4 -------------------------------------------------------------------------------
5 tool for inspection and simple manipulation of eBPF maps
6 -------------------------------------------------------------------------------
13 **bpftool** [*OPTIONS*] **map** *COMMAND*
15 *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
18 { **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext**
19 | **delete** | **pin** | **help** }
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*] \
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**
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** }
57 **bpftool map { show | list }** [*MAP*]
58 Show information about loaded maps. If *MAP* is specified
59 show information only about given maps, otherwise list all
60 maps currently loaded on the system. In case of **name**,
61 *MAP* may match several maps which will all be shown.
63 Output will start with map ID followed by map type and
64 zero or more named attributes (depending on kernel version).
66 Since Linux 5.8 bpftool is able to discover information about
67 processes that hold open file descriptors (FDs) against BPF
68 maps. On such kernels bpftool will automatically emit this
71 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*]
72 Create a new map with given parameters and pin it to *bpffs*
75 *FLAGS* should be an integer which is the combination of
76 desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h
77 UAPI header for existing flags).
79 To create maps of type array-of-maps or hash-of-maps, the
80 **inner_map** keyword must be used to pass an inner map. The
81 kernel needs it to collect metadata related to the inner maps
82 that the new map will work with.
84 Keyword **dev** expects a network interface name, and is used
85 to request hardware offload for the map.
87 **bpftool map dump** *MAP*
88 Dump all entries in a given *MAP*. In case of **name**,
89 *MAP* may match several maps which will all be dumped.
91 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
92 Update map entry for a given *KEY*.
94 *UPDATE_FLAGS* can be one of: **any** update existing entry
95 or add if doesn't exit; **exist** update only if entry already
96 exists; **noexist** update only if entry doesn't exist.
98 If the **hex** keyword is provided in front of the bytes
99 sequence, the bytes are parsed as hexadecimal values, even if
100 no "0x" prefix is added. If the keyword is not provided, then
101 the bytes are parsed as decimal values, unless a "0x" prefix
102 (for hexadecimal) or a "0" prefix (for octal) is provided.
104 **bpftool map lookup** *MAP* [**key** *DATA*]
105 Lookup **key** in the map.
107 **bpftool map getnext** *MAP* [**key** *DATA*]
108 Get next key. If *key* is not specified, get first key.
110 **bpftool map delete** *MAP* **key** *DATA*
111 Remove entry from the map.
113 **bpftool map pin** *MAP* *FILE*
114 Pin map *MAP* as *FILE*.
116 Note: *FILE* must be located in *bpffs* mount. It must not
117 contain a dot character ('.'), which is reserved for future
118 extensions of *bpffs*.
120 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
121 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
123 Install perf rings into a perf event array map and dump
124 output of any **bpf_perf_event_output**\ () call in the kernel.
125 By default read the number of CPUs on the system and
126 install perf ring for each CPU in the corresponding index
129 If **cpu** and **index** are specified, install perf ring
130 for given **cpu** at **index** in the array (single ring).
132 Note that installing a perf ring into an array will silently
133 replace any existing ring. Any other application will stop
134 receiving events if it installed its rings earlier.
136 **bpftool map peek** *MAP*
137 Peek next value in the queue or stack.
139 **bpftool map push** *MAP* **value** *VALUE*
140 Push *VALUE* onto the stack.
142 **bpftool map pop** *MAP*
143 Pop and print value from the stack.
145 **bpftool map enqueue** *MAP* **value** *VALUE*
146 Enqueue *VALUE* into the queue.
148 **bpftool map dequeue** *MAP*
149 Dequeue and print value from the queue.
151 **bpftool map freeze** *MAP*
152 Freeze the map as read-only from user space. Entries from a
153 frozen map can not longer be updated or deleted with the
154 **bpf**\ () system call. This operation is not reversible,
155 and the map remains immutable from user space until its
156 destruction. However, read and write permissions for BPF
157 programs to the map remain unchanged.
160 Print short help message.
164 .. include:: common_options.rst
167 Show file names of pinned maps.
170 Do not automatically attempt to mount any virtual file system
171 (such as tracefs or BPF virtual file system) when necessary.
175 **# bpftool map show**
179 10: hash name some_map flags 0x0
180 key 4B value 8B max_entries 2048 memlock 167936B
183 The following three commands are equivalent:
186 | **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c**
187 | **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c**
188 | **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76**
190 **# bpftool map lookup id 10 key 0 1 2 3**
194 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
197 **# bpftool map dump id 10**
201 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
202 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04
205 **# bpftool map getnext id 10 key 0 1 2 3**
215 | **# mount -t bpf none /sys/fs/bpf/**
216 | **# bpftool map pin id 10 /sys/fs/bpf/map**
217 | **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
219 Note that map update can also be used in order to change the program references
220 hold by a program array map. This can be used, for example, to change the
221 programs used for tail-call jumps at runtime, without having to reload the
222 entry-point program. Below is an example for this use case: we load a program
223 defining a prog array map, and with a main function that contains a tail call
224 to other programs that can be used either to "process" packets or to "debug"
225 processing. Note that the prog array map MUST be pinned into the BPF virtual
226 file system for the map update to work successfully, as kernel flushes prog
227 array maps when they have no more references from user space (and the update
228 would be lost as soon as bpftool exits).
231 | **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
232 | **# bpftool prog --bpffs**
236 545: xdp name main_func tag 674b4b5597193dc3 gpl
237 loaded_at 2018-12-12T15:02:58+0000 uid 0
238 xlated 240B jited 257B memlock 4096B map_ids 294
239 pinned /sys/fs/bpf/foo/xdp
240 546: xdp name bpf_func_process tag e369a529024751fc gpl
241 loaded_at 2018-12-12T15:02:58+0000 uid 0
242 xlated 200B jited 164B memlock 4096B
243 pinned /sys/fs/bpf/foo/process
244 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl
245 loaded_at 2018-12-12T15:02:58+0000 uid 0
246 xlated 200B jited 164B memlock 4096B
247 pinned /sys/fs/bpf/foo/debug
253 294: prog_array name jmp_table flags 0x0
254 key 4B value 4B max_entries 1 memlock 4096B
255 owner_prog_type xdp owner jited
258 | **# bpftool map pin id 294 /sys/fs/bpf/bar**
259 | **# bpftool map dump pinned /sys/fs/bpf/bar**
266 | **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
267 | **# bpftool map dump pinned /sys/fs/bpf/bar**
271 key: 00 00 00 00 value: 22 02 00 00