selftests/bpf: add selftests for wide loads

Mirror existing wide store tests with wide loads. The only significant
difference is expected error string.

Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/verifier/wide_access.c

@@ -34,3 +34,40 @@ BPF_SOCK_ADDR_STORE(msg_src_ip6, 3, REJECT,
 		    "invalid bpf_context access off=56 size=8"),
 
 #undef BPF_SOCK_ADDR_STORE
+
+#define BPF_SOCK_ADDR_LOAD(field, off, res, err) \
+{ \
+	"wide load from bpf_sock_addr." #field "[" #off "]", \
+	.insns = { \
+	BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, \
+		    offsetof(struct bpf_sock_addr, field[off])), \
+	BPF_MOV64_IMM(BPF_REG_0, 1), \
+	BPF_EXIT_INSN(), \
+	}, \
+	.result = res, \
+	.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR, \
+	.expected_attach_type = BPF_CGROUP_UDP6_SENDMSG, \
+	.errstr = err, \
+}
+
+/* user_ip6[0] is u64 aligned */
+BPF_SOCK_ADDR_LOAD(user_ip6, 0, ACCEPT,
+		   NULL),
+BPF_SOCK_ADDR_LOAD(user_ip6, 1, REJECT,
+		   "invalid bpf_context access off=12 size=8"),
+BPF_SOCK_ADDR_LOAD(user_ip6, 2, ACCEPT,
+		   NULL),
+BPF_SOCK_ADDR_LOAD(user_ip6, 3, REJECT,
+		   "invalid bpf_context access off=20 size=8"),
+
+/* msg_src_ip6[0] is _not_ u64 aligned */
+BPF_SOCK_ADDR_LOAD(msg_src_ip6, 0, REJECT,
+		   "invalid bpf_context access off=44 size=8"),
+BPF_SOCK_ADDR_LOAD(msg_src_ip6, 1, ACCEPT,
+		   NULL),
+BPF_SOCK_ADDR_LOAD(msg_src_ip6, 2, REJECT,
+		   "invalid bpf_context access off=52 size=8"),
+BPF_SOCK_ADDR_LOAD(msg_src_ip6, 3, REJECT,
+		   "invalid bpf_context access off=56 size=8"),
+
+#undef BPF_SOCK_ADDR_LOAD