Daniel Borkmann says:
====================
pull-request: bpf-next 2018-07-03
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Various improvements to bpftool and libbpf, that is, bpftool build
speed improvements, missing BPF program types added for detection
by section name, ability to load programs from '.text' section is
made to work again, and better bash completion handling, from Jakub.
2) Improvements to nfp JIT's map read handling which allows for optimizing
memcpy from map to packet, from Jiong.
3) New BPF sample is added which demonstrates XDP in combination with
bpf_perf_event_output() helper to sample packets on all CPUs, from Toke.
4) Add a new BPF kselftest case for tracking connect(2) BPF hooks
infrastructure in combination with TFO, from Andrey.
5) Extend the XDP/BPF xdp_rxq_info sample code with a cmdline option to
read payload from packet data in order to use it for benchmarking.
Also for '--action XDP_TX' option implement swapping of MAC addresses
to avoid drops on some hardware seen during testing, from Jesper.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
eBPF sample programs
====================
This directory contains a test stubs, verifier test-suite and examples
for using eBPF. The examples use libbpf from tools/lib/bpf.
Build dependencies
==================
Compiling requires having installed:
* clang >= version 3.4.0
* llvm >= version 3.7.1
Note that LLVM's tool 'llc' must support target 'bpf', list version
and supported targets with command: ``llc --version``
Kernel headers
--------------
There are usually dependencies to header files of the current kernel.
To avoid installing devel kernel headers system wide, as a normal
user, simply call::
make headers_install
This will creates a local "usr/include" directory in the git/build top
level directory, that the make system automatically pickup first.
Compiling
=========
For building the BPF samples, issue the below command from the kernel
top level directory::
make samples/bpf/
Do notice the "/" slash after the directory name.
It is also possible to call make from this directory. This will just
hide the the invocation of make as above with the appended "/".
Manually compiling LLVM with 'bpf' support
------------------------------------------
Since version 3.7.0, LLVM adds a proper LLVM backend target for the
BPF bytecode architecture.
By default llvm will build all non-experimental backends including bpf.
To generate a smaller llc binary one can use::
-DLLVM_TARGETS_TO_BUILD="BPF"
Quick sniplet for manually compiling LLVM and clang
(build dependencies are cmake and gcc-c++)::
$ git clone http://llvm.org/git/llvm.git
$ cd llvm/tools
$ git clone --depth 1 http://llvm.org/git/clang.git
$ cd ..; mkdir build; cd build
$ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86"
$ make -j $(getconf _NPROCESSORS_ONLN)
It is also possible to point make to the newly compiled 'llc' or
'clang' command via redefining LLC or CLANG on the make command line::
make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
Cross compiling samples
-----------------------
In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
environment variables before calling make. This will direct make to build
samples for the cross target.
export ARCH=arm64
export CROSS_COMPILE="aarch64-linux-gnu-"
make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
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