Re: [PATCH v4 bpf-next 5/5] selftests/bpf: Add sleepable tests

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

On Mon, Jun 29, 2020 at 5:35 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Alexei Starovoitov <ast@kernel.org>
>
> Modify few tests to sanity test sleepable bpf functionality.
>
> Running 'bench trig-fentry-sleep' vs 'bench trig-fentry' and 'perf report':
> sleepable with SRCU:
>    3.86%  bench     [k] __srcu_read_unlock
>    3.22%  bench     [k] __srcu_read_lock
>    0.92%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
>    0.50%  bench     [k] bpf_trampoline_10297
>    0.26%  bench     [k] __bpf_prog_exit_sleepable
>    0.21%  bench     [k] __bpf_prog_enter_sleepable
>
> sleepable with RCU_TRACE:
>    0.79%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
>    0.72%  bench     [k] bpf_trampoline_10381
>    0.31%  bench     [k] __bpf_prog_exit_sleepable
>    0.29%  bench     [k] __bpf_prog_enter_sleepable
>
> non-sleepable with RCU:
>    0.88%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry
>    0.84%  bench     [k] bpf_trampoline_10297
>    0.13%  bench     [k] __bpf_prog_enter
>    0.12%  bench     [k] __bpf_prog_exit
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> Acked-by: KP Singh <kpsingh@google.com>
> ---
>  tools/testing/selftests/bpf/bench.c           |  2 +
>  .../selftests/bpf/benchs/bench_trigger.c      | 17 +++++
>  .../selftests/bpf/prog_tests/test_lsm.c       |  9 +++
>  tools/testing/selftests/bpf/progs/lsm.c       | 64 ++++++++++++++++++-
>  .../selftests/bpf/progs/trigger_bench.c       |  7 ++
>  5 files changed, 97 insertions(+), 2 deletions(-)
>

[...]

> +
> +SEC("fentry.s/__x64_sys_setdomainname")
> +int BPF_PROG(test_sys_setdomainname, struct pt_regs *regs)
> +{
> +       int buf = 0;
> +       long ret;
> +
> +       ret = bpf_copy_from_user(&buf, sizeof(buf), (void *)regs->di);
> +       if (regs->si == -2 && ret == 0 && buf == 1234)
> +               copy_test++;
> +       if (regs->si == -3 && ret == -EFAULT)
> +               copy_test++;
> +       if (regs->si == -4 && ret == -EFAULT)
> +               copy_test++;

regs->si and regs->di won't compile on non-x86 arches, better to use
PT_REGS_PARM1() and PT_REGS_PARM2() from bpf_tracing.h.

> +       return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/progs/trigger_bench.c b/tools/testing/selftests/bpf/progs/trigger_bench.c
> index 8b36b6640e7e..9a4d09590b3d 100644
> --- a/tools/testing/selftests/bpf/progs/trigger_bench.c
> +++ b/tools/testing/selftests/bpf/progs/trigger_bench.c
> @@ -39,6 +39,13 @@ int bench_trigger_fentry(void *ctx)
>         return 0;
>  }
>
> +SEC("fentry.s/__x64_sys_getpgid")
> +int bench_trigger_fentry_sleep(void *ctx)
> +{
> +       __sync_add_and_fetch(&hits, 1);
> +       return 0;
> +}
> +
>  SEC("fmod_ret/__x64_sys_getpgid")
>  int bench_trigger_fmodret(void *ctx)
>  {
> --
> 2.23.0
>