From: Stanislav Fomichev <sdf@google.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
haoluo@google.com, jolsa@kernel.org,
David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Anatoly Burakov <anatoly.burakov@intel.com>,
Alexander Lobakin <alexandr.lobakin@intel.com>,
Magnus Karlsson <magnus.karlsson@gmail.com>,
Maryam Tahhan <mtahhan@redhat.com>,
xdp-hints@xdp-project.net, netdev@vger.kernel.org
Subject: [xdp-hints] Re: [PATCH bpf-next v2 2/8] bpf: XDP metadata RX kfuncs
Date: Mon, 28 Nov 2022 11:21:58 -0800 [thread overview]
Message-ID: <CAKH8qBvp+4MjRpwMeG3G_duC6RCoJurswMFuC9ynf-F9-is0+g@mail.gmail.com> (raw)
In-Reply-To: <CAKH8qBvmgx0Lr7efP0ucdZMEzZM-jzDKcAW9YPBqADWVsHb9cA@mail.gmail.com>
On Mon, Nov 28, 2022 at 10:53 AM Stanislav Fomichev <sdf@google.com> wrote:
>
> s
>
> On Fri, Nov 25, 2022 at 9:53 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > Stanislav Fomichev <sdf@google.com> writes:
> >
> > > There is an ndo handler per kfunc, the verifier replaces a call to the
> > > generic kfunc with a call to the per-device one.
> > >
> > > For XDP, we define a new kfunc set (xdp_metadata_kfunc_ids) which
> > > implements all possible metatada kfuncs. Not all devices have to
> > > implement them. If kfunc is not supported by the target device,
> > > the default implementation is called instead.
> >
> > BTW, this "the default implementation is called instead" bit is not
> > included in this version... :)
>
> fixup_xdp_kfunc_call should return 0 when the device doesn't have a
> kfunc defined and should fallback to the default kfunc implementation,
> right?
> Or am I missing something?
>
> > [...]
> >
> > > +#ifdef CONFIG_DEBUG_INFO_BTF
> > > +BTF_SET8_START(xdp_metadata_kfunc_ids)
> > > +#define XDP_METADATA_KFUNC(name, str) BTF_ID_FLAGS(func, str, 0)
> > > +XDP_METADATA_KFUNC_xxx
> > > +#undef XDP_METADATA_KFUNC
> > > +BTF_SET8_END(xdp_metadata_kfunc_ids)
> > > +
> > > +static const struct btf_kfunc_id_set xdp_metadata_kfunc_set = {
> > > + .owner = THIS_MODULE,
> > > + .set = &xdp_metadata_kfunc_ids,
> > > +};
> > > +
> > > +u32 xdp_metadata_kfunc_id(int id)
> > > +{
> > > + return xdp_metadata_kfunc_ids.pairs[id].id;
> > > +}
> > > +EXPORT_SYMBOL_GPL(xdp_metadata_kfunc_id);
> >
> > So I was getting some really weird values when testing (always getting a
> > timestamp value of '1'), and it turns out to be because this way of
> > looking up the ID doesn't work: The set is always sorted by the BTF ID,
> > not the order it was defined. Which meant that the mapping code got the
> > functions mixed up, and would call a different one instead (so the
> > timestamp value I was getting was really the return value of
> > rx_hash_enabled()).
> >
> > I fixed it by building a secondary lookup table as below; feel free to
> > incorporate that (or if you can come up with a better way, go ahead!).
>
> Interesting, will take a closer look. I took this pattern from
> BTF_SOCK_TYPE_xxx, which means that 'sorting by btf-id' is something
> BTF_SET8_START specific...
> But if it's sorted, probably easier to do a bsearch over this table
> than to build another one?
Ah, I see, there is no place to store an index :-( Maybe the following
is easier still?
diff --git a/net/core/xdp.c b/net/core/xdp.c
index e43f7d4ef4cf..8240805bfdb7 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -743,9 +743,15 @@ static const struct btf_kfunc_id_set
xdp_metadata_kfunc_set = {
.set = &xdp_metadata_kfunc_ids,
};
+BTF_ID_LIST(xdp_metadata_kfunc_ids_unsorted)
+#define XDP_METADATA_KFUNC(name, str) BTF_ID(func, str)
+XDP_METADATA_KFUNC_xxx
+#undef XDP_METADATA_KFUNC
+
u32 xdp_metadata_kfunc_id(int id)
{
- return xdp_metadata_kfunc_ids.pairs[id].id;
+ /* xdp_metadata_kfunc_ids is sorted and can't be used */
+ return xdp_metadata_kfunc_ids_unsorted[id];
}
EXPORT_SYMBOL_GPL(xdp_metadata_kfunc_id);
> > -Toke
> >
> > diff --git a/net/core/xdp.c b/net/core/xdp.c
> > index e43f7d4ef4cf..dc0a9644dacc 100644
> > --- a/net/core/xdp.c
> > +++ b/net/core/xdp.c
> > @@ -738,6 +738,15 @@ XDP_METADATA_KFUNC_xxx
> > #undef XDP_METADATA_KFUNC
> > BTF_SET8_END(xdp_metadata_kfunc_ids)
> >
> > +static struct xdp_metadata_kfunc_map {
> > + const char *fname;
> > + u32 btf_id;
> > +} xdp_metadata_kfunc_lookup_map[MAX_XDP_METADATA_KFUNC] = {
> > +#define XDP_METADATA_KFUNC(name, str) { .fname = __stringify(str) },
> > +XDP_METADATA_KFUNC_xxx
> > +#undef XDP_METADATA_KFUNC
> > +};
> > +
> > static const struct btf_kfunc_id_set xdp_metadata_kfunc_set = {
> > .owner = THIS_MODULE,
> > .set = &xdp_metadata_kfunc_ids,
> > @@ -745,13 +754,41 @@ static const struct btf_kfunc_id_set xdp_metadata_kfunc_set = {
> >
> > u32 xdp_metadata_kfunc_id(int id)
> > {
> > - return xdp_metadata_kfunc_ids.pairs[id].id;
> > + return xdp_metadata_kfunc_lookup_map[id].btf_id;
> > }
> > EXPORT_SYMBOL_GPL(xdp_metadata_kfunc_id);
> >
> > static int __init xdp_metadata_init(void)
> > {
> > - return register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &xdp_metadata_kfunc_set);
> > + const struct btf *btf;
> > + int i, j, ret;
> > +
> > + ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &xdp_metadata_kfunc_set);
> > + if (ret)
> > + return ret;
> > +
> > + btf = bpf_get_btf_vmlinux();
> > +
> > + for (i = 0; i < MAX_XDP_METADATA_KFUNC; i++) {
> > + u32 btf_id = xdp_metadata_kfunc_ids.pairs[i].id;
> > + const struct btf_type *t;
> > + const char *name;
> > +
> > + t = btf_type_by_id(btf, btf_id);
> > + if (WARN_ON_ONCE(!t || !t->name_off))
> > + continue;
> > +
> > + name = btf_name_by_offset(btf, t->name_off);
> > +
> > + for (j = 0; j < MAX_XDP_METADATA_KFUNC; j++) {
> > + if (!strcmp(name, xdp_metadata_kfunc_lookup_map[j].fname)) {
> > + xdp_metadata_kfunc_lookup_map[j].btf_id = btf_id;
> > + break;
> > + }
> > + }
> > + }
> > +
> > + return 0;
> > }
> > late_initcall(xdp_metadata_init);
> > #else /* CONFIG_DEBUG_INFO_BTF */
> >
next prev parent reply other threads:[~2022-11-28 19:22 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 18:25 [xdp-hints] [PATCH bpf-next v2 0/8] xdp: hints via kfuncs Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 1/8] bpf: Document XDP RX metadata Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 2/8] bpf: XDP metadata RX kfuncs Stanislav Fomichev
2022-11-21 23:31 ` [xdp-hints] " kernel test robot
2022-11-23 6:34 ` Martin KaFai Lau
2022-11-23 18:43 ` Stanislav Fomichev
2022-11-23 14:24 ` Toke Høiland-Jørgensen
2022-11-23 18:43 ` Stanislav Fomichev
2022-11-24 2:23 ` kernel test robot
2022-11-24 12:19 ` kernel test robot
2022-11-24 13:09 ` kernel test robot
2022-11-25 17:53 ` Toke Høiland-Jørgensen
2022-11-28 18:53 ` Stanislav Fomichev
2022-11-28 19:21 ` Stanislav Fomichev [this message]
2022-11-28 22:25 ` Toke Høiland-Jørgensen
2022-11-28 22:10 ` Toke Høiland-Jørgensen
2022-11-30 17:24 ` Larysa Zaremba
2022-11-30 19:06 ` Stanislav Fomichev
2022-11-30 20:17 ` Stanislav Fomichev
2022-12-01 13:52 ` Larysa Zaremba
2022-12-01 17:14 ` Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 3/8] veth: Introduce veth_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 4/8] veth: Support RX XDP metadata Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 5/8] selftests/bpf: Verify xdp_metadata xdp->af_xdp path Stanislav Fomichev
2022-11-29 10:06 ` [xdp-hints] " Anton Protopopov
2022-11-29 18:52 ` Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 6/8] mlx4: Introduce mlx4_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-22 13:49 ` [xdp-hints] " Tariq Toukan
2022-11-22 18:08 ` Stanislav Fomichev
2022-11-23 14:33 ` Toke Høiland-Jørgensen
2022-11-23 18:26 ` Stanislav Fomichev
2022-11-23 19:14 ` Jakub Kicinski
2022-11-23 19:52 ` sdf
2022-11-23 21:54 ` Maciej Fijalkowski
2022-11-23 21:55 ` Toke Høiland-Jørgensen
2022-11-24 1:47 ` Jakub Kicinski
2022-11-24 14:39 ` Toke Høiland-Jørgensen
2022-11-24 15:17 ` Maciej Fijalkowski
2022-11-24 16:11 ` Maciej Fijalkowski
2022-11-25 0:36 ` Toke Høiland-Jørgensen
2022-11-28 21:58 ` Stanislav Fomichev
2022-11-28 22:11 ` Toke Høiland-Jørgensen
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 7/8] mxl4: Support RX XDP metadata Stanislav Fomichev
2022-11-22 13:50 ` [xdp-hints] " Tariq Toukan
2022-11-22 18:08 ` Stanislav Fomichev
2022-11-21 18:25 ` [xdp-hints] [PATCH bpf-next v2 8/8] selftests/bpf: Simple program to dump XDP RX metadata Stanislav Fomichev
2022-11-23 14:26 ` [xdp-hints] " Toke Høiland-Jørgensen
2022-11-23 18:29 ` Stanislav Fomichev
2022-11-23 19:17 ` Jakub Kicinski
2022-11-23 19:54 ` Stanislav Fomichev
2022-11-23 14:46 ` [xdp-hints] [PATCH bpf-next 1/2] xdp: Add drv_priv pointer to struct xdp_buff Toke Høiland-Jørgensen
2022-11-23 14:46 ` [xdp-hints] [PATCH bpf-next 2/2] mlx5: Support XDP RX metadata Toke Høiland-Jørgensen
2022-11-23 22:29 ` [xdp-hints] " Saeed Mahameed
2022-11-23 22:44 ` Stanislav Fomichev
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