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*] [**inner_map** *MAP*] \ 27| [**dev** *NAME*] 28| **bpftool** **map dump** *MAP* 29| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*] 30| **bpftool** **map lookup** *MAP* [**key** *DATA*] 31| **bpftool** **map getnext** *MAP* [**key** *DATA*] 32| **bpftool** **map delete** *MAP* **key** *DATA* 33| **bpftool** **map pin** *MAP* *FILE* 34| **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 35| **bpftool** **map peek** *MAP* 36| **bpftool** **map push** *MAP* **value** *VALUE* 37| **bpftool** **map pop** *MAP* 38| **bpftool** **map enqueue** *MAP* **value** *VALUE* 39| **bpftool** **map dequeue** *MAP* 40| **bpftool** **map freeze** *MAP* 41| **bpftool** **map help** 42| 43| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* } 44| *DATA* := { [**hex**] *BYTES* } 45| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* } 46| *VALUE* := { *DATA* | *MAP* | *PROG* } 47| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** } 48| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash** 49| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash** 50| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps** 51| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash** 52| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** 53| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage** } 54 55DESCRIPTION 56=========== 57 **bpftool map { show | list }** [*MAP*] 58 Show information about loaded maps. If *MAP* is specified 59 show information only about given maps, otherwise list all 60 maps currently loaded on the system. In case of **name**, 61 *MAP* may match several maps which will all be shown. 62 63 Output will start with map ID followed by map type and 64 zero or more named attributes (depending on kernel version). 65 66 Since Linux 5.8 bpftool is able to discover information about 67 processes that hold open file descriptors (FDs) against BPF 68 maps. On such kernels bpftool will automatically emit this 69 information as well. 70 71 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*] 72 Create a new map with given parameters and pin it to *bpffs* 73 as *FILE*. 74 75 *FLAGS* should be an integer which is the combination of 76 desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h 77 UAPI header for existing flags). 78 79 To create maps of type array-of-maps or hash-of-maps, the 80 **inner_map** keyword must be used to pass an inner map. The 81 kernel needs it to collect metadata related to the inner maps 82 that the new map will work with. 83 84 Keyword **dev** expects a network interface name, and is used 85 to request hardware offload for the map. 86 87 **bpftool map dump** *MAP* 88 Dump all entries in a given *MAP*. In case of **name**, 89 *MAP* may match several maps which will all be dumped. 90 91 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*] 92 Update map entry for a given *KEY*. 93 94 *UPDATE_FLAGS* can be one of: **any** update existing entry 95 or add if doesn't exit; **exist** update only if entry already 96 exists; **noexist** update only if entry doesn't exist. 97 98 If the **hex** keyword is provided in front of the bytes 99 sequence, the bytes are parsed as hexadecimal values, even if 100 no "0x" prefix is added. If the keyword is not provided, then 101 the bytes are parsed as decimal values, unless a "0x" prefix 102 (for hexadecimal) or a "0" prefix (for octal) is provided. 103 104 **bpftool map lookup** *MAP* [**key** *DATA*] 105 Lookup **key** in the map. 106 107 **bpftool map getnext** *MAP* [**key** *DATA*] 108 Get next key. If *key* is not specified, get first key. 109 110 **bpftool map delete** *MAP* **key** *DATA* 111 Remove entry from the map. 112 113 **bpftool map pin** *MAP* *FILE* 114 Pin map *MAP* as *FILE*. 115 116 Note: *FILE* must be located in *bpffs* mount. It must not 117 contain a dot character ('.'), which is reserved for future 118 extensions of *bpffs*. 119 120 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 121 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map. 122 123 Install perf rings into a perf event array map and dump 124 output of any **bpf_perf_event_output**\ () call in the kernel. 125 By default read the number of CPUs on the system and 126 install perf ring for each CPU in the corresponding index 127 in the array. 128 129 If **cpu** and **index** are specified, install perf ring 130 for given **cpu** at **index** in the array (single ring). 131 132 Note that installing a perf ring into an array will silently 133 replace any existing ring. Any other application will stop 134 receiving events if it installed its rings earlier. 135 136 **bpftool map peek** *MAP* 137 Peek next value in the queue or stack. 138 139 **bpftool map push** *MAP* **value** *VALUE* 140 Push *VALUE* onto the stack. 141 142 **bpftool map pop** *MAP* 143 Pop and print value from the stack. 144 145 **bpftool map enqueue** *MAP* **value** *VALUE* 146 Enqueue *VALUE* into the queue. 147 148 **bpftool map dequeue** *MAP* 149 Dequeue and print value from the queue. 150 151 **bpftool map freeze** *MAP* 152 Freeze the map as read-only from user space. Entries from a 153 frozen map can not longer be updated or deleted with the 154 **bpf**\ () system call. This operation is not reversible, 155 and the map remains immutable from user space until its 156 destruction. However, read and write permissions for BPF 157 programs to the map remain unchanged. 158 159 **bpftool 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 171 (such as 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