selftests/bpf: skip verifier tests for unsupported program types

Use recently introduced bpf_probe_prog_type() to skip tests in the
test_verifier() if bpf_verify_program() fails. The skipped test is
indicated in the output.

Example:

...
679/p bpf_get_stack return R0 within range SKIP (unsupported program
type 5)
680/p ld_abs: invalid op 1 OK
...
Summary: 863 PASSED, 165 SKIPPED, 3 FAILED
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -34,6 +34,7 @@
 #include <linux/if_ether.h>
 
 #include <bpf/bpf.h>
+#include <bpf/libbpf.h>
 
 #ifdef HAVE_GENHDR
 # include "autoconf.h"
@@ -59,6 +60,7 @@
 
 #define UNPRIV_SYSCTL "kernel/unprivileged_bpf_disabled"
 static bool unpriv_disabled = false;
+static int skips;
 
 struct bpf_test {
 	const char *descr;
@@ -598,6 +600,11 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 		pflags |= BPF_F_ANY_ALIGNMENT;
 	fd_prog = bpf_verify_program(prog_type, prog, prog_len, pflags,
 				     "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 1);
+	if (fd_prog < 0 && !bpf_probe_prog_type(prog_type, 0)) {
+		printf("SKIP (unsupported program type %d)\n", prog_type);
+		skips++;
+		goto close_fds;
+	}
 
 	expected_ret = unpriv && test->result_unpriv != UNDEF ?
 		       test->result_unpriv : test->result;
@@ -751,7 +758,7 @@ static bool test_as_unpriv(struct bpf_test *test)
 
 static int do_test(bool unpriv, unsigned int from, unsigned int to)
 {
-	int i, passes = 0, errors = 0, skips = 0;
+	int i, passes = 0, errors = 0;
 
 	for (i = from; i < to; i++) {
 		struct bpf_test *test = &tests[i];