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 155EXAMPLES 156======== 157**# bpftool map show** 158:: 159 160 10: hash name some_map flags 0x0 161 key 4B value 8B max_entries 2048 memlock 167936B 162 163The following three commands are equivalent: 164 165| 166| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c** 167| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c** 168| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76** 169 170**# bpftool map lookup id 10 key 0 1 2 3** 171 172:: 173 174 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 175 176 177**# bpftool map dump id 10** 178:: 179 180 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 181 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04 182 Found 2 elements 183 184**# bpftool map getnext id 10 key 0 1 2 3** 185:: 186 187 key: 188 00 01 02 03 189 next key: 190 0d 00 07 00 191 192| 193| **# mount -t bpf none /sys/fs/bpf/** 194| **# bpftool map pin id 10 /sys/fs/bpf/map** 195| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00** 196 197Note that map update can also be used in order to change the program references 198hold by a program array map. This can be used, for example, to change the 199programs used for tail-call jumps at runtime, without having to reload the 200entry-point program. Below is an example for this use case: we load a program 201defining a prog array map, and with a main function that contains a tail call 202to other programs that can be used either to "process" packets or to "debug" 203processing. Note that the prog array map MUST be pinned into the BPF virtual 204file system for the map update to work successfully, as kernel flushes prog 205array maps when they have no more references from user space (and the update 206would be lost as soon as bpftool exits). 207 208| 209| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp** 210| **# bpftool prog --bpffs** 211 212:: 213 214 545: xdp name main_func tag 674b4b5597193dc3 gpl 215 loaded_at 2018-12-12T15:02:58+0000 uid 0 216 xlated 240B jited 257B memlock 4096B map_ids 294 217 pinned /sys/fs/bpf/foo/xdp 218 546: xdp name bpf_func_process tag e369a529024751fc gpl 219 loaded_at 2018-12-12T15:02:58+0000 uid 0 220 xlated 200B jited 164B memlock 4096B 221 pinned /sys/fs/bpf/foo/process 222 547: xdp name bpf_func_debug tag 0b597868bc7f0976 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/debug 226 227**# bpftool map** 228 229:: 230 231 294: prog_array name jmp_table flags 0x0 232 key 4B value 4B max_entries 1 memlock 4096B 233 owner_prog_type xdp owner jited 234 235| 236| **# bpftool map pin id 294 /sys/fs/bpf/bar** 237| **# bpftool map dump pinned /sys/fs/bpf/bar** 238 239:: 240 241 Found 0 elements 242 243| 244| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug** 245| **# bpftool map dump pinned /sys/fs/bpf/bar** 246 247:: 248 249 key: 00 00 00 00 value: 22 02 00 00 250 Found 1 element 251 252SEE ALSO 253======== 254 **bpf**\ (2), 255 **bpf-helpers**\ (7), 256 **bpftool**\ (8), 257 **bpftool-prog**\ (8), 258 **bpftool-cgroup**\ (8), 259 **bpftool-feature**\ (8), 260 **bpftool-net**\ (8), 261 **bpftool-perf**\ (8) 262