bpftool-map

BPFTOOL-MAP(8)                                                  BPFTOOL-MAP(8)



NAME
       bpftool-map - tool for inspection and simple manipulation of eBPF maps

SYNOPSIS
          bpftool [OPTIONS] map COMMAND

          OPTIONS := { { -j | --json } [{ -p | --pretty }] | { -f | --bpffs }
          }

          COMMANDS := { show | list | create | dump | update | lookup |
          getnext | delete | pin | help }

MAP COMMANDS
       bpftool map { show | list }   [MAP]
       bpftool map create     FILE type TYPE key KEY_SIZE value VALUE_SIZE
         entries MAX_ENTRIES name NAME [flags FLAGS] [dev NAME]
       bpftool map dump       MAP
       bpftool map update     MAP [key DATA] [value VALUE] [UPDATE_FLAGS]
       bpftool map lookup     MAP [key DATA]
       bpftool map getnext    MAP [key DATA]
       bpftool map delete     MAP  key DATA
       bpftool map pin        MAP  FILE
       bpftool map event_pipe MAP [cpu N index M]
       bpftool map peek       MAP
       bpftool map push       MAP value VALUE
       bpftool map pop        MAP
       bpftool map enqueue    MAP value VALUE
       bpftool map dequeue    MAP
       bpftool map help

       MAP := { id MAP_ID | pinned FILE }
       DATA := { [hex] BYTES }
       PROG := { id PROG_ID | pinned FILE | tag PROG_TAG }
       VALUE := { DATA | MAP | PROG }
       UPDATE_FLAGS := { any | exist | noexist }
       TYPE := { hash | array | prog_array | perf_event_array | percpu_hash
         | percpu_array | stack_trace | cgroup_array | lru_hash
         | lru_percpu_hash | lpm_trie | array_of_maps | hash_of_maps
         | devmap | sockmap | cpumap | xskmap | sockhash
         | cgroup_storage | reuseport_sockarray | percpu_cgroup_storage
         | queue | stack }


DESCRIPTION
          bpftool map { show | list } [MAP]
                 Show information about loaded maps.  If MAP is specified show
                 information only about given map, otherwise list all maps
                 currently loaded on the system.

                 Output will start with map ID followed by map type and zero
                 or more named attributes (depending on kernel version).

          bpftool map create FILE type TYPE key KEY_SIZE value VALUE_SIZE
          entries MAX_ENTRIES name NAME [flags FLAGS] [dev NAME]
                 Create a new map with given parameters and pin it to bpffs as
                 FILE.

          bpftool map dump MAP
                 Dump all entries in a given MAP.

          bpftool map update MAP [key DATA] [value VALUE] [UPDATE_FLAGS]
                 Update map entry for a given KEY.

                 UPDATE_FLAGS can be one of: any update existing entry or add
                 if doesn't exit; exist update only if entry already exists;
                 noexist update only if entry doesn't exist.

                 If the hex keyword is provided in front of the bytes
                 sequence, the bytes are parsed as hexadeximal values, even if
                 no "0x" prefix is added. If the keyword is not provided, then
                 the bytes are parsed as decimal values, unless a "0x" prefix
                 (for hexadecimal) or a "0" prefix (for octal) is provided.

          bpftool map lookup MAP [key DATA]
                 Lookup key in the map.

          bpftool map getnext MAP [key DATA]
                 Get next key.  If key is not specified, get first key.

          bpftool map delete MAP key DATA
                 Remove entry from the map.

          bpftool map pin MAP FILE
                 Pin map MAP as FILE.

                 Note: FILE must be located in bpffs mount. It must not
                 contain a dot character ('.'), which is reserved for future
                 extensions of bpffs.

          bpftool map event_pipe MAP [cpu N index M]
                 Read events from a BPF_MAP_TYPE_PERF_EVENT_ARRAY map.

                 Install perf rings into a perf event array map and dump
                 output of any bpf_perf_event_output() call in the kernel.  By
                 default read the number of CPUs on the system and install
                 perf ring for each CPU in the corresponding index in the
                 array.

                 If cpu and index are specified, install perf ring for given
                 cpu at index in the array (single ring).

                 Note that installing a perf ring into an array will silently
                 replace any existing ring.  Any other application will stop
                 receiving events if it installed its rings earlier.

          bpftool map peek MAP
                 Peek next value in the queue or stack.

          bpftool map push MAP value VALUE
                 Push value onto the stack.

          bpftool map pop MAP
                 Pop and print value from the stack.

          bpftool map enqueue MAP value VALUE
                 Enqueue value into the queue.

          bpftool map dequeue MAP
                 Dequeue and print value from the queue.

          bpftool map help
                 Print short help message.

OPTIONS
          -h, --help
                 Print short generic help message (similar to bpftool help).

          -V, --version
                 Print version number (similar to bpftool version).

          -j, --json
                 Generate JSON output. For commands that cannot produce JSON,
                 this option has no effect.

          -p, --pretty
                 Generate human-readable JSON output. Implies -j.

          -f, --bpffs
                 Show file names of pinned maps.

          -n, --nomount
                 Do not automatically attempt to mount any virtual file system
                 (such as tracefs or BPF virtual file system) when necessary.

EXAMPLES
       # bpftool map show

          10: hash  name some_map  flags 0x0
                key 4B  value 8B  max_entries 2048  memlock 167936B

       The following three commands are equivalent:

       # bpftool map update id 10 key hex   20   c4   b7   00 value hex   0f   ff   ff   ab   01   02   03   4c
       # bpftool map update id 10 key     0x20 0xc4 0xb7 0x00 value     0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c
       # bpftool map update id 10 key       32  196  183    0 value       15  255  255  171    1    2    3   76


       # bpftool map lookup id 10 key 0 1 2 3

          key: 00 01 02 03 value: 00 01 02 03 04 05 06 07

       # bpftool map dump id 10

          key: 00 01 02 03  value: 00 01 02 03 04 05 06 07
          key: 0d 00 07 00  value: 02 00 00 00 01 02 03 04
          Found 2 elements

       # bpftool map getnext id 10 key 0 1 2 3

          key:
          00 01 02 03
          next key:
          0d 00 07 00

       # mount -t bpf none /sys/fs/bpf/
       # bpftool map pin id 10 /sys/fs/bpf/map
       # bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00


       Note that map update can also be used in order to change the program
       references hold by a program array map. This can be used, for example,
       to change the programs used for tail-call jumps at runtime, without
       having to reload the entry-point program. Below is an example for this
       use case: we load a program defining a prog array map, and with a main
       function that contains a tail call to other programs that can be used
       either to "process" packets or to "debug" processing. Note that the
       prog array map MUST be pinned into the BPF virtual file system for the
       map update to work successfully, as kernel flushes prog array maps when
       they have no more references from user space (and the update would be
       lost as soon as bpftool exits).

       # bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp
       # bpftool prog --bpffs


          545: xdp  name main_func  tag 674b4b5597193dc3  gpl
                  loaded_at 2018-12-12T15:02:58+0000  uid 0
                  xlated 240B  jited 257B  memlock 4096B  map_ids 294
                  pinned /sys/fs/bpf/foo/xdp
          546: xdp  name bpf_func_process  tag e369a529024751fc  gpl
                  loaded_at 2018-12-12T15:02:58+0000  uid 0
                  xlated 200B  jited 164B  memlock 4096B
                  pinned /sys/fs/bpf/foo/process
          547: xdp  name bpf_func_debug  tag 0b597868bc7f0976  gpl
                  loaded_at 2018-12-12T15:02:58+0000  uid 0
                  xlated 200B  jited 164B  memlock 4096B
                  pinned /sys/fs/bpf/foo/debug

       # bpftool map

          294: prog_array  name jmp_table  flags 0x0
                  key 4B  value 4B  max_entries 1  memlock 4096B
                  owner_prog_type xdp  owner jited

       # bpftool map pin id 294 /sys/fs/bpf/bar
       # bpftool map dump pinned /sys/fs/bpf/bar


          Found 0 elements

       # bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug
       # bpftool map dump pinned /sys/fs/bpf/bar


          key: 00 00 00 00  value: 22 02 00 00
          Found 1 element

SEE ALSO
          bpf(2), bpf-helpers(7), bpftool(8), bpftool-prog(8),
          bpftool-cgroup(8), bpftool-feature(8), bpftool-net(8),
          bpftool-perf(8), bpftool-btf(8)



                                                                BPFTOOL-MAP(8)