Re: [PATCH 18/19] selftests/bpf: Add fentry/fexit multi func test

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sat, Jun 5, 2021 at 4:13 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding selftest for fentry/fexit multi func test that attaches
> to bpf_fentry_test* functions and checks argument values based
> on the processed function.
>
> When multi_arg_check is used from 2 different places I'm getting
> compilation fail, which I did not deciphered yet:
>
>   $ CLANG=/opt/clang/bin/clang LLC=/opt/clang/bin/llc make
>     CLNG-BPF [test_maps] fentry_fexit_multi_test.o
>   progs/fentry_fexit_multi_test.c:18:2: error: too many args to t24: i64 = \
>   GlobalAddress<void (i64, i64, i64, i64, i64, i64, i64, i64*)* @multi_arg_check> 0, \
>   progs/fentry_fexit_multi_test.c:18:2 @[ progs/fentry_fexit_multi_test.c:16:5 ]
>           multi_arg_check(ip, a, b, c, d, e, f, &test1_arg_result);
>           ^
>   progs/fentry_fexit_multi_test.c:25:2: error: too many args to t32: i64 = \
>   GlobalAddress<void (i64, i64, i64, i64, i64, i64, i64, i64*)* @multi_arg_check> 0, \
>   progs/fentry_fexit_multi_test.c:25:2 @[ progs/fentry_fexit_multi_test.c:23:5 ]
>           multi_arg_check(ip, a, b, c, d, e, f, &test2_arg_result);
>           ^
>   In file included from progs/fentry_fexit_multi_test.c:5:
>   /home/jolsa/linux-qemu/tools/testing/selftests/bpf/multi_check.h:9:6: error: defined with too many args
>   void multi_arg_check(unsigned long ip, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f, __u64 *test_result)
>        ^
>   /home/jolsa/linux-qemu/tools/testing/selftests/bpf/multi_check.h:9:6: error: defined with too many args
>   /home/jolsa/linux-qemu/tools/testing/selftests/bpf/multi_check.h:9:6: error: defined with too many args
>   5 errors generated.
>   make: *** [Makefile:470: /home/jolsa/linux-qemu/tools/testing/selftests/bpf/fentry_fexit_multi_test.o] Error 1
>
> I can fix that by defining 2 separate multi_arg_check functions
> with different names, which I did in follow up temporaary patch.
> Not sure I'm hitting some clang/bpf limitation in here?

don't know about  clang limitations, but we should use static linking
proper anyways

>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  .../bpf/prog_tests/fentry_fexit_multi_test.c  | 52 +++++++++++++++++++
>  .../bpf/progs/fentry_fexit_multi_test.c       | 28 ++++++++++
>  2 files changed, 80 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c
>  create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c b/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c
> new file mode 100644
> index 000000000000..76f917ad843d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +#include "fentry_fexit_multi_test.skel.h"
> +
> +void test_fentry_fexit_multi_test(void)
> +{
> +       DECLARE_LIBBPF_OPTS(bpf_link_update_opts, link_upd_opts);
> +       struct fentry_fexit_multi_test *skel = NULL;
> +       unsigned long long *bpf_fentry_test;
> +       __u32 duration = 0, retval;
> +       struct bpf_link *link;
> +       int err, prog_fd;
> +
> +       skel = fentry_fexit_multi_test__open_and_load();
> +       if (!ASSERT_OK_PTR(skel, "fentry_multi_skel_load"))
> +               goto cleanup;
> +
> +       bpf_fentry_test = &skel->bss->bpf_fentry_test[0];
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test1", &bpf_fentry_test[0]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test2", &bpf_fentry_test[1]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test3", &bpf_fentry_test[2]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test4", &bpf_fentry_test[3]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test5", &bpf_fentry_test[4]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test6", &bpf_fentry_test[5]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test7", &bpf_fentry_test[6]), "kallsyms_find");
> +       ASSERT_OK(kallsyms_find("bpf_fentry_test8", &bpf_fentry_test[7]), "kallsyms_find");
> +
> +       link = bpf_program__attach(skel->progs.test1);
> +       if (!ASSERT_OK_PTR(link, "attach_fentry_fexit"))
> +               goto cleanup;
> +
> +       err = bpf_link_update(bpf_link__fd(link),
> +                             bpf_program__fd(skel->progs.test2),
> +                             NULL);
> +       if (!ASSERT_OK(err, "bpf_link_update"))
> +               goto cleanup_link;
> +
> +       prog_fd = bpf_program__fd(skel->progs.test1);
> +       err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> +                               NULL, NULL, &retval, &duration);
> +       ASSERT_OK(err, "test_run");
> +       ASSERT_EQ(retval, 0, "test_run");
> +
> +       ASSERT_EQ(skel->bss->test1_arg_result, 8, "test1_arg_result");
> +       ASSERT_EQ(skel->bss->test2_arg_result, 8, "test2_arg_result");
> +       ASSERT_EQ(skel->bss->test2_ret_result, 8, "test2_ret_result");
> +
> +cleanup_link:
> +       bpf_link__destroy(link);
> +cleanup:
> +       fentry_fexit_multi_test__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c b/tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c
> new file mode 100644
> index 000000000000..e25ab0085399
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c
> @@ -0,0 +1,28 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include "multi_check.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +unsigned long long bpf_fentry_test[8];
> +
> +__u64 test1_arg_result = 0;
> +__u64 test2_arg_result = 0;
> +__u64 test2_ret_result = 0;
> +
> +SEC("fentry.multi/bpf_fentry_test*")
> +int BPF_PROG(test1, unsigned long ip, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f)
> +{
> +       multi_arg_check(ip, a, b, c, d, e, f, &test1_arg_result);
> +       return 0;
> +}
> +
> +SEC("fexit.multi/")
> +int BPF_PROG(test2, unsigned long ip, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f, int ret)
> +{
> +       multi_arg_check(ip, a, b, c, d, e, f, &test2_arg_result);
> +       multi_ret_check(ip, ret, &test2_ret_result);
> +       return 0;
> +}
> --
> 2.31.1
>