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1.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2
3================
4bpftool-map
5================
6-------------------------------------------------------------------------------
7tool for inspection and simple manipulation of eBPF maps
8-------------------------------------------------------------------------------
9
10:Manual section: 8
11
12.. include:: substitutions.rst
13
14SYNOPSIS
15========
16
17 **bpftool** [*OPTIONS*] **map** *COMMAND*
18
19 *OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } }
20
21 *COMMANDS* :=
22 { **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext** |
23 **delete** | **pin** | **help** }
24
25MAP COMMANDS
26=============
27
28| **bpftool** **map** { **show** | **list** } [*MAP*]
29| **bpftool** **map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
30| **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] \
31| [**dev** *NAME*]
32| **bpftool** **map dump** *MAP*
33| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
34| **bpftool** **map lookup** *MAP* [**key** *DATA*]
35| **bpftool** **map getnext** *MAP* [**key** *DATA*]
36| **bpftool** **map delete** *MAP* **key** *DATA*
37| **bpftool** **map pin** *MAP* *FILE*
38| **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
39| **bpftool** **map peek** *MAP*
40| **bpftool** **map push** *MAP* **value** *VALUE*
41| **bpftool** **map pop** *MAP*
42| **bpftool** **map enqueue** *MAP* **value** *VALUE*
43| **bpftool** **map dequeue** *MAP*
44| **bpftool** **map freeze** *MAP*
45| **bpftool** **map help**
46|
47| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* }
48| *DATA* := { [**hex**] *BYTES* }
49| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
50| *VALUE* := { *DATA* | *MAP* | *PROG* }
51| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
52| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
53| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash**
54| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
55| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
56| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage**
57| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage**
58| | **task_storage** | **bloom_filter** | **user_ringbuf** | **cgrp_storage** }
59
60DESCRIPTION
61===========
62 **bpftool map { show | list }** [*MAP*]
63 Show information about loaded maps. If *MAP* is specified
64 show information only about given maps, otherwise list all
65 maps currently loaded on the system. In case of **name**,
66 *MAP* may match several maps which will all be shown.
67
68 Output will start with map ID followed by map type and
69 zero or more named attributes (depending on kernel version).
70
71 Since Linux 5.8 bpftool is able to discover information about
72 processes that hold open file descriptors (FDs) against BPF
73 maps. On such kernels bpftool will automatically emit this
74 information as well.
75
76 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*]
77 Create a new map with given parameters and pin it to *bpffs*
78 as *FILE*.
79
80 *FLAGS* should be an integer which is the combination of
81 desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h
82 UAPI header for existing flags).
83
84 To create maps of type array-of-maps or hash-of-maps, the
85 **inner_map** keyword must be used to pass an inner map. The
86 kernel needs it to collect metadata related to the inner maps
87 that the new map will work with.
88
89 Keyword **dev** expects a network interface name, and is used
90 to request hardware offload for the map.
91
92 **bpftool map dump** *MAP*
93 Dump all entries in a given *MAP*. In case of **name**,
94 *MAP* may match several maps which will all be dumped.
95
96 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
97 Update map entry for a given *KEY*.
98
99 *UPDATE_FLAGS* can be one of: **any** update existing entry
100 or add if doesn't exit; **exist** update only if entry already
101 exists; **noexist** update only if entry doesn't exist.
102
103 If the **hex** keyword is provided in front of the bytes
104 sequence, the bytes are parsed as hexadecimal values, even if
105 no "0x" prefix is added. If the keyword is not provided, then
106 the bytes are parsed as decimal values, unless a "0x" prefix
107 (for hexadecimal) or a "0" prefix (for octal) is provided.
108
109 **bpftool map lookup** *MAP* [**key** *DATA*]
110 Lookup **key** in the map.
111
112 **bpftool map getnext** *MAP* [**key** *DATA*]
113 Get next key. If *key* is not specified, get first key.
114
115 **bpftool map delete** *MAP* **key** *DATA*
116 Remove entry from the map.
117
118 **bpftool map pin** *MAP* *FILE*
119 Pin map *MAP* as *FILE*.
120
121 Note: *FILE* must be located in *bpffs* mount. It must not
122 contain a dot character ('.'), which is reserved for future
123 extensions of *bpffs*.
124
125 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
126 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
127
128 Install perf rings into a perf event array map and dump
129 output of any **bpf_perf_event_output**\ () call in the kernel.
130 By default read the number of CPUs on the system and
131 install perf ring for each CPU in the corresponding index
132 in the array.
133
134 If **cpu** and **index** are specified, install perf ring
135 for given **cpu** at **index** in the array (single ring).
136
137 Note that installing a perf ring into an array will silently
138 replace any existing ring. Any other application will stop
139 receiving events if it installed its rings earlier.
140
141 **bpftool map peek** *MAP*
142 Peek next value in the queue or stack.
143
144 **bpftool map push** *MAP* **value** *VALUE*
145 Push *VALUE* onto the stack.
146
147 **bpftool map pop** *MAP*
148 Pop and print value from the stack.
149
150 **bpftool map enqueue** *MAP* **value** *VALUE*
151 Enqueue *VALUE* into the queue.
152
153 **bpftool map dequeue** *MAP*
154 Dequeue and print value from the queue.
155
156 **bpftool map freeze** *MAP*
157 Freeze the map as read-only from user space. Entries from a
158 frozen map can not longer be updated or deleted with the
159 **bpf**\ () system call. This operation is not reversible,
160 and the map remains immutable from user space until its
161 destruction. However, read and write permissions for BPF
162 programs to the map remain unchanged.
163
164 **bpftool map help**
165 Print short help message.
166
167OPTIONS
168=======
169 .. include:: common_options.rst
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
178EXAMPLES
179========
180**# bpftool map show**
181
182::
183
184 10: hash name some_map flags 0x0
185 key 4B value 8B max_entries 2048 memlock 167936B
186 pids systemd(1)
187
188The following three commands are equivalent:
189
190|
191| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c**
192| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c**
193| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76**
194
195**# bpftool map lookup id 10 key 0 1 2 3**
196
197::
198
199 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
200
201
202**# bpftool map dump id 10**
203
204::
205
206 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
207 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04
208 Found 2 elements
209
210**# bpftool map getnext id 10 key 0 1 2 3**
211
212::
213
214 key:
215 00 01 02 03
216 next key:
217 0d 00 07 00
218
219|
220| **# mount -t bpf none /sys/fs/bpf/**
221| **# bpftool map pin id 10 /sys/fs/bpf/map**
222| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
223
224Note that map update can also be used in order to change the program references
225hold by a program array map. This can be used, for example, to change the
226programs used for tail-call jumps at runtime, without having to reload the
227entry-point program. Below is an example for this use case: we load a program
228defining a prog array map, and with a main function that contains a tail call
229to other programs that can be used either to "process" packets or to "debug"
230processing. Note that the prog array map MUST be pinned into the BPF virtual
231file system for the map update to work successfully, as kernel flushes prog
232array maps when they have no more references from user space (and the update
233would be lost as soon as bpftool exits).
234
235|
236| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
237| **# bpftool prog --bpffs**
238
239::
240
241 545: xdp name main_func tag 674b4b5597193dc3 gpl
242 loaded_at 2018-12-12T15:02:58+0000 uid 0
243 xlated 240B jited 257B memlock 4096B map_ids 294
244 pinned /sys/fs/bpf/foo/xdp
245 546: xdp name bpf_func_process tag e369a529024751fc gpl
246 loaded_at 2018-12-12T15:02:58+0000 uid 0
247 xlated 200B jited 164B memlock 4096B
248 pinned /sys/fs/bpf/foo/process
249 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl
250 loaded_at 2018-12-12T15:02:58+0000 uid 0
251 xlated 200B jited 164B memlock 4096B
252 pinned /sys/fs/bpf/foo/debug
253
254**# bpftool map**
255
256::
257
258 294: prog_array name jmp_table flags 0x0
259 key 4B value 4B max_entries 1 memlock 4096B
260 owner_prog_type xdp owner jited
261
262|
263| **# bpftool map pin id 294 /sys/fs/bpf/bar**
264| **# bpftool map dump pinned /sys/fs/bpf/bar**
265
266::
267
268 Found 0 elements
269
270|
271| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
272| **# bpftool map dump pinned /sys/fs/bpf/bar**
273
274::
275
276 key: 00 00 00 00 value: 22 02 00 00
277 Found 1 element