leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
4b45a0cd39
linux/tools/bpf/bpftool/Documentation/bpftool-struct_ops.rst

117 lines
3.1 KiB
ReStructuredText
Raw Normal View History

bpftool: Add struct_ops support This patch adds struct_ops support to the bpftool. To recap a bit on the recent bpf_struct_ops feature on the kernel side: It currently supports "struct tcp_congestion_ops" to be implemented in bpf. At a high level, bpf_struct_ops is struct_ops map populated with a number of bpf progs. bpf_struct_ops currently supports the "struct tcp_congestion_ops". However, the bpf_struct_ops design is generic enough that other kernel struct ops can be supported in the future. Although struct_ops is map+progs at a high lever, there are differences in details. For example, 1) After registering a struct_ops, the struct_ops is held by the kernel subsystem (e.g. tcp-cc). Thus, there is no need to pin a struct_ops map or its progs in order to keep them around. 2) To iterate all struct_ops in a system, it iterates all maps in type BPF_MAP_TYPE_STRUCT_OPS. BPF_MAP_TYPE_STRUCT_OPS is the current usual filter. In the future, it may need to filter by other struct_ops specific properties. e.g. filter by tcp_congestion_ops or other kernel subsystem ops in the future. 3) struct_ops requires the running kernel having BTF info. That allows more flexibility in handling other kernel structs. e.g. it can always dump the latest bpf_map_info. 4) Also, "struct_ops" command is not intended to repeat all features already provided by "map" or "prog". For example, if there really is a need to pin the struct_ops map, the user can use the "map" cmd to do that. While the first attempt was to reuse parts from map/prog.c, it ended up not a lot to share. The only obvious item is the map_parse_fds() but that still requires modifications to accommodate struct_ops map specific filtering (for the immediate and the future needs). Together with the earlier mentioned differences, it is better to part away from map/prog.c. The initial set of subcmds are, register, unregister, show, and dump. For register, it registers all struct_ops maps that can be found in an obj file. Option can be added in the future to specify a particular struct_ops map. Also, the common bpf_tcp_cc is stateless (e.g. bpf_cubic.c and bpf_dctcp.c). The "reuse map" feature is not implemented in this patch and it can be considered later also. For other subcmds, please see the man doc for details. A sample output of dump: [root@arch-fb-vm1 bpf]# bpftool struct_ops dump name cubic [{ "bpf_map_info": { "type": 26, "id": 64, "key_size": 4, "value_size": 256, "max_entries": 1, "map_flags": 0, "name": "cubic", "ifindex": 0, "btf_vmlinux_value_type_id": 18452, "netns_dev": 0, "netns_ino": 0, "btf_id": 52, "btf_key_type_id": 0, "btf_value_type_id": 0 } },{ "bpf_struct_ops_tcp_congestion_ops": { "refcnt": { "refs": { "counter": 1 } }, "state": "BPF_STRUCT_OPS_STATE_INUSE", "data": { "list": { "next": 0, "prev": 0 }, "key": 0, "flags": 0, "init": "void (struct sock *) bictcp_init/prog_id:138", "release": "void (struct sock *) 0", "ssthresh": "u32 (struct sock *) bictcp_recalc_ssthresh/prog_id:141", "cong_avoid": "void (struct sock *, u32, u32) bictcp_cong_avoid/prog_id:140", "set_state": "void (struct sock *, u8) bictcp_state/prog_id:142", "cwnd_event": "void (struct sock *, enum tcp_ca_event) bictcp_cwnd_event/prog_id:139", "in_ack_event": "void (struct sock *, u32) 0", "undo_cwnd": "u32 (struct sock *) tcp_reno_undo_cwnd/prog_id:144", "pkts_acked": "void (struct sock *, const struct ack_sample *) bictcp_acked/prog_id:143", "min_tso_segs": "u32 (struct sock *) 0", "sndbuf_expand": "u32 (struct sock *) 0", "cong_control": "void (struct sock *, const struct rate_sample *) 0", "get_info": "size_t (struct sock *, u32, int *, union tcp_cc_info *) 0", "name": "bpf_cubic", "owner": 0 } } } ] Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20200318171656.129650-1-kafai@fb.com
2020-03-18 17:16:56 +00:00
==================
bpftool-struct_ops
==================
-------------------------------------------------------------------------------
tool to register/unregister/introspect BPF struct_ops
-------------------------------------------------------------------------------
:Manual section: 8
SYNOPSIS
========
**bpftool** [*OPTIONS*] **struct_ops** *COMMAND*
*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] }
*COMMANDS* :=
{ **show** | **list** | **dump** | **register** | **unregister** | **help** }
STRUCT_OPS COMMANDS
===================
| **bpftool** **struct_ops { show | list }** [*STRUCT_OPS_MAP*]
| **bpftool** **struct_ops dump** [*STRUCT_OPS_MAP*]
| **bpftool** **struct_ops register** *OBJ*
| **bpftool** **struct_ops unregister** *STRUCT_OPS_MAP*
| **bpftool** **struct_ops help**
|
| *STRUCT_OPS_MAP* := { **id** *STRUCT_OPS_MAP_ID* | **name** *STRUCT_OPS_MAP_NAME* }
| *OBJ* := /a/file/of/bpf_struct_ops.o
DESCRIPTION
===========
**bpftool struct_ops { show | list }** [*STRUCT_OPS_MAP*]
Show brief information about the struct_ops in the system.
If *STRUCT_OPS_MAP* is specified, it shows information only
for the given struct_ops. Otherwise, it lists all struct_ops
currently existing in the system.
Output will start with struct_ops map ID, followed by its map
name and its struct_ops's kernel type.
**bpftool struct_ops dump** [*STRUCT_OPS_MAP*]
Dump details information about the struct_ops in the system.
If *STRUCT_OPS_MAP* is specified, it dumps information only
for the given struct_ops. Otherwise, it dumps all struct_ops
currently existing in the system.
**bpftool struct_ops register** *OBJ*
Register bpf struct_ops from *OBJ*. All struct_ops under
the ELF section ".struct_ops" will be registered to
its kernel subsystem.
**bpftool struct_ops unregister** *STRUCT_OPS_MAP*
Unregister the *STRUCT_OPS_MAP* from the kernel subsystem.
**bpftool struct_ops 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**.
-d, --debug
Print all logs available, even debug-level information. This
includes logs from libbpf as well as from the verifier, when
attempting to load programs.
EXAMPLES
========
**# bpftool struct_ops show**
::
100: dctcp tcp_congestion_ops
105: cubic tcp_congestion_ops
**# bpftool struct_ops unregister id 105**
::
Unregistered tcp_congestion_ops cubic id 105
**# bpftool struct_ops register bpf_cubic.o**
::
Registered tcp_congestion_ops cubic id 110
SEE ALSO
========
**bpf**\ (2),
**bpf-helpers**\ (7),
**bpftool**\ (8),
**bpftool-prog**\ (8),
**bpftool-map**\ (8),
**bpftool-cgroup**\ (8),
**bpftool-feature**\ (8),
**bpftool-net**\ (8),
**bpftool-perf**\ (8),
**bpftool-btf**\ (8)
**bpftool-gen**\ (8)
Reference in New Issue Copy Permalink