On Sun, Oct 3, 2021 at 12:22 PM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote: > > API headers from libbpf should not be accessed directly from the > library's source directory. Instead, they should be exported with "make > install_headers". Let's make sure that bpf/preload/Makefile installs the > headers properly when building. > > Note that we declare an additional dependency for iterators/iterators.o: > having $(LIBBPF_A) as a dependency to "$(obj)/bpf_preload_umd" is not > sufficient, as it makes it required only at the linking step. But we > need libbpf to be compiled, and in particular its headers to be > exported, before we attempt to compile iterators.o. The issue would not > occur before this commit, because libbpf's headers were not exported and > were always available under tools/lib/bpf. > > Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> > --- > kernel/bpf/preload/Makefile | 25 ++++++++++++++++++++----- > 1 file changed, 20 insertions(+), 5 deletions(-) > > diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile > index 1951332dd15f..efccf857f7ed 100644 > --- a/kernel/bpf/preload/Makefile > +++ b/kernel/bpf/preload/Makefile > @@ -1,21 +1,36 @@ > # SPDX-License-Identifier: GPL-2.0 > > LIBBPF_SRCS = $(srctree)/tools/lib/bpf/ > -LIBBPF_A = $(obj)/libbpf.a > -LIBBPF_OUT = $(abspath $(obj)) > +LIBBPF_OUT = $(abspath $(obj))/libbpf > +LIBBPF_A = $(LIBBPF_OUT)/libbpf.a > +LIBBPF_DESTDIR = $(LIBBPF_OUT) > +LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include > > # Although not in use by libbpf's Makefile, set $(O) so that the "dummy" test > # in tools/scripts/Makefile.include always succeeds when building the kernel > # with $(O) pointing to a relative path, as in "make O=build bindeb-pkg". > -$(LIBBPF_A): > - $(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a > +$(LIBBPF_A): | $(LIBBPF_OUT) > + $(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ \ > + DESTDIR=$(LIBBPF_DESTDIR) prefix= \ > + $(LIBBPF_OUT)/libbpf.a install_headers > + > +libbpf_hdrs: $(LIBBPF_A) > + > +.PHONY: libbpf_hdrs > + > +$(LIBBPF_OUT): > + $(call msg,MKDIR,$@) > + $(Q)mkdir -p $@ > > userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ > - -I $(srctree)/tools/lib/ -Wno-unused-result > + -I $(LIBBPF_INCLUDE) -Wno-unused-result > > userprogs := bpf_preload_umd > > clean-files := $(userprogs) bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/ > +clean-files += $(LIBBPF_OUT) $(LIBBPF_DESTDIR) > + > +$(obj)/iterators/iterators.o: libbpf_hdrs this should probably be order-only dependency as well > > bpf_preload_umd-objs := iterators/iterators.o > bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz > -- > 2.30.2 >
