From: Paul Chaignon <paul@isovalent.com>
Date: Tue, 4 Jan 2022 18:59:29 +0100
Subject: bpftool: Refactor misc. feature probe
Patch-mainline: v5.17-rc1
Git-commit: b22bf1b9979a608827dea98c61ed9ec297bcc513
References: jsc#PED-1368

There is currently a single miscellaneous feature probe,
HAVE_LARGE_INSN_LIMIT, to check for the 1M instructions limit in the
verifier. Subsequent patches will add additional miscellaneous probes,
which follow the same pattern at the existing probe. This patch
therefore refactors the probe to avoid code duplication in subsequent
patches.

The BPF program type and the checked error numbers in the
HAVE_LARGE_INSN_LIMIT probe are changed to better generalize to other
probes. The feature probe retains its current behavior despite those
changes.

Signed-off-by: Paul Chaignon <paul@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/956c9329a932c75941194f91790d01f31dfbe01b.1641314075.git.paul@isovalent.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 tools/bpf/bpftool/feature.c |   45 ++++++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 16 deletions(-)

--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -642,6 +642,30 @@ probe_helpers_for_progtype(enum bpf_prog
 		printf("\n");
 }
 
+static void
+probe_misc_feature(struct bpf_insn *insns, size_t len,
+		   const char *define_prefix, __u32 ifindex,
+		   const char *feat_name, const char *plain_name,
+		   const char *define_name)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, opts,
+		.prog_ifindex = ifindex,
+	);
+	bool res;
+	int fd;
+
+	errno = 0;
+	fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
+			   insns, len, &opts);
+	res = fd >= 0 || !errno;
+
+	if (fd >= 0)
+		close(fd);
+
+	print_bool_feature(feat_name, plain_name, define_name, res,
+			   define_prefix);
+}
+
 /*
  * Probe for availability of kernel commit (5.3):
  *
@@ -649,29 +673,18 @@ probe_helpers_for_progtype(enum bpf_prog
  */
 static void probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
 {
-	LIBBPF_OPTS(bpf_prog_load_opts, opts,
-		.prog_ifindex = ifindex,
-	);
 	struct bpf_insn insns[BPF_MAXINSNS + 1];
-	bool res;
-	int i, fd;
+	int i;
 
 	for (i = 0; i < BPF_MAXINSNS; i++)
 		insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
 	insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
 
-	errno = 0;
-	fd = bpf_prog_load(BPF_PROG_TYPE_SCHED_CLS, NULL, "GPL",
-			   insns, ARRAY_SIZE(insns), &opts);
-	res = fd >= 0 || (errno != E2BIG && errno != EINVAL);
-
-	if (fd >= 0)
-		close(fd);
-
-	print_bool_feature("have_large_insn_limit",
+	probe_misc_feature(insns, ARRAY_SIZE(insns),
+			   define_prefix, ifindex,
+			   "have_large_insn_limit",
 			   "Large program size limit",
-			   "LARGE_INSN_LIMIT",
-			   res, define_prefix);
+			   "LARGE_INSN_LIMIT");
 }
 
 static void