[PATCH RFC net-next 1/5] selftests: drv-net: Test XDP_TX with bpf_dynptr

[Nimrod Oren]

Update xdp_mode_tx_handler to use bpf_dynptr_slice_rdwr instead of
accessing the packet data directly.

This makes the test viable for drivers that do not store any
packet data in the linear part when in multi-buffer mode.

While here, remove the unused local min() helper.

Signed-off-by: Nimrod Oren <no...@nvidia.com>
Reviewed-by: Carolina Jubran <cjub...@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatu...@nvidia.com>
---
 .../selftests/net/lib/xdp_native.bpf.c        | 49 +++++++++----------
 1 file changed, 23 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/net/lib/xdp_native.bpf.c 
b/tools/testing/selftests/net/lib/xdp_native.bpf.c
index 521ba38f2ddd..346cbba9afec 100644
--- a/tools/testing/selftests/net/lib/xdp_native.bpf.c
+++ b/tools/testing/selftests/net/lib/xdp_native.bpf.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <stddef.h>
+#include <stdbool.h>
 #include <linux/bpf.h>
 #include <linux/in.h>
 #include <linux/if_ether.h>
@@ -9,6 +10,7 @@
 #include <linux/udp.h>
 #include <bpf/bpf_endian.h>
 #include <bpf/bpf_helpers.h>
+#include "../../bpf/bpf_kfuncs.h"
 
 #define MAX_ADJST_OFFSET 256
 #define MAX_PAYLOAD_LEN 5000
@@ -51,11 +53,6 @@ struct {
        __type(value, __u64);
 } map_xdp_stats SEC(".maps");
 
-static __u32 min(__u32 a, __u32 b)
-{
-       return a < b ? a : b;
-}
-
 static void record_stats(struct xdp_md *ctx, __u32 stat_type)
 {
        __u64 *count;
@@ -145,32 +142,33 @@ static void swap_machdr(void *data)
 
 static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 port)
 {
-       void *data_end = (void *)(long)ctx->data_end;
-       void *data = (void *)(long)ctx->data;
        struct udphdr *udph = NULL;
-       struct ethhdr *eth = data;
+       struct ethhdr *eth = NULL;
+       struct bpf_dynptr ptr;
 
-       if (data + sizeof(*eth) > data_end)
+       bpf_dynptr_from_xdp(ctx, 0, &ptr);
+       eth = bpf_dynptr_slice_rdwr(&ptr, 0, NULL, sizeof(*eth));
+       if (!eth)
                return XDP_PASS;
 
        if (eth->h_proto == bpf_htons(ETH_P_IP)) {
-               struct iphdr *iph = data + sizeof(*eth);
-               __be32 tmp_ip = iph->saddr;
+               struct iphdr *iph = NULL;
+               __be32 tmp_ip;
 
-               if (iph + 1 > (struct iphdr *)data_end ||
-                   iph->protocol != IPPROTO_UDP)
+               iph = bpf_dynptr_slice_rdwr(&ptr, sizeof(*eth), NULL,
+                                           sizeof(*iph));
+               if (!iph || iph->protocol != IPPROTO_UDP)
                        return XDP_PASS;
 
-               udph = data + sizeof(*iph) + sizeof(*eth);
-
-               if (udph + 1 > (struct udphdr *)data_end)
-                       return XDP_PASS;
-               if (udph->dest != bpf_htons(port))
+               udph = bpf_dynptr_slice(&ptr, sizeof(*iph) + sizeof(*eth), NULL,
+                                       sizeof(*udph));
+               if (!udph || udph->dest != bpf_htons(port))
                        return XDP_PASS;
 
                record_stats(ctx, STATS_RX);
                swap_machdr((void *)eth);
 
+               tmp_ip = iph->saddr;
                iph->saddr = iph->daddr;
                iph->daddr = tmp_ip;
 
@@ -179,18 +177,17 @@ static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 
port)
                return XDP_TX;
 
        } else if (eth->h_proto  == bpf_htons(ETH_P_IPV6)) {
-               struct ipv6hdr *ipv6h = data + sizeof(*eth);
+               struct ipv6hdr *ipv6h = NULL;
                struct in6_addr tmp_ipv6;
 
-               if (ipv6h + 1 > (struct ipv6hdr *)data_end ||
-                   ipv6h->nexthdr != IPPROTO_UDP)
+               ipv6h = bpf_dynptr_slice_rdwr(&ptr, sizeof(*eth), NULL,
+                                             sizeof(*ipv6h));
+               if (!ipv6h || ipv6h->nexthdr != IPPROTO_UDP)
                        return XDP_PASS;
 
-               udph = data + sizeof(*ipv6h) + sizeof(*eth);
-
-               if (udph + 1 > (struct udphdr *)data_end)
-                       return XDP_PASS;
-               if (udph->dest != bpf_htons(port))
+               udph = bpf_dynptr_slice(&ptr, sizeof(*ipv6h) + sizeof(*eth),
+                                       NULL, sizeof(*udph));
+               if (!udph || udph->dest != bpf_htons(port))
                        return XDP_PASS;
 
                record_stats(ctx, STATS_RX);
-- 
2.45.0