selftests/bpf: Add uprobe_multi path_fd test

Add a uprobe_multi link API selftest that opens /proc/self/exe and passes
the resulting descriptor through opts.uprobe_multi.path_fd with
BPF_F_UPROBE_MULTI_PATH_FD set.

Assisted-by: Codex:GPT-5.4
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260611114230.950379-6-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
index 56cbea280fbd21ef7f34973a35e28d65e0f2a095..ffcf3c92f047458afb93a0de7e877c4494d116be 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -2,6 +2,7 @@
 
 #include <unistd.h>
 #include <pthread.h>
+#include <fcntl.h>
 #include <test_progs.h>
 #include "uprobe_multi.skel.h"
 #include "uprobe_multi_bench.skel.h"
@@ -757,6 +758,65 @@ static void test_link_api(void)
        __test_link_api(&child);
 }
 
+static void test_link_api_path_fd(void)
+{
+       LIBBPF_OPTS(bpf_link_create_opts, opts);
+       const char *resolve_path = "/proc/self/exe";
+       int prog_fd, link_fd = -1, path_fd = -1;
+       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(resolve_path, ARRAY_SIZE(syms), syms,
+                                      &offsets, STT_FUNC);
+       if (!ASSERT_OK(err, "elf_resolve_syms_offsets"))
+               return;
+
+       path_fd = open(resolve_path, O_RDONLY);
+       if (!ASSERT_GE(path_fd, 0, "path_fd"))
+               goto cleanup;
+
+       opts.uprobe_multi.path_fd = path_fd;
+       opts.uprobe_multi.offsets = offsets;
+       opts.uprobe_multi.cnt = ARRAY_SIZE(syms);
+       opts.uprobe_multi.flags = BPF_F_UPROBE_MULTI_PATH_FD;
+
+       skel = uprobe_multi__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load"))
+               goto cleanup;
+
+       prog_fd = bpf_program__fd(skel->progs.uprobe);
+       link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
+       if (!ASSERT_GE(link_fd, 0, "bpf_link_create"))
+               goto cleanup;
+
+       skel->bss->uprobe_multi_func_1_addr = (__u64)uprobe_multi_func_1;
+       skel->bss->uprobe_multi_func_2_addr = (__u64)uprobe_multi_func_2;
+       skel->bss->uprobe_multi_func_3_addr = (__u64)uprobe_multi_func_3;
+       skel->bss->pid = getpid();
+
+       uprobe_multi_func_1();
+       uprobe_multi_func_2();
+       uprobe_multi_func_3();
+
+       ASSERT_EQ(skel->bss->uprobe_multi_func_1_result, 1, "uprobe_multi_func_1_result");
+       ASSERT_EQ(skel->bss->uprobe_multi_func_2_result, 1, "uprobe_multi_func_2_result");
+       ASSERT_EQ(skel->bss->uprobe_multi_func_3_result, 1, "uprobe_multi_func_3_result");
+
+cleanup:
+       if (link_fd >= 0)
+               close(link_fd);
+       if (path_fd >= 0)
+               close(path_fd);
+       uprobe_multi__destroy(skel);
+       free(offsets);
+}
+
 static struct bpf_program *
 get_program(struct uprobe_multi_consumers *skel, int prog)
 {
@@ -1354,6 +1414,8 @@ void test_uprobe_multi_test(void)
                test_attach_api_syms();
        if (test__start_subtest("link_api"))
                test_link_api();
+       if (test__start_subtest("link_api_path_fd"))
+               test_link_api_path_fd();
        if (test__start_subtest("bench_uprobe"))
                test_bench_attach_uprobe();
        if (test__start_subtest("bench_usdt"))