selftests/bpf: Test skops->skb_hwtstamp

This patch tests reading the skops->skb_hwtstamp field.

A local test was also done such that the shinfo hwtstamp was temporary
set to a non zero value in the kernel bpf_skops_parse_hdr()
and the same value can be read by the skops test.

An adjustment is needed to the btf_dump selftest because
the changes in the 'struct bpf_sock_ops'.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221107230420.4192307-4-martin.lau@linux.dev

tools/testing/selftests/bpf/prog_tests/btf_dump.c

@@ -791,11 +791,11 @@ static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d,
 	TEST_BTF_DUMP_DATA_OVER(btf, d, "struct", str, struct bpf_sock_ops,
 				sizeof(struct bpf_sock_ops) - 1,
 				"(struct bpf_sock_ops){\n\t.op = (__u32)1,\n",
-				{ .op = 1, .skb_tcp_flags = 2});
+				{ .op = 1, .skb_hwtstamp = 2});
 	TEST_BTF_DUMP_DATA_OVER(btf, d, "struct", str, struct bpf_sock_ops,
 				sizeof(struct bpf_sock_ops) - 1,
 				"(struct bpf_sock_ops){\n\t.op = (__u32)1,\n",
-				{ .op = 1, .skb_tcp_flags = 0});
+				{ .op = 1, .skb_hwtstamp = 0});
 }
 
 static void test_btf_dump_var_data(struct btf *btf, struct btf_dump *d,

tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c

@@ -505,6 +505,8 @@ static void misc(void)
 
 	ASSERT_EQ(misc_skel->bss->nr_fin, 1, "unexpected nr_fin");
 
+	ASSERT_EQ(misc_skel->bss->nr_hwtstamp, 0, "nr_hwtstamp");
+
 check_linum:
 	ASSERT_FALSE(check_error_linum(&sk_fds), "check_error_linum");
 	sk_fds_close(&sk_fds);

tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c

@@ -27,6 +27,7 @@ unsigned int nr_pure_ack = 0;
 unsigned int nr_data = 0;
 unsigned int nr_syn = 0;
 unsigned int nr_fin = 0;
+unsigned int nr_hwtstamp = 0;
 
 /* Check the header received from the active side */
 static int __check_active_hdr_in(struct bpf_sock_ops *skops, bool check_syn)
@@ -146,6 +147,9 @@ static int check_active_hdr_in(struct bpf_sock_ops *skops)
 	if (th->ack && !th->fin && tcp_hdrlen(th) == skops->skb_len)
 		nr_pure_ack++;
 
+	if (skops->skb_hwtstamp)
+		nr_hwtstamp++;
+
 	return CG_OK;
 }