Daniel Borkmann says:
====================
pull-request: bpf 2019-07-03
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) Fix the interpreter to properly handle BPF_ALU32 | BPF_ARSH
on BE architectures, from Jiong.
2) Fix several bugs in the x32 BPF JIT for handling shifts by 0,
from Luke and Xi.
3) Fix NULL pointer deref in btf_type_is_resolve_source_only(),
from Stanislav.
4) Properly handle the check that forwarding is enabled on the device
in bpf_ipv6_fib_lookup() helper code, from Anton.
5) Fix UAPI bpf_prog_info fields alignment for archs that have 16 bit
alignment such as m68k, from Baruch.
6) Fix kernel hanging in unregister_netdevice loop while unregistering
device bound to XDP socket, from Ilya.
7) Properly terminate tail update in xskq_produce_flush_desc(), from Nathan.
8) Fix broken always_inline handling in test_lwt_seg6local, from Jiri.
9) Fix bpftool to use correct argument in cgroup errors, from Jakub.
10) Fix detaching dummy prog in XDP redirect sample code, from Prashant.
11) Add Jonathan to AF_XDP reviewers, from Björn.
====================
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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