, fd, i;
+
+	skel = test_btf_ext__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.global_func, true);
+
+	err = test_btf_ext__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto out;
+
+	fd = bpf_program__fd(skel->progs.global_func);
+
+	memset(&info, 0, sizeof(info));
+	info.line_info = ptr_to_u64(&line_info);
+	info.nr_line_info = sizeof(line_info);
+	info.line_info_rec_size = sizeof(*line_info);
+	err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
+	if (!ASSERT_OK(err, "prog_info"))
+		goto out;
+
+	libbpf_line_info = bpf_program__line_info(skel->progs.global_func);
+	libbbpf_line_info_cnt = bpf_program__line_info_cnt(skel->progs.global_func);
+
+	if (!ASSERT_OK_PTR(libbpf_line_info, "bpf_program__line_info"))
+		goto out;
+	if (!ASSERT_GT(libbbpf_line_info_cnt, 0, "line_info_cnt>0"))
+		goto out;
+	if (!ASSERT_EQ(libbbpf_line_info_cnt, info.nr_line_info, "line_info_cnt"))
+		goto out;
+
+	for (i = 0; i < libbbpf_line_info_cnt; ++i) {
+		int eq = memcmp(libbpf_line_info + i, line_info + i, sizeof(*line_info));
+
+		if (!ASSERT_EQ(eq, 0, "line_info"))
+			goto out;
+	}
+
+out:
+	test_btf_ext__destroy(skel);
+}
+
+static void subtest_func_info(void)
+{
+	struct test_btf_ext *skel;
+	struct bpf_prog_info info;
+	struct bpf_func_info func_info[1024], *libbpf_func_info;
+	__u32 info_len = sizeof(info), libbbpf_func_info_cnt;
+	int err, fd, i;
+
+	skel = test_btf_ext__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.global_func, true);
+
+	err = test_btf_ext__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto out;
+
+	fd = bpf_program__fd(skel->progs.global_func);
+
+	memset(&info, 0, sizeof(info));
+	info.func_info = ptr_to_u64(&func_info);
+	info.nr_func_info = sizeof(func_info);
+	info.func_info_rec_size = sizeof(*func_info);
+	err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
+	if (!ASSERT_OK(err, "prog_info"))
+		goto out;
+
+	libbpf_func_info = bpf_program__func_info(skel->progs.global_func);
+	libbbpf_func_info_cnt = bpf_program__func_info_cnt(skel->progs.global_func);
+
+	if (!ASSERT_OK_PTR(libbpf_func_info, "bpf_program__func_info"))
+		goto out;
+	if (!ASSERT_GT(libbbpf_func_info_cnt, 0, "func_info_cnt>0"))
+		goto out;
+	if (!ASSERT_EQ(libbbpf_func_info_cnt, info.nr_func_info, "func_info_cnt"))
+		goto out;
+
+	for (i = 0; i < libbbpf_func_info_cnt; ++i) {
+		int eq = memcmp(libbpf_func_info + i, func_info + i, sizeof(*func_info));
+
+		if (!ASSERT_EQ(eq, 0, "func_info"))
+			goto out;
+	}
+
+out:
+	test_btf_ext__destroy(skel);
+}
+
+void test_btf_ext(void)
+{
+	if (test__start_subtest("func_info"))
+		subtest_func_info();
+	if (test__start_subtest("line_info"))
+		subtest_line_info();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_btf_ext.c b/tools/testing/selftests/bpf/progs/test_btf_ext.c
new file mode 100644
index 000000000000..be92e445a988
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_btf_ext.c
@@ -0,0 +1,21 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2025 Meta Platforms Inc. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+const volatile int val = 3;
+
+static __attribute__ ((noinline))
+int f0(int var)
+{
+	int retval = var + val;
+
+	return retval;
+}
+
+SEC("tc")
+int global_func(struct __sk_buff *skb)
+{
+	return f0(skb->len);
+}