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Minor improvements to the documentation for BPF helpers:
* Fix formatting for the description of "bpf_socket" for
bpf_getsockopt() and bpf_setsockopt(), thus suppressing two warnings
from rst2man about "Unexpected indentation".
* Fix formatting for return values for bpf_sk_assign() and seq_file
helpers.
* Fix and harmonise formatting, in particular for function/struct names.
* Remove blank lines before "Return:" sections.
* Replace tabs found in the middle of text lines.
* Fix typos.
* Add a note to the footer (in Python script) about "bpftool feature
probe", including for listing features available to unprivileged
users, and add a reference to bpftool man page.
Thanks to Florian for reporting two typos (duplicated words).
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200511161536.29853-4-quentin@isovalent.com
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Two helpers bpf_seq_printf and bpf_seq_write, are added for
writing data to the seq_file buffer.
bpf_seq_printf supports common format string flag/width/type
fields so at least I can get identical results for
netlink and ipv6_route targets.
For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW
specifically indicates a write failure due to overflow, which
means the object will be repeated in the next bpf invocation
if object collection stays the same. Note that if the object
collection is changed, depending how collection traversal is
done, even if the object still in the collection, it may not
be visited.
For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to
read kernel memory. Reading kernel memory may fail in
the following two cases:
- invalid kernel address, or
- valid kernel address but requiring a major fault
If reading kernel memory failed, the %s string will be
an empty string and %p{i,I}{4,6} will be all 0.
Not returning error to bpf program is consistent with
what bpf_trace_printk() does for now.
bpf_seq_printf may return -EBUSY meaning that internal percpu
buffer for memory copy of strings or other pointees is
not available. Bpf program can return 1 to indicate it
wants the same object to be repeated. Right now, this should not
happen on no-RT kernels since migrate_disable(), which guards
bpf prog call, calls preempt_disable().
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
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When compiling bpftool the following warning is found: "declaration of
'struct bpf_pidns_info' will not be visible outside of this function."
This patch adds struct bpf_pidns_info to type_fwds array to fix this.
Fixes: b4490c5c4e02 ("bpf: Added new helper bpf_get_ns_current_pid_tgid")
Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200313154650.13366-1-cneirabustos@gmail.com
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New bpf helper bpf_get_ns_current_pid_tgid,
This helper will return pid and tgid from current task
which namespace matches dev_t and inode number provided,
this will allows us to instrument a process inside a container.
Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200304204157.58695-3-cneirabustos@gmail.com
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Change "/usr/bin/python3" to "/usr/bin/env python3" for
more portable solution in bpf_helpers_doc.py.
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225205426.6975-1-scott.branden@broadcom.com
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bpf_helpers_doc.py script, used to generate bpf_helper_defs.h, unconditionally
emits one informational message to stderr. Remove it and preserve stderr to
contain only relevant errors. Also make sure script invocations command is
muted by default in libbpf's Makefile.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200113073143.1779940-3-andriin@fb.com
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Don't generate a broken bpf_helper_defs.h header if the helper script needs
updating because it doesn't recognize a newly added type. Instead print an
error that explains why the build is failing, clean up the partially
generated header and stop.
v1->v2:
- Switched from temporary file to .DELETE_ON_ERROR.
Fixes: 456a513bb5d4 ("scripts/bpf: Emit an #error directive known types list needs updating")
Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191020112344.19395-1-jakub@cloudflare.com
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Make the compiler report a clear error when bpf_helpers_doc.py needs
updating rather than rely on the fact that Clang fails to compile
English:
../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized'
Unrecognized type 'struct bpf_inet_lookup', please add it to known types!
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191016085811.11700-1-jakub@cloudflare.com
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Fix typo in struct xpd_md, generated from bpf_helpers_doc.py, which is
causing compilation warnings for programs using bpf_helpers.h
Fixes: 7a387bed47f7 ("scripts/bpf: teach bpf_helpers_doc.py to dump BPF helper definitions")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191010042534.290562-1-andriin@fb.com
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Enhance scripts/bpf_helpers_doc.py to emit C header with BPF helper
definitions (to be included from libbpf's bpf_helpers.h).
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The script broke on parsing function prototype for bpf_strtoul(). This
is because the last argument for the function is a pointer to an
"unsigned long". The current version of the script only accepts "const"
and "struct", but not "unsigned", at the beginning of argument types
made of several words.
One solution could be to add "unsigned" to the list, but the issue could
come up again in the future (what about "long int"?). It turns out we do
not need to have such restrictions on the words: so let's simply accept
any series of words instead.
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Documentation for eBPF helpers can be parsed from bpf.h and eventually
turned into a man page. Commit 6f96674dbd8c ("bpf: relax constraints on
formatting for eBPF helper documentation") changed the script used to
parse it, in order to allow for different indent style and to ease the
work for writing documentation for future helpers.
The script currently considers that the first tab can be replaced by 6
to 8 spaces. But the documentation for bpf_fib_lookup() uses a mix of
tabs (for the "Description" part) and of spaces ("Return" part), and
only has 5 space long indent for the latter.
We probably do not want to change the values accepted by the script each
time a new helper gets a new indent style. However, it is worth noting
that with those 5 spaces, the "Description" and "Return" part *look*
aligned in the generated patch and in `git show`, so it is likely other
helper authors will use the same length. Therefore, allow for helper
documentation to use 5 spaces only for the first indent level.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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The Python script used to parse and extract eBPF helpers documentation
from include/uapi/linux/bpf.h expects a very specific formatting for the
descriptions (single dot represents a space, '>' stands for a tab):
/*
...
*.int bpf_helper(list of arguments)
*.> Description
*.> > Start of description
*.> > Another line of description
*.> > And yet another line of description
*.> Return
*.> > 0 on success, or a negative error in case of failure
...
*/
This is too strict, and painful for developers who wants to add
documentation for new helpers. Worse, it is extremely difficult to check
that the formatting is correct during reviews. Change the format
expected by the script and make it more flexible. The script now works
whether or not the initial space (right after the star) is present, and
accepts both tabs and white spaces (or a combination of both) for
indenting description sections and contents.
Concretely, something like the following would now be supported:
/*
...
*int bpf_helper(list of arguments)
*......Description
*.> > Start of description...
*> > Another line of description
*..............And yet another line of description
*> Return
*.> ........0 on success, or a negative error in case of failure
...
*/
While at it, remove unnecessary carets from each regex used with match()
in the script. They are redundant, as match() tries to match from the
beginning of the string by default.
v2: Remove unnecessary caret when a regex is used with match().
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Remove previous "overview" of eBPF helpers from user bpf.h header.
Replace it by a comment explaining how to process the new documentation
(to come in following patches) with a Python script to produce RST, then
man page documentation.
Also add the aforementioned Python script under scripts/. It is used to
process include/uapi/linux/bpf.h and to extract helper descriptions, to
turn it into a RST document that can further be processed with rst2man
to produce a man page. The script takes one "--filename <path/to/file>"
option. If the script is launched from scripts/ in the kernel root
directory, it should be able to find the location of the header to
parse, and "--filename <path/to/file>" is then optional. If it cannot
find the file, then the option becomes mandatory. RST-formatted
documentation is printed to standard output.
Typical workflow for producing the final man page would be:
$ ./scripts/bpf_helpers_doc.py \
--filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
$ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
$ man /tmp/bpf-helpers.7
Note that the tool kernel-doc cannot be used to document eBPF helpers,
whose signatures are not available directly in the header files
(pre-processor directives are used to produce them at the beginning of
the compilation process).
v4:
- Also remove overviews for newly added bpf_xdp_adjust_tail() and
bpf_skb_get_xfrm_state().
- Remove vague statement about what helpers are restricted to GPL
programs in "LICENSE" section for man page footer.
- Replace license boilerplate with SPDX tag for Python script.
v3:
- Change license for man page.
- Remove "for safety reasons" from man page header text.
- Change "packets metadata" to "packets" in man page header text.
- Move and fix comment on helpers introducing no overhead.
- Remove "NOTES" section from man page footer.
- Add "LICENSE" section to man page footer.
- Edit description of file include/uapi/linux/bpf.h in man page footer.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Quentin Monnet
Yonghong Song
Carlos Neira
Scott Branden
Andrii Nakryiko
Jakub Sitnicki
Quentin Monnet