Commit 3f7a3318 authored by Quentin Monnet's avatar Quentin Monnet Committed by Andrii Nakryiko
Browse files

samples/bpf: Install libbpf headers when building 



API headers from libbpf should not be accessed directly from the source
directory. Instead, they should be exported with "make install_headers".
Make sure that samples/bpf/Makefile installs the headers properly when
building.

The object compiled from and exported by libbpf are now placed into a
subdirectory of sample/bpf/ instead of remaining in tools/lib/bpf/. We
attempt to remove this directory on "make clean". However, the "clean"
target re-enters the samples/bpf/ directory from the root of the
repository ("$(MAKE) -C ../../ M=$(CURDIR) clean"), in such a way that
$(srctree) and $(src) are not defined, making it impossible to use
$(LIBBPF_OUTPUT) and $(LIBBPF_DESTDIR) in the recipe. So we only attempt
to clean $(CURDIR)/libbpf, which is the default value.

Add a dependency on libbpf's headers for the $(TRACE_HELPERS).

We also change the output directory for bpftool, to place the generated
objects under samples/bpf/bpftool/ instead of building in bpftool's
directory directly. Doing so, we make sure bpftool reuses the libbpf
library previously compiled and installed.

Signed-off-by: default avatarQuentin Monnet <quentin@isovalent.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211007194438.34443-10-quentin@isovalent.com
parent 62fde1c8

samples/bpf/Makefile

+30 −10
Original line number Diff line number Diff line
@@ -61,7 +61,11 @@ tprogs-y += xdp_redirect 
tprogs-y += xdp_monitor



# Libbpf dependencies

LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a

LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf

LIBBPF_OUTPUT = $(abspath $(BPF_SAMPLES_PATH))/libbpf

LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)

LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include

LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a



CGROUP_HELPERS := ../../tools/testing/selftests/bpf/cgroup_helpers.o

TRACE_HELPERS := ../../tools/testing/selftests/bpf/trace_helpers.o
@@ -200,7 +204,7 @@ TPROGS_CFLAGS += -Wstrict-prototypes 


TPROGS_CFLAGS += -I$(objtree)/usr/include

TPROGS_CFLAGS += -I$(srctree)/tools/testing/selftests/bpf/

TPROGS_CFLAGS += -I$(srctree)/tools/lib/

TPROGS_CFLAGS += -I$(LIBBPF_INCLUDE)

TPROGS_CFLAGS += -I$(srctree)/tools/include

TPROGS_CFLAGS += -I$(srctree)/tools/perf

TPROGS_CFLAGS += -DHAVE_ATTR_TEST=0
@@ -270,16 +274,27 @@ all: 
clean:

	$(MAKE) -C ../../ M=$(CURDIR) clean

	@find $(CURDIR) -type f -name '*~' -delete

	@$(RM) -r $(CURDIR)/libbpf $(CURDIR)/bpftool



$(LIBBPF): FORCE

$(LIBBPF): FORCE | $(LIBBPF_OUTPUT)

# Fix up variables inherited from Kbuild that tools/ build system won't like

	$(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \

		LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ O=

	$(MAKE) -C $(LIBBPF_SRC) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \

		LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ \

		O= OUTPUT=$(LIBBPF_OUTPUT)/ DESTDIR=$(LIBBPF_DESTDIR) prefix= \

		$@ install_headers



BPFTOOLDIR := $(TOOLS_PATH)/bpf/bpftool

BPFTOOL := $(BPFTOOLDIR)/bpftool

$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)

	    $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../

BPFTOOL_OUTPUT := $(abspath $(BPF_SAMPLES_PATH))/bpftool

BPFTOOL := $(BPFTOOL_OUTPUT)/bpftool

$(BPFTOOL): $(LIBBPF) $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)

	    $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \

		OUTPUT=$(BPFTOOL_OUTPUT)/ \

		LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/ \

		LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/



$(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):

	$(call msg,MKDIR,$@)

	$(Q)mkdir -p $@



$(obj)/syscall_nrs.h:	$(obj)/syscall_nrs.s FORCE

	$(call filechk,offsets,__SYSCALL_NRS_H__)
@@ -311,6 +326,11 @@ verify_target_bpf: verify_cmds 
$(BPF_SAMPLES_PATH)/*.c: verify_target_bpf $(LIBBPF)

$(src)/*.c: verify_target_bpf $(LIBBPF)



libbpf_hdrs: $(LIBBPF)

$(obj)/$(TRACE_HELPERS): | libbpf_hdrs



.PHONY: libbpf_hdrs



$(obj)/xdp_redirect_cpu_user.o: $(obj)/xdp_redirect_cpu.skel.h

$(obj)/xdp_redirect_map_multi_user.o: $(obj)/xdp_redirect_map_multi.skel.h

$(obj)/xdp_redirect_map_user.o: $(obj)/xdp_redirect_map.skel.h
@@ -369,7 +389,7 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/x 
	$(Q)$(CLANG) -g -O2 -target bpf -D__TARGET_ARCH_$(SRCARCH) \

		-Wno-compare-distinct-pointer-types -I$(srctree)/include \

		-I$(srctree)/samples/bpf -I$(srctree)/tools/include \

		-I$(srctree)/tools/lib $(CLANG_SYS_INCLUDES) \

		-I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES) \

		-c $(filter %.bpf.c,$^) -o $@



LINKED_SKELS := xdp_redirect_cpu.skel.h xdp_redirect_map_multi.skel.h \
@@ -406,7 +426,7 @@ $(obj)/%.o: $(src)/%.c 
	@echo "  CLANG-bpf " $@

	$(Q)$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(BPF_EXTRA_CFLAGS) \

		-I$(obj) -I$(srctree)/tools/testing/selftests/bpf/ \

		-I$(srctree)/tools/lib/ \

		-I$(LIBBPF_INCLUDE) \

		-D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign \

		-D__TARGET_ARCH_$(SRCARCH) -Wno-compare-distinct-pointer-types \

		-Wno-gnu-variable-sized-type-not-at-end \