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1================
2bpftool-map
3================
4-------------------------------------------------------------------------------
5tool for inspection and simple manipulation of eBPF maps
6-------------------------------------------------------------------------------
7
8:Manual section: 8
9
10SYNOPSIS
11========
12
13 **bpftool** [*OPTIONS*] **map** *COMMAND*
14
15 *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
16
17 *COMMANDS* :=
18 { **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext**
19 | **delete** | **pin** | **help** }
20
21MAP COMMANDS
22=============
23
24| **bpftool** **map** { **show** | **list** } [*MAP*]
25| **bpftool** **map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
26| **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*]
27| **bpftool** **map dump** *MAP*
28| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
29| **bpftool** **map lookup** *MAP* [**key** *DATA*]
30| **bpftool** **map getnext** *MAP* [**key** *DATA*]
31| **bpftool** **map delete** *MAP* **key** *DATA*
32| **bpftool** **map pin** *MAP* *FILE*
33| **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
34| **bpftool** **map peek** *MAP*
35| **bpftool** **map push** *MAP* **value** *VALUE*
36| **bpftool** **map pop** *MAP*
37| **bpftool** **map enqueue** *MAP* **value** *VALUE*
38| **bpftool** **map dequeue** *MAP*
39| **bpftool** **map freeze** *MAP*
40| **bpftool** **map help**
41|
42| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* }
43| *DATA* := { [**hex**] *BYTES* }
44| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
45| *VALUE* := { *DATA* | *MAP* | *PROG* }
46| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
47| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
48| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash**
49| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
50| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
51| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage**
52| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** }
53
54DESCRIPTION
55===========
56 **bpftool map { show | list }** [*MAP*]
57 Show information about loaded maps. If *MAP* is specified
58 show information only about given maps, otherwise list all
59 maps currently loaded on the system. In case of **name**,
60 *MAP* may match several maps which will all be shown.
61
62 Output will start with map ID followed by map type and
63 zero or more named attributes (depending on kernel version).
64
65 Since Linux 5.8 bpftool is able to discover information about
66 processes that hold open file descriptors (FDs) against BPF
67 maps. On such kernels bpftool will automatically emit this
68 information as well.
69
70 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*]
71 Create a new map with given parameters and pin it to *bpffs*
72 as *FILE*.
73
74 *FLAGS* should be an integer which is the combination of
75 desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h
76 UAPI header for existing flags).
77
78 Keyword **dev** expects a network interface name, and is used
79 to request hardware offload for the map.
80
81 **bpftool map dump** *MAP*
82 Dump all entries in a given *MAP*. In case of **name**,
83 *MAP* may match several maps which will all be dumped.
84
85 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
86 Update map entry for a given *KEY*.
87
88 *UPDATE_FLAGS* can be one of: **any** update existing entry
89 or add if doesn't exit; **exist** update only if entry already
90 exists; **noexist** update only if entry doesn't exist.
91
92 If the **hex** keyword is provided in front of the bytes
93 sequence, the bytes are parsed as hexadecimal values, even if
94 no "0x" prefix is added. If the keyword is not provided, then
95 the bytes are parsed as decimal values, unless a "0x" prefix
96 (for hexadecimal) or a "0" prefix (for octal) is provided.
97
98 **bpftool map lookup** *MAP* [**key** *DATA*]
99 Lookup **key** in the map.
100
101 **bpftool map getnext** *MAP* [**key** *DATA*]
102 Get next key. If *key* is not specified, get first key.
103
104 **bpftool map delete** *MAP* **key** *DATA*
105 Remove entry from the map.
106
107 **bpftool map pin** *MAP* *FILE*
108 Pin map *MAP* as *FILE*.
109
110 Note: *FILE* must be located in *bpffs* mount. It must not
111 contain a dot character ('.'), which is reserved for future
112 extensions of *bpffs*.
113
114 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
115 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
116
117 Install perf rings into a perf event array map and dump
118 output of any **bpf_perf_event_output**\ () call in the kernel.
119 By default read the number of CPUs on the system and
120 install perf ring for each CPU in the corresponding index
121 in the array.
122
123 If **cpu** and **index** are specified, install perf ring
124 for given **cpu** at **index** in the array (single ring).
125
126 Note that installing a perf ring into an array will silently
127 replace any existing ring. Any other application will stop
128 receiving events if it installed its rings earlier.
129
130 **bpftool map peek** *MAP*
131 Peek next value in the queue or stack.
132
133 **bpftool map push** *MAP* **value** *VALUE*
134 Push *VALUE* onto the stack.
135
136 **bpftool map pop** *MAP*
137 Pop and print value from the stack.
138
139 **bpftool map enqueue** *MAP* **value** *VALUE*
140 Enqueue *VALUE* into the queue.
141
142 **bpftool map dequeue** *MAP*
143 Dequeue and print value from the queue.
144
145 **bpftool map freeze** *MAP*
146 Freeze the map as read-only from user space. Entries from a
147 frozen map can not longer be updated or deleted with the
148 **bpf**\ () system call. This operation is not reversible,
149 and the map remains immutable from user space until its
150 destruction. However, read and write permissions for BPF
151 programs to the map remain unchanged.
152
153 **bpftool map help**
154 Print short help message.
155
156OPTIONS
157=======
158 -h, --help
159 Print short generic help message (similar to **bpftool help**).
160
161 -V, --version
162 Print version number (similar to **bpftool version**).
163
164 -j, --json
165 Generate JSON output. For commands that cannot produce JSON, this
166 option has no effect.
167
168 -p, --pretty
169 Generate human-readable JSON output. Implies **-j**.
170
171 -f, --bpffs
172 Show file names of pinned maps.
173
174 -n, --nomount
175 Do not automatically attempt to mount any virtual file system
176 (such as tracefs or BPF virtual file system) when necessary.
177
178 -d, --debug
179 Print all logs available from libbpf, including debug-level
180 information.
181
182EXAMPLES
183========
184**# bpftool map show**
185::
186
187 10: hash name some_map flags 0x0
188 key 4B value 8B max_entries 2048 memlock 167936B
189 pids systemd(1)
190
191The following three commands are equivalent:
192
193|
194| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c**
195| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c**
196| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76**
197
198**# bpftool map lookup id 10 key 0 1 2 3**
199
200::
201
202 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
203
204
205**# bpftool map dump id 10**
206::
207
208 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
209 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04
210 Found 2 elements
211
212**# bpftool map getnext id 10 key 0 1 2 3**
213::
214
215 key:
216 00 01 02 03
217 next key:
218 0d 00 07 00
219
220|
221| **# mount -t bpf none /sys/fs/bpf/**
222| **# bpftool map pin id 10 /sys/fs/bpf/map**
223| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
224
225Note that map update can also be used in order to change the program references
226hold by a program array map. This can be used, for example, to change the
227programs used for tail-call jumps at runtime, without having to reload the
228entry-point program. Below is an example for this use case: we load a program
229defining a prog array map, and with a main function that contains a tail call
230to other programs that can be used either to "process" packets or to "debug"
231processing. Note that the prog array map MUST be pinned into the BPF virtual
232file system for the map update to work successfully, as kernel flushes prog
233array maps when they have no more references from user space (and the update
234would be lost as soon as bpftool exits).
235
236|
237| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
238| **# bpftool prog --bpffs**
239
240::
241
242 545: xdp name main_func tag 674b4b5597193dc3 gpl
243 loaded_at 2018-12-12T15:02:58+0000 uid 0
244 xlated 240B jited 257B memlock 4096B map_ids 294
245 pinned /sys/fs/bpf/foo/xdp
246 546: xdp name bpf_func_process tag e369a529024751fc gpl
247 loaded_at 2018-12-12T15:02:58+0000 uid 0
248 xlated 200B jited 164B memlock 4096B
249 pinned /sys/fs/bpf/foo/process
250 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl
251 loaded_at 2018-12-12T15:02:58+0000 uid 0
252 xlated 200B jited 164B memlock 4096B
253 pinned /sys/fs/bpf/foo/debug
254
255**# bpftool map**
256
257::
258
259 294: prog_array name jmp_table flags 0x0
260 key 4B value 4B max_entries 1 memlock 4096B
261 owner_prog_type xdp owner jited
262
263|
264| **# bpftool map pin id 294 /sys/fs/bpf/bar**
265| **# bpftool map dump pinned /sys/fs/bpf/bar**
266
267::
268
269 Found 0 elements
270
271|
272| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
273| **# bpftool map dump pinned /sys/fs/bpf/bar**
274
275::
276
277 key: 00 00 00 00 value: 22 02 00 00
278 Found 1 element
279
280SEE ALSO
281========
282 **bpf**\ (2),
283 **bpf-helpers**\ (7),
284 **bpftool**\ (8),
285 **bpftool-btf**\ (8),
286 **bpftool-cgroup**\ (8),
287 **bpftool-feature**\ (8),
288 **bpftool-gen**\ (8),
289 **bpftool-iter**\ (8),
290 **bpftool-link**\ (8),
291 **bpftool-net**\ (8),
292 **bpftool-perf**\ (8),
293 **bpftool-prog**\ (8),
294 **bpftool-struct_ops**\ (8)