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SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 3================ 4bpftool-map 5================ 6------------------------------------------------------------------------------- 7tool for inspection and simple manipulation of eBPF maps 8------------------------------------------------------------------------------- 9 10:Manual section: 8 11 12.. include:: substitutions.rst 13 14SYNOPSIS 15======== 16 17 **bpftool** [*OPTIONS*] **map** *COMMAND* 18 19 *OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } } 20 21 *COMMANDS* := 22 { **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext** | 23 **delete** | **pin** | **help** } 24 25MAP COMMANDS 26============= 27 28| **bpftool** **map** { **show** | **list** } [*MAP*] 29| **bpftool** **map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \ 30| **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] \ 31| [**dev** *NAME*] 32| **bpftool** **map dump** *MAP* 33| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*] 34| **bpftool** **map lookup** *MAP* [**key** *DATA*] 35| **bpftool** **map getnext** *MAP* [**key** *DATA*] 36| **bpftool** **map delete** *MAP* **key** *DATA* 37| **bpftool** **map pin** *MAP* *FILE* 38| **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 39| **bpftool** **map peek** *MAP* 40| **bpftool** **map push** *MAP* **value** *VALUE* 41| **bpftool** **map pop** *MAP* 42| **bpftool** **map enqueue** *MAP* **value** *VALUE* 43| **bpftool** **map dequeue** *MAP* 44| **bpftool** **map freeze** *MAP* 45| **bpftool** **map help** 46| 47| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* } 48| *DATA* := { [**hex**] *BYTES* } 49| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* } 50| *VALUE* := { *DATA* | *MAP* | *PROG* } 51| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** } 52| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash** 53| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash** 54| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps** 55| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash** 56| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** 57| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage** 58| | **task_storage** | **bloom_filter** } 59 60DESCRIPTION 61=========== 62 **bpftool map { show | list }** [*MAP*] 63 Show information about loaded maps. If *MAP* is specified 64 show information only about given maps, otherwise list all 65 maps currently loaded on the system. In case of **name**, 66 *MAP* may match several maps which will all be shown. 67 68 Output will start with map ID followed by map type and 69 zero or more named attributes (depending on kernel version). 70 71 Since Linux 5.8 bpftool is able to discover information about 72 processes that hold open file descriptors (FDs) against BPF 73 maps. On such kernels bpftool will automatically emit this 74 information as well. 75 76 **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*] 77 Create a new map with given parameters and pin it to *bpffs* 78 as *FILE*. 79 80 *FLAGS* should be an integer which is the combination of 81 desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h 82 UAPI header for existing flags). 83 84 To create maps of type array-of-maps or hash-of-maps, the 85 **inner_map** keyword must be used to pass an inner map. The 86 kernel needs it to collect metadata related to the inner maps 87 that the new map will work with. 88 89 Keyword **dev** expects a network interface name, and is used 90 to request hardware offload for the map. 91 92 **bpftool map dump** *MAP* 93 Dump all entries in a given *MAP*. In case of **name**, 94 *MAP* may match several maps which will all be dumped. 95 96 **bpftool map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*] 97 Update map entry for a given *KEY*. 98 99 *UPDATE_FLAGS* can be one of: **any** update existing entry 100 or add if doesn't exit; **exist** update only if entry already 101 exists; **noexist** update only if entry doesn't exist. 102 103 If the **hex** keyword is provided in front of the bytes 104 sequence, the bytes are parsed as hexadecimal values, even if 105 no "0x" prefix is added. If the keyword is not provided, then 106 the bytes are parsed as decimal values, unless a "0x" prefix 107 (for hexadecimal) or a "0" prefix (for octal) is provided. 108 109 **bpftool map lookup** *MAP* [**key** *DATA*] 110 Lookup **key** in the map. 111 112 **bpftool map getnext** *MAP* [**key** *DATA*] 113 Get next key. If *key* is not specified, get first key. 114 115 **bpftool map delete** *MAP* **key** *DATA* 116 Remove entry from the map. 117 118 **bpftool map pin** *MAP* *FILE* 119 Pin map *MAP* as *FILE*. 120 121 Note: *FILE* must be located in *bpffs* mount. It must not 122 contain a dot character ('.'), which is reserved for future 123 extensions of *bpffs*. 124 125 **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*] 126 Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map. 127 128 Install perf rings into a perf event array map and dump 129 output of any **bpf_perf_event_output**\ () call in the kernel. 130 By default read the number of CPUs on the system and 131 install perf ring for each CPU in the corresponding index 132 in the array. 133 134 If **cpu** and **index** are specified, install perf ring 135 for given **cpu** at **index** in the array (single ring). 136 137 Note that installing a perf ring into an array will silently 138 replace any existing ring. Any other application will stop 139 receiving events if it installed its rings earlier. 140 141 **bpftool map peek** *MAP* 142 Peek next value in the queue or stack. 143 144 **bpftool map push** *MAP* **value** *VALUE* 145 Push *VALUE* onto the stack. 146 147 **bpftool map pop** *MAP* 148 Pop and print value from the stack. 149 150 **bpftool map enqueue** *MAP* **value** *VALUE* 151 Enqueue *VALUE* into the queue. 152 153 **bpftool map dequeue** *MAP* 154 Dequeue and print value from the queue. 155 156 **bpftool map freeze** *MAP* 157 Freeze the map as read-only from user space. Entries from a 158 frozen map can not longer be updated or deleted with the 159 **bpf**\ () system call. This operation is not reversible, 160 and the map remains immutable from user space until its 161 destruction. However, read and write permissions for BPF 162 programs to the map remain unchanged. 163 164 **bpftool map help** 165 Print short help message. 166 167OPTIONS 168======= 169 .. include:: common_options.rst 170 171 -f, --bpffs 172 Show file names of pinned maps. 173 174 -n, --nomount 175 Do not automatically attempt to mount any virtual file system 176 (such as tracefs or BPF virtual file system) when necessary. 177 178EXAMPLES 179======== 180**# bpftool map show** 181 182:: 183 184 10: hash name some_map flags 0x0 185 key 4B value 8B max_entries 2048 memlock 167936B 186 pids systemd(1) 187 188The following three commands are equivalent: 189 190| 191| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c** 192| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c** 193| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76** 194 195**# bpftool map lookup id 10 key 0 1 2 3** 196 197:: 198 199 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 200 201 202**# bpftool map dump id 10** 203 204:: 205 206 key: 00 01 02 03 value: 00 01 02 03 04 05 06 07 207 key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04 208 Found 2 elements 209 210**# bpftool map getnext id 10 key 0 1 2 3** 211 212:: 213 214 key: 215 00 01 02 03 216 next key: 217 0d 00 07 00 218 219| 220| **# mount -t bpf none /sys/fs/bpf/** 221| **# bpftool map pin id 10 /sys/fs/bpf/map** 222| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00** 223 224Note that map update can also be used in order to change the program references 225hold by a program array map. This can be used, for example, to change the 226programs used for tail-call jumps at runtime, without having to reload the 227entry-point program. Below is an example for this use case: we load a program 228defining a prog array map, and with a main function that contains a tail call 229to other programs that can be used either to "process" packets or to "debug" 230processing. Note that the prog array map MUST be pinned into the BPF virtual 231file system for the map update to work successfully, as kernel flushes prog 232array maps when they have no more references from user space (and the update 233would be lost as soon as bpftool exits). 234 235| 236| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp** 237| **# bpftool prog --bpffs** 238 239:: 240 241 545: xdp name main_func tag 674b4b5597193dc3 gpl 242 loaded_at 2018-12-12T15:02:58+0000 uid 0 243 xlated 240B jited 257B memlock 4096B map_ids 294 244 pinned /sys/fs/bpf/foo/xdp 245 546: xdp name bpf_func_process tag e369a529024751fc gpl 246 loaded_at 2018-12-12T15:02:58+0000 uid 0 247 xlated 200B jited 164B memlock 4096B 248 pinned /sys/fs/bpf/foo/process 249 547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl 250 loaded_at 2018-12-12T15:02:58+0000 uid 0 251 xlated 200B jited 164B memlock 4096B 252 pinned /sys/fs/bpf/foo/debug 253 254**# bpftool map** 255 256:: 257 258 294: prog_array name jmp_table flags 0x0 259 key 4B value 4B max_entries 1 memlock 4096B 260 owner_prog_type xdp owner jited 261 262| 263| **# bpftool map pin id 294 /sys/fs/bpf/bar** 264| **# bpftool map dump pinned /sys/fs/bpf/bar** 265 266:: 267 268 Found 0 elements 269 270| 271| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug** 272| **# bpftool map dump pinned /sys/fs/bpf/bar** 273 274:: 275 276 key: 00 00 00 00 value: 22 02 00 00 277 Found 1 element 278