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 <[e-mail]>
Reviewed-by: Quentin Monnet <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/bpf/bpftool/Documentation/bpftool-map.rst

···
 	*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
 
 	*COMMANDS* :=
-	{ **show** | **list** | **dump** | **update** | **lookup** | **getnext** | **delete**
-	| **pin** | **help** }
+	{ **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext**
+	| **delete** | **pin** | **help** }
 
 MAP COMMANDS
 =============
 
 |	**bpftool** **map { show | list }**   [*MAP*]
+|	**bpftool** **map create**     *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
+|		**entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*]
 |	**bpftool** **map dump**       *MAP*
 |	**bpftool** **map update**     *MAP*  **key** *DATA*   **value** *VALUE* [*UPDATE_FLAGS*]
 |	**bpftool** **map lookup**     *MAP*  **key** *DATA*
···
 |	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
 |	*VALUE* := { *DATA* | *MAP* | *PROG* }
 |	*UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
+|	*TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
+|		| **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash**
+|		| **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
+|		| **devmap** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
+|		| **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** }
 
 DESCRIPTION
 ===========
···
 
 		  Output will start with map ID followed by map type and
 		  zero or more named attributes (depending on kernel version).
+
+	**bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE*  **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*]
+		  Create a new map with given parameters and pin it to *bpffs*
+		  as *FILE*.
 
 	**bpftool map dump**    *MAP*
 		  Dump all entries in a given *MAP*.

tools/bpf/bpftool/Documentation/bpftool.rst

···
 	| { **-j** | **--json** } [{ **-p** | **--pretty** }] }
 
 	*MAP-COMMANDS* :=
-	{ **show** | **list** | **dump** | **update** | **lookup** | **getnext** | **delete**
-	| **pin** | **event_pipe** | **help** }
+	{ **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext**
+	| **delete** | **pin** | **event_pipe** | **help** }
 
 	*PROG-COMMANDS* := { **show** | **list** | **dump jited** | **dump xlated** | **pin**
 	| **load** | **attach** | **detach** | **help** }

tools/bpf/bpftool/bash-completion/bpftool

···
                             ;;
                     esac
                     ;;
+                create)
+                    case $prev in
+                        $command)
+                            _filedir
+                            return 0
+                            ;;
+                        type)
+                            COMPREPLY=( $( compgen -W 'hash array prog_array \
+                                perf_event_array percpu_hash percpu_array \
+                                stack_trace cgroup_array lru_hash \
+                                lru_percpu_hash lpm_trie array_of_maps \
+                                hash_of_maps devmap sockmap cpumap xskmap \
+                                sockhash cgroup_storage reuseport_sockarray \
+                                percpu_cgroup_storage' -- \
+                                                   "$cur" ) )
+                            return 0
+                            ;;
+                        key|value|flags|name|entries)
+                            return 0
+                            ;;
+                        dev)
+                            _sysfs_get_netdevs
+                            return 0
+                            ;;
+                        *)
+                            _bpftool_once_attr 'type'
+                            _bpftool_once_attr 'key'
+                            _bpftool_once_attr 'value'
+                            _bpftool_once_attr 'entries'
+                            _bpftool_once_attr 'name'
+                            _bpftool_once_attr 'flags'
+                            _bpftool_once_attr 'dev'
+                            return 0
+                            ;;
+                    esac
+                    ;;
                 lookup|getnext|delete)
                     case $prev in
                         $command)
···
                 *)
                     [[ $prev == $object ]] && \
                         COMPREPLY=( $( compgen -W 'delete dump getnext help \
-                            lookup pin event_pipe show list update' -- \
+                            lookup pin event_pipe show list update create' -- \
                             "$cur" ) )
                     ;;
             esac

tools/bpf/bpftool/common.c

···
 		jsonw_string_field(json_wtr, "ifname", name);
 	jsonw_end_object(json_wtr);
 }
+
+int parse_u32_arg(int *argc, char ***argv, __u32 *val, const char *what)
+{
+	char *endptr;
+
+	NEXT_ARGP();
+
+	if (*val) {
+		p_err("%s already specified", what);
+		return -1;
+	}
+
+	*val = strtoul(**argv, &endptr, 0);
+	if (*endptr) {
+		p_err("can't parse %s as %s", **argv, what);
+		return -1;
+	}
+	NEXT_ARGP();
+
+	return 0;
+}

tools/bpf/bpftool/main.h

···
 int do_perf(int argc, char **arg);
 int do_net(int argc, char **arg);
 
+int parse_u32_arg(int *argc, char ***argv, __u32 *val, const char *what);
 int prog_parse_fd(int *argc, char ***argv);
 int map_parse_fd(int *argc, char ***argv);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);

tools/bpf/bpftool/map.c

···
 #include <fcntl.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
+#include <net/if.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
···
 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)
···
 	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) {
···
 
 	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"
···
 		"       " 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;
 }
···
 	{ "delete",	do_delete },
 	{ "pin",	do_pin },
 	{ "event_pipe",	do_event_pipe },
+	{ "create",	do_create },
 	{ 0 }
 };