1BPFTOOL-MAP(8) BPFTOOL-MAP(8)
2
6 bpftool-map - tool for inspection and simple manipulation of eBPF maps
7
9 bpftool [OPTIONS] map COMMAND
10 OPTIONS := { { -j | --json } [{ -p | --pretty }] | { -f | --bpffs }
12 }
13 COMMANDS := { show | list | create | dump | update | lookup | get‐
15 next | delete | pin | help }
16
18 bpftool map { show | list } [MAP]
19 bpftool map create FILE type TYPE key KEY_SIZE value VALUE_SIZE
20 entries MAX_ENTRIES name NAME [flags FLAGS] [dev NAME]
21 bpftool map dump MAP
22 bpftool map update MAP [key DATA] [value VALUE] [UPDATE_FLAGS]
23 bpftool map lookup MAP [key DATA]
24 bpftool map getnext MAP [key DATA]
25 bpftool map delete MAP key DATA
26 bpftool map pin MAP FILE
27 bpftool map event_pipe MAP [cpu N index M]
28 bpftool map peek MAP
29 bpftool map push MAP value VALUE
30 bpftool map pop MAP
31 bpftool map enqueue MAP value VALUE
32 bpftool map dequeue MAP
33 bpftool map freeze MAP
34 bpftool map help
35 MAP := { id MAP_ID | pinned FILE | name MAP_NAME }
37 DATA := { [hex] BYTES }
38 PROG := { id PROG_ID | pinned FILE | tag PROG_TAG | name PROG_NAME }
39 VALUE := { DATA | MAP | PROG }
40 UPDATE_FLAGS := { any | exist | noexist }
41 TYPE := { hash | array | prog_array | perf_event_array | percpu_hash
42 | percpu_array | stack_trace | cgroup_array | lru_hash
43 | lru_percpu_hash | lpm_trie | array_of_maps | hash_of_maps
44 | devmap | devmap_hash | sockmap | cpumap | xskmap | sockhash
45 | cgroup_storage | reuseport_sockarray | percpu_cgroup_storage
46 | queue | stack }
47
50 bpftool map { show | list } [MAP]
51 Show information about loaded maps. If MAP is specified show
52 information only about given maps, otherwise list all maps
53 currently loaded on the system. In case of name, MAP may
54 match several maps which will all be shown.
55 Output will start with map ID followed by map type and zero
57 or more named attributes (depending on kernel version).
58 bpftool map create FILE type TYPE key KEY_SIZE value VALUE_SIZE
60 entries MAX_ENTRIES name NAME [flags FLAGS] [dev NAME]
61 Create a new map with given parameters and pin it to bpffs as
62 FILE.
63 bpftool map dump MAP
65 Dump all entries in a given MAP. In case of name, MAP may
66 match several maps which will all be dumped.
67 bpftool map update MAP [key DATA] [value VALUE] [UPDATE_FLAGS]
69 Update map entry for a given KEY.
70 UPDATE_FLAGS can be one of: any update existing entry or add
72 if doesn't exit; exist update only if entry already exists;
73 noexist update only if entry doesn't exist.
74 If the hex keyword is provided in front of the bytes
76 sequence, the bytes are parsed as hexadeximal values, even if
77 no "0x" prefix is added. If the keyword is not provided, then
78 the bytes are parsed as decimal values, unless a "0x" prefix
79 (for hexadecimal) or a "0" prefix (for octal) is provided.
80 bpftool map lookup MAP [key DATA]
82 Lookup key in the map.
83 bpftool map getnext MAP [key DATA]
85 Get next key. If key is not specified, get first key.
86 bpftool map delete MAP key DATA
88 Remove entry from the map.
89 bpftool map pin MAP FILE
91 Pin map MAP as FILE.
92 Note: FILE must be located in bpffs mount. It must not con‐
94 tain a dot character ('.'), which is reserved for future
95 extensions of bpffs.
96 bpftool map event_pipe MAP [cpu N index M]
98 Read events from a BPF_MAP_TYPE_PERF_EVENT_ARRAY map.
99 Install perf rings into a perf event array map and dump out‐
101 put of any bpf_perf_event_output() call in the kernel. By
102 default read the number of CPUs on the system and install
103 perf ring for each CPU in the corresponding index in the
104 array.
105 If cpu and index are specified, install perf ring for given
107 cpu at index in the array (single ring).
108 Note that installing a perf ring into an array will silently
110 replace any existing ring. Any other application will stop
111 receiving events if it installed its rings earlier.
112 bpftool map peek MAP
114 Peek next value in the queue or stack.
115 bpftool map push MAP value VALUE
117 Push value onto the stack.
118 bpftool map pop MAP
120 Pop and print value from the stack.
121 bpftool map enqueue MAP value VALUE
123 Enqueue value into the queue.
124 bpftool map dequeue MAP
126 Dequeue and print value from the queue.
127 bpftool map freeze MAP
129 Freeze the map as read-only from user space. Entries from a
130 frozen map can not longer be updated or deleted with the
131 bpf() system call. This operation is not reversible, and the
132 map remains immutable from user space until its destruction.
133 However, read and write permissions for BPF programs to the
134 map remain unchanged.
135 bpftool map help
137 Print short help message.
138
140 -h, --help
141 Print short generic help message (similar to bpftool help).
142 -V, --version
144 Print version number (similar to bpftool version).
145 -j, --json
147 Generate JSON output. For commands that cannot produce JSON,
148 this option has no effect.
149 -p, --pretty
151 Generate human-readable JSON output. Implies -j.
152 -f, --bpffs
154 Show file names of pinned maps.
155 -n, --nomount
157 Do not automatically attempt to mount any virtual file system
158 (such as tracefs or BPF virtual file system) when necessary.
159 -d, --debug
161 Print all logs available from libbpf, including debug-level
162 information.
163
165 # bpftool map show
166 10: hash name some_map flags 0x0
168 key 4B value 8B max_entries 2048 memlock 167936B
169 The following three commands are equivalent:
171 # bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c
173 # bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c
174 # bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76
175 # bpftool map lookup id 10 key 0 1 2 3
178 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
180 # bpftool map dump id 10
182 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
184 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04
185 Found 2 elements
186 # bpftool map getnext id 10 key 0 1 2 3
188 key:
190 00 01 02 03
191 next key:
192 0d 00 07 00
193 # mount -t bpf none /sys/fs/bpf/
195 # bpftool map pin id 10 /sys/fs/bpf/map
196 # bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00
197 Note that map update can also be used in order to change the program
200 references hold by a program array map. This can be used, for example,
201 to change the programs used for tail-call jumps at runtime, without
202 having to reload the entry-point program. Below is an example for this
203 use case: we load a program defining a prog array map, and with a main
204 function that contains a tail call to other programs that can be used
205 either to "process" packets or to "debug" processing. Note that the
206 prog array map MUST be pinned into the BPF virtual file system for the
207 map update to work successfully, as kernel flushes prog array maps when
208 they have no more references from user space (and the update would be
209 lost as soon as bpftool exits).
210 # bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp
212 # bpftool prog --bpffs
213 545: xdp name main_func tag 674b4b5597193dc3 gpl
216 loaded_at 2018-12-12T15:02:58+0000 uid 0
217 xlated 240B jited 257B memlock 4096B map_ids 294
218 pinned /sys/fs/bpf/foo/xdp
219 546: xdp name bpf_func_process tag e369a529024751fc gpl
220 loaded_at 2018-12-12T15:02:58+0000 uid 0
221 xlated 200B jited 164B memlock 4096B
222 pinned /sys/fs/bpf/foo/process
223 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl
224 loaded_at 2018-12-12T15:02:58+0000 uid 0
225 xlated 200B jited 164B memlock 4096B
226 pinned /sys/fs/bpf/foo/debug
227 # bpftool map
229 294: prog_array name jmp_table flags 0x0
231 key 4B value 4B max_entries 1 memlock 4096B
232 owner_prog_type xdp owner jited
233 # bpftool map pin id 294 /sys/fs/bpf/bar
235 # bpftool map dump pinned /sys/fs/bpf/bar
236 Found 0 elements
239 # bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug
241 # bpftool map dump pinned /sys/fs/bpf/bar
242 key: 00 00 00 00 value: 22 02 00 00
245 Found 1 element
246
248 bpf(2), bpf-helpers(7), bpftool(8), bpftool-prog(8),
249 bpftool-cgroup(8), bpftool-feature(8), bpftool-net(8),
250 bpftool-perf(8), bpftool-btf(8)
251 BPFTOOL-MAP(8)