selftests/bpf: Check alignment flag if expected result is REJECT

CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is set unconditionally for the
most archs such as x86_64, aarch64, ppc64el and s390x, but this config
may be not set by users for riscv64 and loongarch64.

If CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is not set, the BPF verifier
detects if a program has unaligned access and then rejects them. So it
should also check the flag F_NEEDS_EFFICIENT_UNALIGNED_ACCESS if the
expected result is REJECT and set alignment_prevented_execution as 1,
then the message "(NOTE: not executed due to unknown alignment)" can
be printed for some testcases of test_verifier to reflect the reality.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

Author: seehearfeel

tools/testing/selftests/bpf/test_verifier.c

@@ -1640,6 +1640,11 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 			printf("FAIL\nUnexpected success to load!\n");
 			goto fail_log;
 		}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+		if (fd_prog < 0 &&
+		    (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS))
+			alignment_prevented_execution = 1;
+#endif
 		if (!expected_err || !cmp_str_seq(bpf_vlog, expected_err)) {
 			printf("FAIL\nUnexpected error message!\n\tEXP: %s\n\tRES: %s\n",
 			      expected_err, bpf_vlog);