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 help** 35| 36| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* } 37| *DATA* := { [**hex**] *BYTES* } 38| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* } 39| *VALUE* := { *DATA* | *MAP* | *PROG* } 40| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** } 41| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash** 42| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash** 43| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps** 44| | **devmap** | **sockmap** | **cpumap** | **xskmap** | **sockhash** 45| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** 46| | **queue** | **stack** } 47 48DESCRIPTION 49=========== 50 **bpftool map { show | list }** [*MAP*] 51 Show information about loaded maps. If *MAP* is specified 52 show information only about given map, otherwise list all 53 maps currently loaded on the system. 54 55 Output will start with map ID followed by map type and 56 zero or more named attributes (depending on kernel version). 57 58 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*] 59 Create a new map with given parameters and pin it to *bpffs* 60 as *FILE*. 61 62 **bpftool map dump** *MAP* 63 Dump all entries in a given *MAP*. 64 65 **bpftool map update** *MAP* **key** *DATA* **value** *VALUE* [*UPDATE_FLAGS*] 66 Update map entry for a given *KEY*. 67 68 *UPDATE_FLAGS* can be one of: **any** update existing entry 69 or add if doesn't exit; **exist** update only if entry already 70 exists; **noexist** update only if entry doesn't exist. 71 72 If the **hex** keyword is provided in front of the bytes 73 sequence, the bytes are parsed as hexadeximal values, even if 74 no "0x" prefix is added. If the keyword is not provided, then 75 the bytes are parsed as decimal values, unless a "0x" prefix 76 (for hexadecimal) or a "0" prefix (for octal) is provided. 77 78 **bpftool map lookup** *MAP* **key** *DATA* 79 Lookup **key** in the map. 80 81 **bpftool map getnext** *MAP* [**key** *DATA*] 82 Get next key. If *key* is not specified, get first key. 83 84 **bpftool map delete** *MAP* **key** *DATA* 85 Remove entry from the map. 86 87 **bpftool map pin** *MAP* *FILE* 88 Pin map *MAP* as *FILE*. 89 90 Note: *FILE* must be located in *bpffs* mount. It must not 91 contain a dot character ('.'), which is reserved for future 92 extensions of *bpffs*. 93 94 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 95 Read events from a BPF_MAP_TYPE_PERF_EVENT_ARRAY map. 96 97 Install perf rings into a perf event array map and dump 98 output of any bpf_perf_event_output() call in the kernel. 99 By default read the number of CPUs on the system and 100 install perf ring for each CPU in the corresponding index 101 in the array. 102 103 If **cpu** and **index** are specified, install perf ring 104 for given **cpu** at **index** in the array (single ring). 105 106 Note that installing a perf ring into an array will silently 107 replace any existing ring. Any other application will stop 108 receiving events if it installed its rings earlier. 109 110 **bpftool map help** 111 Print short help message. 112 113OPTIONS 114======= 115 -h, --help 116 Print short generic help message (similar to **bpftool help**). 117 118 -v, --version 119 Print version number (similar to **bpftool version**). 120 121 -j, --json 122 Generate JSON output. For commands that cannot produce JSON, this 123 option has no effect. 124 125 -p, --pretty 126 Generate human-readable JSON output. Implies **-j**. 127 128 -f, --bpffs 129 Show file names of pinned maps. 130 131 -n, --nomount 132 Do not automatically attempt to mount any virtual file system 133 (such as tracefs or BPF virtual file system) when necessary. 134 135EXAMPLES 136======== 137**# bpftool map show** 138:: 139 140 10: hash name some_map flags 0x0 141 key 4B value 8B max_entries 2048 memlock 167936B 142 143The following three commands are equivalent: 144 145| 146| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c** 147| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c** 148| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76** 149 150**# bpftool map lookup id 10 key 0 1 2 3** 151 152:: 153 154 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 155 156 157**# bpftool map dump id 10** 158:: 159 160 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 161 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04 162 Found 2 elements 163 164**# bpftool map getnext id 10 key 0 1 2 3** 165:: 166 167 key: 168 00 01 02 03 169 next key: 170 0d 00 07 00 171 172| 173| **# mount -t bpf none /sys/fs/bpf/** 174| **# bpftool map pin id 10 /sys/fs/bpf/map** 175| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00** 176 177Note that map update can also be used in order to change the program references 178hold by a program array map. This can be used, for example, to change the 179programs used for tail-call jumps at runtime, without having to reload the 180entry-point program. Below is an example for this use case: we load a program 181defining a prog array map, and with a main function that contains a tail call 182to other programs that can be used either to "process" packets or to "debug" 183processing. Note that the prog array map MUST be pinned into the BPF virtual 184file system for the map update to work successfully, as kernel flushes prog 185array maps when they have no more references from user space (and the update 186would be lost as soon as bpftool exits). 187 188| 189| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp** 190| **# bpftool prog --bpffs** 191 192:: 193 194 545: xdp name main_func tag 674b4b5597193dc3 gpl 195 loaded_at 2018-12-12T15:02:58+0000 uid 0 196 xlated 240B jited 257B memlock 4096B map_ids 294 197 pinned /sys/fs/bpf/foo/xdp 198 546: xdp name bpf_func_process tag e369a529024751fc gpl 199 loaded_at 2018-12-12T15:02:58+0000 uid 0 200 xlated 200B jited 164B memlock 4096B 201 pinned /sys/fs/bpf/foo/process 202 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl 203 loaded_at 2018-12-12T15:02:58+0000 uid 0 204 xlated 200B jited 164B memlock 4096B 205 pinned /sys/fs/bpf/foo/debug 206 207**# bpftool map** 208 209:: 210 211 294: prog_array name jmp_table flags 0x0 212 key 4B value 4B max_entries 1 memlock 4096B 213 owner_prog_type xdp owner jited 214 215| 216| **# bpftool map pin id 294 /sys/fs/bpf/bar** 217| **# bpftool map dump pinned /sys/fs/bpf/bar** 218 219:: 220 221 Found 0 elements 222 223| 224| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug** 225| **# bpftool map dump pinned /sys/fs/bpf/bar** 226 227:: 228 229 key: 00 00 00 00 value: 22 02 00 00 230 Found 1 element 231 232SEE ALSO 233======== 234 **bpf**\ (2), 235 **bpf-helpers**\ (7), 236 **bpftool**\ (8), 237 **bpftool-prog**\ (8), 238 **bpftool-cgroup**\ (8), 239 **bpftool-net**\ (8), 240 **bpftool-perf**\ (8) 241