selftests/bpf: Add uprobe_multi link test

Adding uprobe_multi test for bpf_link_create attach function.

Testing attachment using the struct bpf_link_create_opts.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-22-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c

@@ -3,6 +3,7 @@
 #include <unistd.h>
 #include <test_progs.h>
 #include "uprobe_multi.skel.h"
+#include "bpf/libbpf_internal.h"
 
 static char test_data[] = "test_data";
 
@@ -130,6 +131,72 @@ static void test_attach_api_syms(void)
 	test_attach_api("/proc/self/exe", NULL, &opts);
 }
 
+static void test_link_api(void)
+{
+	int prog_fd, link1_fd = -1, link2_fd = -1, link3_fd = -1, link4_fd = -1;
+	LIBBPF_OPTS(bpf_link_create_opts, opts);
+	const char *path = "/proc/self/exe";
+	struct uprobe_multi *skel = NULL;
+	unsigned long *offsets = NULL;
+	const char *syms[3] = {
+		"uprobe_multi_func_1",
+		"uprobe_multi_func_2",
+		"uprobe_multi_func_3",
+	};
+	int err;
+
+	err = elf_resolve_syms_offsets(path, 3, syms, (unsigned long **) &offsets);
+	if (!ASSERT_OK(err, "elf_resolve_syms_offsets"))
+		return;
+
+	opts.uprobe_multi.path = path;
+	opts.uprobe_multi.offsets = offsets;
+	opts.uprobe_multi.cnt = ARRAY_SIZE(syms);
+
+	skel = uprobe_multi__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load"))
+		goto cleanup;
+
+	opts.kprobe_multi.flags = 0;
+	prog_fd = bpf_program__fd(skel->progs.uprobe);
+	link1_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
+	if (!ASSERT_GE(link1_fd, 0, "link1_fd"))
+		goto cleanup;
+
+	opts.kprobe_multi.flags = BPF_F_UPROBE_MULTI_RETURN;
+	prog_fd = bpf_program__fd(skel->progs.uretprobe);
+	link2_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
+	if (!ASSERT_GE(link2_fd, 0, "link2_fd"))
+		goto cleanup;
+
+	opts.kprobe_multi.flags = 0;
+	prog_fd = bpf_program__fd(skel->progs.uprobe_sleep);
+	link3_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
+	if (!ASSERT_GE(link3_fd, 0, "link3_fd"))
+		goto cleanup;
+
+	opts.kprobe_multi.flags = BPF_F_UPROBE_MULTI_RETURN;
+	prog_fd = bpf_program__fd(skel->progs.uretprobe_sleep);
+	link4_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
+	if (!ASSERT_GE(link4_fd, 0, "link4_fd"))
+		goto cleanup;
+
+	uprobe_multi_test_run(skel);
+
+cleanup:
+	if (link1_fd >= 0)
+		close(link1_fd);
+	if (link2_fd >= 0)
+		close(link2_fd);
+	if (link3_fd >= 0)
+		close(link3_fd);
+	if (link4_fd >= 0)
+		close(link4_fd);
+
+	uprobe_multi__destroy(skel);
+	free(offsets);
+}
+
 void test_uprobe_multi_test(void)
 {
 	if (test__start_subtest("skel_api"))
@@ -138,4 +205,6 @@ void test_uprobe_multi_test(void)
 		test_attach_api_pattern();
 	if (test__start_subtest("attach_api_syms"))
 		test_attach_api_syms();
+	if (test__start_subtest("link_api"))
+		test_link_api();
 }