[net-next,v4,6/6] selftests/bpf: Add test for default devmap allocation

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 77b73b892136..07f2f54a6a87 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -54,7 +54,8 @@  TEST_PROGS := test_kmod.sh \
 	test_lwt_ip_encap.sh \
 	test_tcp_check_syncookie.sh \
 	test_tc_tunnel.sh \
-	test_tc_edt.sh
+	test_tc_edt.sh \
+	test_xdp_devmap_alloc.sh
 
 TEST_PROGS_EXTENDED := with_addr.sh \
 	with_tunnels.sh \
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_tail_call.c b/tools/testing/selftests/bpf/progs/test_xdp_tail_call.c
new file mode 100644
index 000000000000..6c89dc4ad341
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_tail_call.c
@@ -0,0 +1,39 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#define KBUILD_MODNAME "xdp_dummy"
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") jmp_table = {
+	.type = BPF_MAP_TYPE_PROG_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 8,
+};
+
+struct bpf_map_def SEC("maps") arr_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+};
+
+
+SEC("xdp_dummy_tail_call")
+int xdp_dummy_prog(struct xdp_md *ctx)
+{
+        long *value;
+        __u32 key = 0;
+
+        /* We just need the call instruction in the program, so it is fine that
+         * this fails, but it should not be optimised out by the compiler (so
+         * can't just do if (false)).
+         */
+        value = bpf_map_lookup_elem(&arr_map, &key);
+        if (value)
+                bpf_tail_call(ctx, &jmp_table, 1);
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_xdp_devmap_alloc.sh b/tools/testing/selftests/bpf/test_xdp_devmap_alloc.sh
new file mode 100755
index 000000000000..0431f94f136a
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_xdp_devmap_alloc.sh
@@ -0,0 +1,94 @@ 
+#!/bin/bash
+
+cleanup()
+{
+	if [ "$?" = "0" ]; then
+		echo "selftests: test_xdp_devmap_alloc [PASS]";
+	else
+		echo "selftests: test_xdp_devmap_alloc [FAILED]";
+	fi
+
+	set +e
+	ip link del veth1 2> /dev/null
+	ip netns del ns1 2> /dev/null
+	ip netns del ns2 2> /dev/null
+}
+
+check_alloc()
+{
+    ns="$1"
+    expected="$2 $3"
+
+    if [[ "$ns" == "root" ]]; then
+        actual=$(< /proc/net/default_dev_map)
+    else
+        actual=$(ip netns exec "$ns" cat /proc/net/default_dev_map)
+    fi
+
+    if [[ "$expected" != "$actual" ]]; then
+        echo "Expected allocation '$expected' got '$actual'" >&2
+        exit 1
+    fi
+}
+
+ip link set dev lo xdp off 2>/dev/null > /dev/null
+if [ $? -ne 0 ];then
+	echo "selftests: [SKIP] Could not run test without ip xdp support"
+	exit 0
+fi
+set -e
+
+ip netns add ns1
+ip netns add ns2
+
+trap cleanup 0 2 3 6 9
+
+ip link add veth1 type veth peer name veth2
+
+ip link set veth1 netns ns1
+ip link set veth2 netns ns2
+
+check_alloc ns1 0 0
+check_alloc ns2 0 0
+
+# Check that loading an xdp tail call program increases counter, but doesn't
+# load a program
+ip netns exec ns2 ip link set dev veth2 xdp obj test_xdp_tail_call.o sec xdp_dummy_tail_call
+check_alloc ns2 1 0
+
+# Check that loading a redirect program allocates a map, and
+# removing that program de-allocates the map again.
+ip netns exec ns1 ip link set dev veth1 xdp obj test_xdp_redirect.o sec redirect_to_111
+check_alloc ns1 1 1
+# Now we should have a map allocated in the other ns
+check_alloc ns2 1 1
+ip netns exec ns1 ip link set dev veth1 xdp off
+check_alloc ns1 0 0
+check_alloc ns2 1 0
+ip netns exec ns2 ip link set dev veth2 xdp off
+check_alloc ns2 0 0
+
+# Check that switching between redirect and non-redirect programs correctly
+# allocs/de-allocs map
+ip netns exec ns1 ip link set dev veth1 xdp obj xdp_dummy.o sec xdp_dummy
+check_alloc ns1 0 0
+ip netns exec ns1 ip -force link set dev veth1 xdp obj test_xdp_redirect.o sec redirect_to_111
+check_alloc ns1 1 1
+ip netns exec ns1 ip -force link set dev veth1 xdp obj xdp_dummy.o sec xdp_dummy
+check_alloc ns1 0 0
+
+ip netns exec ns1 ip link set dev veth1 xdp off
+
+# Check that moving an interface into a namespace will allocate the map
+ip netns del ns1
+ip netns add ns1
+ip link add veth1 type veth peer name veth2
+
+ip link set dev veth1 xdp obj test_xdp_redirect.o sec redirect_to_111
+check_alloc root 1 1
+check_alloc ns1 0 0
+ip link set dev veth1 netns ns1
+check_alloc ns1 1 1
+check_alloc root 0 0
+
+exit 0