1 .. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
6 -------------------------------------------------------------------------------
7 tool for inspection and simple manipulation of eBPF maps
8 -------------------------------------------------------------------------------
12 .. include:: substitutions.rst
17 **bpftool** [*OPTIONS*] **map** *COMMAND*
19 *OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } }
22 { **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext** |
23 **delete** | **pin** | **help** }
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**
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** }
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.
68 Output will start with map ID followed by map type and
69 zero or more named attributes (depending on kernel version).
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
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*
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).
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.
89 Keyword **offload_dev** expects a network interface name,
90 and is used to request hardware offload for the map.
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.
96 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
97 Update map entry for a given *KEY*.
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.
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.
109 **bpftool map lookup** *MAP* [**key** *DATA*]
110 Lookup **key** in the map.
112 **bpftool map getnext** *MAP* [**key** *DATA*]
113 Get next key. If *key* is not specified, get first key.
115 **bpftool map delete** *MAP* **key** *DATA*
116 Remove entry from the map.
118 **bpftool map pin** *MAP* *FILE*
119 Pin map *MAP* as *FILE*.
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*.
125 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
126 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
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
134 If **cpu** and **index** are specified, install perf ring
135 for given **cpu** at **index** in the array (single ring).
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.
141 **bpftool map peek** *MAP*
142 Peek next value in the queue or stack.
144 **bpftool map push** *MAP* **value** *VALUE*
145 Push *VALUE* onto the stack.
147 **bpftool map pop** *MAP*
148 Pop and print value from the stack.
150 **bpftool map enqueue** *MAP* **value** *VALUE*
151 Enqueue *VALUE* into the queue.
153 **bpftool map dequeue** *MAP*
154 Dequeue and print value from the queue.
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.
165 Print short help message.
169 .. include:: common_options.rst
172 Show file names of pinned maps.
175 Do not automatically attempt to mount any virtual file system
176 (such as tracefs or BPF virtual file system) when necessary.
180 **# bpftool map show**
184 10: hash name some_map flags 0x0
185 key 4B value 8B max_entries 2048 memlock 167936B
188 The following three commands are equivalent:
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**
195 **# bpftool map lookup id 10 key 0 1 2 3**
199 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
202 **# bpftool map dump id 10**
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
210 **# bpftool map getnext id 10 key 0 1 2 3**
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**
224 Note that map update can also be used in order to change the program references
225 hold by a program array map. This can be used, for example, to change the
226 programs used for tail-call jumps at runtime, without having to reload the
227 entry-point program. Below is an example for this use case: we load a program
228 defining a prog array map, and with a main function that contains a tail call
229 to other programs that can be used either to "process" packets or to "debug"
230 processing. Note that the prog array map MUST be pinned into the BPF virtual
231 file system for the map update to work successfully, as kernel flushes prog
232 array maps when they have no more references from user space (and the update
233 would be lost as soon as bpftool exits).
236 | **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
237 | **# bpftool prog --bpffs**
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
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
263 | **# bpftool map pin id 294 /sys/fs/bpf/bar**
264 | **# bpftool map dump pinned /sys/fs/bpf/bar**
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**
276 key: 00 00 00 00 value: 22 02 00 00