On Mon, Nov 18, 2019 at 5:38 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> Add several BPF kselftest cases for tail calls which test the various
> patch directions (NOP -> JMP, JMP -> JMP, JMP -> NOP), and that multiple
> locations are patched.
>
> # ./test_progs -n 44
> #44 tailcalls:OK
> Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
>
> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> ---
> .../selftests/bpf/prog_tests/tailcalls.c | 210 ++++++++++++++++++
> tools/testing/selftests/bpf/progs/tailcall1.c | 48 ++++
> tools/testing/selftests/bpf/progs/tailcall2.c | 59 +++++
> 3 files changed, 317 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/tailcalls.c
> create mode 100644 tools/testing/selftests/bpf/progs/tailcall1.c
> create mode 100644 tools/testing/selftests/bpf/progs/tailcall2.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
> new file mode 100644
> index 000000000000..6862bb5f9688
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
> @@ -0,0 +1,210 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +
> +static void test_tailcall_1(void)
> +{
> + int err, map_fd, prog_fd, main_fd, i, j;
> + struct bpf_map *prog_array;
> + struct bpf_program *prog;
> + struct bpf_object *obj;
> + __u32 retval, duration;
> + char prog_name[32];
> + char buff[128] = {};
> +
> + err = bpf_prog_load("tailcall1.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
> + &prog_fd);
> + if (CHECK_FAIL(err))
> + return;
> +
> + prog = bpf_object__find_program_by_title(obj, "classifier");
> + if (CHECK_FAIL(!prog))
> + goto out;
> +
> + main_fd = bpf_program__fd(prog);
> + if (CHECK_FAIL(main_fd < 0))
> + goto out;
can this happen if bpf_prog_load succeeded? same for a bunch of
prog_fd checks below.
> +
> + prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
> + if (CHECK_FAIL(!prog_array))
> + goto out;
> +
[...]
> +
> + for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
> + err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
> + &duration, &retval, NULL);
> + CHECK(err || retval != i, "tailcall",
> + "err %d errno %d retval %d\n", err, errno, retval);
> +
> + err = bpf_map_delete_elem(map_fd, &i);
> + if (CHECK_FAIL(err))
> + goto out;
> + }
> +
> + /* Testing JMP -> NOP */
nit: this comment should probably go before previous loop?
> + err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
> + &duration, &retval, NULL);
> + CHECK(err || retval != 3, "tailcall", "err %d errno %d retval %d\n",
> + err, errno, retval);
> +
[...]
> + for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
> + j = bpf_map__def(prog_array)->max_entries - 1 - i;
> +
> + err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
> + &duration, &retval, NULL);
> + CHECK(err || retval != j, "tailcall",
> + "err %d errno %d retval %d\n", err, errno, retval);
> +
> + err = bpf_map_delete_elem(map_fd, &i);
in addition to explicit delete, can you test update to NULL? Also, I
think it might be useful to validate update from NULL to NULL (it's a
separate check in your poke_run code).
> + if (CHECK_FAIL(err))
> + goto out;
> + }
> +
> + err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
> + &duration, &retval, NULL);
> + CHECK(err || retval != 3, "tailcall", "err %d errno %d retval %d\n",
> + err, errno, retval);
> +out:
> + bpf_object__close(obj);
> +}
> +
[...]
> +void test_tailcalls(void)
> +{
> + test_tailcall_1();
> + test_tailcall_2();
> +}
these could be sub-tests:
if (test__start_subtest("tailcall_1"))
test_tailcall_1();
if (test__start_subtest("tailcall_2"))
test_tailcall_2();
though, a bit more descriptive names would be certainly better :)
> diff --git a/tools/testing/selftests/bpf/progs/tailcall1.c b/tools/testing/selftests/bpf/progs/tailcall1.c
> new file mode 100644
> index 000000000000..63531e1a9fa4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/tailcall1.c
> @@ -0,0 +1,48 @@
[...]
