bpftool: Update doc (use susbtitutions) and test_bpftool_synctypes.py

test_bpftool_synctypes.py helps detecting inconsistencies in bpftool
between the different list of types and options scattered in the
sources, the documentation, and the bash completion. For options that
apply to all bpftool commands, the script had a hardcoded list of
values, and would use them to check whether the man pages are
up-to-date. When writing the script, it felt acceptable to have this
list in order to avoid to open and parse bpftool's main.h every time,
and because the list of global options in bpftool doesn't change so
often.

However, this is prone to omissions, and we recently added a new
-l|--legacy option which was described in common_options.rst, but not
listed in the options summary of each manual page. The script did not
complain, because it keeps comparing the hardcoded list to the (now)
outdated list in the header file.

To address the issue, this commit brings the following changes:

- Options that are common to all bpftool commands (--json, --pretty, and
--debug) are moved to a dedicated file, and used in the definition of
a RST substitution. This substitution is used in the sources of all
the man pages.

- This list of common options is updated, with the addition of the new
-l|--legacy option.

- The script test_bpftool_synctypes.py is updated to compare:
- Options specific to a command, found in C files, for the
interactive help messages, with the same specific options from the
relevant man page for that command.
- Common options, checked just once: the list in main.h is
compared with the new list in substitutions.rst.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211115225844.33943-3-quentin@isovalent.com

bpftool: Add SPDX tags to RST documentation files

Most files in the kernel repository have a SPDX tags. The files that
don't have such a tag (or another license boilerplate) tend to fall
under the GPL-2.0 license. In the past, bpftool's Makefile (for example)
has been marked as GPL-2.0 for that reason, when in fact all bpftool is
dual-licensed.

To prevent a similar confusion from happening with the RST documentation
files for bpftool, let's explicitly mark all files as dual-licensed.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211115225844.33943-2-quentin@isovalent.com

bpftool: Fix indent in option lists in the documentation

Mixed indentation levels in the lists of options in bpftool's
documentation produces some unexpected results. For the "bpftool" man
page, it prints a warning:

$ make -C bpftool.8
GEN bpftool.8
<stdin>:26: (ERROR/3) Unexpected indentation.

For other pages, there is no warning, but it results in a line break
appearing in the option lists in the generated man pages.

RST paragraphs should have a uniform indentation level. Let's fix it.

Fixes: c07ba629df97 ("tools: bpftool: Update and synchronise option list in doc and help msg")
Fixes: 8cc8c6357c8f ("tools: bpftool: Document and add bash completion for -L, -B options")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211110114632.24537-5-quentin@isovalent.com

tools: bpftool: Update and synchronise option list in doc and help msg

All bpftool commands support the options for JSON output and debug from
libbpf. In addition, some commands support additional options
corresponding to specific use cases.

The list of options described in the man pages for the different
commands are not always accurate. The messages for interactive help are
mostly limited to HELP_SPEC_OPTIONS, and are even less representative of
the actual set of options supported for the commands.

Let's update the lists:

- HELP_SPEC_OPTIONS is modified to contain the "default" options (JSON
and debug), and to be extensible (no ending curly bracket).
- All commands use HELP_SPEC_OPTIONS in their help message, and then
complete the list with their specific options.
- The lists of options in the man pages are updated.
- The formatting of the list for bpftool.rst is adjusted to match
formatting for the other man pages. This is for consistency, and also
because it will be helpful in a future patch to automatically check
that the files are synchronised.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210730215435.7095-5-quentin@isovalent.com

tools: bpftool: Automate generation for "SEE ALSO" sections in man pages

The "SEE ALSO" sections of bpftool's manual pages refer to bpf(2),
bpf-helpers(7), then all existing bpftool man pages (save the current
one).

This leads to nearly-identical lists being duplicated in all manual
pages. Ideally, when a new page is created, all lists should be updated
accordingly, but this has led to omissions and inconsistencies multiple
times in the past.

Let's take it out of the RST files and generate the "SEE ALSO" sections
automatically in the Makefile when generating the man pages. The lists
are not really useful in the RST anyway because all other pages are
available in the same directory.

v3:
- Fix conflict with a previous patchset that introduced RST2MAN_OPTS
variable passed to rst2man.

v2:
- Use "echo -n" instead of "printf" in Makefile, to avoid any risk of
passing a format string directly to the command.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910203935.25304-1-quentin@isovalent.com

tools: bpftool: Include common options from separate file

Nearly all man pages for bpftool have the same common set of option
flags (--help, --version, --json, --pretty, --debug). The description is
duplicated across all the pages, which is more difficult to maintain if
the description of an option changes. It may also be confusing to sort
out what options are not "common" and should not be copied when creating
new manual pages.

Let's move the description for those common options to a separate file,
which is included with a RST directive when generating the man pages.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162500.17010-3-quentin@isovalent.com

tools: bpftool: Fix formatting in bpftool-link documentation

Fix a formatting error in the documentation for bpftool-link, so that
the man page can build correctly.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904161454.31135-2-quentin@isovalent.com

tools/bpftool: Add documentation and bash-completion for `link detach`

Add info on link detach sub-command to man page. Add detach to bash-completion
as well.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com.
Link: https://lore.kernel.org/bpf/20200731182830.286260-6-andriin@fb.com

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

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

tools, bpftool: Minor fixes for documentation

Bring minor improvements to bpftool documentation. Fix or harmonise
formatting, update map types (including in interactive help), improve
description for "map create", fix a build warning due to a missing line
after the double-colon for the "bpftool prog profile" example,
complete/harmonise/sort the list of related bpftool man pages in
footers.

v2:
- Remove (instead of changing) mark-up on "value" in bpftool-map.rst,
when it does not refer to something passed on the command line.
- Fix an additional typo ("hexadeximal") in the same file.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200511161536.29853-3-quentin@isovalent.com

bpftool: Add bpftool-link manpage

Add bpftool-link manpage with information and examples of link-related
commands.

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/20200429001614.1544-10-andriin@fb.com