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