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As it turns out, the terms in definition lists in the rST file are
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all double-star sequences we have in the commands for the command
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Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com>
Signed-off-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240331200346.29118-3-qmo@kernel.org
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272 lines
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ReStructuredText
.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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================
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bpftool-map
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================
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-------------------------------------------------------------------------------
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tool for inspection and simple manipulation of eBPF maps
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-------------------------------------------------------------------------------
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:Manual section: 8
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.. include:: substitutions.rst
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SYNOPSIS
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========
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**bpftool** [*OPTIONS*] **map** *COMMAND*
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*OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } }
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*COMMANDS* :=
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{ **show** | **list** | **create** | **dump** | **update** | **lookup** | **getnext** |
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**delete** | **pin** | **help** }
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MAP COMMANDS
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=============
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| **bpftool** **map** { **show** | **list** } [*MAP*]
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| **bpftool** **map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
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| **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] \
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| [**offload_dev** *NAME*]
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| **bpftool** **map dump** *MAP*
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| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
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| **bpftool** **map lookup** *MAP* [**key** *DATA*]
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| **bpftool** **map getnext** *MAP* [**key** *DATA*]
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| **bpftool** **map delete** *MAP* **key** *DATA*
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| **bpftool** **map pin** *MAP* *FILE*
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| **bpftool** **map event_pipe** *MAP* [**cpu** *N* **index** *M*]
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| **bpftool** **map peek** *MAP*
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| **bpftool** **map push** *MAP* **value** *VALUE*
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| **bpftool** **map pop** *MAP*
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| **bpftool** **map enqueue** *MAP* **value** *VALUE*
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| **bpftool** **map dequeue** *MAP*
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| **bpftool** **map freeze** *MAP*
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| **bpftool** **map help**
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| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* | **name** *MAP_NAME* }
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| *DATA* := { [**hex**] *BYTES* }
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| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
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| *VALUE* := { *DATA* | *MAP* | *PROG* }
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| *UPDATE_FLAGS* := { **any** | **exist** | **noexist** }
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| *TYPE* := { **hash** | **array** | **prog_array** | **perf_event_array** | **percpu_hash**
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| | **percpu_array** | **stack_trace** | **cgroup_array** | **lru_hash**
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| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
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| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
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| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage**
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| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage**
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| | **task_storage** | **bloom_filter** | **user_ringbuf** | **cgrp_storage** | **arena** }
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DESCRIPTION
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===========
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bpftool map { show | list } [*MAP*]
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Show information about loaded maps. If *MAP* is specified show information
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only about given maps, otherwise list all maps currently loaded on the
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system. In case of **name**, *MAP* may match several maps which will all
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be shown.
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Output will start with map ID followed by map type and zero or more named
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attributes (depending on kernel version).
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Since Linux 5.8 bpftool is able to discover information about processes
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that hold open file descriptors (FDs) against BPF maps. On such kernels
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bpftool will automatically emit this information as well.
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bpftool map create *FILE* type *TYPE* key *KEY_SIZE* value *VALUE_SIZE* entries *MAX_ENTRIES* name *NAME* [flags *FLAGS*] [inner_map *MAP*] [offload_dev *NAME*]
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Create a new map with given parameters and pin it to *bpffs* as *FILE*.
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*FLAGS* should be an integer which is the combination of desired flags,
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e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h UAPI header for existing
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flags).
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To create maps of type array-of-maps or hash-of-maps, the **inner_map**
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keyword must be used to pass an inner map. The kernel needs it to collect
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metadata related to the inner maps that the new map will work with.
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Keyword **offload_dev** expects a network interface name, and is used to
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request hardware offload for the map.
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bpftool map dump *MAP*
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Dump all entries in a given *MAP*. In case of **name**, *MAP* may match
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several maps which will all be dumped.
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bpftool map update *MAP* [key *DATA*] [value *VALUE*] [*UPDATE_FLAGS*]
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Update map entry for a given *KEY*.
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*UPDATE_FLAGS* can be one of: **any** update existing entry or add if
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doesn't exit; **exist** update only if entry already exists; **noexist**
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update only if entry doesn't exist.
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If the **hex** keyword is provided in front of the bytes sequence, the
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bytes are parsed as hexadecimal values, even if no "0x" prefix is added. If
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the keyword is not provided, then the bytes are parsed as decimal values,
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unless a "0x" prefix (for hexadecimal) or a "0" prefix (for octal) is
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provided.
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bpftool map lookup *MAP* [key *DATA*]
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Lookup **key** in the map.
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bpftool map getnext *MAP* [key *DATA*]
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Get next key. If *key* is not specified, get first key.
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bpftool map delete *MAP* key *DATA*
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Remove entry from the map.
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bpftool map pin *MAP* *FILE*
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Pin map *MAP* as *FILE*.
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Note: *FILE* must be located in *bpffs* mount. It must not contain a dot
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character ('.'), which is reserved for future extensions of *bpffs*.
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bpftool map event_pipe *MAP* [cpu *N* index *M*]
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Read events from a **BPF_MAP_TYPE_PERF_EVENT_ARRAY** map.
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Install perf rings into a perf event array map and dump output of any
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**bpf_perf_event_output**\ () call in the kernel. By default read the
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number of CPUs on the system and install perf ring for each CPU in the
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corresponding index in the array.
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If **cpu** and **index** are specified, install perf ring for given **cpu**
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at **index** in the array (single ring).
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Note that installing a perf ring into an array will silently replace any
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existing ring. Any other application will stop receiving events if it
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installed its rings earlier.
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bpftool map peek *MAP*
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Peek next value in the queue or stack.
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bpftool map push *MAP* value *VALUE*
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Push *VALUE* onto the stack.
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bpftool map pop *MAP*
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Pop and print value from the stack.
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bpftool map enqueue *MAP* value *VALUE*
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Enqueue *VALUE* into the queue.
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bpftool map dequeue *MAP*
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Dequeue and print value from the queue.
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bpftool map freeze *MAP*
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Freeze the map as read-only from user space. Entries from a frozen map can
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not longer be updated or deleted with the **bpf**\ () system call. This
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operation is not reversible, and the map remains immutable from user space
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until its destruction. However, read and write permissions for BPF programs
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to the map remain unchanged.
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bpftool map help
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Print short help message.
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OPTIONS
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=======
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.. include:: common_options.rst
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-f, --bpffs
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Show file names of pinned maps.
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-n, --nomount
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Do not automatically attempt to mount any virtual file system (such as
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tracefs or BPF virtual file system) when necessary.
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EXAMPLES
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========
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**# bpftool map show**
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::
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10: hash name some_map flags 0x0
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key 4B value 8B max_entries 2048 memlock 167936B
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pids systemd(1)
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The following three commands are equivalent:
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| **# bpftool map update id 10 key hex 20 c4 b7 00 value hex 0f ff ff ab 01 02 03 4c**
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| **# bpftool map update id 10 key 0x20 0xc4 0xb7 0x00 value 0x0f 0xff 0xff 0xab 0x01 0x02 0x03 0x4c**
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| **# bpftool map update id 10 key 32 196 183 0 value 15 255 255 171 1 2 3 76**
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**# bpftool map lookup id 10 key 0 1 2 3**
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::
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key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
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**# bpftool map dump id 10**
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::
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key: 00 01 02 03 value: 00 01 02 03 04 05 06 07
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key: 0d 00 07 00 value: 02 00 00 00 01 02 03 04
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Found 2 elements
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**# bpftool map getnext id 10 key 0 1 2 3**
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::
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key:
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00 01 02 03
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next key:
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0d 00 07 00
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| **# mount -t bpf none /sys/fs/bpf/**
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| **# bpftool map pin id 10 /sys/fs/bpf/map**
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| **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
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Note that map update can also be used in order to change the program references
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hold by a program array map. This can be used, for example, to change the
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programs used for tail-call jumps at runtime, without having to reload the
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entry-point program. Below is an example for this use case: we load a program
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defining a prog array map, and with a main function that contains a tail call
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to other programs that can be used either to "process" packets or to "debug"
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processing. Note that the prog array map MUST be pinned into the BPF virtual
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file system for the map update to work successfully, as kernel flushes prog
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array maps when they have no more references from user space (and the update
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would be lost as soon as bpftool exits).
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| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
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| **# bpftool prog --bpffs**
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::
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545: xdp name main_func tag 674b4b5597193dc3 gpl
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loaded_at 2018-12-12T15:02:58+0000 uid 0
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xlated 240B jited 257B memlock 4096B map_ids 294
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pinned /sys/fs/bpf/foo/xdp
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546: xdp name bpf_func_process tag e369a529024751fc gpl
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loaded_at 2018-12-12T15:02:58+0000 uid 0
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xlated 200B jited 164B memlock 4096B
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pinned /sys/fs/bpf/foo/process
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547: xdp name bpf_func_debug tag 0b597868bc7f0976 gpl
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loaded_at 2018-12-12T15:02:58+0000 uid 0
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xlated 200B jited 164B memlock 4096B
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pinned /sys/fs/bpf/foo/debug
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**# bpftool map**
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::
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294: prog_array name jmp_table flags 0x0
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key 4B value 4B max_entries 1 memlock 4096B
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owner_prog_type xdp owner jited
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| **# bpftool map pin id 294 /sys/fs/bpf/bar**
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| **# bpftool map dump pinned /sys/fs/bpf/bar**
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::
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Found 0 elements
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| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
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| **# bpftool map dump pinned /sys/fs/bpf/bar**
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::
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key: 00 00 00 00 value: 22 02 00 00
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Found 1 element
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