Merge branch 'bpftool-match-by-name'

Paul Chaignon says:

====================
When working with frequently modified BPF programs, both the ID and the
tag may change.  bpftool currently doesn't provide a "stable" way to match
such programs.  This patchset allows bpftool to match programs and maps by
name.

When given a tag that matches several programs, bpftool currently only
considers the first match.  The first patch changes that behavior to
either process all matching programs (for the show and dump commands) or
error out.  The second patch implements program lookup by name, with the
same behavior as for tags in case of ambiguity.  The last patch implements
map lookup by name.

Changelogs:
  Changes in v2:
    - Fix buffer overflow after realloc.
    - Add example output to commit message.
    - Properly close JSON arrays on errors.
    - Fix style errors (line breaks, for loops, exit labels, type for
      tagname).
    - Move do_show code for argc == 2 to do_show_subset functions.
    - Rebase.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -39,9 +39,9 @@ MAP COMMANDS
 |	**bpftool** **map freeze**     *MAP*
 |	**bpftool** **map help**
 |
-|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
+|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* }
 |	*DATA* := { [**hex**] *BYTES* }
-|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
+|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
 |	*VALUE* := { *DATA* | *MAP* | *PROG* }
 |	*UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
 |	*TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
@@ -55,8 +55,9 @@ DESCRIPTION
 ===========
 	**bpftool map { show | list }**   [*MAP*]
 		  Show information about loaded maps.  If *MAP* is specified
-		  show information only about given map, otherwise list all
-		  maps currently loaded on the system.
+		  show information only about given maps, otherwise list all
+		  maps currently loaded on the system.  In case of **name**,
+		  *MAP* may match several maps which will all be shown.
 
 		  Output will start with map ID followed by map type and
 		  zero or more named attributes (depending on kernel version).
@@ -66,7 +67,8 @@ DESCRIPTION
 		  as *FILE*.
 
 	**bpftool map dump**    *MAP*
-		  Dump all entries in a given *MAP*.
+		  Dump all entries in a given *MAP*.  In case of **name**,
+		  *MAP* may match several maps which will all be dumped.
 
 	**bpftool map update**  *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
 		  Update map entry for a given *KEY*.

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

@@ -33,7 +33,7 @@ PROG COMMANDS
 |	**bpftool** **prog help**
 |
 |	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
-|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
+|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
 |	*TYPE* := {
 |		**socket** | **kprobe** | **kretprobe** | **classifier** | **action** |
 |		**tracepoint** | **raw_tracepoint** | **xdp** | **perf_event** | **cgroup/skb** |
@@ -53,8 +53,10 @@ DESCRIPTION
 ===========
 	**bpftool prog { show | list }** [*PROG*]
 		  Show information about loaded programs.  If *PROG* is
-		  specified show information only about given program, otherwise
-		  list all programs currently loaded on the system.
+		  specified show information only about given programs,
+		  otherwise list all programs currently loaded on the system.
+		  In case of **tag** or **name**, *PROG* may match several
+		  programs which will all be shown.
 
 		  Output will start with program ID followed by program type and
 		  zero or more named attributes (depending on kernel version).
@@ -68,11 +70,15 @@ DESCRIPTION
 		  performed via the **kernel.bpf_stats_enabled** sysctl knob.
 
 	**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | **opcodes** | **visual** | **linum** }]
-		  Dump eBPF instructions of the program from the kernel. By
+		  Dump eBPF instructions of the programs from the kernel. By
 		  default, eBPF will be disassembled and printed to standard
 		  output in human-readable format. In this case, **opcodes**
 		  controls if raw opcodes should be printed as well.
 
+		  In case of **tag** or **name**, *PROG* may match several
+		  programs which will all be dumped.  However, if **file** or
+		  **visual** is specified, *PROG* must match a single program.
+
 		  If **file** is specified, the binary image will instead be
 		  written to *FILE*.
 
@@ -80,15 +86,17 @@ DESCRIPTION
 		  built instead, and eBPF instructions will be presented with
 		  CFG in DOT format, on standard output.
 
-		  If the prog has line_info available, the source line will
+		  If the programs have line_info available, the source line will
 		  be displayed by default.  If **linum** is specified,
 		  the filename, line number and line column will also be
 		  displayed on top of the source line.
 
 	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | **opcodes** | **linum** }]
 		  Dump jited image (host machine code) of the program.
+
 		  If *FILE* is specified image will be written to a file,
 		  otherwise it will be disassembled and printed to stdout.
+		  *PROG* must match a single program when **file** is specified.
 
 		  **opcodes** controls if raw opcodes will be printed.
 

tools/bpf/bpftool/bash-completion/bpftool

@@ -59,6 +59,21 @@ _bpftool_get_map_ids_for_type()
         command sed -n 's/.*"id": \(.*\),$/\1/p' )" -- "$cur" ) )
 }
 
+_bpftool_get_map_names()
+{
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp map  2>&1 | \
+        command sed -n 's/.*"name": \(.*\),$/\1/p' )" -- "$cur" ) )
+}
+
+# Takes map type and adds matching map names to the list of suggestions.
+_bpftool_get_map_names_for_type()
+{
+    local type="$1"
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp map  2>&1 | \
+        command grep -C2 "$type" | \
+        command sed -n 's/.*"name": \(.*\),$/\1/p' )" -- "$cur" ) )
+}
+
 _bpftool_get_prog_ids()
 {
     COMPREPLY+=( $( compgen -W "$( bpftool -jp prog 2>&1 | \
@@ -71,6 +86,12 @@ _bpftool_get_prog_tags()
         command sed -n 's/.*"tag": "\(.*\)",$/\1/p' )" -- "$cur" ) )
 }
 
+_bpftool_get_prog_names()
+{
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp prog 2>&1 | \
+        command sed -n 's/.*"name": "\(.*\)",$/\1/p' )" -- "$cur" ) )
+}
+
 _bpftool_get_btf_ids()
 {
     COMPREPLY+=( $( compgen -W "$( bpftool -jp btf 2>&1 | \
@@ -180,6 +201,52 @@ _bpftool_map_update_get_id()
     esac
 }
 
+_bpftool_map_update_get_name()
+{
+    local command="$1"
+
+    # Is it the map to update, or a map to insert into the map to update?
+    # Search for "value" keyword.
+    local idx value
+    for (( idx=7; idx < ${#words[@]}-1; idx++ )); do
+        if [[ ${words[idx]} == "value" ]]; then
+            value=1
+            break
+        fi
+    done
+    if [[ $value -eq 0 ]]; then
+        case "$command" in
+            push)
+                _bpftool_get_map_names_for_type stack
+                ;;
+            enqueue)
+                _bpftool_get_map_names_for_type queue
+                ;;
+            *)
+                _bpftool_get_map_names
+                ;;
+        esac
+        return 0
+    fi
+
+    # Name to complete is for a value. It can be either prog name or map name. This
+    # depends on the type of the map to update.
+    local type=$(_bpftool_map_guess_map_type)
+    case $type in
+        array_of_maps|hash_of_maps)
+            _bpftool_get_map_names
+            return 0
+            ;;
+        prog_array)
+            _bpftool_get_prog_names
+            return 0
+            ;;
+        *)
+            return 0
+            ;;
+    esac
+}
+
 _bpftool()
 {
     local cur prev words objword
@@ -251,7 +318,8 @@ _bpftool()
     # Completion depends on object and command in use
     case $object in
         prog)
-            # Complete id, only for subcommands that use prog (but no map) ids
+            # Complete id and name, only for subcommands that use prog (but no
+            # map) ids/names.
             case $command in
                 show|list|dump|pin)
                     case $prev in
@@ -259,12 +327,16 @@ _bpftool()
                             _bpftool_get_prog_ids
                             return 0
                             ;;
+                        name)
+                            _bpftool_get_prog_names
+                            return 0
+                            ;;
                     esac
                     ;;
             esac
 
-            local PROG_TYPE='id pinned tag'
-            local MAP_TYPE='id pinned'
+            local PROG_TYPE='id pinned tag name'
+            local MAP_TYPE='id pinned name'
             case $command in
                 show|list)
                     [[ $prev != "$command" ]] && return 0
@@ -315,6 +387,9 @@ _bpftool()
                                 id)
                                     _bpftool_get_prog_ids
                                     ;;
+                                name)
+                                    _bpftool_get_map_names
+                                    ;;
                                 pinned)
                                     _filedir
                                     ;;
@@ -335,6 +410,9 @@ _bpftool()
                                 id)
                                     _bpftool_get_map_ids
                                     ;;
+                                name)
+                                    _bpftool_get_map_names
+                                    ;;
                                 pinned)
                                     _filedir
                                     ;;
@@ -399,6 +477,10 @@ _bpftool()
                             _bpftool_get_map_ids
                             return 0
                             ;;
+                        name)
+                            _bpftool_get_map_names
+                            return 0
+                            ;;
                         pinned|pinmaps)
                             _filedir
                             return 0
@@ -447,7 +529,7 @@ _bpftool()
             esac
             ;;
         map)
-            local MAP_TYPE='id pinned'
+            local MAP_TYPE='id pinned name'
             case $command in
                 show|list|dump|peek|pop|dequeue|freeze)
                     case $prev in
@@ -473,6 +555,24 @@ _bpftool()
                             esac
                             return 0
                             ;;
+                        name)
+                            case "$command" in
+                                peek)
+                                    _bpftool_get_map_names_for_type stack
+                                    _bpftool_get_map_names_for_type queue
+                                    ;;
+                                pop)
+                                    _bpftool_get_map_names_for_type stack
+                                    ;;
+                                dequeue)
+                                    _bpftool_get_map_names_for_type queue
+                                    ;;
+                                *)
+                                    _bpftool_get_map_names
+                                    ;;
+                            esac
+                            return 0
+                            ;;
                         *)
                             return 0
                             ;;
@@ -520,6 +620,10 @@ _bpftool()
                             _bpftool_get_map_ids
                             return 0
                             ;;
+                        name)
+                            _bpftool_get_map_names
+                            return 0
+                            ;;
                         key)
                             COMPREPLY+=( $( compgen -W 'hex' -- "$cur" ) )
                             ;;
@@ -545,6 +649,10 @@ _bpftool()
                             _bpftool_map_update_get_id $command
                             return 0
                             ;;
+                        name)
+                            _bpftool_map_update_get_name $command
+                            return 0
+                            ;;
                         key)
                             COMPREPLY+=( $( compgen -W 'hex' -- "$cur" ) )
                             ;;
@@ -553,13 +661,13 @@ _bpftool()
                             # map, depending on the type of the map to update.
                             case "$(_bpftool_map_guess_map_type)" in
                                 array_of_maps|hash_of_maps)
-                                    local MAP_TYPE='id pinned'
+                                    local MAP_TYPE='id pinned name'
                                     COMPREPLY+=( $( compgen -W "$MAP_TYPE" \
                                         -- "$cur" ) )
                                     return 0
                                     ;;
                                 prog_array)
-                                    local PROG_TYPE='id pinned tag'
+                                    local PROG_TYPE='id pinned tag name'
                                     COMPREPLY+=( $( compgen -W "$PROG_TYPE" \
                                         -- "$cur" ) )
                                     return 0
@@ -621,6 +729,10 @@ _bpftool()
                             _bpftool_get_map_ids_for_type perf_event_array
                             return 0
                             ;;
+                        name)
+                            _bpftool_get_map_names_for_type perf_event_array
+                            return 0
+                            ;;
                         cpu)
                             return 0
                             ;;
@@ -644,8 +756,8 @@ _bpftool()
             esac
             ;;
         btf)
-            local PROG_TYPE='id pinned tag'
-            local MAP_TYPE='id pinned'
+            local PROG_TYPE='id pinned tag name'
+            local MAP_TYPE='id pinned name'
             case $command in
                 dump)
                     case $prev in
@@ -676,6 +788,17 @@ _bpftool()
                             esac
                             return 0
                             ;;
+                        name)
+                            case $pprev in
+                                prog)
+                                    _bpftool_get_prog_names
+                                    ;;
+                                map)
+                                    _bpftool_get_map_names
+                                    ;;
+                            esac
+                            return 0
+                            ;;
                         format)
                             COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) )
                             ;;
@@ -735,7 +858,7 @@ _bpftool()
                         connect6 sendmsg4 sendmsg6 recvmsg4 recvmsg6 sysctl \
                         getsockopt setsockopt'
                     local ATTACH_FLAGS='multi override'
-                    local PROG_TYPE='id pinned tag'
+                    local PROG_TYPE='id pinned tag name'
                     case $prev in
                         $command)
                             _filedir
@@ -760,7 +883,7 @@ _bpftool()
                             elif [[ "$command" == "attach" ]]; then
                                 # We have an attach type on the command line,
                                 # but it is not the previous word, or
-                                # "id|pinned|tag" (we already checked for
+                                # "id|pinned|tag|name" (we already checked for
                                 # that). This should only leave the case when
                                 # we need attach flags for "attach" commamnd.
                                 _bpftool_one_of_list "$ATTACH_FLAGS"
@@ -786,7 +909,7 @@ _bpftool()
             esac
             ;;
         net)
-            local PROG_TYPE='id pinned tag'
+            local PROG_TYPE='id pinned tag name'
             local ATTACH_TYPES='xdp xdpgeneric xdpdrv xdpoffload'
             case $command in
                 show|list)

tools/bpf/bpftool/main.h

@@ -42,12 +42,12 @@
 #define BPF_TAG_FMT	"%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
 
 #define HELP_SPEC_PROGRAM						\
-	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG }"
+	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG | name PROG_NAME }"
 #define HELP_SPEC_OPTIONS						\
 	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} |\n"	\
 	"\t            {-m|--mapcompat} | {-n|--nomount} }"
 #define HELP_SPEC_MAP							\
-	"MAP := { id MAP_ID | pinned FILE }"
+	"MAP := { id MAP_ID | pinned FILE | name MAP_NAME }"
 
 static const char * const prog_type_name[] = {
 	[BPF_PROG_TYPE_UNSPEC]			= "unspec",

tools/bpf/bpftool/map.c

@@ -91,10 +91,66 @@ static void *alloc_value(struct bpf_map_info *info)
 		return malloc(info->value_size);
 }
 
-int map_parse_fd(int *argc, char ***argv)
+static int map_fd_by_name(char *name, int **fds)
 {
-	int fd;
+	unsigned int id = 0;
+	int fd, nb_fds = 0;
+	void *tmp;
+	int err;
+
+	while (true) {
+		struct bpf_map_info info = {};
+		__u32 len = sizeof(info);
+
+		err = bpf_map_get_next_id(id, &id);
+		if (err) {
+			if (errno != ENOENT) {
+				p_err("%s", strerror(errno));
+				goto err_close_fds;
+			}
+			return nb_fds;
+		}
+
+		fd = bpf_map_get_fd_by_id(id);
+		if (fd < 0) {
+			p_err("can't get map by id (%u): %s",
+			      id, strerror(errno));
+			goto err_close_fds;
+		}
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (err) {
+			p_err("can't get map info (%u): %s",
+			      id, strerror(errno));
+			goto err_close_fd;
+		}
+
+		if (strncmp(name, info.name, BPF_OBJ_NAME_LEN)) {
+			close(fd);
+			continue;
+		}
+
+		if (nb_fds > 0) {
+			tmp = realloc(*fds, (nb_fds + 1) * sizeof(int));
+			if (!tmp) {
+				p_err("failed to realloc");
+				goto err_close_fd;
+			}
+			*fds = tmp;
+		}
+		(*fds)[nb_fds++] = fd;
+	}
+
+err_close_fd:
+	close(fd);
+err_close_fds:
+	while (--nb_fds >= 0)
+		close((*fds)[nb_fds]);
+	return -1;
+}
 
+static int map_parse_fds(int *argc, char ***argv, int **fds)
+{
 	if (is_prefix(**argv, "id")) {
 		unsigned int id;
 		char *endptr;
@@ -108,10 +164,25 @@ int map_parse_fd(int *argc, char ***argv)
 		}
 		NEXT_ARGP();
 
-		fd = bpf_map_get_fd_by_id(id);
-		if (fd < 0)
+		(*fds)[0] = bpf_map_get_fd_by_id(id);
+		if ((*fds)[0] < 0) {
 			p_err("get map by id (%u): %s", id, strerror(errno));
-		return fd;
+			return -1;
+		}
+		return 1;
+	} else if (is_prefix(**argv, "name")) {
+		char *name;
+
+		NEXT_ARGP();
+
+		name = **argv;
+		if (strlen(name) > BPF_OBJ_NAME_LEN - 1) {
+			p_err("can't parse name");
+			return -1;
+		}
+		NEXT_ARGP();
+
+		return map_fd_by_name(name, fds);
 	} else if (is_prefix(**argv, "pinned")) {
 		char *path;
 
@@ -120,13 +191,43 @@ int map_parse_fd(int *argc, char ***argv)
 		path = **argv;
 		NEXT_ARGP();
 
-		return open_obj_pinned_any(path, BPF_OBJ_MAP);
+		(*fds)[0] = open_obj_pinned_any(path, BPF_OBJ_MAP);
+		if ((*fds)[0] < 0)
+			return -1;
+		return 1;
 	}
 
-	p_err("expected 'id' or 'pinned', got: '%s'?", **argv);
+	p_err("expected 'id', 'name' or 'pinned', got: '%s'?", **argv);
 	return -1;
 }
 
+int map_parse_fd(int *argc, char ***argv)
+{
+	int *fds = NULL;
+	int nb_fds, fd;
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = map_parse_fds(argc, argv, &fds);
+	if (nb_fds != 1) {
+		if (nb_fds > 1) {
+			p_err("several maps match this handle");
+			while (nb_fds--)
+				close(fds[nb_fds]);
+		}
+		fd = -1;
+		goto exit_free;
+	}
+
+	fd = fds[0];
+exit_free:
+	free(fds);
+	return fd;
+}
+
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len)
 {
 	int err;
@@ -479,6 +580,21 @@ static int parse_elem(char **argv, struct bpf_map_info *info,
 	return -1;
 }
 
+static void show_map_header_json(struct bpf_map_info *info, json_writer_t *wtr)
+{
+	jsonw_uint_field(wtr, "id", info->id);
+	if (info->type < ARRAY_SIZE(map_type_name))
+		jsonw_string_field(wtr, "type", map_type_name[info->type]);
+	else
+		jsonw_uint_field(wtr, "type", info->type);
+
+	if (*info->name)
+		jsonw_string_field(wtr, "name", info->name);
+
+	jsonw_name(wtr, "flags");
+	jsonw_printf(wtr, "%d", info->map_flags);
+}
+
 static int show_map_close_json(int fd, struct bpf_map_info *info)
 {
 	char *memlock, *frozen_str;
@@ -489,18 +605,7 @@ static int show_map_close_json(int fd, struct bpf_map_info *info)
 
 	jsonw_start_object(json_wtr);
 
-	jsonw_uint_field(json_wtr, "id", info->id);
-	if (info->type < ARRAY_SIZE(map_type_name))
-		jsonw_string_field(json_wtr, "type",
-				   map_type_name[info->type]);
-	else
-		jsonw_uint_field(json_wtr, "type", info->type);
-
-	if (*info->name)
-		jsonw_string_field(json_wtr, "name", info->name);
-
-	jsonw_name(json_wtr, "flags");
-	jsonw_printf(json_wtr, "%d", info->map_flags);
+	show_map_header_json(info, json_wtr);
 
 	print_dev_json(info->ifindex, info->netns_dev, info->netns_ino);
 
@@ -561,14 +666,8 @@ static int show_map_close_json(int fd, struct bpf_map_info *info)
 	return 0;
 }
 
-static int show_map_close_plain(int fd, struct bpf_map_info *info)
+static void show_map_header_plain(struct bpf_map_info *info)
 {
-	char *memlock, *frozen_str;
-	int frozen = 0;
-
-	memlock = get_fdinfo(fd, "memlock");
-	frozen_str = get_fdinfo(fd, "frozen");
-
 	printf("%u: ", info->id);
 	if (info->type < ARRAY_SIZE(map_type_name))
 		printf("%s  ", map_type_name[info->type]);
@@ -581,6 +680,17 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
 	printf("flags 0x%x", info->map_flags);
 	print_dev_plain(info->ifindex, info->netns_dev, info->netns_ino);
 	printf("\n");
+}
+
+static int show_map_close_plain(int fd, struct bpf_map_info *info)
+{
+	char *memlock, *frozen_str;
+	int frozen = 0;
+
+	memlock = get_fdinfo(fd, "memlock");
+	frozen_str = get_fdinfo(fd, "frozen");
+
+	show_map_header_plain(info);
 	printf("\tkey %uB  value %uB  max_entries %u",
 	       info->key_size, info->value_size, info->max_entries);
 
@@ -642,6 +752,50 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
 	return 0;
 }
 
+static int do_show_subset(int argc, char **argv)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	int *fds = NULL;
+	int nb_fds, i;
+	int err = -1;
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = map_parse_fds(&argc, &argv, &fds);
+	if (nb_fds < 1)
+		goto exit_free;
+
+	if (json_output && nb_fds > 1)
+		jsonw_start_array(json_wtr);	/* root array */
+	for (i = 0; i < nb_fds; i++) {
+		err = bpf_obj_get_info_by_fd(fds[i], &info, &len);
+		if (err) {
+			p_err("can't get map info: %s",
+			      strerror(errno));
+			for (; i < nb_fds; i++)
+				close(fds[i]);
+			break;
+		}
+
+		if (json_output)
+			show_map_close_json(fds[i], &info);
+		else
+			show_map_close_plain(fds[i], &info);
+
+		close(fds[i]);
+	}
+	if (json_output && nb_fds > 1)
+		jsonw_end_array(json_wtr);	/* root array */
+
+exit_free:
+	free(fds);
+	return err;
+}
+
 static int do_show(int argc, char **argv)
 {
 	struct bpf_map_info info = {};
@@ -653,16 +807,8 @@ static int do_show(int argc, char **argv)
 	if (show_pinned)
 		build_pinned_obj_table(&map_table, BPF_OBJ_MAP);
 
-	if (argc == 2) {
-		fd = map_parse_fd_and_info(&argc, &argv, &info, &len);
-		if (fd < 0)
-			return -1;
-
-		if (json_output)
-			return show_map_close_json(fd, &info);
-		else
-			return show_map_close_plain(fd, &info);
-	}
+	if (argc == 2)
+		return do_show_subset(argc, argv);
 
 	if (argc)
 		return BAD_ARG();
@@ -765,26 +911,49 @@ static int dump_map_elem(int fd, void *key, void *value,
 	return 0;
 }
 
-static int do_dump(int argc, char **argv)
+static int maps_have_btf(int *fds, int nb_fds)
 {
 	struct bpf_map_info info = {};
-	void *key, *value, *prev_key;
-	unsigned int num_elems = 0;
 	__u32 len = sizeof(info);
-	json_writer_t *btf_wtr;
 	struct btf *btf = NULL;
-	int err;
-	int fd;
+	int err, i;
 
-	if (argc != 2)
-		usage();
+	for (i = 0; i < nb_fds; i++) {
+		err = bpf_obj_get_info_by_fd(fds[i], &info, &len);
+		if (err) {
+			p_err("can't get map info: %s", strerror(errno));
+			goto err_close;
+		}
 
-	fd = map_parse_fd_and_info(&argc, &argv, &info, &len);
-	if (fd < 0)
-		return -1;
+		err = btf__get_from_id(info.btf_id, &btf);
+		if (err) {
+			p_err("failed to get btf");
+			goto err_close;
+		}
 
-	key = malloc(info.key_size);
-	value = alloc_value(&info);
+		if (!btf)
+			return 0;
+	}
+
+	return 1;
+
+err_close:
+	for (; i < nb_fds; i++)
+		close(fds[i]);
+	return -1;
+}
+
+static int
+map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
+	 bool enable_btf, bool show_header)
+{
+	void *key, *value, *prev_key;
+	unsigned int num_elems = 0;
+	struct btf *btf = NULL;
+	int err;
+
+	key = malloc(info->key_size);
+	value = alloc_value(info);
 	if (!key || !value) {
 		p_err("mem alloc failed");
 		err = -1;
@@ -793,30 +962,32 @@ static int do_dump(int argc, char **argv)
 
 	prev_key = NULL;
 
-	err = btf__get_from_id(info.btf_id, &btf);
-	if (err) {
-		p_err("failed to get btf");
-		goto exit_free;
+	if (enable_btf) {
+		err = btf__get_from_id(info->btf_id, &btf);
+		if (err || !btf) {
+			/* enable_btf is true only if we've already checked
+			 * that all maps have BTF information.
+			 */
+			p_err("failed to get btf");
+			goto exit_free;
+		}
 	}
 
-	if (json_output)
-		jsonw_start_array(json_wtr);
-	else
-		if (btf) {
-			btf_wtr = get_btf_writer();
-			if (!btf_wtr) {
-				p_info("failed to create json writer for btf. falling back to plain output");
-				btf__free(btf);
-				btf = NULL;
-			} else {
-				jsonw_start_array(btf_wtr);
-			}
+	if (wtr) {
+		if (show_header) {
+			jsonw_start_object(wtr);	/* map object */
+			show_map_header_json(info, wtr);
+			jsonw_name(wtr, "elements");
 		}
+		jsonw_start_array(wtr);		/* elements */
+	} else if (show_header) {
+		show_map_header_plain(info);
+	}
 
-	if (info.type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
-	    info.value_size != 8)
+	if (info->type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
+	    info->value_size != 8)
 		p_info("Warning: cannot read values from %s map with value_size != 8",
-		       map_type_name[info.type]);
+		       map_type_name[info->type]);
 	while (true) {
 		err = bpf_map_get_next_key(fd, prev_key, key);
 		if (err) {
@@ -824,15 +995,14 @@ static int do_dump(int argc, char **argv)
 				err = 0;
 			break;
 		}
-		num_elems += dump_map_elem(fd, key, value, &info, btf, btf_wtr);
+		num_elems += dump_map_elem(fd, key, value, info, btf, wtr);
 		prev_key = key;
 	}
 
-	if (json_output)
-		jsonw_end_array(json_wtr);
-	else if (btf) {
-		jsonw_end_array(btf_wtr);
-		jsonw_destroy(&btf_wtr);
+	if (wtr) {
+		jsonw_end_array(wtr);	/* elements */
+		if (show_header)
+			jsonw_end_object(wtr);	/* map object */
 	} else {
 		printf("Found %u element%s\n", num_elems,
 		       num_elems != 1 ? "s" : "");
@@ -847,6 +1017,72 @@ static int do_dump(int argc, char **argv)
 	return err;
 }
 
+static int do_dump(int argc, char **argv)
+{
+	json_writer_t *wtr = NULL, *btf_wtr = NULL;
+	struct bpf_map_info info = {};
+	int nb_fds, i = 0, btf = 0;
+	__u32 len = sizeof(info);
+	int *fds = NULL;
+	int err = -1;
+
+	if (argc != 2)
+		usage();
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = map_parse_fds(&argc, &argv, &fds);
+	if (nb_fds < 1)
+		goto exit_free;
+
+	if (json_output) {
+		wtr = json_wtr;
+	} else {
+		btf = maps_have_btf(fds, nb_fds);
+		if (btf < 0)
+			goto exit_close;
+		if (btf) {
+			btf_wtr = get_btf_writer();
+			if (btf_wtr) {
+				wtr = btf_wtr;
+			} else {
+				p_info("failed to create json writer for btf. falling back to plain output");
+				btf = 0;
+			}
+		}
+	}
+
+	if (wtr && nb_fds > 1)
+		jsonw_start_array(wtr);	/* root array */
+	for (i = 0; i < nb_fds; i++) {
+		if (bpf_obj_get_info_by_fd(fds[i], &info, &len)) {
+			p_err("can't get map info: %s", strerror(errno));
+			break;
+		}
+		err = map_dump(fds[i], &info, wtr, btf, nb_fds > 1);
+		if (!wtr && i != nb_fds - 1)
+			printf("\n");
+
+		if (err)
+			break;
+		close(fds[i]);
+	}
+	if (wtr && nb_fds > 1)
+		jsonw_end_array(wtr);	/* root array */
+
+	if (btf)
+		jsonw_destroy(&btf_wtr);
+exit_close:
+	for (; i < nb_fds; i++)
+		close(fds[i]);
+exit_free:
+	free(fds);
+	return err;
+}
+
 static int alloc_key_value(struct bpf_map_info *info, void **key, void **value)
 {
 	*key = NULL;

tools/bpf/bpftool/prog.c

@@ -25,6 +25,11 @@
 #include "main.h"
 #include "xlated_dumper.h"
 
+enum dump_mode {
+	DUMP_JITED,
+	DUMP_XLATED,
+};
+
 static const char * const attach_type_strings[] = {
 	[BPF_SK_SKB_STREAM_PARSER] = "stream_parser",
 	[BPF_SK_SKB_STREAM_VERDICT] = "stream_verdict",
@@ -77,11 +82,12 @@ static void print_boot_time(__u64 nsecs, char *buf, unsigned int size)
 		strftime(buf, size, "%FT%T%z", &load_tm);
 }
 
-static int prog_fd_by_tag(unsigned char *tag)
+static int prog_fd_by_nametag(void *nametag, int **fds, bool tag)
 {
 	unsigned int id = 0;
+	int fd, nb_fds = 0;
+	void *tmp;
 	int err;
-	int fd;
 
 	while (true) {
 		struct bpf_prog_info info = {};
@@ -89,36 +95,54 @@ static int prog_fd_by_tag(unsigned char *tag)
 
 		err = bpf_prog_get_next_id(id, &id);
 		if (err) {
-			p_err("%s", strerror(errno));
-			return -1;
+			if (errno != ENOENT) {
+				p_err("%s", strerror(errno));
+				goto err_close_fds;
+			}
+			return nb_fds;
 		}
 
 		fd = bpf_prog_get_fd_by_id(id);
 		if (fd < 0) {
 			p_err("can't get prog by id (%u): %s",
 			      id, strerror(errno));
-			return -1;
+			goto err_close_fds;
 		}
 
 		err = bpf_obj_get_info_by_fd(fd, &info, &len);
 		if (err) {
 			p_err("can't get prog info (%u): %s",
 			      id, strerror(errno));
-			close(fd);
-			return -1;
+			goto err_close_fd;
 		}
 
-		if (!memcmp(tag, info.tag, BPF_TAG_SIZE))
-			return fd;
+		if ((tag && memcmp(nametag, info.tag, BPF_TAG_SIZE)) ||
+		    (!tag && strncmp(nametag, info.name, BPF_OBJ_NAME_LEN))) {
+			close(fd);
+			continue;
+		}
 
-		close(fd);
+		if (nb_fds > 0) {
+			tmp = realloc(*fds, (nb_fds + 1) * sizeof(int));
+			if (!tmp) {
+				p_err("failed to realloc");
+				goto err_close_fd;
+			}
+			*fds = tmp;
+		}
+		(*fds)[nb_fds++] = fd;
 	}
+
+err_close_fd:
+	close(fd);
+err_close_fds:
+	while (--nb_fds >= 0)
+		close((*fds)[nb_fds]);
+	return -1;
 }
 
-int prog_parse_fd(int *argc, char ***argv)
+static int prog_parse_fds(int *argc, char ***argv, int **fds)
 {
-	int fd;
-
 	if (is_prefix(**argv, "id")) {
 		unsigned int id;
 		char *endptr;
@@ -132,10 +156,12 @@ int prog_parse_fd(int *argc, char ***argv)
 		}
 		NEXT_ARGP();
 
-		fd = bpf_prog_get_fd_by_id(id);
-		if (fd < 0)
+		(*fds)[0] = bpf_prog_get_fd_by_id(id);
+		if ((*fds)[0] < 0) {
 			p_err("get by id (%u): %s", id, strerror(errno));
-		return fd;
+			return -1;
+		}
+		return 1;
 	} else if (is_prefix(**argv, "tag")) {
 		unsigned char tag[BPF_TAG_SIZE];
 
@@ -149,7 +175,20 @@ int prog_parse_fd(int *argc, char ***argv)
 		}
 		NEXT_ARGP();
 
-		return prog_fd_by_tag(tag);
+		return prog_fd_by_nametag(tag, fds, true);
+	} else if (is_prefix(**argv, "name")) {
+		char *name;
+
+		NEXT_ARGP();
+
+		name = **argv;
+		if (strlen(name) > BPF_OBJ_NAME_LEN - 1) {
+			p_err("can't parse name");
+			return -1;
+		}
+		NEXT_ARGP();
+
+		return prog_fd_by_nametag(name, fds, false);
 	} else if (is_prefix(**argv, "pinned")) {
 		char *path;
 
@@ -158,13 +197,43 @@ int prog_parse_fd(int *argc, char ***argv)
 		path = **argv;
 		NEXT_ARGP();
 
-		return open_obj_pinned_any(path, BPF_OBJ_PROG);
+		(*fds)[0] = open_obj_pinned_any(path, BPF_OBJ_PROG);
+		if ((*fds)[0] < 0)
+			return -1;
+		return 1;
 	}
 
-	p_err("expected 'id', 'tag' or 'pinned', got: '%s'?", **argv);
+	p_err("expected 'id', 'tag', 'name' or 'pinned', got: '%s'?", **argv);
 	return -1;
 }
 
+int prog_parse_fd(int *argc, char ***argv)
+{
+	int *fds = NULL;
+	int nb_fds, fd;
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = prog_parse_fds(argc, argv, &fds);
+	if (nb_fds != 1) {
+		if (nb_fds > 1) {
+			p_err("several programs match this handle");
+			while (nb_fds--)
+				close(fds[nb_fds]);
+		}
+		fd = -1;
+		goto exit_free;
+	}
+
+	fd = fds[0];
+exit_free:
+	free(fds);
+	return fd;
+}
+
 static void show_prog_maps(int fd, u32 num_maps)
 {
 	struct bpf_prog_info info = {};
@@ -194,11 +263,8 @@ static void show_prog_maps(int fd, u32 num_maps)
 	}
 }
 
-static void print_prog_json(struct bpf_prog_info *info, int fd)
+static void print_prog_header_json(struct bpf_prog_info *info)
 {
-	char *memlock;
-
-	jsonw_start_object(json_wtr);
 	jsonw_uint_field(json_wtr, "id", info->id);
 	if (info->type < ARRAY_SIZE(prog_type_name))
 		jsonw_string_field(json_wtr, "type",
@@ -219,7 +285,14 @@ static void print_prog_json(struct bpf_prog_info *info, int fd)
 		jsonw_uint_field(json_wtr, "run_time_ns", info->run_time_ns);
 		jsonw_uint_field(json_wtr, "run_cnt", info->run_cnt);
 	}
+}
 
+static void print_prog_json(struct bpf_prog_info *info, int fd)
+{
+	char *memlock;
+
+	jsonw_start_object(json_wtr);
+	print_prog_header_json(info);
 	print_dev_json(info->ifindex, info->netns_dev, info->netns_ino);
 
 	if (info->load_time) {
@@ -268,10 +341,8 @@ static void print_prog_json(struct bpf_prog_info *info, int fd)
 	jsonw_end_object(json_wtr);
 }
 
-static void print_prog_plain(struct bpf_prog_info *info, int fd)
+static void print_prog_header_plain(struct bpf_prog_info *info)
 {
-	char *memlock;
-
 	printf("%u: ", info->id);
 	if (info->type < ARRAY_SIZE(prog_type_name))
 		printf("%s  ", prog_type_name[info->type]);
@@ -289,6 +360,13 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd)
 		printf(" run_time_ns %lld run_cnt %lld",
 		       info->run_time_ns, info->run_cnt);
 	printf("\n");
+}
+
+static void print_prog_plain(struct bpf_prog_info *info, int fd)
+{
+	char *memlock;
+
+	print_prog_header_plain(info);
 
 	if (info->load_time) {
 		char buf[32];
@@ -349,6 +427,40 @@ static int show_prog(int fd)
 	return 0;
 }
 
+static int do_show_subset(int argc, char **argv)
+{
+	int *fds = NULL;
+	int nb_fds, i;
+	int err = -1;
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = prog_parse_fds(&argc, &argv, &fds);
+	if (nb_fds < 1)
+		goto exit_free;
+
+	if (json_output && nb_fds > 1)
+		jsonw_start_array(json_wtr);	/* root array */
+	for (i = 0; i < nb_fds; i++) {
+		err = show_prog(fds[i]);
+		if (err) {
+			for (; i < nb_fds; i++)
+				close(fds[i]);
+			break;
+		}
+		close(fds[i]);
+	}
+	if (json_output && nb_fds > 1)
+		jsonw_end_array(json_wtr);	/* root array */
+
+exit_free:
+	free(fds);
+	return err;
+}
+
 static int do_show(int argc, char **argv)
 {
 	__u32 id = 0;
@@ -358,15 +470,8 @@ static int do_show(int argc, char **argv)
 	if (show_pinned)
 		build_pinned_obj_table(&prog_table, BPF_OBJ_PROG);
 
-	if (argc == 2) {
-		fd = prog_parse_fd(&argc, &argv);
-		if (fd < 0)
-			return -1;
-
-		err = show_prog(fd);
-		close(fd);
-		return err;
-	}
+	if (argc == 2)
+		return do_show_subset(argc, argv);
 
 	if (argc)
 		return BAD_ARG();
@@ -408,101 +513,32 @@ static int do_show(int argc, char **argv)
 	return err;
 }
 
-static int do_dump(int argc, char **argv)
+static int
+prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
+	  char *filepath, bool opcodes, bool visual, bool linum)
 {
-	struct bpf_prog_info_linear *info_linear;
 	struct bpf_prog_linfo *prog_linfo = NULL;
-	enum {DUMP_JITED, DUMP_XLATED} mode;
 	const char *disasm_opt = NULL;
-	struct bpf_prog_info *info;
 	struct dump_data dd = {};
 	void *func_info = NULL;
 	struct btf *btf = NULL;
-	char *filepath = NULL;
-	bool opcodes = false;
-	bool visual = false;
 	char func_sig[1024];
 	unsigned char *buf;
-	bool linum = false;
 	__u32 member_len;
-	__u64 arrays;
 	ssize_t n;
 	int fd;
 
-	if (is_prefix(*argv, "jited")) {
-		if (disasm_init())
-			return -1;
-		mode = DUMP_JITED;
-	} else if (is_prefix(*argv, "xlated")) {
-		mode = DUMP_XLATED;
-	} else {
-		p_err("expected 'xlated' or 'jited', got: %s", *argv);
-		return -1;
-	}
-	NEXT_ARG();
-
-	if (argc < 2)
-		usage();
-
-	fd = prog_parse_fd(&argc, &argv);
-	if (fd < 0)
-		return -1;
-
-	if (is_prefix(*argv, "file")) {
-		NEXT_ARG();
-		if (!argc) {
-			p_err("expected file path");
-			return -1;
-		}
-
-		filepath = *argv;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "opcodes")) {
-		opcodes = true;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "visual")) {
-		visual = true;
-		NEXT_ARG();
-	} else if (is_prefix(*argv, "linum")) {
-		linum = true;
-		NEXT_ARG();
-	}
-
-	if (argc) {
-		usage();
-		return -1;
-	}
-
-	if (mode == DUMP_JITED)
-		arrays = 1UL << BPF_PROG_INFO_JITED_INSNS;
-	else
-		arrays = 1UL << BPF_PROG_INFO_XLATED_INSNS;
-
-	arrays |= 1UL << BPF_PROG_INFO_JITED_KSYMS;
-	arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
-	arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
-	arrays |= 1UL << BPF_PROG_INFO_LINE_INFO;
-	arrays |= 1UL << BPF_PROG_INFO_JITED_LINE_INFO;
-
-	info_linear = bpf_program__get_prog_info_linear(fd, arrays);
-	close(fd);
-	if (IS_ERR_OR_NULL(info_linear)) {
-		p_err("can't get prog info: %s", strerror(errno));
-		return -1;
-	}
-
-	info = &info_linear->info;
 	if (mode == DUMP_JITED) {
 		if (info->jited_prog_len == 0) {
 			p_info("no instructions returned");
-			goto err_free;
+			return -1;
 		}
 		buf = (unsigned char *)(info->jited_prog_insns);
 		member_len = info->jited_prog_len;
 	} else {	/* DUMP_XLATED */
 		if (info->xlated_prog_len == 0) {
 			p_err("error retrieving insn dump: kernel.kptr_restrict set?");
-			goto err_free;
+			return -1;
 		}
 		buf = (unsigned char *)info->xlated_prog_insns;
 		member_len = info->xlated_prog_len;
@@ -510,7 +546,7 @@ static int do_dump(int argc, char **argv)
 
 	if (info->btf_id && btf__get_from_id(info->btf_id, &btf)) {
 		p_err("failed to get btf");
-		goto err_free;
+		return -1;
 	}
 
 	func_info = (void *)info->func_info;
@@ -526,7 +562,7 @@ static int do_dump(int argc, char **argv)
 		if (fd < 0) {
 			p_err("can't open file %s: %s", filepath,
 			      strerror(errno));
-			goto err_free;
+			return -1;
 		}
 
 		n = write(fd, buf, member_len);
@@ -534,7 +570,7 @@ static int do_dump(int argc, char **argv)
 		if (n != member_len) {
 			p_err("error writing output file: %s",
 			      n < 0 ? strerror(errno) : "short write");
-			goto err_free;
+			return -1;
 		}
 
 		if (json_output)
@@ -548,7 +584,7 @@ static int do_dump(int argc, char **argv)
 						     info->netns_ino,
 						     &disasm_opt);
 			if (!name)
-				goto err_free;
+				return -1;
 		}
 
 		if (info->nr_jited_func_lens && info->jited_func_lens) {
@@ -643,12 +679,130 @@ static int do_dump(int argc, char **argv)
 		kernel_syms_destroy(&dd);
 	}
 
-	free(info_linear);
 	return 0;
+}
 
-err_free:
-	free(info_linear);
-	return -1;
+static int do_dump(int argc, char **argv)
+{
+	struct bpf_prog_info_linear *info_linear;
+	char *filepath = NULL;
+	bool opcodes = false;
+	bool visual = false;
+	enum dump_mode mode;
+	bool linum = false;
+	int *fds = NULL;
+	int nb_fds, i = 0;
+	int err = -1;
+	__u64 arrays;
+
+	if (is_prefix(*argv, "jited")) {
+		if (disasm_init())
+			return -1;
+		mode = DUMP_JITED;
+	} else if (is_prefix(*argv, "xlated")) {
+		mode = DUMP_XLATED;
+	} else {
+		p_err("expected 'xlated' or 'jited', got: %s", *argv);
+		return -1;
+	}
+	NEXT_ARG();
+
+	if (argc < 2)
+		usage();
+
+	fds = malloc(sizeof(int));
+	if (!fds) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+	nb_fds = prog_parse_fds(&argc, &argv, &fds);
+	if (nb_fds < 1)
+		goto exit_free;
+
+	if (is_prefix(*argv, "file")) {
+		NEXT_ARG();
+		if (!argc) {
+			p_err("expected file path");
+			goto exit_close;
+		}
+		if (nb_fds > 1) {
+			p_err("several programs matched");
+			goto exit_close;
+		}
+
+		filepath = *argv;
+		NEXT_ARG();
+	} else if (is_prefix(*argv, "opcodes")) {
+		opcodes = true;
+		NEXT_ARG();
+	} else if (is_prefix(*argv, "visual")) {
+		if (nb_fds > 1) {
+			p_err("several programs matched");
+			goto exit_close;
+		}
+
+		visual = true;
+		NEXT_ARG();
+	} else if (is_prefix(*argv, "linum")) {
+		linum = true;
+		NEXT_ARG();
+	}
+
+	if (argc) {
+		usage();
+		goto exit_close;
+	}
+
+	if (mode == DUMP_JITED)
+		arrays = 1UL << BPF_PROG_INFO_JITED_INSNS;
+	else
+		arrays = 1UL << BPF_PROG_INFO_XLATED_INSNS;
+
+	arrays |= 1UL << BPF_PROG_INFO_JITED_KSYMS;
+	arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
+	arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
+	arrays |= 1UL << BPF_PROG_INFO_LINE_INFO;
+	arrays |= 1UL << BPF_PROG_INFO_JITED_LINE_INFO;
+
+	if (json_output && nb_fds > 1)
+		jsonw_start_array(json_wtr);	/* root array */
+	for (i = 0; i < nb_fds; i++) {
+		info_linear = bpf_program__get_prog_info_linear(fds[i], arrays);
+		if (IS_ERR_OR_NULL(info_linear)) {
+			p_err("can't get prog info: %s", strerror(errno));
+			break;
+		}
+
+		if (json_output && nb_fds > 1) {
+			jsonw_start_object(json_wtr);	/* prog object */
+			print_prog_header_json(&info_linear->info);
+			jsonw_name(json_wtr, "insns");
+		} else if (nb_fds > 1) {
+			print_prog_header_plain(&info_linear->info);
+		}
+
+		err = prog_dump(&info_linear->info, mode, filepath, opcodes,
+				visual, linum);
+
+		if (json_output && nb_fds > 1)
+			jsonw_end_object(json_wtr);	/* prog object */
+		else if (i != nb_fds - 1 && nb_fds > 1)
+			printf("\n");
+
+		free(info_linear);
+		if (err)
+			break;
+		close(fds[i]);
+	}
+	if (json_output && nb_fds > 1)
+		jsonw_end_array(json_wtr);	/* root array */
+
+exit_close:
+	for (; i < nb_fds; i++)
+		close(fds[i]);
+exit_free:
+	free(fds);
+	return err;
 }
 
 static int do_pin(int argc, char **argv)