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From: Larysa Zaremba <larysa.zaremba@intel.com>
To: bpf@vger.kernel.org
Cc: Larysa Zaremba <larysa.zaremba@intel.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>,
	Jesper Dangaard Brouer <brouer@redhat.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] [PATCH 14/15] net, xdp: allow metadata > 32
Date: Fri, 12 May 2023 17:16:38 +0200	[thread overview]
Message-ID: <20230512151639.992033-15-larysa.zaremba@intel.com> (raw)
In-Reply-To: <20230512151639.992033-1-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 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 {
-- 
2.35.3


  parent reply	other threads:[~2023-05-12 15:21 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-12 15:16 [xdp-hints] [PATCH bpf-next 00/15] new kfunc XDP hints and ice implementation Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 01/15] ice: make RX hash reading code more reusable Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 02/15] ice: make RX HW timestamp " Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 03/15] ice: make RX checksum checking " Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 04/15] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 05/15] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 06/15] ice: Support HW timestamp hint Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 07/15] ice: Support RX hash XDP hint Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 08/15] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 09/15] xdp: Add VLAN tag hint Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 10/15] ice: Implement " Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 11/15] xdp: Add checksum level hint Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 12/15] ice: Implement " Larysa Zaremba
2023-05-12 15:16 ` [xdp-hints] [PATCH 13/15] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-05-12 15:16 ` Larysa Zaremba [this message]
2023-05-12 15:16 ` [xdp-hints] [PATCH 15/15] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba

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