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