diff options
| -rw-r--r-- | samples/bpf/Makefile | 37 | ||||
| -rw-r--r-- | samples/bpf/README.rst | 66 |
2 files changed, 101 insertions, 2 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 744dd7a16144..66897e61232c 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -81,10 +81,43 @@ HOSTLOADLIBES_spintest += -lelf HOSTLOADLIBES_map_perf_test += -lelf -lrt HOSTLOADLIBES_test_overhead += -lelf -lrt +# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline: +# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang +LLC ?= llc +CLANG ?= clang + +# Trick to allow make to be run from this directory +all: + $(MAKE) -C ../../ $$PWD/ + +clean: + $(MAKE) -C ../../ M=$$PWD clean + @rm -f *~ + +# Verify LLVM compiler tools are available and bpf target is supported by llc +.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC) + +verify_cmds: $(CLANG) $(LLC) + @for TOOL in $^ ; do \ + if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \ + echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\ + exit 1; \ + else true; fi; \ + done + +verify_target_bpf: verify_cmds + @if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \ + echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\ + echo " NOTICE: LLVM version >= 3.7.1 required" ;\ + exit 2; \ + else true; fi + +$(src)/*.c: verify_target_bpf + # asm/sysreg.h - inline assembly used by it is incompatible with llvm. # But, there is no easy way to fix it, so just exclude it since it is # useless for BPF samples. $(obj)/%.o: $(src)/%.c - clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \ + $(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \ -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \ - -O2 -emit-llvm -c $< -o -| llc -march=bpf -filetype=obj -o $@ + -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@ diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst new file mode 100644 index 000000000000..a43eae3f0551 --- /dev/null +++ b/samples/bpf/README.rst @@ -0,0 +1,66 @@ +eBPF sample programs +==================== + +This directory contains a mini eBPF library, test stubs, verifier +test-suite and examples for using eBPF. + +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 |