On Thu, Sep 9, 2021 at 5:58 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On 9/8/21 11:32 PM, Andrii Nakryiko wrote: > > From: Quentin Monnet <quentin@xxxxxxxxxxxxx> > > > > Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare > > the deprecation of two API functions. This macro marks functions as deprecated > > when libbpf's version reaches the values passed as an argument. > > > > As part of this change libbpf_version.h header is added with recorded major > > (LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros. > > They are now part of libbpf public API and can be relied upon by user code. > > libbpf_version.h is installed system-wide along other libbpf public headers. > > > > Due to this new build-time auto-generated header, in-kernel applications > > relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to > > include libbpf's output directory as part of a list of include search paths. > > Better fix would be to use libbpf's make_install target to install public API > > headers, but that clean up is left out as a future improvement. The build > > changes were tested by building kernel (with KBUILD_OUTPUT and O= specified > > explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No > > problems were detected. > > > > Note that because of the constraints of the C preprocessor we have to write > > a few lines of macro magic for each version used to prepare deprecation (0.6 > > for now). > > > > Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of > > btf__get_from_id() and btf__load(), which are replaced by > > btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively, > > starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]). > > > > [0] Closes: https://github.com/libbpf/libbpf/issues/278 > > > > Co-developed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> > > Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > --- > > v2->v3: > > - adding `sleep 10` revealed two more missing dependencies in resolve_btfids > > and selftest/bpf's bench, which were fixed (BPF CI); > > v1->v2: > > - fix bpf_preload build by adding dependency for iterators/iterators.o on > > libbpf.a generation (caught by BPF CI); > > > > kernel/bpf/preload/Makefile | 7 +++++-- > > tools/bpf/bpftool/Makefile | 4 ++++ > > tools/bpf/resolve_btfids/Makefile | 6 ++++-- > > tools/lib/bpf/Makefile | 24 +++++++++++++++++------- > > tools/lib/bpf/btf.h | 2 ++ > > tools/lib/bpf/libbpf_common.h | 19 +++++++++++++++++++ > > tools/testing/selftests/bpf/Makefile | 4 ++-- > > 7 files changed, 53 insertions(+), 13 deletions(-) > > > > diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile > > index 1951332dd15f..ac29d4e9a384 100644 > > --- a/kernel/bpf/preload/Makefile > > +++ b/kernel/bpf/preload/Makefile > > @@ -10,12 +10,15 @@ LIBBPF_OUT = $(abspath $(obj)) > > $(LIBBPF_A): > > $(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a > > > > -userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ > > +userccflags += -I$(LIBBPF_OUT) -I $(srctree)/tools/include/ \ > > + -I $(srctree)/tools/include/uapi \ > > -I $(srctree)/tools/lib/ -Wno-unused-result > > > > userprogs := bpf_preload_umd > > > > -clean-files := $(userprogs) bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/ > > +clean-files := $(userprogs) libbpf_version.h bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/ > > + > > +$(obj)/iterators/iterators.o: $(LIBBPF_A) > > > > bpf_preload_umd-objs := iterators/iterators.o > > bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz > > One small issue I ran into by accident while testing: > > [root@linux bpf-next]# make -j8 kernel/bpf/ > SYNC include/config/auto.conf.cmd > DESCEND objtool > CALL scripts/atomic/check-atomics.sh > CALL scripts/checksyscalls.sh > CC kernel/bpf/syscall.o > AR kernel/bpf/preload/built-in.a > CC [M] kernel/bpf/preload/bpf_preload_kern.o > CC [U] kernel/bpf/preload/iterators/iterators.o > In file included from ./tools/lib/bpf/libbpf.h:20, > from kernel/bpf/preload/iterators/iterators.c:10: > ./tools/lib/bpf/libbpf_common.h:13:10: fatal error: libbpf_version.h: No such file or directory > 13 | #include "libbpf_version.h" > | ^~~~~~~~~~~~~~~~~~ > compilation terminated. > make[3]: *** [scripts/Makefile.userprogs:43: kernel/bpf/preload/iterators/iterators.o] Error 1 > make[3]: *** Waiting for unfinished jobs.... > make[2]: *** [scripts/Makefile.build:540: kernel/bpf/preload] Error 2 > make[2]: *** Waiting for unfinished jobs.... > make[1]: *** [scripts/Makefile.build:540: kernel/bpf] Error 2 > make: *** [Makefile:1872: kernel] Error 2 > > For me it was the case where tools/lib/bpf/ was already built _before_ this patch > was applied, then I applied it, and just ran make -j8 kernel/bpf/ where the above > can then be reproduced. I'd assume that as-is, this would affect many folks on update. We had a similar issue even before these changes with resolve_btfids build, because Kbuild doesn't record dependency on libbpf build properly. I'll see how hard it is to record that in a non-intrusive way for both resolve_btfids and preload/iterators, because doing `make resolve_btfids_clean` or, worse, `make clean` isn't great. > > Thanks, > Daniel
