selftests/bpf: Test autocreate behavior for struct_ops maps

Check that bpf_map__set_autocreate() can be used to disable automatic
creation for struct_ops maps.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-8-eddyz87@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/struct_ops_autocreate.c b/tools/testing/selftests/bpf/prog_tests/struct_ops_autocreate.c
new file mode 100644 (file)
index 0000000..a5c8bb9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/struct_ops_autocreate.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "struct_ops_autocreate.skel.h"
+
+static void cant_load_full_object(void)
+{
+       struct struct_ops_autocreate *skel;
+       char *log = NULL;
+       int err;
+
+       skel = struct_ops_autocreate__open();
+       if (!ASSERT_OK_PTR(skel, "struct_ops_autocreate__open"))
+               return;
+
+       if (start_libbpf_log_capture())
+               goto cleanup;
+       /* The testmod_2 map BTF type (struct bpf_testmod_ops___v2) doesn't
+        * match the BTF of the actual struct bpf_testmod_ops defined in the
+        * kernel, so we should fail to load it if we don't disable autocreate
+        * for that map.
+        */
+       err = struct_ops_autocreate__load(skel);
+       log = stop_libbpf_log_capture();
+       if (!ASSERT_ERR(err, "struct_ops_autocreate__load"))
+               goto cleanup;
+
+       ASSERT_HAS_SUBSTR(log, "libbpf: struct_ops init_kern", "init_kern message");
+       ASSERT_EQ(err, -ENOTSUP, "errno should be ENOTSUP");
+
+cleanup:
+       free(log);
+       struct_ops_autocreate__destroy(skel);
+}
+
+static void can_load_partial_object(void)
+{
+       struct struct_ops_autocreate *skel;
+       struct bpf_link *link = NULL;
+       int err;
+
+       skel = struct_ops_autocreate__open();
+       if (!ASSERT_OK_PTR(skel, "struct_ops_autocreate__open_opts"))
+               return;
+
+       err = bpf_program__set_autoload(skel->progs.test_2, false);
+       if (!ASSERT_OK(err, "bpf_program__set_autoload"))
+               goto cleanup;
+
+       err = bpf_map__set_autocreate(skel->maps.testmod_2, false);
+       if (!ASSERT_OK(err, "bpf_map__set_autocreate"))
+               goto cleanup;
+
+       err = struct_ops_autocreate__load(skel);
+       if (ASSERT_OK(err, "struct_ops_autocreate__load"))
+               goto cleanup;
+
+       link = bpf_map__attach_struct_ops(skel->maps.testmod_1);
+       if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops"))
+               goto cleanup;
+
+       /* test_1() would be called from bpf_dummy_reg2() in bpf_testmod.c */
+       ASSERT_EQ(skel->bss->test_1_result, 42, "test_1_result");
+
+cleanup:
+       bpf_link__destroy(link);
+       struct_ops_autocreate__destroy(skel);
+}
+
+void test_struct_ops_autocreate(void)
+{
+       if (test__start_subtest("cant_load_full_object"))
+               cant_load_full_object();
+       if (test__start_subtest("can_load_partial_object"))
+               can_load_partial_object();
+}

diff --git a/tools/testing/selftests/bpf/progs/struct_ops_autocreate.c b/tools/testing/selftests/bpf/progs/struct_ops_autocreate.c
new file mode 100644 (file)
index 0000000..9a951ee
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_autocreate.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+int test_1_result = 0;
+
+SEC("struct_ops/test_1")
+int BPF_PROG(test_1)
+{
+       test_1_result = 42;
+       return 0;
+}
+
+SEC("struct_ops/test_1")
+int BPF_PROG(test_2)
+{
+       return 0;
+}
+
+struct bpf_testmod_ops___v1 {
+       int (*test_1)(void);
+};
+
+struct bpf_testmod_ops___v2 {
+       int (*test_1)(void);
+       int (*does_not_exist)(void);
+};
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops___v1 testmod_1 = {
+       .test_1 = (void *)test_1
+};
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops___v2 testmod_2 = {
+       .test_1 = (void *)test_1,
+       .does_not_exist = (void *)test_2
+};