tools: bpftool: add map create command

Add a way of creating maps from user space.  The command takes
as parameters most of the attributes of the map creation system
call command.  After map is created its pinned to bpffs.  This makes
it possible to easily and dynamically (without rebuilding programs)
test various corner cases related to map creation.

Map type names are taken from bpftool's array used for printing.
In general these days we try to make use of libbpf type names, but
there are no map type names in libbpf as of today.

As with most features I add the motivation is testing (offloads) :)

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 109 insertions, 1 deletions

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 9f5de48f8a99..7bf38f0e152e 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -36,6 +36,7 @@
 #include <fcntl.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
+#include <net/if.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -94,6 +95,17 @@ static bool map_is_map_of_progs(__u32 type)
 	return type == BPF_MAP_TYPE_PROG_ARRAY;
 }
 
+static int map_type_from_str(const char *type)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(map_type_name); i++)
+		/* Don't allow prefixing in case of possible future shadowing */
+		if (map_type_name[i] && !strcmp(map_type_name[i], type))
+			return i;
+	return -1;
+}
+
 static void *alloc_value(struct bpf_map_info *info)
 {
 	if (map_is_per_cpu(info->type))
@@ -1058,6 +1070,92 @@ static int do_pin(int argc, char **argv)
 	return err;
 }
 
+static int do_create(int argc, char **argv)
+{
+	struct bpf_create_map_attr attr = { NULL, };
+	const char *pinfile;
+	int err, fd;
+
+	if (!REQ_ARGS(7))
+		return -1;
+	pinfile = GET_ARG();
+
+	while (argc) {
+		if (!REQ_ARGS(2))
+			return -1;
+
+		if (is_prefix(*argv, "type")) {
+			NEXT_ARG();
+
+			if (attr.map_type) {
+				p_err("map type already specified");
+				return -1;
+			}
+
+			attr.map_type = map_type_from_str(*argv);
+			if ((int)attr.map_type < 0) {
+				p_err("unrecognized map type: %s", *argv);
+				return -1;
+			}
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "name")) {
+			NEXT_ARG();
+			attr.name = GET_ARG();
+		} else if (is_prefix(*argv, "key")) {
+			if (parse_u32_arg(&argc, &argv, &attr.key_size,
+					  "key size"))
+				return -1;
+		} else if (is_prefix(*argv, "value")) {
+			if (parse_u32_arg(&argc, &argv, &attr.value_size,
+					  "value size"))
+				return -1;
+		} else if (is_prefix(*argv, "entries")) {
+			if (parse_u32_arg(&argc, &argv, &attr.max_entries,
+					  "max entries"))
+				return -1;
+		} else if (is_prefix(*argv, "flags")) {
+			if (parse_u32_arg(&argc, &argv, &attr.map_flags,
+					  "flags"))
+				return -1;
+		} else if (is_prefix(*argv, "dev")) {
+			NEXT_ARG();
+
+			if (attr.map_ifindex) {
+				p_err("offload device already specified");
+				return -1;
+			}
+
+			attr.map_ifindex = if_nametoindex(*argv);
+			if (!attr.map_ifindex) {
+				p_err("unrecognized netdevice '%s': %s",
+				      *argv, strerror(errno));
+				return -1;
+			}
+			NEXT_ARG();
+		}
+	}
+
+	if (!attr.name) {
+		p_err("map name not specified");
+		return -1;
+	}
+
+	fd = bpf_create_map_xattr(&attr);
+	if (fd < 0) {
+		p_err("map create failed: %s", strerror(errno));
+		return -1;
+	}
+
+	err = do_pin_fd(fd, pinfile);
+	close(fd);
+	if (err)
+		return err;
+
+	if (json_output)
+		jsonw_null(json_wtr);
+	return 0;
+}
+
 static int do_help(int argc, char **argv)
 {
 	if (json_output) {
@@ -1067,6 +1165,9 @@ static int do_help(int argc, char **argv)
 
 	fprintf(stderr,
 		"Usage: %s %s { show | list }   [MAP]\n"
+		"       %s %s create     FILE type TYPE key KEY_SIZE value VALUE_SIZE \\\n"
+		"                              entries MAX_ENTRIES name NAME [flags FLAGS] \\\n"
+		"                              [dev NAME]\n"
 		"       %s %s dump       MAP\n"
 		"       %s %s update     MAP  key DATA value VALUE [UPDATE_FLAGS]\n"
 		"       %s %s lookup     MAP  key DATA\n"
@@ -1081,11 +1182,17 @@ static int do_help(int argc, char **argv)
 		"       " HELP_SPEC_PROGRAM "\n"
 		"       VALUE := { DATA | MAP | PROG }\n"
 		"       UPDATE_FLAGS := { any | exist | noexist }\n"
+		"       TYPE := { hash | array | prog_array | perf_event_array | percpu_hash |\n"
+		"                 percpu_array | stack_trace | cgroup_array | lru_hash |\n"
+		"                 lru_percpu_hash | lpm_trie | array_of_maps | hash_of_maps |\n"
+		"                 devmap | sockmap | cpumap | xskmap | sockhash |\n"
+		"                 cgroup_storage | reuseport_sockarray | percpu_cgroup_storage }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
 		"",
 		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],
 		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],
-		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]);
+		bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],
+		bin_name, argv[-2]);
 
 	return 0;
 }
@@ -1101,6 +1208,7 @@ static const struct cmd cmds[] = {
 	{ "delete",	do_delete },
 	{ "pin",	do_pin },
 	{ "event_pipe",	do_event_pipe },
+	{ "create",	do_create },
 	{ 0 }
 };