[dpdk-dev] [PATCH v6 2/6] net/tap: add eBPF program file

Ophir Munk ophirmu at mellanox.com
Sat Jan 20 22:11:33 CET 2018


File tap_bpf_program.c was added with two ELF sections
corresponding to two BPF programs and one BPF map.

Section cls_q - BPF classifier to classify packets to their
corresponding queue after an RSS hash was calculated on the packet
and saved in skb->cb[1]
Section l3_l4 - BPF action to calculate RSS hash on packet
layers 3 and 4
This file is not part of DPDK tree compilation.

Signed-off-by: Ophir Munk <ophirmu at mellanox.com>
Acked-by: Pascal Mazon <pascal.mazon at 6wind.com>
---
 drivers/net/tap/tap_bpf_program.c | 221 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 221 insertions(+)
 create mode 100644 drivers/net/tap/tap_bpf_program.c

diff --git a/drivers/net/tap/tap_bpf_program.c b/drivers/net/tap/tap_bpf_program.c
new file mode 100644
index 0000000..848c50b
--- /dev/null
+++ b/drivers/net/tap/tap_bpf_program.c
@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+ * Copyright 2017 Mellanox Technologies, Ltd.
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <asm/types.h>
+#include <linux/in.h>
+#include <linux/if.h>
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/if_tunnel.h>
+#include <linux/filter.h>
+#include <linux/bpf.h>
+
+#include "tap_rss.h"
+
+/** Create IPv4 address */
+#define IPv4(a, b, c, d) ((__u32)(((a) & 0xff) << 24) | \
+		(((b) & 0xff) << 16) | \
+		(((c) & 0xff) << 8)  | \
+		((d) & 0xff))
+
+#define PORT(a, b) ((__u16)(((a) & 0xff) << 8) | \
+		((b) & 0xff))
+
+/*
+ * The queue number is offset by 1, to distinguish packets that have
+ * gone through this rule (skb->cb[1] != 0) from others.
+ */
+#define QUEUE_OFFSET		1
+#define PIN_GLOBAL_NS		2
+
+#define KEY_IDX			0
+#define BPF_MAP_ID_KEY	1
+
+struct vlan_hdr {
+	__be16 proto;
+	__be16 tci;
+};
+
+struct bpf_elf_map __attribute__((section("maps"), used))
+map_keys = {
+	.type           =       BPF_MAP_TYPE_HASH,
+	.id             =       BPF_MAP_ID_KEY,
+	.size_key       =       sizeof(__u32),
+	.size_value     =       sizeof(struct rss_key),
+	.max_elem       =       256,
+	.pinning        =       PIN_GLOBAL_NS,
+};
+
+__section("cls_q") int
+match_q(struct __sk_buff *skb)
+{
+	__u32 queue = skb->cb[1];
+	volatile __u32 q = 0xdeadbeef;
+	__u32 match_queue = QUEUE_OFFSET + q;
+
+	/* printt("match_q$i() queue = %d\n", queue); */
+
+	if (queue != match_queue)
+		return TC_ACT_OK;
+	return TC_ACT_UNSPEC;
+}
+
+
+struct ipv4_l3_l4_tuple {
+	__u32    src_addr;
+	__u32    dst_addr;
+	__u16    dport;
+	__u16    sport;
+} __attribute__((packed));
+
+struct ipv6_l3_l4_tuple {
+	__u8        src_addr[16];
+	__u8        dst_addr[16];
+	__u16       dport;
+	__u16       sport;
+} __attribute__((packed));
+
+static const __u8 def_rss_key[] = {
+	0xd1, 0x81, 0xc6, 0x2c,
+	0xf7, 0xf4, 0xdb, 0x5b,
+	0x19, 0x83, 0xa2, 0xfc,
+	0x94, 0x3e, 0x1a, 0xdb,
+	0xd9, 0x38, 0x9e, 0x6b,
+	0xd1, 0x03, 0x9c, 0x2c,
+	0xa7, 0x44, 0x99, 0xad,
+	0x59, 0x3d, 0x56, 0xd9,
+	0xf3, 0x25, 0x3c, 0x06,
+	0x2a, 0xdc, 0x1f, 0xfc,
+};
+
+static __u32  __attribute__((always_inline))
+rte_softrss_be(const __u32 *input_tuple, const uint8_t *rss_key,
+		__u8 input_len)
+{
+	__u32 i, j, hash = 0;
+#pragma unroll
+	for (j = 0; j < input_len; j++) {
+#pragma unroll
+		for (i = 0; i < 32; i++) {
+			if (input_tuple[j] & (1 << (31 - i))) {
+				hash ^= ((const __u32 *)def_rss_key)[j] << i |
+				(__u32)((uint64_t)
+				(((const __u32 *)def_rss_key)[j + 1])
+					>> (32 - i));
+			}
+		}
+	}
+	return hash;
+}
+
+static int __attribute__((always_inline))
+rss_l3_l4(struct __sk_buff *skb)
+{
+	void *data_end = (void *)(long)skb->data_end;
+	void *data = (void *)(long)skb->data;
+	__u16 proto = (__u16)skb->protocol;
+	__u32 key_idx = 0xdeadbeef;
+	__u32 hash;
+	struct rss_key *rsskey;
+	__u64 off = ETH_HLEN;
+	int j;
+	__u8 *key = 0;
+	__u32 len;
+	__u32 queue = 0;
+
+	rsskey = map_lookup_elem(&map_keys, &key_idx);
+	if (!rsskey) {
+		printt("hash(): rss key is not configured\n");
+		return TC_ACT_OK;
+	}
+	key = (__u8 *)rsskey->key;
+
+	/* Get correct proto for 802.1ad */
+	if (skb->vlan_present && skb->vlan_proto == htons(ETH_P_8021AD)) {
+		if (data + ETH_ALEN * 2 + sizeof(struct vlan_hdr) +
+		    sizeof(proto) > data_end)
+			return TC_ACT_OK;
+		proto = *(__u16 *)(data + ETH_ALEN * 2 +
+				   sizeof(struct vlan_hdr));
+		off += sizeof(struct vlan_hdr);
+	}
+
+	if (proto == htons(ETH_P_IP)) {
+		if (data + off + sizeof(struct iphdr) + sizeof(__u32)
+			> data_end)
+			return TC_ACT_OK;
+
+		__u8 *src_dst_addr = data + off + offsetof(struct iphdr, saddr);
+		__u8 *src_dst_port = data + off + sizeof(struct iphdr);
+		struct ipv4_l3_l4_tuple v4_tuple = {
+			.src_addr = IPv4(*(src_dst_addr + 0),
+					*(src_dst_addr + 1),
+					*(src_dst_addr + 2),
+					*(src_dst_addr + 3)),
+			.dst_addr = IPv4(*(src_dst_addr + 4),
+					*(src_dst_addr + 5),
+					*(src_dst_addr + 6),
+					*(src_dst_addr + 7)),
+			.sport = PORT(*(src_dst_port + 0),
+					*(src_dst_port + 1)),
+			.dport = PORT(*(src_dst_port + 2),
+					*(src_dst_port + 3)),
+		};
+		__u8 input_len = sizeof(v4_tuple) / sizeof(__u32);
+		if (rsskey->hash_fields & (1 << HASH_FIELD_IPV4_L3))
+			input_len--;
+		hash = rte_softrss_be((__u32 *)&v4_tuple, key, 3);
+	} else if (proto == htons(ETH_P_IPV6)) {
+		if (data + off + sizeof(struct ipv6hdr) +
+					sizeof(__u32) > data_end)
+			return TC_ACT_OK;
+		__u8 *src_dst_addr = data + off +
+					offsetof(struct ipv6hdr, saddr);
+		__u8 *src_dst_port = data + off +
+					sizeof(struct ipv6hdr);
+		struct ipv6_l3_l4_tuple v6_tuple;
+		for (j = 0; j < 4; j++)
+			*((uint32_t *)&v6_tuple.src_addr + j) =
+				__builtin_bswap32(*((uint32_t *)
+						src_dst_addr + j));
+		for (j = 0; j < 4; j++)
+			*((uint32_t *)&v6_tuple.dst_addr + j) =
+				__builtin_bswap32(*((uint32_t *)
+						src_dst_addr + 4 + j));
+		v6_tuple.sport = PORT(*(src_dst_port + 0),
+			      *(src_dst_port + 1));
+		v6_tuple.dport = PORT(*(src_dst_port + 2),
+			      *(src_dst_port + 3));
+
+		__u8 input_len = sizeof(v6_tuple) / sizeof(__u32);
+		if (rsskey->hash_fields & (1 << HASH_FIELD_IPV6_L3))
+			input_len--;
+		hash = rte_softrss_be((__u32 *)&v6_tuple, key, 9);
+	} else {
+		return TC_ACT_PIPE;
+	}
+
+	queue = rsskey->queues[(hash % rsskey->nb_queues) &
+				       (TAP_MAX_QUEUES - 1)];
+	skb->cb[1] = QUEUE_OFFSET + queue;
+	/* printt(">>>>> rss_l3_l4 hash=0x%x queue=%u\n", hash, queue); */
+
+	return TC_ACT_RECLASSIFY;
+}
+
+#define RSS(L)						\
+	__section(#L) int				\
+		L ## _hash(struct __sk_buff *skb)	\
+	{						\
+		return rss_ ## L (skb);			\
+	}
+
+RSS(l3_l4)
+
+BPF_LICENSE("Dual BSD/GPL");
-- 
2.7.4



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