1 files changed, 131 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
new file mode 100644
index 000000000000..954fb12a5228
--- /dev/null
+++ b/tools/bpf/bpftool/feature.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (c) 2019 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/utsname.h>
+
+#include <linux/filter.h>
+#include <linux/limits.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+enum probe_component {
+	COMPONENT_UNSPEC,
+	COMPONENT_KERNEL,
+};
+
+/* Printing utility functions */
+
+static void
+print_bool_feature(const char *feat_name, const char *plain_name, bool res)
+{
+	if (json_output)
+		jsonw_bool_field(json_wtr, feat_name, res);
+	else
+		printf("%s is %savailable\n", plain_name, res ? "" : "NOT ");
+}
+
+static void
+print_start_section(const char *json_title, const char *plain_title)
+{
+	if (json_output) {
+		jsonw_name(json_wtr, json_title);
+		jsonw_start_object(json_wtr);
+	} else {
+		printf("%s\n", plain_title);
+	}
+}
+
+/* Probing functions */
+
+static bool probe_bpf_syscall(void)
+{
+	bool res;
+
+	bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0);
+	res = (errno != ENOSYS);
+
+	print_bool_feature("have_bpf_syscall",
+			   "bpf() syscall",
+			   res);
+
+	return res;
+}
+
+static int do_probe(int argc, char **argv)
+{
+	enum probe_component target = COMPONENT_UNSPEC;
+
+	/* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN).
+	 * Let's approximate, and restrict usage to root user only.
+	 */
+	if (geteuid()) {
+		p_err("please run this command as root user");
+		return -1;
+	}
+
+	set_max_rlimit();
+
+	while (argc) {
+		if (is_prefix(*argv, "kernel")) {
+			if (target != COMPONENT_UNSPEC) {
+				p_err("component to probe already specified");
+				return -1;
+			}
+			target = COMPONENT_KERNEL;
+			NEXT_ARG();
+		} else {
+			p_err("expected no more arguments, 'kernel', got: '%s'?",
+			      *argv);
+			return -1;
+		}
+	}
+
+	if (json_output)
+		jsonw_start_object(json_wtr);
+
+	print_start_section("syscall_config",
+			    "Scanning system call availability...");
+
+	probe_bpf_syscall();
+
+	if (json_output) {
+		/* End current "section" of probes */
+		jsonw_end_object(json_wtr);
+		/* End root object */
+		jsonw_end_object(json_wtr);
+	}
+
+	return 0;
+}
+
+static int do_help(int argc, char **argv)
+{
+	if (json_output) {
+		jsonw_null(json_wtr);
+		return 0;
+	}
+
+	fprintf(stderr,
+		"Usage: %s %s probe [kernel]\n"
+		"       %s %s help\n"
+		"",
+		bin_name, argv[-2], bin_name, argv[-2]);
+
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "help",	do_help },
+	{ "probe",	do_probe },
+	{ 0 }
+};
+
+int do_feature(int argc, char **argv)
+{
+	return cmd_select(cmds, argc, argv, do_help);
+}