linux-kernel - Re: [PATCH bpf-next 2/5] libbpf: support BPF_PROG_TYPE

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Message-ID: <CAEf4BzZcn_44DE4Zr9YKGaPoGvZzgv0tvZbZP-0nuwA5RVPbog@mail.gmail.com>
Date:   Sun, 2 Aug 2020 22:05:39 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Song Liu <songliubraving@...com>
Cc:     open list <linux-kernel@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Daniel Xu <dlxu@...com>
Subject: Re: [PATCH bpf-next 2/5] libbpf: support BPF_PROG_TYPE_USER programs

On Sun, Aug 2, 2020 at 9:21 PM Song Liu <songliubraving@...com> wrote:
>
>
>
> > On Aug 2, 2020, at 6:40 PM, Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:
> >
> > On Sat, Aug 1, 2020 at 1:50 AM Song Liu <songliubraving@...com> wrote:
> >>
> >> Add cpu_plus to bpf_prog_test_run_attr. Add BPF_PROG_SEC "user" for
> >> BPF_PROG_TYPE_USER programs.
> >>
> >> Signed-off-by: Song Liu <songliubraving@...com>
> >> ---
> >> tools/lib/bpf/bpf.c           | 1 +
> >> tools/lib/bpf/bpf.h           | 3 +++
> >> tools/lib/bpf/libbpf.c        | 1 +
> >> tools/lib/bpf/libbpf_probes.c | 1 +
> >> 4 files changed, 6 insertions(+)
> >>
> >> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> >> index e1bdf214f75fe..b28c3daa9c270 100644
> >> --- a/tools/lib/bpf/bpf.c
> >> +++ b/tools/lib/bpf/bpf.c
> >> @@ -693,6 +693,7 @@ int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
> >>        attr.test.ctx_size_in = test_attr->ctx_size_in;
> >>        attr.test.ctx_size_out = test_attr->ctx_size_out;
> >>        attr.test.repeat = test_attr->repeat;
> >> +       attr.test.cpu_plus = test_attr->cpu_plus;
> >>
> >>        ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, sizeof(attr));
> >>        test_attr->data_size_out = attr.test.data_size_out;
> >> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> >> index 6d367e01d05e9..0c799740df566 100644
> >> --- a/tools/lib/bpf/bpf.h
> >> +++ b/tools/lib/bpf/bpf.h
> >> @@ -205,6 +205,9 @@ struct bpf_prog_test_run_attr {
> >>        void *ctx_out;      /* optional */
> >>        __u32 ctx_size_out; /* in: max length of ctx_out
> >>                             * out: length of cxt_out */
> >> +       __u32 cpu_plus;     /* specify which cpu to run the test with
> >> +                            * cpu_plus = cpu_id + 1.
> >> +                            * If cpu_plus = 0, run on current cpu */
> >
> > We can't do this due to ABI guarantees. We'll have to add a new API
> > using OPTS arguments.
>
> To make sure I understand this correctly, the concern is when we compile
> the binary with one version of libbpf and run it with libbpf.so of a
> different version, right?
>

yep, exactly

> Thanks,
> Song
>
> >
> >> };
> >>
> >> LIBBPF_API int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr);
> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> >> index b9f11f854985b..9ce175a486214 100644
> >> --- a/tools/lib/bpf/libbpf.c
> >> +++ b/tools/lib/bpf/libbpf.c
> >> @@ -6922,6 +6922,7 @@ static const struct bpf_sec_def section_defs[] = {
> >>        BPF_PROG_SEC("lwt_out",                 BPF_PROG_TYPE_LWT_OUT),
> >>        BPF_PROG_SEC("lwt_xmit",                BPF_PROG_TYPE_LWT_XMIT),
> >>        BPF_PROG_SEC("lwt_seg6local",           BPF_PROG_TYPE_LWT_SEG6LOCAL),
> >> +       BPF_PROG_SEC("user",                    BPF_PROG_TYPE_USER),
> >
> > let's do "user/" for consistency with most other prog types (and nice
> > separation between prog type and custom user name)
>
> Will update.
>

thanks!