Commit Graph

29 Commits

Author SHA1 Message Date
Jiong Wang c231c22a98 bpf: doc: update answer for 32-bit subregister question
There has been quite a few progress around the two steps mentioned in the
answer to the following question:

  Q: BPF 32-bit subregister requirements

This patch updates the answer to reflect what has been done.

v2:
 - Add missing full stop. (Song Liu)
 - Minor tweak on one sentence. (Song Liu)

v1:
 - Integrated rephrase from Quentin and Jakub

Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-31 17:07:13 -07:00
Gary Lin 948dc8c99a bpf: btf: fix the brackets of BTF_INT_OFFSET()
'VAL' should be protected by the brackets.

v2:
* Squash the fix for Documentation/bpf/btf.rst

Fixes: 69b693f0ae ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Gary Lin <glin@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-05-14 10:05:18 +02:00
Gary Lin 3ef4641fbf docs/btf: fix the missing section marks
The section titles of 3.4 and 3.5 are not marked correctly.

Signed-off-by: Gary Lin <glin@suse.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-09 15:59:59 -07:00
Alexei Starovoitov 3b8802446d bpf: document the verifier limits
Document the verifier limits.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-23 00:39:12 +02:00
Stanislav Fomichev 8069594673 bpf: move BPF_PROG_TYPE_FLOW_DISSECTOR documentation to a new common place
In commit da70314917 ("bpf: Document BPF_PROG_TYPE_CGROUP_SYSCTL")
Andrey proposes to put per-prog type docs under Documentation/bpf/

Let's move flow dissector documentation there as well.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-18 16:59:42 -07:00
Andrey Ignatov da70314917 bpf: Document BPF_PROG_TYPE_CGROUP_SYSCTL
Add documentation for BPF_PROG_TYPE_CGROUP_SYSCTL, including general
info, attach type, context, return code, helpers, example and usage
considerations.

A separate file prog_cgroup_sysctl.rst is added to Documentation/bpf/.

In the future more program types can be documented in their own
prog_<name>.rst files.

Another way to place program type specific documentation would be to
group program types somehow (e.g. cgroup.rst for all cgroup-bpf
programs), but it may not scale well since some program types may belong
to different groups, e.g. BPF_PROG_TYPE_CGROUP_SKB can be documented
together with either cgroup-bpf programs or programs that access skb.

The new file is added to the index and verified by `make htmldocs` /
sanity-check by lynx.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-18 16:05:36 -07:00
David S. Miller bb23581b9b Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:

====================
pull-request: bpf-next 2019-04-12

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Improve BPF verifier scalability for large programs through two
   optimizations: i) remove verifier states that are not useful in pruning,
   ii) stop walking parentage chain once first LIVE_READ is seen. Combined
   gives approx 20x speedup. Increase limits for accepting large programs
   under root, and add various stress tests, from Alexei.

2) Implement global data support in BPF. This enables static global variables
   for .data, .rodata and .bss sections to be properly handled which allows
   for more natural program development. This also opens up the possibility
   to optimize program workflow by compiling ELFs only once and later only
   rewriting section data before reload, from Daniel and with test cases and
   libbpf refactoring from Joe.

3) Add config option to generate BTF type info for vmlinux as part of the
   kernel build process. DWARF debug info is converted via pahole to BTF.
   Latter relies on libbpf and makes use of BTF deduplication algorithm which
   results in 100x savings compared to DWARF data. Resulting .BTF section is
   typically about 2MB in size, from Andrii.

4) Add BPF verifier support for stack access with variable offset from
   helpers and add various test cases along with it, from Andrey.

5) Extend bpf_skb_adjust_room() growth BPF helper to mark inner MAC header
   so that L2 encapsulation can be used for tc tunnels, from Alan.

6) Add support for input __sk_buff context in BPF_PROG_TEST_RUN so that
   users can define a subset of allowed __sk_buff fields that get fed into
   the test program, from Stanislav.

7) Add bpf fs multi-dimensional array tests for BTF test suite and fix up
   various UBSAN warnings in bpftool, from Yonghong.

8) Generate a pkg-config file for libbpf, from Luca.

9) Dump program's BTF id in bpftool, from Prashant.

10) libbpf fix to use smaller BPF log buffer size for AF_XDP's XDP
    program, from Magnus.

11) kallsyms related fixes for the case when symbols are not present in
    BPF selftests and samples, from Daniel
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-11 17:00:05 -07:00
Daniel Borkmann f063c889c9 bpf: add specification for BTF Var and DataSec kinds
This adds the BTF specification and UAPI bits for supporting BTF Var
and DataSec kinds. This is following LLVM upstream commit ac4082b77e07
("[BPF] Add BTF Var and DataSec Support") which has been merged recently.
Var itself is for describing a global variable and DataSec to describe
ELF sections e.g. data/bss/rodata sections that hold one or multiple
global variables.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-09 17:05:46 -07:00
Jesper Dangaard Brouer f52c97d9df bpf, doc: fix BTF docs reflow of bullet list
Section 2.2.1 BTF_KIND_INT a bullet list was collapsed due to
text reflow in commit 9ab5305dbe ("docs/btf: reflow text to
fill up to 78 characters").

This patch correct the mistake. Also adjust next bullet list,
which is used for comparison, to get rendered the same way.

Fixes: 9ab5305dbe ("docs/btf: reflow text to fill up to 78 characters")
Link: https://www.kernel.org/doc/html/latest/bpf/btf.html#btf-kind-int
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-03-26 13:13:42 -07:00
Andrii Nakryiko 46604676c8 docs/bpf: minor casing/punctuation fixes
Fix few casing and punctuation glitches.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-03-02 00:40:04 +01:00
Andrii Nakryiko 9ab5305dbe docs/btf: reflow text to fill up to 78 characters
Reflow paragraphs to more fully and evenly fill 78 character lines.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-03-02 00:40:04 +01:00
Andrii Nakryiko 5efc529fb4 docs/btf: fix typos, improve wording
Fix various typos, some of the formatting and wording for
Documentation/btf.rst.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-03-02 00:40:04 +01:00
Yonghong Song ffcf7ce933 bpf: btf: add btf documentation
This patch added documentation for BTF (BPF Debug Format).
The document is placed under linux:Documentation/bpf directory.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-01-22 23:50:02 -08:00
Daniel Borkmann a769fa7208 bpf, doc: update design qa to reflect kern_version requirement
Update the bpf_design_QA.rst to also reflect recent changes in
6c4fc209fc ("bpf: remove useless version check for prog load").

Suggested-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-01-07 15:52:00 -08:00
David S. Miller 1ba982806c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:

====================
pull-request: bpf-next 2018-08-07

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Add cgroup local storage for BPF programs, which provides a fast
   accessible memory for storing various per-cgroup data like number
   of transmitted packets, etc, from Roman.

2) Support bpf_get_socket_cookie() BPF helper in several more program
   types that have a full socket available, from Andrey.

3) Significantly improve the performance of perf events which are
   reported from BPF offload. Also convert a couple of BPF AF_XDP
   samples overto use libbpf, both from Jakub.

4) seg6local LWT provides the End.DT6 action, which allows to
   decapsulate an outer IPv6 header containing a Segment Routing Header.
   Adds this action now to the seg6local BPF interface, from Mathieu.

5) Do not mark dst register as unbounded in MOV64 instruction when
   both src and dst register are the same, from Arthur.

6) Define u_smp_rmb() and u_smp_wmb() to their respective barrier
   instructions on arm64 for the AF_XDP sample code, from Brian.

7) Convert the tcp_client.py and tcp_server.py BPF selftest scripts
   over from Python 2 to Python 3, from Jeremy.

8) Enable BTF build flags to the BPF sample code Makefile, from Taeung.

9) Remove an unnecessary rcu_read_lock() in run_lwt_bpf(), from Taehee.

10) Several improvements to the README.rst from the BPF documentation
    to make it more consistent with RST format, from Tobin.

11) Replace all occurrences of strerror() by calls to strerror_r()
    in libbpf and fix a FORTIFY_SOURCE build error along with it,
    from Thomas.

12) Fix a bug in bpftool's get_btf() function to correctly propagate
    an error via PTR_ERR(), from Yue.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-07 11:02:05 -07:00
Tobin C. Harding 6919bcc8aa docs: bpf: Capitalise document heading
The majority of files in the kernel documentation index use
capitalisation for all words, especially the shorter ones.  BPF docs
better fit in with the rest of the documentation if the heading is all
capitalised.

Capitalise document heading.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-27 07:23:48 +02:00
Tobin C. Harding b3d40f63d2 docs: bpf: Add toctree to index
Recently bpf/ docs were converted to us RST format.  bp/index.rst was
created out of README but toctree was not added to include files within
Documentation/bpf/

Add toctree to Documentation/bpf/index.rst

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-27 07:23:48 +02:00
Tobin C. Harding d9b9170a26 docs: bpf: Rename README.rst to index.rst
Recently bpf/ docs were converted to use RST format.  'README.rst' was
created but in order to fit in with the Sphinx build system this file
should be named 'index.rst'.  Rename file, fixes to integrate into
Sphinx build system in following patches.

docs: Rename Documentation/bpf/README.rst to Documentation/bpf/index.rst

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-27 07:23:48 +02:00
Tobin C. Harding 287f4fa99a docs: Update references to netdev-FAQ
File 'Documentation/networking/netdev-FAQ.txt' has been converted to RST
format.  We should update all links/references to point to the new file.

Update references to netdev-FAQ

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-26 21:27:54 -07:00
Jesper Dangaard Brouer b7a27c3aaf bpf, doc: howto use/run the BPF selftests
I always forget howto run the BPF selftests. Thus, lets add that info
to the QA document.

Documentation was based on Cilium's documentation:
 http://cilium.readthedocs.io/en/latest/bpf/#verifying-the-setup

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 23:02:58 -07:00
Jesper Dangaard Brouer 5422283848 bpf, doc: convert bpf_devel_QA.rst to use RST formatting
Same story as bpf_design_QA.rst RST format conversion.

Again thanks to Quentin Monnet <quentin.monnet@netronome.com> for
fixes and patches that have been squashed.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 23:02:58 -07:00
Jesper Dangaard Brouer 1a6ac1d59d bpf, doc: convert bpf_design_QA.rst to use RST formatting
The RST formatting is done such that that when rendered or converted
to different formats, an automatic index with links are created to the
subsections.

Thus, the questions are created as sections (or subsections), in-order
to get the wanted auto-generated FAQ/QA index.

Special thanks to Quentin Monnet <quentin.monnet@netronome.com> who
have reviewed and corrected both RST formatting and GitHub rendering
issues in this file.  Those commits have been squashed.

I've manually tested that this also renders nicely if included as part
of the kernel 'make htmldocs'.  As the end-goal is for this to become
more integrated with kernel-doc project/movement.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 23:02:58 -07:00
Jesper Dangaard Brouer 192092faa0 bpf, doc: rename txt files to rst files
This will cause them to get auto rendered, e.g. when viewing them on GitHub.
Followup patches will correct the content to be RST compliant.

Also adjust README.rst to point to the renamed files.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 23:02:58 -07:00
Jesper Dangaard Brouer 4712c1b203 bpf, doc: add basic README.rst file
A README.rst file in a directory have special meaning for sites like
github, which auto renders the contents.  Plus search engines like
Google also index these README.rst files.

Auto rendering allow us to use links, for (re)directing eBPF users to
other places where docs live.  The end-goal would be to direct users
towards https://www.kernel.org/doc/html/latest but we haven't written
the full docs yet, so we start out small and take this incrementally.

This directory itself contains some useful docs, which can be linked
to from the README.rst file (verified this works for github).

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 23:02:58 -07:00
John Fastabend 514d6c1959 bpf: Document sockmap '-target bpf' requirement for PROG_TYPE_SK_MSG
BPF_PROG_TYPE_SK_MSG programs use a 'void *' for both data and the
data_end pointers. Additionally, the verifier ensures that every
accesses into the values is a __u64 read. This correctly maps on
to the BPF 64-bit architecture.

However, to ensure that when building on 32bit architectures that
clang uses correct types the '-target bpf' option _must_ be
specified. To make this clear add a note to the Documentation.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-23 23:42:21 +02:00
Daniel Borkmann 78262f4575 bpf, doc: add description wrt native/bpf clang target and pointer size
As this recently came up on netdev [0], lets add it to the BPF devel doc.

  [0] https://www.spinics.net/lists/netdev/msg489612.html

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-03-20 15:47:45 -07:00
Yonghong Song 6215ea6b7e bpf: add documentation to compare clang "-target bpf" and default target
The added documentation explains how generated codes may differ
between clang bpf target and default target, and when to use
each target.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-02-02 11:14:19 +01:00
Daniel Borkmann 34f15bf31e bpf, doc: add faq about bpf development process
In the same spirit of netdev FAQ, start a BPF FAQ as a collection
of expectations and/or workflow details in the context of BPF patch
processing.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-06 14:32:42 -08:00
Alexei Starovoitov 2e39748a42 bpf: document answers to common questions about BPF
to address common misconceptions about what BPF is and what it's not
add short BPF Q&A that clarifies core BPF design principles and
answers some common questions.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-01 21:01:47 +09:00