Daniel Borkmann says:
====================
pull-request: bpf-next 2017-12-03
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Addition of a software model for BPF offloads in order to ease
testing code changes in that area and make semantics more clear.
This is implemented in a new driver called netdevsim, which can
later also be extended for other offloads. SR-IOV support is added
as well to netdevsim. BPF kernel selftests for offloading are
added so we can track basic functionality as well as exercising
all corner cases around BPF offloading, from Jakub.
2) Today drivers have to drop the reference on BPF progs they hold
due to XDP on device teardown themselves. Change this in order
to make XDP handling inside the drivers less error prone, and
move disabling XDP to the core instead, also from Jakub.
3) Misc set of BPF verifier improvements and cleanups as preparatory
work for upcoming BPF-to-BPF calls. Among others, this set also
improves liveness marking such that pruning can be slightly more
effective. Register and stack liveness information is now included
in the verifier log as well, from Alexei.
4) nfp JIT improvements in order to identify load/store sequences in
the BPF prog e.g. coming from memcpy lowering and optimizing them
through the NPU's command push pull (CPP) instruction, from Jiong.
5) Cleanups to test_cgrp2_attach2.c BPF sample code in oder to remove
bpf_prog_attach() magic values and replacing them with actual proper
attach flag instead, from David.
====================
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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