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

The idea is to run same test as for test_pid_filter_process, but instead
of standard fork-ed process we create the process with clone(CLONE_VM..)
to make sure the thread leader process filter works properly in this case.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240905115124.1503998-5-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 9c2f99233304f051f8b1bd98b3fb51df38b52b7a..f160d01ba5dab93f603bb3cfce0bf69e8c14abb2 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -40,6 +40,7 @@ struct child {
        int pid;
        int tid;
        pthread_t thread;
+       char stack[65536];
 };
 
 static void release_child(struct child *child)
@@ -69,41 +70,56 @@ static void kick_child(struct child *child)
        fflush(NULL);
 }
 
-static int spawn_child(struct child *child)
+static int child_func(void *arg)
 {
+       struct child *child = arg;
        int err, c;
 
+       close(child->go[1]);
+
+       /* wait for parent's kick */
+       err = read(child->go[0], &c, 1);
+       if (err != 1)
+               exit(err);
+
+       uprobe_multi_func_1();
+       uprobe_multi_func_2();
+       uprobe_multi_func_3();
+       usdt_trigger();
+
+       exit(errno);
+}
+
+static int spawn_child_flag(struct child *child, bool clone_vm)
+{
        /* pipe to notify child to execute the trigger functions */
        if (pipe(child->go))
                return -1;
 
-       child->pid = child->tid = fork();
+       if (clone_vm) {
+               child->pid = child->tid = clone(child_func, child->stack + sizeof(child->stack)/2,
+                                               CLONE_VM|SIGCHLD, child);
+       } else {
+               child->pid = child->tid = fork();
+       }
        if (child->pid < 0) {
                release_child(child);
                errno = EINVAL;
                return -1;
        }
 
-       /* child */
-       if (child->pid == 0) {
-               close(child->go[1]);
-
-               /* wait for parent's kick */
-               err = read(child->go[0], &c, 1);
-               if (err != 1)
-                       exit(err);
-
-               uprobe_multi_func_1();
-               uprobe_multi_func_2();
-               uprobe_multi_func_3();
-               usdt_trigger();
-
-               exit(errno);
-       }
+       /* fork-ed child */
+       if (!clone_vm && child->pid == 0)
+               child_func(child);
 
        return 0;
 }
 
+static int spawn_child(struct child *child)
+{
+       return spawn_child_flag(child, false);
+}
+
 static void *child_thread(void *ctx)
 {
        struct child *child = ctx;
@@ -948,7 +964,7 @@ static struct bpf_program *uprobe_multi_program(struct uprobe_multi_pid_filter *
 
 #define TASKS 3
 
-static void run_pid_filter(struct uprobe_multi_pid_filter *skel, bool retprobe)
+static void run_pid_filter(struct uprobe_multi_pid_filter *skel, bool clone_vm, bool retprobe)
 {
        LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .retprobe = retprobe);
        struct bpf_link *link[TASKS] = {};
@@ -958,7 +974,7 @@ static void run_pid_filter(struct uprobe_multi_pid_filter *skel, bool retprobe)
        memset(skel->bss->test, 0, sizeof(skel->bss->test));
 
        for (i = 0; i < TASKS; i++) {
-               if (!ASSERT_OK(spawn_child(&child[i]), "spawn_child"))
+               if (!ASSERT_OK(spawn_child_flag(&child[i], clone_vm), "spawn_child"))
                        goto cleanup;
                skel->bss->pids[i] = child[i].pid;
        }
@@ -986,7 +1002,7 @@ cleanup:
                release_child(&child[i]);
 }
 
-static void test_pid_filter_process(void)
+static void test_pid_filter_process(bool clone_vm)
 {
        struct uprobe_multi_pid_filter *skel;
 
@@ -994,8 +1010,8 @@ static void test_pid_filter_process(void)
        if (!ASSERT_OK_PTR(skel, "uprobe_multi_pid_filter__open_and_load"))
                return;
 
-       run_pid_filter(skel, false);
-       run_pid_filter(skel, true);
+       run_pid_filter(skel, clone_vm, false);
+       run_pid_filter(skel, clone_vm, true);
 
        uprobe_multi_pid_filter__destroy(skel);
 }
@@ -1093,5 +1109,7 @@ void test_uprobe_multi_test(void)
        if (test__start_subtest("consumers"))
                test_consumers();
        if (test__start_subtest("filter_fork"))
-               test_pid_filter_process();
+               test_pid_filter_process(false);
+       if (test__start_subtest("filter_clone_vm"))
+               test_pid_filter_process(true);
 }