samples: bpf: Convert xdp_redirect_kern.o to XDP samples helper

We moved swap_src_dst_mac to xdp_sample.bpf.h to be shared with other
potential users, so drop it while moving code to the new file.
Also, consistently use SEC("xdp") naming instead.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-16-memxor@gmail.com

samples/bpf/Makefile

@@ -163,7 +163,6 @@ always-y += tcp_clamp_kern.o
 always-y += tcp_basertt_kern.o
 always-y += tcp_tos_reflect_kern.o
 always-y += tcp_dumpstats_kern.o
-always-y += xdp_redirect_kern.o
 always-y += xdp_redirect_map_kern.o
 always-y += xdp_redirect_map_multi_kern.o
 always-y += xdp_redirect_cpu_kern.o
@@ -356,6 +355,7 @@ endef
 
 CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
 
+$(obj)/xdp_redirect.bpf.o: $(obj)/xdp_sample.bpf.o
 $(obj)/xdp_monitor.bpf.o: $(obj)/xdp_sample.bpf.o
 
 $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/xdp_sample_shared.h
@@ -366,9 +366,10 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/x
 		-I$(srctree)/tools/lib $(CLANG_SYS_INCLUDES) \
 		-c $(filter %.bpf.c,$^) -o $@
 
-LINKED_SKELS := xdp_monitor.skel.h
+LINKED_SKELS := xdp_redirect.skel.h xdp_monitor.skel.h
 clean-files += $(LINKED_SKELS)
 
+xdp_redirect.skel.h-deps := xdp_redirect.bpf.o xdp_sample.bpf.o
 xdp_monitor.skel.h-deps := xdp_monitor.bpf.o xdp_sample.bpf.o
 
 LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))

samples/bpf/xdp_redirect_kern.c → samples/bpf/xdp_redirect.bpf.c

+// SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2016 John Fastabend <john.r.fastabend@intel.com>
  *
  * This program is free software; you can redistribute it and/or
@@ -9,79 +10,37 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * General Public License for more details.
  */
-#define KBUILD_MODNAME "foo"
-#include <uapi/linux/bpf.h>
-#include <linux/in.h>
-#include <linux/if_ether.h>
-#include <linux/if_packet.h>
-#include <linux/if_vlan.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <bpf/bpf_helpers.h>
+#include "vmlinux.h"
+#include "xdp_sample.bpf.h"
+#include "xdp_sample_shared.h"
 
-struct {
-	__uint(type, BPF_MAP_TYPE_ARRAY);
-	__type(key, int);
-	__type(value, int);
-	__uint(max_entries, 1);
-} tx_port SEC(".maps");
+const volatile int ifindex_out;
 
-/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
- * feedback.  Redirect TX errors can be caught via a tracepoint.
- */
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, long);
-	__uint(max_entries, 1);
-} rxcnt SEC(".maps");
-
-static void swap_src_dst_mac(void *data)
-{
-	unsigned short *p = data;
-	unsigned short dst[3];
-
-	dst[0] = p[0];
-	dst[1] = p[1];
-	dst[2] = p[2];
-	p[0] = p[3];
-	p[1] = p[4];
-	p[2] = p[5];
-	p[3] = dst[0];
-	p[4] = dst[1];
-	p[5] = dst[2];
-}
-
-SEC("xdp_redirect")
+SEC("xdp")
 int xdp_redirect_prog(struct xdp_md *ctx)
 {
 	void *data_end = (void *)(long)ctx->data_end;
 	void *data = (void *)(long)ctx->data;
+	u32 key = bpf_get_smp_processor_id();
 	struct ethhdr *eth = data;
-	int rc = XDP_DROP;
-	int *ifindex, port = 0;
-	long *value;
-	u32 key = 0;
+	struct datarec *rec;
 	u64 nh_off;
 
 	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
-		return rc;
+		return XDP_DROP;
 
-	ifindex = bpf_map_lookup_elem(&tx_port, &port);
-	if (!ifindex)
-		return rc;
-
-	value = bpf_map_lookup_elem(&rxcnt, &key);
-	if (value)
-		*value += 1;
+	rec = bpf_map_lookup_elem(&rx_cnt, &key);
+	if (!rec)
+		return XDP_PASS;
+	NO_TEAR_INC(rec->processed);
 
 	swap_src_dst_mac(data);
-	return bpf_redirect(*ifindex, 0);
+	return bpf_redirect(ifindex_out, 0);
 }
 
 /* Redirect require an XDP bpf_prog loaded on the TX device */
-SEC("xdp_redirect_dummy")
+SEC("xdp")
 int xdp_redirect_dummy_prog(struct xdp_md *ctx)
 {
 	return XDP_PASS;