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diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst new file mode 100644 index 000000000..7f3b67a8b --- /dev/null +++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst @@ -0,0 +1,277 @@ +.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) + +================ +bpftool-map +================ +------------------------------------------------------------------------------- +tool for inspection and simple manipulation of eBPF maps +------------------------------------------------------------------------------- + +:Manual section: 8 + +.. include:: substitutions.rst + +SYNOPSIS +======== + + **bpftool** [*OPTIONS*] **map** *COMMAND* + + *OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } } + + *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*] [**inner_map** *MAP*] \ +| [**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 freeze** *MAP* +| **bpftool** **map help** +| +| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* } +| *DATA* := { [**hex**] *BYTES* } +| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* } +| *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** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash** +| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage** +| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage** +| | **task_storage** | **bloom_filter** | **user_ringbuf** } + +DESCRIPTION +=========== + **bpftool map { show | list }** [*MAP*] + Show information about loaded maps. If *MAP* is specified + show information only about given maps, otherwise list all + maps currently loaded on the system. In case of **name**, + *MAP* may match several maps which will all be shown. + + Output will start with map ID followed by map type and + zero or more named attributes (depending on kernel version). + + Since Linux 5.8 bpftool is able to discover information about + processes that hold open file descriptors (FDs) against BPF + maps. On such kernels bpftool will automatically emit this + information as well. + + **bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*] + Create a new map with given parameters and pin it to *bpffs* + as *FILE*. + + *FLAGS* should be an integer which is the combination of + desired flags, e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h + UAPI header for existing flags). + + To create maps of type array-of-maps or hash-of-maps, the + **inner_map** keyword must be used to pass an inner map. The + kernel needs it to collect metadata related to the inner maps + that the new map will work with. + + Keyword **dev** expects a network interface name, and is used + to request hardware offload for the map. + + **bpftool map dump** *MAP* + Dump all entries in a given *MAP*. In case of **name**, + *MAP* may match several maps which will all be dumped. + + **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 hexadecimal 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 freeze** *MAP* + Freeze the map as read-only from user space. Entries from a + frozen map can not longer be updated or deleted with the + **bpf**\ () system call. This operation is not reversible, + and the map remains immutable from user space until its + destruction. However, read and write permissions for BPF + programs to the map remain unchanged. + + **bpftool map help** + Print short help message. + +OPTIONS +======= + .. include:: common_options.rst + + -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 + pids systemd(1) + +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 |