From: Larysa Zaremba <larysa.zaremba@intel.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc: bpf@vger.kernel.org, brouer@redhat.com,
Stanislav Fomichev <sdf@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Tony Nguyen <anthony.l.nguyen@intel.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,
intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org,
Aleksander Lobakin <aleksander.lobakin@intel.com>
Subject: [xdp-hints] Re: [PATCH RESEND bpf-next 14/15] net, xdp: allow metadata > 32
Date: Mon, 15 May 2023 19:08:39 +0200 [thread overview]
Message-ID: <ZGJnFxzDTV2qE4zZ@lincoln> (raw)
In-Reply-To: <ee1ad4f2-34ab-4377-14d5-532cb0687180@redhat.com>
On Mon, May 15, 2023 at 06:17:02PM +0200, Jesper Dangaard Brouer wrote:
>
>
> On 12/05/2023 17.26, Larysa Zaremba wrote:
> > From: Aleksander Lobakin <aleksander.lobakin@intel.com>
> >
> > When using XDP hints, metadata sometimes has to be much bigger
> > than 32 bytes. Relax the restriction, allow metadata larger than 32 bytes
> > and make __skb_metadata_differs() work with bigger lengths.
> >
> > Now size of metadata is only limited by the fact it is stored as u8
> > in skb_shared_info, so maximum possible value is 255.
>
> I'm confused, IIRC the metadata area isn't stored "in skb_shared_info".
> The maximum possible size is limited by the XDP headroom, which is also
> shared/limited with/by xdp_frame. I must be reading the sentence wrong,
> somehow.
It's not 'metadata is stored as u8', it's 'metadata size is stored as u8' :)
Maybe I should rephrase it better in v2.
>
> > Other important
> > conditions, such as having enough space for xdp_frame building, are already
> > checked in bpf_xdp_adjust_meta().
> >
> > The requirement of having its length aligned to 4 bytes is still
> > valid.
> >
> > Signed-off-by: Aleksander Lobakin <aleksander.lobakin@intel.com>
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > ---
> > include/linux/skbuff.h | 13 ++++++++-----
> > include/net/xdp.h | 7 ++++++-
> > 2 files changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index 8ddb4af1a501..afcd372aecdf 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -4219,10 +4219,13 @@ static inline bool __skb_metadata_differs(const struct sk_buff *skb_a,
> > {
> > const void *a = skb_metadata_end(skb_a);
> > const void *b = skb_metadata_end(skb_b);
> > - /* Using more efficient varaiant than plain call to memcmp(). */
> > -#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
> > u64 diffs = 0;
> > + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
> > + BITS_PER_LONG != 64)
> > + goto slow;
> > +
> > + /* Using more efficient variant than plain call to memcmp(). */
> > switch (meta_len) {
> > #define __it(x, op) (x -= sizeof(u##op))
> > #define __it_diff(a, b, op) (*(u##op *)__it(a, op)) ^ (*(u##op *)__it(b, op))
> > @@ -4242,11 +4245,11 @@ static inline bool __skb_metadata_differs(const struct sk_buff *skb_a,
> > fallthrough;
> > case 4: diffs |= __it_diff(a, b, 32);
> > break;
> > + default:
> > +slow:
> > + return memcmp(a - meta_len, b - meta_len, meta_len);
> > }
> > return diffs;
> > -#else
> > - return memcmp(a - meta_len, b - meta_len, meta_len);
> > -#endif
> > }
> > static inline bool skb_metadata_differs(const struct sk_buff *skb_a,
> > diff --git a/include/net/xdp.h b/include/net/xdp.h
> > index 0fbd25616241..f48723250c7c 100644
> > --- a/include/net/xdp.h
> > +++ b/include/net/xdp.h
> > @@ -370,7 +370,12 @@ xdp_data_meta_unsupported(const struct xdp_buff *xdp)
> > static inline bool xdp_metalen_invalid(unsigned long metalen)
> > {
> > - return (metalen & (sizeof(__u32) - 1)) || (metalen > 32);
> > + typeof(metalen) meta_max;
> > +
> > + meta_max = type_max(typeof_member(struct skb_shared_info, meta_len));
> > + BUILD_BUG_ON(!__builtin_constant_p(meta_max));
> > +
> > + return !IS_ALIGNED(metalen, sizeof(u32)) || metalen > meta_max;
> > }
> > struct xdp_attachment_info {
>
>
next prev parent reply other threads:[~2023-05-15 17:11 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-12 15:25 [xdp-hints] [PATCH RESEND bpf-next 00/15] new kfunc XDP hints and ice implementation Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 01/15] ice: make RX hash reading code more reusable Larysa Zaremba
2023-05-19 16:46 ` [xdp-hints] " Alexander Lobakin
2023-05-22 15:03 ` Larysa Zaremba
2023-05-22 15:36 ` Alexander Lobakin
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 02/15] ice: make RX HW timestamp " Larysa Zaremba
2023-05-19 16:52 ` [xdp-hints] " Alexander Lobakin
2023-05-22 15:07 ` Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 03/15] ice: make RX checksum checking " Larysa Zaremba
2023-05-22 15:51 ` [xdp-hints] " Alexander Lobakin
2023-05-22 16:05 ` Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 04/15] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 05/15] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-05-22 16:46 ` [xdp-hints] " Alexander Lobakin
2023-05-23 8:02 ` Larysa Zaremba
2023-05-25 11:02 ` Alexander Lobakin
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 06/15] ice: Support HW timestamp hint Larysa Zaremba
2023-05-12 18:19 ` [xdp-hints] " Stanislav Fomichev
2023-05-16 16:17 ` Jesper Dangaard Brouer
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 07/15] ice: Support RX hash XDP hint Larysa Zaremba
2023-05-12 18:22 ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:46 ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 08/15] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 09/15] xdp: Add VLAN tag hint Larysa Zaremba
2023-05-12 18:28 ` [xdp-hints] " Stanislav Fomichev
2023-05-15 15:36 ` Jesper Dangaard Brouer
2023-05-15 16:09 ` Larysa Zaremba
2023-05-22 8:37 ` Jesper Dangaard Brouer
2023-05-22 15:48 ` Larysa Zaremba
2023-05-23 10:16 ` Jesper Dangaard Brouer
2023-05-23 17:35 ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 10/15] ice: Implement " Larysa Zaremba
2023-05-12 18:31 ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:41 ` Larysa Zaremba
2023-05-15 15:07 ` Jesper Dangaard Brouer
2023-05-15 15:45 ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 11/15] xdp: Add checksum level hint Larysa Zaremba
2023-05-12 18:34 ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:49 ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 12/15] ice: Implement " Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 13/15] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-05-12 18:33 ` [xdp-hints] " Stanislav Fomichev
2023-05-15 14:05 ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 14/15] net, xdp: allow metadata > 32 Larysa Zaremba
2023-05-15 16:17 ` [xdp-hints] " Jesper Dangaard Brouer
2023-05-15 17:08 ` Larysa Zaremba [this message]
2023-05-16 12:37 ` Alexander Lobakin
2023-05-16 15:35 ` Jesper Dangaard Brouer
2023-05-19 16:35 ` Alexander Lobakin
2023-05-22 11:41 ` Jesper Dangaard Brouer
2023-05-22 15:28 ` Alexander Lobakin
2023-05-22 15:55 ` Daniel Borkmann
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 15/15] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-05-12 18:37 ` [xdp-hints] " Stanislav Fomichev
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