selftests/bpf: Skip verifier tests that fail to load with ENOTSUPP

The verifier tests added in commit c48e51c8b0 ("bpf: selftests: Add
selftests for module kfunc support") fail on s390, since the JIT does
not support calling kernel functions. This is most likely an issue for
all the other non-Intel arches, as well as on Intel with
!CONFIG_DEBUG_INFO_BTF or !CONFIG_BPF_JIT.

Trying to check for messages from all the possible add_kfunc_call()
failure cases in test_verifier looks pointless, so do a much simpler
thing instead: just like it's already done in do_prog_test_run(), skip
the tests that fail to load with ENOTSUPP.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211007173329.381754-1-iii@linux.ibm.com

tools/testing/selftests/bpf/test_verifier.c

@@ -47,6 +47,10 @@
 #include "test_btf.h"
 #include "../../../include/linux/filter.h"
 
+#ifndef ENOTSUPP
+#define ENOTSUPP 524
+#endif
+
 #define MAX_INSNS	BPF_MAXINSNS
 #define MAX_TEST_INSNS	1000000
 #define MAX_FIXUPS	8
@@ -974,7 +978,7 @@ static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val,
 
 	if (err) {
 		switch (saved_errno) {
-		case 524/*ENOTSUPP*/:
+		case ENOTSUPP:
 			printf("Did not run the program (not supported) ");
 			return 0;
 		case EPERM:
@@ -1119,6 +1123,12 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 		goto close_fds;
 	}
 
+	if (fd_prog < 0 && saved_errno == ENOTSUPP) {
+		printf("SKIP (program uses an unsupported feature)\n");
+		skips++;
+		goto close_fds;
+	}
+
 	alignment_prevented_execution = 0;
 
 	if (expected_ret == ACCEPT || expected_ret == VERBOSE_ACCEPT) {