linux-stable.git/Documentation/bpf, branch v5.13

bpf: Document the pahole release info related to libbpf in bpf_devel_QA.rst

2021-04-24T00:11:58+00:00

pahole starts to use libbpf definitions and APIs since v1.13 after the
commit 21507cd3e97b ("pahole: add libbpf as submodule under lib/bpf").
It works well with the git repository because the libbpf submodule will
use "git submodule update --init --recursive" to update.

Unfortunately, the default github release source code does not contain
libbpf submodule source code and this will cause build issues, the tarball
from https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ is same with
github, you can get the source tarball with corresponding libbpf submodule
codes from

https://fedorapeople.org/~acme/dwarves

This change documents the above issues to give more information so that
we can get the tarball from the right place, early discussion is here:

https://lore.kernel.org/bpf/2de4aad5-fa9e-1c39-3c92-9bb9229d0966@loongson.cn/

Signed-off-by: Tiezhu Yang 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/bpf/1619141010-12521-1-git-send-email-yangtiezhu@loongson.cn

bpf, doc: Fix some invalid links in bpf_devel_QA.rst

2021-04-22T21:27:11+00:00

There exist some errors "404 Not Found" when I click the link
of "MAINTAINERS" [1], "samples/bpf/" [2] and "selftests" [3]
in the documentation "HOWTO interact with BPF subsystem" [4].

As Alexei Starovoitov suggested, just remove "MAINTAINERS" and
"samples/bpf/" links and use correct link of "selftests".

  [1] https://www.kernel.org/doc/html/MAINTAINERS
  [2] https://www.kernel.org/doc/html/samples/bpf/
  [3] https://www.kernel.org/doc/html/tools/testing/selftests/bpf/
  [4] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html

Fixes: 542228384888 ("bpf, doc: convert bpf_devel_QA.rst to use RST formatting")
Signed-off-by: Tiezhu Yang 
Signed-off-by: Daniel Borkmann 
Acked-by: Jesper Dangaard Brouer 
Link: https://lore.kernel.org/bpf/1619062560-30483-1-git-send-email-yangtiezhu@loongson.cn

bpf: Update bpf_design_QA.rst to clarify the kfunc call is not ABI

2021-03-30T14:31:01+00:00

This patch updates bpf_design_QA.rst to clarify that the kernel
function callable by bpf program is not an ABI.

Signed-off-by: Martin KaFai Lau 
Signed-off-by: Alexei Starovoitov 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20210330054150.2933542-1-kafai@fb.com

docs/bpf: Add bpf() syscall command reference

2021-03-05T02:39:46+00:00

Generate the syscall command reference from the UAPI header file and
include it in the main bpf docs page.

Signed-off-by: Joe Stringer 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Quentin Monnet 
Acked-by: Toke Høiland-Jørgensen 
Link: https://lore.kernel.org/bpf/20210302171947.2268128-15-joe@cilium.io

bpf: Document BTF_KIND_FLOAT in btf.rst

2021-03-05T02:31:53+00:00

Also document the expansion of the kind bitfield.

Signed-off-by: Ilya Leoshkevich 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20210226202256.116518-11-iii@linux.ibm.com

bpf, docs: Update build procedure for manually compiling LLVM and Clang

2021-01-22T23:09:03+00:00

The current LLVM and Clang build procedure in samples/bpf/README.rst is
out of date. See below that the links are not accessible any more.

  $ git clone http://llvm.org/git/llvm.git
  Cloning into 'llvm'...
  fatal: unable to access 'http://llvm.org/git/llvm.git/': Maximum (20) redirects followed
  $ git clone --depth 1 http://llvm.org/git/clang.git
  Cloning into 'clang'...
  fatal: unable to access 'http://llvm.org/git/clang.git/': Maximum (20) redirects followed

The LLVM community has adopted new ways to build the compiler. There are
different ways to build LLVM and Clang, the Clang Getting Started page [1]
has one way. As Yonghong said, it is better to copy the build procedure
in Documentation/bpf/bpf_devel_QA.rst to keep consistent.

I verified the procedure and it is proved to be feasible, so we should
update README.rst to reflect the reality. At the same time, update the
related comment in Makefile.

Additionally, as Fangrui said, the dir llvm-project/llvm/build/install is
not used, BUILD_SHARED_LIBS=OFF is the default option [2], so also change
Documentation/bpf/bpf_devel_QA.rst together.

At last, we recommend that developers who want the fastest incremental
builds use the Ninja build system [1], you can find it in your system's
package manager, usually the package is ninja or ninja-build [3], so add
ninja to build dependencies suggested by Nathan.

  [1] https://clang.llvm.org/get_started.html
  [2] https://www.llvm.org/docs/CMake.html
  [3] https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages

Signed-off-by: Tiezhu Yang 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Nathan Chancellor 
Acked-by: Yonghong Song 
Cc: Fangrui Song 
Link: https://lore.kernel.org/bpf/1611279584-26047-1-git-send-email-yangtiezhu@loongson.cn

trace: bpf: Allow bpf to attach to bare tracepoints

2021-01-20T22:13:59+00:00

Some subsystems only have bare tracepoints (a tracepoint with no
associated trace event) to avoid the problem of trace events being an
ABI that can't be changed.

>From bpf presepective, bare tracepoints are what it calls
RAW_TRACEPOINT().

Since bpf assumed there's 1:1 mapping, it relied on hooking to
DEFINE_EVENT() macro to create bpf mapping of the tracepoints. Since
bare tracepoints use DECLARE_TRACE() to create the tracepoint, bpf had
no knowledge about their existence.

By teaching bpf_probe.h to parse DECLARE_TRACE() in a similar fashion to
DEFINE_EVENT(), bpf can find and attach to the new raw tracepoints.

Enabling that comes with the contract that changes to raw tracepoints
don't constitute a regression if they break existing bpf programs.
We need the ability to continue to morph and modify these raw
tracepoints without worrying about any ABI.

Update Documentation/bpf/bpf_design_QA.rst to document this contract.

Signed-off-by: Qais Yousef 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20210119122237.2426878-2-qais.yousef@arm.com

bpf: Migrate from patchwork.ozlabs.org to patchwork.kernel.org.

2020-10-11T20:05:47+00:00

Move the bpf/bpf-next patch processing queue to patchwork.kernel.org.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20201011200149.66537-1-alexei.starovoitov@gmail.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-09-22T23:45:34+00:00

Two minor conflicts:

1) net/ipv4/route.c, adding a new local variable while
   moving another local variable and removing it's
   initial assignment.

2) drivers/net/dsa/microchip/ksz9477.c, overlapping changes.
   One pretty prints the port mode differently, whilst another
   changes the driver to try and obtain the port mode from
   the port node rather than the switch node.

Signed-off-by: David S. Miller

docs/bpf: Remove source code links

2020-09-15T01:46:54+00:00

Make path to bench_ringbufs.c just a text, not a special link.

Fixes: 97abb2b39682 ("docs/bpf: Add BPF ring buffer design notes")
Reported-by: Mauro Carvalho Chehab 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200915005031.2748397-1-andriin@fb.com