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| | **insn_array** } 60 61DESCRIPTION 62=========== 63bpftool map { show | list } [*MAP*] 64 Show information about loaded maps. If *MAP* is specified show information 65 only about given maps, otherwise list all maps currently loaded on the 66 system. In case of **name**, *MAP* may match several maps which will all 67 be shown. 68 69 Output will start with map ID followed by map type and zero or more named 70 attributes (depending on kernel version). 71 72 Since Linux 5.8 bpftool is able to discover information about processes 73 that hold open file descriptors (FDs) against BPF maps. On such kernels 74 bpftool will automatically emit this information as well. 75 76bpftool 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* as *FILE*. 78 79 *FLAGS* should be an integer which is the combination of desired flags, 80 e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h UAPI header for existing 81 flags). 82 83 To create maps of type array-of-maps or hash-of-maps, the **inner_map** 84 keyword must be used to pass an inner map. The kernel needs it to collect 85 metadata related to the inner maps that the new map will work with. 86 87 Keyword **offload_dev** expects a network interface name, and is used to 88 request hardware offload for the map. 89 90bpftool map dump *MAP* 91 Dump all entries in a given *MAP*. In case of **name**, *MAP* may match 92 several maps which will all be dumped. 93 94bpftool map update *MAP* [key *DATA*] [value *VALUE*] [*UPDATE_FLAGS*] 95 Update map entry for a given *KEY*. 96 97 *UPDATE_FLAGS* can be one of: **any** update existing entry or add if 98 doesn't exit; **exist** update only if entry already exists; **noexist** 99 update only if entry doesn't exist. 100 101 If the **hex** keyword is provided in front of the bytes sequence, the 102 bytes are parsed as hexadecimal values, even if no "0x" prefix is added. If 103 the keyword is not provided, then the bytes are parsed as decimal values, 104 unless a "0x" prefix (for hexadecimal) or a "0" prefix (for octal) is 105 provided. 106 107bpftool map lookup *MAP* [key *DATA*] 108 Lookup **key** in the map. 109 110bpftool map getnext *MAP* [key *DATA*] 111 Get next key. If *key* is not specified, get first key. 112 113bpftool map delete *MAP* key *DATA* 114 Remove entry from the map. 115 116bpftool map pin *MAP* *FILE* 117 Pin map *MAP* as *FILE*. 118 119 Note: *FILE* must be located in *bpffs* mount. It must not contain a dot 120 character ('.'), which is reserved for future extensions of *bpffs*. 121 122bpftool map event_pipe *MAP* [cpu *N* index *M*] 123 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map. 124 125 Install perf rings into a perf event array map and dump output of any 126 **bpf_perf_event_output**\ () call in the kernel. By default read the 127 number of CPUs on the system and install perf ring for each CPU in the 128 corresponding index in the array. 129 130 If **cpu** and **index** are specified, install perf ring for given **cpu** 131 at **index** in the array (single ring). 132 133 Note that installing a perf ring into an array will silently replace any 134 existing ring. Any other application will stop receiving events if it 135 installed its rings earlier. 136 137bpftool map peek *MAP* 138 Peek next value in the queue or stack. 139 140bpftool map push *MAP* value *VALUE* 141 Push *VALUE* onto the stack. 142 143bpftool map pop *MAP* 144 Pop and print value from the stack. 145 146bpftool map enqueue *MAP* value *VALUE* 147 Enqueue *VALUE* into the queue. 148 149bpftool map dequeue *MAP* 150 Dequeue and print value from the queue. 151 152bpftool map freeze *MAP* 153 Freeze the map as read-only from user space. Entries from a frozen map can 154 not longer be updated or deleted with the **bpf**\ () system call. This 155 operation is not reversible, and the map remains immutable from user space 156 until its destruction. However, read and write permissions for BPF programs 157 to the map remain unchanged. 158 159bpftool map help 160 Print short help message. 161 162OPTIONS 163======= 164.. include:: common_options.rst 165 166-f, --bpffs 167 Show file names of pinned maps. 168 169-n, --nomount 170 Do not automatically attempt to mount any virtual file system (such as 171 tracefs or BPF virtual file system) when necessary. 172 173EXAMPLES 174======== 175**# bpftool map show** 176 177:: 178 179 10: hash name some_map flags 0x0 180 key 4B value 8B max_entries 2048 memlock 167936B 181 pids systemd(1) 182 183The following three commands are equivalent: 184 185| 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** 189 190**# bpftool map lookup id 10 key 0 1 2 3** 191 192:: 193 194 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 195 196 197**# bpftool map dump id 10** 198 199:: 200 201 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 04 203 Found 2 elements 204 205**# bpftool map getnext id 10 key 0 1 2 3** 206 207:: 208 209 key: 210 00 01 02 03 211 next key: 212 0d 00 07 00 213 214| 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** 218 219Note that map update can also be used in order to change the program references 220hold by a program array map. This can be used, for example, to change the 221programs used for tail-call jumps at runtime, without having to reload the 222entry-point program. Below is an example for this use case: we load a program 223defining a prog array map, and with a main function that contains a tail call 224to other programs that can be used either to "process" packets or to "debug" 225processing. Note that the prog array map MUST be pinned into the BPF virtual 226file system for the map update to work successfully, as kernel flushes prog 227array maps when they have no more references from user space (and the update 228would be lost as soon as bpftool exits). 229 230| 231| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp** 232| **# bpftool prog --bpffs** 233 234:: 235 236 545: 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 248 249**# bpftool map** 250 251:: 252 253 294: prog_array name jmp_table flags 0x0 254 key 4B value 4B max_entries 1 memlock 4096B 255 owner_prog_type xdp owner jited 256 257| 258| **# bpftool map pin id 294 /sys/fs/bpf/bar** 259| **# bpftool map dump pinned /sys/fs/bpf/bar** 260 261:: 262 263 Found 0 elements 264 265| 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** 268 269:: 270 271 key: 00 00 00 00 value: 22 02 00 00 272 Found 1 element 273