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Commit cbeaad90 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpftool-probes' 



Quentin Monnet says:

====================
Hi,
This set adds a new command to bpftool in order to dump a list of
eBPF-related parameters for the system (or for a specific network
device) to the console. Once again, this is based on a suggestion from
Daniel.

At this time, output includes:

    - Availability of bpf() system call
    - Availability of bpf() system call for unprivileged users
    - JIT status (enabled or not, with or without debugging traces)
    - JIT hardening status
    - JIT kallsyms exports status
    - Global memory limit for JIT compiler for unprivileged users
    - Status of kernel compilation options related to BPF features
    - Availability of known eBPF program types
    - Availability of known eBPF map types
    - Availability of known eBPF helper functions

There are three different ways to dump this information at this time:

    - Plain output dumps probe results in plain text. It is the most
      flexible options for providing descriptive output to the user, but
      should not be relied upon for parsing the output.
    - JSON output is supported.
    - A third mode, available through the "macros" keyword appended to the
      command line, dumps some of those parameters (not all) as a series of
      "#define" directives, that can be included into a C header file for
      example.

Probes for supported program and map types, and supported helpers, are
directly added to libbpf, so that other applications (or selftests) can
reuse them as necessary.

If the user does not have root privileges (or more precisely, the
CAP_SYS_ADMIN capability) detection will be erroneous for most
parameters. Therefore, forbid non-root users to run the command.

v5:
- Move exported symbols to a new LIBBPF_0.0.2 section in libbpf.map
  (patches 4 to 6).
- Minor fixes on patches 3 and 4.

v4:
- Probe bpf_jit_limit parameter (patch 2).
- Probe some additional kernel config options (patch 3).
- Minor fixes on patch 6.

v3:
- Do not probe kernel version in bpftool (just retrieve it to probe support
  for kprobes in libbpf).
- Change the way results for helper support is displayed: now one list of
  compatible helpers for each program type (and C-style output gets a
  HAVE_PROG_TYPE_HELPER(prog_type, helper) macro to help with tests. See
  patches 6, 7.
- Address other comments from feedback from v2 (please refer to individual
  patches' history).

v2 (please also refer to individual patches' history):
- Move probes for prog/map types, helpers, from bpftool to libbpf.
- Move C-style output as a separate patch, and restrict it to a subset of
  collected information (bpf() availability, prog/map types, helpers).
- Now probe helpers with all supported program types, and display a list of
  compatible program types (as supported on the system) for each helper.
- NOT addressed: grouping compilation options for kernel into subsections
  (patch 3) (I don't see an easy way of grouping them at the moment, please
  see also the discussion on v1 thread).
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents d0b2818e 948703e8

tools/bpf/bpftool/Documentation/bpftool-cgroup.rst

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Original line number Diff line number Diff line
@@ -142,5 +142,6 @@ SEE ALSO 
	**bpftool**\ (8),

	**bpftool-prog**\ (8),

	**bpftool-map**\ (8),

	**bpftool-feature**\ (8),

	**bpftool-net**\ (8),

	**bpftool-perf**\ (8)

tools/bpf/bpftool/Documentation/bpftool-feature.rst

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===============

bpftool-feature

===============

-------------------------------------------------------------------------------

tool for inspection of eBPF-related parameters for Linux kernel or net device

-------------------------------------------------------------------------------



:Manual section: 8



SYNOPSIS

========



	**bpftool** [*OPTIONS*] **feature** *COMMAND*



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



	*COMMANDS* := { **probe** | **help** }



MAP COMMANDS

=============



|	**bpftool** **feature probe** [*COMPONENT*] [**macros** [**prefix** *PREFIX*]]

|	**bpftool** **feature help**

|

|	*COMPONENT* := { **kernel** | **dev** *NAME* }



DESCRIPTION

===========

	**bpftool feature probe** [**kernel**] [**macros** [**prefix** *PREFIX*]]

		  Probe the running kernel and dump a number of eBPF-related

		  parameters, such as availability of the **bpf()** system call,

		  JIT status, eBPF program types availability, eBPF helper

		  functions availability, and more.



		  If the **macros** keyword (but not the **-j** option) is

		  passed, a subset of the output is dumped as a list of

		  **#define** macros that are ready to be included in a C

		  header file, for example. If, additionally, **prefix** is

		  used to define a *PREFIX*, the provided string will be used

		  as a prefix to the names of the macros: this can be used to

		  avoid conflicts on macro names when including the output of

		  this command as a header file.



		  Keyword **kernel** can be omitted. If no probe target is

		  specified, probing the kernel is the default behaviour.



		  Note that when probed, some eBPF helpers (e.g.

		  **bpf_trace_printk**\ () or **bpf_probe_write_user**\ ()) may

		  print warnings to kernel logs.



	**bpftool feature probe dev** *NAME* [**macros** [**prefix** *PREFIX*]]

		  Probe network device for supported eBPF features and dump

		  results to the console.



		  The two keywords **macros** and **prefix** have the same

		  role as when probing the kernel.



	**bpftool feature 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**.



SEE ALSO

========

	**bpf**\ (2),

	**bpf-helpers**\ (7),

	**bpftool**\ (8),

	**bpftool-prog**\ (8),

	**bpftool-map**\ (8),

	**bpftool-cgroup**\ (8),

	**bpftool-net**\ (8),

	**bpftool-perf**\ (8)

tools/bpf/bpftool/Documentation/bpftool-map.rst

+1 −0
Original line number Diff line number Diff line
@@ -256,5 +256,6 @@ SEE ALSO 
	**bpftool**\ (8),

	**bpftool-prog**\ (8),

	**bpftool-cgroup**\ (8),

	**bpftool-feature**\ (8),

	**bpftool-net**\ (8),

	**bpftool-perf**\ (8)

tools/bpf/bpftool/Documentation/bpftool-net.rst

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Original line number Diff line number Diff line
@@ -142,4 +142,5 @@ SEE ALSO 
	**bpftool-prog**\ (8),

	**bpftool-map**\ (8),

	**bpftool-cgroup**\ (8),

	**bpftool-feature**\ (8),

	**bpftool-perf**\ (8)

tools/bpf/bpftool/Documentation/bpftool-perf.rst

+1 −0
Original line number Diff line number Diff line
@@ -84,4 +84,5 @@ SEE ALSO 
	**bpftool-prog**\ (8),

	**bpftool-map**\ (8),

	**bpftool-cgroup**\ (8),

	**bpftool-feature**\ (8),

	**bpftool-net**\ (8)