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 help** 40| 41| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* } 42| *DATA* := { [**hex**] *BYTES* } 43| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* } 44| *VALUE* := { *DATA* | *MAP* | *PROG* } 45| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** } 46| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash** 47| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash** 48| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps** 49| | **devmap** | **sockmap** | **cpumap** | **xskmap** | **sockhash** 50| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** 51| | **queue** | **stack** } 52 53DESCRIPTION 54=========== 55 **bpftool map { show | list }** [*MAP*] 56 Show information about loaded maps. If *MAP* is specified 57 show information only about given map, otherwise list all 58 maps currently loaded on the system. 59 60 Output will start with map ID followed by map type and 61 zero or more named attributes (depending on kernel version). 62 63 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*] 64 Create a new map with given parameters and pin it to *bpffs* 65 as *FILE*. 66 67 **bpftool map dump** *MAP* 68 Dump all entries in a given *MAP*. 69 70 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*] 71 Update map entry for a given *KEY*. 72 73 *UPDATE_FLAGS* can be one of: **any** update existing entry 74 or add if doesn't exit; **exist** update only if entry already 75 exists; **noexist** update only if entry doesn't exist. 76 77 If the **hex** keyword is provided in front of the bytes 78 sequence, the bytes are parsed as hexadeximal values, even if 79 no "0x" prefix is added. If the keyword is not provided, then 80 the bytes are parsed as decimal values, unless a "0x" prefix 81 (for hexadecimal) or a "0" prefix (for octal) is provided. 82 83 **bpftool map lookup** *MAP* [**key** *DATA*] 84 Lookup **key** in the map. 85 86 **bpftool map getnext** *MAP* [**key** *DATA*] 87 Get next key. If *key* is not specified, get first key. 88 89 **bpftool map delete** *MAP* **key** *DATA* 90 Remove entry from the map. 91 92 **bpftool map pin** *MAP* *FILE* 93 Pin map *MAP* as *FILE*. 94 95 Note: *FILE* must be located in *bpffs* mount. It must not 96 contain a dot character ('.'), which is reserved for future 97 extensions of *bpffs*. 98 99 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 100 Read events from a BPF_MAP_TYPE_PERF_EVENT_ARRAY map. 101 102 Install perf rings into a perf event array map and dump 103 output of any bpf_perf_event_output() call in the kernel. 104 By default read the number of CPUs on the system and 105 install perf ring for each CPU in the corresponding index 106 in the array. 107 108 If **cpu** and **index** are specified, install perf ring 109 for given **cpu** at **index** in the array (single ring). 110 111 Note that installing a perf ring into an array will silently 112 replace any existing ring. Any other application will stop 113 receiving events if it installed its rings earlier. 114 115 **bpftool map peek** *MAP* 116 Peek next **value** in the queue or stack. 117 118 **bpftool map push** *MAP* **value** *VALUE* 119 Push **value** onto the stack. 120 121 **bpftool map pop** *MAP* 122 Pop and print **value** from the stack. 123 124 **bpftool map enqueue** *MAP* **value** *VALUE* 125 Enqueue **value** into the queue. 126 127 **bpftool map dequeue** *MAP* 128 Dequeue and print **value** from the queue. 129 130 **bpftool map help** 131 Print short help message. 132 133OPTIONS 134======= 135 -h, --help 136 Print short generic help message (similar to **bpftool help**). 137 138 -V, --version 139 Print version number (similar to **bpftool version**). 140 141 -j, --json 142 Generate JSON output. For commands that cannot produce JSON, this 143 option has no effect. 144 145 -p, --pretty 146 Generate human-readable JSON output. Implies **-j**. 147 148 -f, --bpffs 149 Show file names of pinned maps. 150 151 -n, --nomount 152 Do not automatically attempt to mount any virtual file system 153 (such as tracefs or BPF virtual file system) when necessary. 154 155 -d, --debug 156 Print all logs available from libbpf, including debug-level 157 information. 158 159EXAMPLES 160======== 161**# bpftool map show** 162:: 163 164 10: hash name some_map flags 0x0 165 key 4B value 8B max_entries 2048 memlock 167936B 166 167The following three commands are equivalent: 168 169| 170| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c** 171| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c** 172| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76** 173 174**# bpftool map lookup id 10 key 0 1 2 3** 175 176:: 177 178 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 179 180 181**# bpftool map dump id 10** 182:: 183 184 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 185 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04 186 Found 2 elements 187 188**# bpftool map getnext id 10 key 0 1 2 3** 189:: 190 191 key: 192 00 01 02 03 193 next key: 194 0d 00 07 00 195 196| 197| **# mount -t bpf none /sys/fs/bpf/** 198| **# bpftool map pin id 10 /sys/fs/bpf/map** 199| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00** 200 201Note that map update can also be used in order to change the program references 202hold by a program array map. This can be used, for example, to change the 203programs used for tail-call jumps at runtime, without having to reload the 204entry-point program. Below is an example for this use case: we load a program 205defining a prog array map, and with a main function that contains a tail call 206to other programs that can be used either to "process" packets or to "debug" 207processing. Note that the prog array map MUST be pinned into the BPF virtual 208file system for the map update to work successfully, as kernel flushes prog 209array maps when they have no more references from user space (and the update 210would be lost as soon as bpftool exits). 211 212| 213| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp** 214| **# bpftool prog --bpffs** 215 216:: 217 218 545: xdp name main_func tag 674b4b5597193dc3 gpl 219 loaded_at 2018-12-12T15:02:58+0000 uid 0 220 xlated 240B jited 257B memlock 4096B map_ids 294 221 pinned /sys/fs/bpf/foo/xdp 222 546: xdp name bpf_func_process tag e369a529024751fc gpl 223 loaded_at 2018-12-12T15:02:58+0000 uid 0 224 xlated 200B jited 164B memlock 4096B 225 pinned /sys/fs/bpf/foo/process 226 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl 227 loaded_at 2018-12-12T15:02:58+0000 uid 0 228 xlated 200B jited 164B memlock 4096B 229 pinned /sys/fs/bpf/foo/debug 230 231**# bpftool map** 232 233:: 234 235 294: prog_array name jmp_table flags 0x0 236 key 4B value 4B max_entries 1 memlock 4096B 237 owner_prog_type xdp owner jited 238 239| 240| **# bpftool map pin id 294 /sys/fs/bpf/bar** 241| **# bpftool map dump pinned /sys/fs/bpf/bar** 242 243:: 244 245 Found 0 elements 246 247| 248| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug** 249| **# bpftool map dump pinned /sys/fs/bpf/bar** 250 251:: 252 253 key: 00 00 00 00 value: 22 02 00 00 254 Found 1 element 255 256SEE ALSO 257======== 258 **bpf**\ (2), 259 **bpf-helpers**\ (7), 260 **bpftool**\ (8), 261 **bpftool-prog**\ (8), 262 **bpftool-cgroup**\ (8), 263 **bpftool-feature**\ (8), 264 **bpftool-net**\ (8), 265 **bpftool-perf**\ (8), 266 **bpftool-btf**\ (8) 267