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From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: "Alexander Lobakin" <alexandr.lobakin@intel.com>,
	"Larysa Zaremba" <larysa.zaremba@intel.com>,
	"Michal Swiatkowski" <michal.swiatkowski@linux.intel.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Maciej Fijalkowski" <maciej.fijalkowski@intel.com>,
	"Jonathan Lemon" <jonathan.lemon@gmail.com>,
	"Toke Hoiland-Jorgensen" <toke@redhat.com>,
	"Lorenzo Bianconi" <lorenzo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Yajun Deng" <yajun.deng@linux.dev>,
	"Willem de Bruijn" <willemb@google.com>,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, xdp-hints@xdp-project.net
Subject: [xdp-hints] [PATCH RFC bpf-next 21/52] net, xdp: allow metadata > 32
Date: Tue, 28 Jun 2022 21:47:41 +0200	[thread overview]
Message-ID: <20220628194812.1453059-22-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <20220628194812.1453059-1-alexandr.lobakin@intel.com>

Hardware/driver-prepended XDP metadata might be much bigger than 32
bytes, especially if it includes a piece of a descriptor.
Relax the restriction and allow metadata larger than 32 bytes and
make __skb_metadata_differs() work with bigger lengths. The new
restriction is pretty much mechanical -- skb_shared_info::meta_len
is a u8 and XDP_PACKET_HEADROOM is 256 (minus
`sizeof(struct xdp_frame)`).
The requirement of having its length aligned to 4 bytes is still
valid.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
 include/linux/skbuff.h | 13 ++++++++-----
 include/net/xdp_meta.h | 21 ++++++++++++++++++++-
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 82edf0359ab3..a825ea7f375d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4096,10 +4096,13 @@ 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))
@@ -4119,11 +4122,11 @@ 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_meta.h b/include/net/xdp_meta.h
index e1f3df9ceb93..3a40189d71c6 100644
--- a/include/net/xdp_meta.h
+++ b/include/net/xdp_meta.h
@@ -5,6 +5,7 @@
 #define __LINUX_NET_XDP_META_H__
 
 #include <net/xdp.h>
+#include <uapi/linux/bpf.h>
 
 /* Drivers not supporting XDP metadata can use this helper, which
  * rejects any room expansion for metadata as a result.
@@ -21,9 +22,27 @@ xdp_data_meta_unsupported(const struct xdp_buff *xdp)
 	return unlikely(xdp->data_meta > xdp->data);
 }
 
+/**
+ * xdp_metalen_invalid -- check if the length of a frame's metadata is valid
+ * @metalen: the length of the frame's metadata
+ *
+ * skb_shared_info::meta_len is of 1 byte long, thus it can't be longer than
+ * 255, but this always can change. XDP_PACKET_HEADROOM is 256, and this is a
+ * UAPI. sizeof(struct xdp_frame) is reserved since xdp_frame is being placed
+ * at xdp_buff::data_hard_start whilst being constructed on XDP_REDIRECT.
+ * The 32-bit alignment requirement is arbitrary, kept for simplicity and,
+ * sometimes, speed.
+ */
 static inline bool xdp_metalen_invalid(unsigned long metalen)
 {
-	return (metalen & (sizeof(__u32) - 1)) || (metalen > 32);
+	typeof(metalen) max;
+
+	max = min_t(typeof(max),
+		    (typeof_member(struct skb_shared_info, meta_len))~0UL,
+		    XDP_PACKET_HEADROOM - sizeof(struct xdp_frame));
+	BUILD_BUG_ON(!__builtin_constant_p(max));
+
+	return (metalen & (sizeof(u32) - 1)) || metalen > max;
 }
 
 #endif /* __LINUX_NET_XDP_META_H__ */
-- 
2.36.1


  parent reply	other threads:[~2022-06-28 19:49 UTC|newest]

Thread overview: 98+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-28 19:47 [xdp-hints] [PATCH RFC bpf-next 00/52] bpf, xdp: introduce and use Generic Hints/metadata Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 01/52] libbpf: factor out BTF loading from load_module_btfs() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 02/52] libbpf: try to load vmlinux BTF from the kernel first Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 03/52] libbpf: add function to get the pair BTF ID + type ID for a given type Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 04/52] libbpf: patch module BTF ID into BPF insns Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 05/52] net, xdp: decouple XDP code from the core networking code Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 06/52] bpf: pass a pointer to union bpf_attr to bpf_link_ops::update_prog() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 07/52] net, xdp: remove redundant arguments from dev_xdp_{at,de}tach_link() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 08/52] net, xdp: factor out XDP install arguments to a separate structure Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 09/52] net, xdp: add ability to specify BTF ID for XDP metadata Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 10/52] net, xdp: add ability to specify frame size threshold " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 11/52] libbpf: factor out __bpf_set_link_xdp_fd_replace() args into a struct Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 12/52] libbpf: add ability to set the BTF/type ID on setting XDP prog Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 13/52] libbpf: add ability to set the meta threshold " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 14/52] libbpf: pass &bpf_link_create_opts directly to bpf_program__attach_fd() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 15/52] libbpf: add bpf_program__attach_xdp_opts() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 16/52] selftests/bpf: expand xdp_link to check that setting meta opts works Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 17/52] samples/bpf: pass a struct to sample_install_xdp() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 18/52] samples/bpf: add ability to specify metadata threshold Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 19/52] stddef: make __struct_group() UAPI C++-friendly Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 20/52] net, xdp: move XDP metadata helpers into new xdp_meta.h Alexander Lobakin
2022-06-28 19:47 ` Alexander Lobakin [this message]
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 22/52] net, skbuff: add ability to skip skb metadata comparison Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 23/52] net, skbuff: constify the @skb argument of skb_hwtstamps() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 24/52] bpf, xdp: declare generic XDP metadata structure Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 25/52] net, xdp: add basic generic metadata accessors Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 26/52] bpf, btf: add a pair of function to work with the BTF ID + type ID pair Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 27/52] net, xdp: add &sk_buff <-> &xdp_meta_generic converters Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 28/52] net, xdp: prefetch data a bit when building an skb from an &xdp_frame Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 29/52] net, xdp: try to fill skb fields when converting " Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 30/52] net, gro: decouple GRO from the NAPI layer Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 31/52] net, gro: expose some GRO API to use outside of NAPI Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 32/52] bpf, cpumap: switch to GRO from netif_receive_skb_list() Alexander Lobakin
2024-08-07 20:38   ` [xdp-hints] " Daniel Xu
2024-08-08  4:54     ` Lorenzo Bianconi
2024-08-08 11:57       ` Alexander Lobakin
2024-08-08 17:22         ` Lorenzo Bianconi
2024-08-08 20:52         ` Daniel Xu
2024-08-09 10:02           ` Jesper Dangaard Brouer
2024-08-09 12:20           ` Alexander Lobakin
2024-08-09 12:45             ` Toke Høiland-Jørgensen
2024-08-09 12:56               ` Alexander Lobakin
2024-08-09 13:42                 ` Toke Høiland-Jørgensen
2024-08-10  0:54                   ` Martin KaFai Lau
2024-08-10  8:02                   ` Lorenzo Bianconi
2024-08-13  1:33             ` Jakub Kicinski
2024-08-13  9:51               ` Jesper Dangaard Brouer
2024-08-10  8:00         ` Lorenzo Bianconi
2024-08-13 14:09         ` Alexander Lobakin
2024-08-13 14:54           ` Toke Høiland-Jørgensen
2024-08-13 15:57             ` Jesper Dangaard Brouer
2024-08-19 14:50               ` Alexander Lobakin
2024-08-21  0:29                 ` Daniel Xu
2024-08-21 13:16                   ` Alexander Lobakin
2024-08-21 16:36                     ` Daniel Xu
2024-08-13 16:14           ` Lorenzo Bianconi
2024-08-13 16:27           ` Lorenzo Bianconi
2024-08-13 16:31             ` Alexander Lobakin
2024-08-08 20:44       ` Daniel Xu
2024-08-09  9:32         ` Jesper Dangaard Brouer
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 33/52] bpf, cpumap: add option to set a timeout for deferred flush Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 34/52] samples/bpf: add 'timeout' option to xdp_redirect_cpu Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 35/52] net, skbuff: introduce napi_skb_cache_get_bulk() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 36/52] bpf, cpumap: switch to napi_skb_cache_get_bulk() Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 37/52] rcupdate: fix access helpers for incomplete struct pointers on GCC < 10 Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 38/52] net, xdp: remove unused xdp_attachment_info::flags Alexander Lobakin
2022-06-28 19:47 ` [xdp-hints] [PATCH RFC bpf-next 39/52] net, xdp: make &xdp_attachment_info a bit more useful in drivers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 40/52] net, xdp: add an RCU version of xdp_attachment_setup() Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 41/52] net, xdp: replace net_device::xdp_prog pointer with &xdp_attachment_info Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 42/52] net, xdp: shortcut skb->dev in bpf_prog_run_generic_xdp() Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 43/52] net, xdp: build XDP generic metadata on Generic (skb) XDP path Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 44/52] net, ice: allow XDP prog hot-swapping Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 45/52] net, ice: consolidate all skb fields processing Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 46/52] net, ice: use an onstack &xdp_meta_generic_rx to store HW frame info Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 47/52] net, ice: build XDP generic metadata Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 48/52] libbpf: compress Endianness ops with a macro Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 49/52] libbpf: add LE <--> CPU conversion helpers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 50/52] libbpf: introduce a couple memory access helpers Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 51/52] selftests/bpf: fix using test_xdp_meta BPF prog via skeleton infra Alexander Lobakin
2022-06-28 19:48 ` [xdp-hints] [PATCH RFC bpf-next 52/52] selftests/bpf: add XDP Generic Hints selftest Alexander Lobakin
2022-06-29  6:15 ` [xdp-hints] Re: [PATCH RFC bpf-next 00/52] bpf, xdp: introduce and use Generic Hints/metadata John Fastabend
2022-06-29 13:43   ` Toke Høiland-Jørgensen
2022-07-04 15:44     ` Alexander Lobakin
2022-07-04 17:13       ` Jesper Dangaard Brouer
2022-07-05 14:38         ` Alexander Lobakin
2022-07-05 19:08           ` Daniel Borkmann
2022-07-04 17:14       ` Toke Høiland-Jørgensen
2022-07-05 15:41         ` Alexander Lobakin
2022-07-05 18:51           ` Toke Høiland-Jørgensen
2022-07-06 13:50             ` Alexander Lobakin
2022-07-06 23:22               ` Toke Høiland-Jørgensen
2022-07-07 11:41                 ` Jesper Dangaard Brouer
2022-07-12 10:33                 ` Magnus Karlsson
2022-07-12 14:14                   ` Jesper Dangaard Brouer
2022-07-15 11:11                     ` Magnus Karlsson
2022-06-29 17:56   ` Zvi Effron
2022-06-30  7:39     ` Magnus Karlsson
2022-07-04 15:31   ` Alexander Lobakin

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