netdev - [PATCH net-next v2] samples/bpf: fixup some tools to be able to support xdp multibuffer

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Message-Id: <20220621175402.35327-1-gospo@broadcom.com>
Date:   Tue, 21 Jun 2022 17:54:02 +0000
From:   Andy Gospodarek <andrew.gospodarek@...adcom.com>
To:     ast@...nel.org, daniel@...earbox.net, davem@...emloft.net,
        kuba@...nel.org, hawk@...nel.org, john.fastabend@...il.com,
        andrii@...nel.org, kafai@...com, songliubraving@...com, yhs@...com,
        kpsingh@...nel.org, toke@...hat.com, lorenzo.bianconi@...hat.com,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     Andy Gospodarek <gospo@...adcom.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>
Subject: [PATCH net-next v2] samples/bpf: fixup some tools to be able to support xdp multibuffer

This changes the section name for the bpf program embedded in these
files to "xdp.frags" to allow the programs to be loaded on drivers that
are using an MTU greater than PAGE_SIZE.  Rather than directly accessing
the buffers, the packet data is now accessed via xdp helper functions to
provide an example for those who may need to write more complex
programs.

v2: remove new unnecessary variable

Signed-off-by: Andy Gospodarek <gospo@...adcom.com>
Acked-by: John Fastabend <john.fastabend@...il.com>
Acked-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 samples/bpf/xdp1_kern.c            | 11 ++++++++---
 samples/bpf/xdp2_kern.c            | 11 ++++++++---
 samples/bpf/xdp_tx_iptunnel_kern.c |  2 +-
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/samples/bpf/xdp1_kern.c b/samples/bpf/xdp1_kern.c
index f0c5d95084de..0a5c704badd0 100644
--- a/samples/bpf/xdp1_kern.c
+++ b/samples/bpf/xdp1_kern.c
@@ -39,11 +39,13 @@ static int parse_ipv6(void *data, u64 nh_off, void *data_end)
 	return ip6h->nexthdr;
 }
 
-SEC("xdp1")
+#define XDPBUFSIZE	64
+SEC("xdp.frags")
 int xdp_prog1(struct xdp_md *ctx)
 {
-	void *data_end = (void *)(long)ctx->data_end;
-	void *data = (void *)(long)ctx->data;
+	__u8 pkt[XDPBUFSIZE] = {};
+	void *data_end = &pkt[XDPBUFSIZE-1];
+	void *data = pkt;
 	struct ethhdr *eth = data;
 	int rc = XDP_DROP;
 	long *value;
@@ -51,6 +53,9 @@ int xdp_prog1(struct xdp_md *ctx)
 	u64 nh_off;
 	u32 ipproto;
 
+	if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
+		return rc;
+
 	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
 		return rc;
diff --git a/samples/bpf/xdp2_kern.c b/samples/bpf/xdp2_kern.c
index d8a64ab077b0..3332ba6bb95f 100644
--- a/samples/bpf/xdp2_kern.c
+++ b/samples/bpf/xdp2_kern.c
@@ -55,11 +55,13 @@ static int parse_ipv6(void *data, u64 nh_off, void *data_end)
 	return ip6h->nexthdr;
 }
 
-SEC("xdp1")
+#define XDPBUFSIZE	64
+SEC("xdp.frags")
 int xdp_prog1(struct xdp_md *ctx)
 {
-	void *data_end = (void *)(long)ctx->data_end;
-	void *data = (void *)(long)ctx->data;
+	__u8 pkt[XDPBUFSIZE] = {};
+	void *data_end = &pkt[XDPBUFSIZE-1];
+	void *data = pkt;
 	struct ethhdr *eth = data;
 	int rc = XDP_DROP;
 	long *value;
@@ -67,6 +69,9 @@ int xdp_prog1(struct xdp_md *ctx)
 	u64 nh_off;
 	u32 ipproto;
 
+	if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
+		return rc;
+
 	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
 		return rc;
diff --git a/samples/bpf/xdp_tx_iptunnel_kern.c b/samples/bpf/xdp_tx_iptunnel_kern.c
index 575d57e4b8d6..0e2bca3a3fff 100644
--- a/samples/bpf/xdp_tx_iptunnel_kern.c
+++ b/samples/bpf/xdp_tx_iptunnel_kern.c
@@ -212,7 +212,7 @@ static __always_inline int handle_ipv6(struct xdp_md *xdp)
 	return XDP_TX;
 }
 
-SEC("xdp_tx_iptunnel")
+SEC("xdp.frags")
 int _xdp_tx_iptunnel(struct xdp_md *xdp)
 {
 	void *data_end = (void *)(long)xdp->data_end;
-- 
2.25.1


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