selftests/bpf: Add uprobe multi pid filter test for fork-ed processes

The idea is to create and monitor 3 uprobes, each trigered in separate
process and make sure the bpf program gets executed just for the proper
PID specified via pid filter.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240905115124.1503998-4-jolsa@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 250eb47c68f9e888784592e4bfcb7edfafbdcc7a..9c2f99233304f051f8b1bd98b3fb51df38b52b7a 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -7,6 +7,7 @@
 #include "uprobe_multi_bench.skel.h"
 #include "uprobe_multi_usdt.skel.h"
 #include "uprobe_multi_consumers.skel.h"
+#include "uprobe_multi_pid_filter.skel.h"
 #include "bpf/libbpf_internal.h"
 #include "testing_helpers.h"
 #include "../sdt.h"
@@ -935,6 +936,70 @@ static void test_consumers(void)
        uprobe_multi_consumers__destroy(skel);
 }
 
+static struct bpf_program *uprobe_multi_program(struct uprobe_multi_pid_filter *skel, int idx)
+{
+       switch (idx) {
+       case 0: return skel->progs.uprobe_multi_0;
+       case 1: return skel->progs.uprobe_multi_1;
+       case 2: return skel->progs.uprobe_multi_2;
+       }
+       return NULL;
+}
+
+#define TASKS 3
+
+static void run_pid_filter(struct uprobe_multi_pid_filter *skel, bool retprobe)
+{
+       LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .retprobe = retprobe);
+       struct bpf_link *link[TASKS] = {};
+       struct child child[TASKS] = {};
+       int i;
+
+       memset(skel->bss->test, 0, sizeof(skel->bss->test));
+
+       for (i = 0; i < TASKS; i++) {
+               if (!ASSERT_OK(spawn_child(&child[i]), "spawn_child"))
+                       goto cleanup;
+               skel->bss->pids[i] = child[i].pid;
+       }
+
+       for (i = 0; i < TASKS; i++) {
+               link[i] = bpf_program__attach_uprobe_multi(uprobe_multi_program(skel, i),
+                                                          child[i].pid, "/proc/self/exe",
+                                                          "uprobe_multi_func_1", &opts);
+               if (!ASSERT_OK_PTR(link[i], "bpf_program__attach_uprobe_multi"))
+                       goto cleanup;
+       }
+
+       for (i = 0; i < TASKS; i++)
+               kick_child(&child[i]);
+
+       for (i = 0; i < TASKS; i++) {
+               ASSERT_EQ(skel->bss->test[i][0], 1, "pid");
+               ASSERT_EQ(skel->bss->test[i][1], 0, "unknown");
+       }
+
+cleanup:
+       for (i = 0; i < TASKS; i++)
+               bpf_link__destroy(link[i]);
+       for (i = 0; i < TASKS; i++)
+               release_child(&child[i]);
+}
+
+static void test_pid_filter_process(void)
+{
+       struct uprobe_multi_pid_filter *skel;
+
+       skel = uprobe_multi_pid_filter__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "uprobe_multi_pid_filter__open_and_load"))
+               return;
+
+       run_pid_filter(skel, false);
+       run_pid_filter(skel, true);
+
+       uprobe_multi_pid_filter__destroy(skel);
+}
+
 static void test_bench_attach_uprobe(void)
 {
        long attach_start_ns = 0, attach_end_ns = 0;
@@ -1027,4 +1092,6 @@ void test_uprobe_multi_test(void)
                test_attach_uprobe_fails();
        if (test__start_subtest("consumers"))
                test_consumers();
+       if (test__start_subtest("filter_fork"))
+               test_pid_filter_process();
 }

diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_pid_filter.c b/tools/testing/selftests/bpf/progs/uprobe_multi_pid_filter.c
new file mode 100644 (file)
index 0000000..67fcbad
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_pid_filter.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 pids[3];
+__u32 test[3][2];
+
+static void update_pid(int idx)
+{
+       __u32 pid = bpf_get_current_pid_tgid() >> 32;
+
+       if (pid == pids[idx])
+               test[idx][0]++;
+       else
+               test[idx][1]++;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_0(struct pt_regs *ctx)
+{
+       update_pid(0);
+       return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_1(struct pt_regs *ctx)
+{
+       update_pid(1);
+       return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_2(struct pt_regs *ctx)
+{
+       update_pid(2);
+       return 0;
+}