Makefile

# List of programs to build
hostprogs-y := sockmap

# Libbpf dependencies
LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o

HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS += -I$(srctree)/tools/lib/
HOSTCFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
HOSTCFLAGS += -I$(srctree)/tools/lib/ -I$(srctree)/tools/include
HOSTCFLAGS += -I$(srctree)/tools/perf

sockmap-objs := ../bpf/bpf_load.o $(LIBBPF) sockmap_user.o

# Tell kbuild to always build the programs
always := $(hostprogs-y)
always += sockmap_kern.o

HOSTLOADLIBES_sockmap += -lelf -lpthread

# 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 ../../ $(CURDIR)/

clean:
	$(MAKE) -C ../../ M=$(CURDIR) clean
	@rm -f *~

$(obj)/syscall_nrs.s:	$(src)/syscall_nrs.c
	$(call if_changed_dep,cc_s_c)

$(obj)/syscall_nrs.h:	$(obj)/syscall_nrs.s FORCE
	$(call filechk,offsets,__SYSCALL_NRS_H__)

clean-files += syscall_nrs.h

FORCE:


# 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.
#
# -target bpf option required with SK_MSG programs, this is to ensure
#  reading 'void *' data types for data and data_end are __u64 reads.
$(obj)/%.o: $(src)/%.c
	$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) -I$(obj) \
		-D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
		-Wno-compare-distinct-pointer-types \
		-Wno-gnu-variable-sized-type-not-at-end \
		-Wno-address-of-packed-member -Wno-tautological-compare \
		-Wno-unknown-warning-option -O2 -target bpf \
		-emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@