77 lines
2.3 KiB
ReStructuredText
77 lines
2.3 KiB
ReStructuredText
eBPF sample programs
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====================
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This directory contains a test stubs, verifier test-suite and examples
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for using eBPF. The examples use libbpf from tools/lib/bpf.
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Build dependencies
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==================
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Compiling requires having installed:
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* clang >= version 3.4.0
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* llvm >= version 3.7.1
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Note that LLVM's tool 'llc' must support target 'bpf', list version
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and supported targets with command: ``llc --version``
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Kernel headers
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--------------
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There are usually dependencies to header files of the current kernel.
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To avoid installing devel kernel headers system wide, as a normal
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user, simply call::
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make headers_install
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This will creates a local "usr/include" directory in the git/build top
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level directory, that the make system automatically pickup first.
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Compiling
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=========
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For building the BPF samples, issue the below command from the kernel
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top level directory::
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make samples/bpf/
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Do notice the "/" slash after the directory name.
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It is also possible to call make from this directory. This will just
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hide the the invocation of make as above with the appended "/".
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Manually compiling LLVM with 'bpf' support
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------------------------------------------
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Since version 3.7.0, LLVM adds a proper LLVM backend target for the
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BPF bytecode architecture.
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By default llvm will build all non-experimental backends including bpf.
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To generate a smaller llc binary one can use::
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-DLLVM_TARGETS_TO_BUILD="BPF"
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Quick sniplet for manually compiling LLVM and clang
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(build dependencies are cmake and gcc-c++)::
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$ git clone http://llvm.org/git/llvm.git
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$ cd llvm/tools
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$ git clone --depth 1 http://llvm.org/git/clang.git
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$ cd ..; mkdir build; cd build
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$ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86"
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$ make -j $(getconf _NPROCESSORS_ONLN)
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It is also possible to point make to the newly compiled 'llc' or
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'clang' command via redefining LLC or CLANG on the make command line::
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make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
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Cross compiling samples
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-----------------------
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In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
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environment variables before calling make. This will direct make to build
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samples for the cross target.
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export ARCH=arm64
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export CROSS_COMPILE="aarch64-linux-gnu-"
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make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
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