Daniel Borkmann says:
====================
pull-request: bpf 2017-12-02
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) Fix a compilation warning in xdp redirect tracepoint due to
missing bpf.h include that pulls in struct bpf_map, from Xie.
2) Limit the maximum number of attachable BPF progs for a given
perf event as long as uabi is not frozen yet. The hard upper
limit is now 64 and therefore the same as with BPF multi-prog
for cgroups. Also add related error checking for the sample
BPF loader when enabling and attaching to the perf event, from
Yonghong.
3) Specifically set the RLIMIT_MEMLOCK for the test_verifier_log
case, so that the test case can always pass and not fail in
some environments due to too low default limit, also from
Yonghong.
4) Fix up a missing license header comment for kernel/bpf/offload.c,
from Jakub.
5) Several fixes for bpftool, among others a crash on incorrect
arguments when json output is used, error message handling
fixes on unknown options and proper destruction of json writer
for some exit cases, all from Quentin.
====================
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
c2eb6d07a6