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) 276
