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tools/bpftool: Add documentation and sample output for process info

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Add statements about bpftool being able to discover process info, holding
reference to BPF map, prog, link, or BTF. Show example output as well.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-10-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-06-19 16:17:03 -07:00 committed by Alexei Starovoitov
parent d53dee3fe0
commit 075c776658
4 changed files with 35 additions and 2 deletions
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5
tools/bpf/bpftool/Documentation/bpftool-btf.rst
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@ -36,6 +36,11 @@ DESCRIPTION
otherwise list all BTF objects currently loaded on the
system.
Since Linux 5.8 bpftool is able to discover information about
processes that hold open file descriptors (FDs) against BTF
objects. On such kernels bpftool will automatically emit this
information as well.
**bpftool btf dump** *BTF_SRC*
Dump BTF entries from a given *BTF_SRC*.

13
tools/bpf/bpftool/Documentation/bpftool-link.rst
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@ -37,6 +37,11 @@ DESCRIPTION
zero or more named attributes, some of which depend on type
of link.
Since Linux 5.8 bpftool is able to discover information about
processes that hold open file descriptors (FDs) against BPF
links. On such kernels bpftool will automatically emit this
information as well.
**bpftool link pin** *LINK* *FILE*
Pin link *LINK* as *FILE*.
@ -82,6 +87,7 @@ EXAMPLES
10: cgroup prog 25
cgroup_id 614 attach_type egress
pids test_progs(223)
**# bpftool --json --pretty link show**
@ -91,7 +97,12 @@ EXAMPLES
"type": "cgroup",
"prog_id": 25,
"cgroup_id": 614,
"attach_type": "egress"
"attach_type": "egress",
"pids": [{
"pid": 223,
"comm": "test_progs"
}
]
}
]

8
tools/bpf/bpftool/Documentation/bpftool-map.rst
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@ -62,6 +62,11 @@ DESCRIPTION
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*] [**dev** *NAME*]
Create a new map with given parameters and pin it to *bpffs*
as *FILE*.
@ -180,7 +185,8 @@ EXAMPLES
::
10: hash name some_map flags 0x0
key 4B value 8B max_entries 2048 memlock 167936B
key 4B value 8B max_entries 2048 memlock 167936B
pids systemd(1)
The following three commands are equivalent:

11
tools/bpf/bpftool/Documentation/bpftool-prog.rst
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@ -75,6 +75,11 @@ DESCRIPTION
program run. Activation or deactivation of the feature is
performed via the **kernel.bpf_stats_enabled** sysctl knob.
Since Linux 5.8 bpftool is able to discover information about
processes that hold open file descriptors (FDs) against BPF
programs. On such kernels bpftool will automatically emit this
information as well.
**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | **opcodes** | **visual** | **linum** }]
Dump eBPF instructions of the programs from the kernel. By
default, eBPF will be disassembled and printed to standard
@ -243,6 +248,7 @@ EXAMPLES
10: xdp name some_prog tag 005a3d2123620c8b gpl run_time_ns 81632 run_cnt 10
loaded_at 2017-09-29T20:11:00+0000 uid 0
xlated 528B jited 370B memlock 4096B map_ids 10
pids systemd(1)
**# bpftool --json --pretty prog show**
@ -262,6 +268,11 @@ EXAMPLES
"bytes_jited": 370,
"bytes_memlock": 4096,
"map_ids": [10
],
"pids": [{
"pid": 1,
"comm": "systemd"
}
]
}
]