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