selftests/bpf: Test subskeleton functionality

This patch changes the selftests/bpf Makefile to also generate
a subskel.h for every skel.h it would have normally generated.

Separately, it also introduces a new subskeleton test which tests
library objects, externs, weak symbols, kconfigs, and user maps.

Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1bd24956940bbbfe169bb34f7f87b11df52ef011.1647473511.git.delyank@fb.com

1 files changed, 78 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/subskeleton.c b/tools/testing/selftests/bpf/prog_tests/subskeleton.c
new file mode 100644
index 000000000000..9c31b7004f9c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/subskeleton.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include "test_subskeleton.skel.h"
+#include "test_subskeleton_lib.subskel.h"
+
+static void subskeleton_lib_setup(struct bpf_object *obj)
+{
+	struct test_subskeleton_lib *lib = test_subskeleton_lib__open(obj);
+
+	if (!ASSERT_OK_PTR(lib, "open subskeleton"))
+		return;
+
+	*lib->rodata.var1 = 1;
+	*lib->data.var2 = 2;
+	lib->bss.var3->var3_1 = 3;
+	lib->bss.var3->var3_2 = 4;
+
+	test_subskeleton_lib__destroy(lib);
+}
+
+static int subskeleton_lib_subresult(struct bpf_object *obj)
+{
+	struct test_subskeleton_lib *lib = test_subskeleton_lib__open(obj);
+	int result;
+
+	if (!ASSERT_OK_PTR(lib, "open subskeleton"))
+		return -EINVAL;
+
+	result = *lib->bss.libout1;
+	ASSERT_EQ(result, 1 + 2 + 3 + 4 + 5 + 6, "lib subresult");
+
+	ASSERT_OK_PTR(lib->progs.lib_perf_handler, "lib_perf_handler");
+	ASSERT_STREQ(bpf_program__name(lib->progs.lib_perf_handler),
+		     "lib_perf_handler", "program name");
+
+	ASSERT_OK_PTR(lib->maps.map1, "map1");
+	ASSERT_STREQ(bpf_map__name(lib->maps.map1), "map1", "map name");
+
+	ASSERT_EQ(*lib->data.var5, 5, "__weak var5");
+	ASSERT_EQ(*lib->data.var6, 6, "extern var6");
+	ASSERT_TRUE(*lib->kconfig.CONFIG_BPF_SYSCALL, "CONFIG_BPF_SYSCALL");
+
+	test_subskeleton_lib__destroy(lib);
+	return result;
+}
+
+void test_subskeleton(void)
+{
+	int err, result;
+	struct test_subskeleton *skel;
+
+	skel = test_subskeleton__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->rodata->rovar1 = 10;
+	skel->rodata->var1 = 1;
+	subskeleton_lib_setup(skel->obj);
+
+	err = test_subskeleton__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	err = test_subskeleton__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto cleanup;
+
+	/* trigger tracepoint */
+	usleep(1);
+
+	result = subskeleton_lib_subresult(skel->obj) * 10;
+	ASSERT_EQ(skel->bss->out1, result, "unexpected calculation");
+
+cleanup:
+	test_subskeleton__destroy(skel);
+}