bpftool: Add misc section and probe for large INSN limit

Introduce a new probe section (misc) for probes not related to concrete
map types, program types, functions or kernel configuration. Introduce a
probe for large INSN limit as the first one in that section.

Example outputs:

  # bpftool feature probe
  [...]
  Scanning miscellaneous eBPF features...
  Large program size limit is available

  # bpftool feature probe macros
  [...]
  /*** eBPF misc features ***/
  #define HAVE_HAVE_LARGE_INSN_LIMIT

  # bpftool feature probe -j | jq '.["misc"]'
  {
    "have_large_insn_limit": true
  }
Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Link: https://lore.kernel.org/bpf/20200108162428.25014-3-mrostecki@opensuse.org

tools/bpf/bpftool/feature.c

@@ -572,6 +572,18 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
 		printf("\n");
 }
 
+static void
+probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
+{
+	bool res;
+
+	res = bpf_probe_large_insn_limit(ifindex);
+	print_bool_feature("have_large_insn_limit",
+			   "Large program size limit",
+			   "HAVE_LARGE_INSN_LIMIT",
+			   res, define_prefix);
+}
+
 static int do_probe(int argc, char **argv)
 {
 	enum probe_component target = COMPONENT_UNSPEC;
@@ -724,6 +736,12 @@ static int do_probe(int argc, char **argv)
 		probe_helpers_for_progtype(i, supported_types[i],
 					   define_prefix, ifindex);
 
+	print_end_then_start_section("misc",
+				     "Scanning miscellaneous eBPF features...",
+				     "/*** eBPF misc features ***/",
+				     define_prefix);
+	probe_large_insn_limit(define_prefix, ifindex);
+
 exit_close_json:
 	if (json_output) {
 		/* End current "section" of probes */