selftests/bpf: Add test for recursion counts of perf event link kprobe

Adding selftest that puts kprobe.multi on bpf_fentry_test1 that
calls bpf_kfunc_common_test kfunc which has 3 perf event kprobes
and 1 kprobe.multi attached.

Because fprobe (kprobe.multi attach layear) does not have strict
recursion check the kprobe's bpf_prog_active check is hit for test2-5.

Disabling this test for arm64, because there's no fprobe support yet.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Song Liu <song@kernel.org>
Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-9-jolsa@kernel.org

diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64
index 1e827c24761c631a4d09e5fc4419645124ff3f5b..5c2cc7e8c5d075aa01fd80b057e2bcf1f19d817a 100644 (file)
--- a/tools/testing/selftests/bpf/DENYLIST.aarch64
+++ b/tools/testing/selftests/bpf/DENYLIST.aarch64
@@ -10,3 +10,4 @@ fexit_test/fexit_many_args                       # fexit_many_args:FAIL:fexit_ma
 fill_link_info/kprobe_multi_link_info            # bpf_program__attach_kprobe_multi_opts unexpected error: -95
 fill_link_info/kretprobe_multi_link_info         # bpf_program__attach_kprobe_multi_opts unexpected error: -95
 fill_link_info/kprobe_multi_invalid_ubuff        # bpf_program__attach_kprobe_multi_opts unexpected error: -95
+missed/kprobe_recursion                          # missed_kprobe_recursion__attach unexpected error: -95 (errno 95)

diff --git a/tools/testing/selftests/bpf/prog_tests/missed.c b/tools/testing/selftests/bpf/prog_tests/missed.c
index ca52be3d80f38ea5d566d6b6564a15720d9ef65c..54aaf2f8ad8c37a6b4166d71171c8c11237df812 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/missed.c
+++ b/tools/testing/selftests/bpf/prog_tests/missed.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 #include "missed_kprobe.skel.h"
+#include "missed_kprobe_recursion.skel.h"
 
 /*
  * Putting kprobe on bpf_fentry_test1 that calls bpf_kfunc_common_test
@@ -40,8 +41,58 @@ cleanup:
        missed_kprobe__destroy(skel);
 }
 
+static __u64 get_missed_count(int fd)
+{
+       struct bpf_prog_info info = {};
+       __u32 len = sizeof(info);
+       int err;
+
+       err = bpf_prog_get_info_by_fd(fd, &info, &len);
+       if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd"))
+               return (__u64) -1;
+       return info.recursion_misses;
+}
+
+/*
+ * Putting kprobe.multi on bpf_fentry_test1 that calls bpf_kfunc_common_test
+ * kfunc which has 3 perf event kprobes and 1 kprobe.multi attached.
+ *
+ * Because fprobe (kprobe.multi attach layear) does not have strict recursion
+ * check the kprobe's bpf_prog_active check is hit for test2-5.
+ */
+static void test_missed_kprobe_recursion(void)
+{
+       LIBBPF_OPTS(bpf_test_run_opts, topts);
+       struct missed_kprobe_recursion *skel;
+       int err, prog_fd;
+
+       skel = missed_kprobe_recursion__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "missed_kprobe_recursion__open_and_load"))
+               goto cleanup;
+
+       err = missed_kprobe_recursion__attach(skel);
+       if (!ASSERT_OK(err, "missed_kprobe_recursion__attach"))
+               goto cleanup;
+
+       prog_fd = bpf_program__fd(skel->progs.trigger);
+       err = bpf_prog_test_run_opts(prog_fd, &topts);
+       ASSERT_OK(err, "test_run");
+       ASSERT_EQ(topts.retval, 0, "test_run");
+
+       ASSERT_EQ(get_missed_count(bpf_program__fd(skel->progs.test1)), 0, "test1_recursion_misses");
+       ASSERT_EQ(get_missed_count(bpf_program__fd(skel->progs.test2)), 1, "test2_recursion_misses");
+       ASSERT_EQ(get_missed_count(bpf_program__fd(skel->progs.test3)), 1, "test3_recursion_misses");
+       ASSERT_EQ(get_missed_count(bpf_program__fd(skel->progs.test4)), 1, "test4_recursion_misses");
+       ASSERT_EQ(get_missed_count(bpf_program__fd(skel->progs.test5)), 1, "test5_recursion_misses");
+
+cleanup:
+       missed_kprobe_recursion__destroy(skel);
+}
+
 void test_missed(void)
 {
        if (test__start_subtest("perf_kprobe"))
                test_missed_perf_kprobe();
+       if (test__start_subtest("kprobe_recursion"))
+               test_missed_kprobe_recursion();
 }

diff --git a/tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c b/tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c
new file mode 100644 (file)
index 0000000..8ea71cb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod_kfunc.h"
+
+char _license[] SEC("license") = "GPL";
+
+/*
+ * No tests in here, just to trigger 'bpf_fentry_test*'
+ * through tracing test_run
+ */
+SEC("fentry/bpf_modify_return_test")
+int BPF_PROG(trigger)
+{
+       return 0;
+}
+
+SEC("kprobe.multi/bpf_fentry_test1")
+int test1(struct pt_regs *ctx)
+{
+       bpf_kfunc_common_test();
+       return 0;
+}
+
+SEC("kprobe/bpf_kfunc_common_test")
+int test2(struct pt_regs *ctx)
+{
+       return 0;
+}
+
+SEC("kprobe/bpf_kfunc_common_test")
+int test3(struct pt_regs *ctx)
+{
+       return 0;
+}
+
+SEC("kprobe/bpf_kfunc_common_test")
+int test4(struct pt_regs *ctx)
+{
+       return 0;
+}
+
+SEC("kprobe.multi/bpf_kfunc_common_test")
+int test5(struct pt_regs *ctx)
+{
+       return 0;
+}