[PATCH bpf-next v3 8/8] selftests/bpf: skip the struct_ops arena tests without compiler support

[Vineet Gupta]

trigger() in struct_ops_arena.c and its three siblings puts the
__BPF_FEATURE_ADDR_SPACE_CAST guard inside the function, so without
arena support the body is gone and the program falls through to
"return 0".  The host side then does

  err = bpf_prog_test_run_opts(bpf_program__fd(trigger), &topts);
  ASSERT_OK(err, "test_run");
  ASSERT_EQ(topts.retval, 0, "trigger_retval");

and passes, having run a program that did nothing.  Two tests report OK
under a stock bpf-gcc on that basis: arena_arg and arena_autobind.  The
other two, arena_member and arena_member_render, need a testmod BTF
carrying the arena type tag and are not reached without one, but are
fixed the same way.

These are not driven by test_loader, so __skip_without_arena does not
reach them.  Use the flag-in-.data pattern linked_externs.c already
uses for the same situation: the program exports skip_tests, and the
host checks it before attaching and reports SKIP.

Signed-off-by: Vineet Gupta <vineet.gupta@xxxxxxxxx>
---
 .../bpf/prog_tests/test_struct_ops_arena.c    | 27 +++++++++++++++++++
 .../selftests/bpf/progs/struct_ops_arena.c    | 10 +++++++
 .../bpf/progs/struct_ops_arena_autobind.c     | 10 +++++++
 .../bpf/progs/struct_ops_arena_member.c       | 10 +++++++
 .../progs/struct_ops_arena_member_render.c    | 10 +++++++
 5 files changed, 67 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_arena.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_arena.c
index e7580b9f0fc2..11b7dab77ff7 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_arena.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_arena.c
@@ -31,6 +31,12 @@ static void arena_arg(void)
 	if (!ASSERT_OK_PTR(skel, "struct_ops_arena__open_and_load"))
 		return;
 
+	if (skel->data->skip_tests) {
+		printf("%s:SKIP: no addr_space_cast support in the BPF compiler\n", __func__);
+		test__skip();
+		goto out;
+	}
+
 	link = bpf_map__attach_struct_ops(skel->maps.testmod_arena);
 	if (!ASSERT_OK_PTR(link, "attach_struct_ops"))
 		goto out;
@@ -142,6 +148,13 @@ static void arena_member(void)
 	if (!ASSERT_OK_PTR(skel, "struct_ops_arena_member__open_and_load"))
 		return;
 
+	if (skel->data->skip_tests) {
+		printf("%s:SKIP: no addr_space_cast support in the BPF compiler\n", __func__);
+		test__skip();
+		struct_ops_arena_member__destroy(skel);
+		return;
+	}
+
 	attach_and_trigger(skel->maps.testmod_arena_member, skel->progs.trigger);
 	struct_ops_arena_member__destroy(skel);
 }
@@ -186,6 +199,13 @@ static void arena_autobind(void)
 	assert_prog_map(bpf_program__fd(skel->progs.test_arena_cb), info.id, "test_arena_cb");
 	assert_prog_map(bpf_program__fd(skel->progs.unrelated), info.id, "unrelated");
 
+	if (skel->data->skip_tests) {
+		printf("%s:SKIP: no addr_space_cast support in the BPF compiler\n", __func__);
+		test__skip();
+		struct_ops_arena_autobind__destroy(skel);
+		return;
+	}
+
 	attach_and_trigger(skel->maps.testmod_arena_autobind, skel->progs.trigger);
 out:
 	struct_ops_arena_autobind__destroy(skel);
@@ -268,6 +288,13 @@ static void arena_member_render(void)
 	if (!ASSERT_OK_PTR(skel, "struct_ops_arena_member_render__open_and_load"))
 		return;
 
+	if (skel->data->skip_tests) {
+		printf("%s:SKIP: no addr_space_cast support in the BPF compiler\n", __func__);
+		test__skip();
+		struct_ops_arena_member_render__destroy(skel);
+		return;
+	}
+
 	attach_and_trigger(skel->maps.testmod_arena_member_render, skel->progs.trigger);
 	struct_ops_arena_member_render__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena.c b/tools/testing/selftests/bpf/progs/struct_ops_arena.c
index 8aa8639df91f..612ca868c8fe 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena.c
@@ -83,6 +83,16 @@ struct bpf_testmod_ops3 testmod_arena = {
 	.test_arena_multislot = (void *)test_arena_multislot_cb,
 };
 
+/*
+ * These tests are not driven by test_loader, so __skip_without_arena
+ * cannot reach them; the host side reads this flag and skips instead.
+ */
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+bool skip_tests __attribute((__section__(".data"))) = false;
+#else
+bool skip_tests = true;
+#endif
+
 SEC("syscall")
 int trigger(void *ctx)
 {
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
index 495faa0f4a8b..de026d901dcb 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
@@ -42,6 +42,16 @@ int unrelated(void *ctx)
 	return 0;
 }
 
+/*
+ * These tests are not driven by test_loader, so __skip_without_arena
+ * cannot reach them; the host side reads this flag and skips instead.
+ */
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+bool skip_tests __attribute((__section__(".data"))) = false;
+#else
+bool skip_tests = true;
+#endif
+
 SEC("syscall")
 int trigger(void *ctx)
 {
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
index a2218cd81619..4ec0aead3e95 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
@@ -77,6 +77,16 @@ struct bpf_testmod_ops3 testmod_arena_member = {
 	.test_arena_member = (void *)test_arena_member_cb,
 };
 
+/*
+ * These tests are not driven by test_loader, so __skip_without_arena
+ * cannot reach them; the host side reads this flag and skips instead.
+ */
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+bool skip_tests __attribute((__section__(".data"))) = false;
+#else
+bool skip_tests = true;
+#endif
+
 SEC("syscall")
 int trigger(void *ctx)
 {
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
index 09b4c740bdca..3ccbc6e71626 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
@@ -60,6 +60,16 @@ struct bpf_testmod_ops3 testmod_arena_member_render = {
 	.test_arena_member = (void *)test_arena_member_render_cb,
 };
 
+/*
+ * These tests are not driven by test_loader, so __skip_without_arena
+ * cannot reach them; the host side reads this flag and skips instead.
+ */
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+bool skip_tests __attribute((__section__(".data"))) = false;
+#else
+bool skip_tests = true;
+#endif
+
 SEC("syscall")
 int trigger(void *ctx)
 {
-- 
2.53.0-Meta