netdev - [bpf-next PATCH] bpf: simplify xdp_convert_ctx_access for xdp_rxq

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Message-ID: <151568874925.5413.12343433820668284586.stgit@firesoul>
Date:   Thu, 11 Jan 2018 17:39:09 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org, Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>
Subject: [bpf-next PATCH] bpf: simplify xdp_convert_ctx_access for
 xdp_rxq_info

As pointed out by Daniel Borkmann, using bpf_target_off() is not
necessary for xdp_rxq_info when extracting queue_index and
ifindex, as these members are u32 like BPF_W.

Also fix trivial spelling mistake introduced in same commit.

Fixes: 02dd3291b2f0 ("bpf: finally expose xdp_rxq_info to XDP bpf-programs")
Reported-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 include/uapi/linux/bpf.h |    2 +-
 net/core/filter.c        |    7 +++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 405317f9c064..395d261948de 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -899,7 +899,7 @@ struct xdp_md {
 	__u32 data;
 	__u32 data_end;
 	__u32 data_meta;
-	/* Below access go though struct xdp_rxq_info */
+	/* Below access go through struct xdp_rxq_info */
 	__u32 ingress_ifindex; /* rxq->dev->ifindex */
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
diff --git a/net/core/filter.c b/net/core/filter.c
index acdb94c0e97f..4ce50306154d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4312,16 +4312,15 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type,
 				      si->dst_reg, si->dst_reg,
 				      offsetof(struct xdp_rxq_info, dev));
 		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
-				      bpf_target_off(struct net_device,
-						     ifindex, 4, target_size));
+				      offsetof(struct net_device, ifindex));
 		break;
 	case offsetof(struct xdp_md, rx_queue_index):
 		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, rxq),
 				      si->dst_reg, si->src_reg,
 				      offsetof(struct xdp_buff, rxq));
 		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
-				      bpf_target_off(struct xdp_rxq_info,
-						queue_index, 4, target_size));
+				      offsetof(struct xdp_rxq_info,
+					       queue_index));
 		break;
 	}