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

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Message-Id: <20220617220738.3593-1-gospo@broadcom.com>
Date:   Fri, 17 Jun 2022 22:07:38 +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>
Subject: [PATCH net-next] samples/bpf: fixup some xdp progs 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.

Signed-off-by: Andy Gospodarek <gospo@...adcom.com>
---
 samples/bpf/xdp1_kern.c            | 13 ++++++++++---
 samples/bpf/xdp2_kern.c            | 13 ++++++++++---
 samples/bpf/xdp_tx_iptunnel_kern.c |  2 +-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/samples/bpf/xdp1_kern.c b/samples/bpf/xdp1_kern.c
index f0c5d95084de..a798553fca3b 100644
--- a/samples/bpf/xdp1_kern.c
+++ b/samples/bpf/xdp1_kern.c
@@ -39,17 +39,24 @@ 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;
 	u16 h_proto;
 	u64 nh_off;
 	u32 ipproto;
+	int err;
+
+	err = bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt));
+	if (err < 0)
+		return rc;
 
 	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
diff --git a/samples/bpf/xdp2_kern.c b/samples/bpf/xdp2_kern.c
index d8a64ab077b0..1502ef820aed 100644
--- a/samples/bpf/xdp2_kern.c
+++ b/samples/bpf/xdp2_kern.c
@@ -55,17 +55,24 @@ 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;
 	u16 h_proto;
 	u64 nh_off;
 	u32 ipproto;
+	int err;
+
+	err = bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt));
+	if (err < 0)
+		return rc;
 
 	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
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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