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From: Larysa Zaremba <larysa.zaremba@intel.com>
To: bpf@vger.kernel.org
Cc: Larysa Zaremba <larysa.zaremba@intel.com>,
	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, sdf@google.com,
	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,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Simon Horman <simon.horman@corigine.com>,
	Aleksander Lobakin <aleksander.lobakin@intel.com>
Subject: [xdp-hints] [PATCH bpf-next v5 15/21] net, xdp: allow metadata > 32
Date: Fri, 11 Aug 2023 18:15:03 +0200	[thread overview]
Message-ID: <20230811161509.19722-16-larysa.zaremba@intel.com> (raw)
In-Reply-To: <20230811161509.19722-1-larysa.zaremba@intel.com>

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. 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 aa57e2eca33b..0e455678cb8a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4216,10 +4216,13 @@ 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))
@@ -4239,11 +4242,11 @@ 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 495c4d2a2c50..05234f156a73 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -369,7 +369,12 @@ 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 {
-- 
2.41.0


  parent reply	other threads:[~2023-08-11 16:20 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-11 16:14 [xdp-hints] [PATCH bpf-next v5 00/21] XDP metadata via kfuncs for ice Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 01/21] ice: make RX hash reading code more reusable Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 02/21] ice: make RX HW timestamp " Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 03/21] ice: make RX checksum checking " Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 04/21] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 05/21] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 06/21] ice: Support HW timestamp hint Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 07/21] ice: Support RX hash XDP hint Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 08/21] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 09/21] xdp: Add VLAN tag hint Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 10/21] ice: Implement " Larysa Zaremba
2023-08-11 16:14 ` [xdp-hints] [PATCH bpf-next v5 11/21] ice: use VLAN proto from ring packet context in skb path Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 12/21] xdp: Add checksum hint Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 13/21] ice: Implement " Larysa Zaremba
2023-08-17 21:58   ` [xdp-hints] " Alexei Starovoitov
2023-08-22  9:07     ` Larysa Zaremba
2023-08-22 19:50       ` Alexei Starovoitov
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 14/21] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-08-11 16:15 ` Larysa Zaremba [this message]
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 16/21] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 17/21] veth: Implement VLAN tag and checksum XDP hint Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 18/21] net: make vlan_get_tag() return -ENODATA instead of -EINVAL Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 19/21] selftests/bpf: Use AF_INET for TX in xdp_metadata Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 20/21] selftests/bpf: Check VLAN tag and proto " Larysa Zaremba
2023-08-11 16:15 ` [xdp-hints] [PATCH bpf-next v5 21/21] selftests/bpf: check checksum state " Larysa Zaremba
2023-08-11 16:23 ` [xdp-hints] Re: [PATCH bpf-next v5 00/21] XDP metadata via kfuncs for ice Larysa Zaremba
2023-08-15 18:45 ` Stanislav Fomichev

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