On Thu, Sep 9, 2021 at 2:43 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On 9/9/21 8:08 PM, Andrii Nakryiko wrote: > > On Thu, Sep 9, 2021 at 9:37 AM Andrii Nakryiko > > <andrii.nakryiko@xxxxxxxxx> wrote: > >> 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. > > > > Hm... I can't repro this. Both preload/iterators and resolve_btfids > > have $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) > > dependency which will trigger libbpf rebuild if any of libbpf source > > files changes. I added `sleep 1000` and everything under kernel/bpf is > > blocked on this until libbpf build completes. For full kernel build it > > also shouldn't happen because we build resolve_btfids first before > > proceeding to building other files and resolve_btfids should trigger > > libbpf build. > > > > I assume `make clean kernel/bpf` fixed the issue for you in that case? > > No, fixing on that node was done via re-building libbpf via tools/lib/bpf/. > > > Also, how did you build tools/lib/bpf before running `make -j8 kernel/bpf`? > > Basically just i) cd tools/lib/bpf, ii) make clean, iii) make, then applying > the patch, and then running make -j8 kernel/bpf. I just tried on a different > build node with newer user space, and there it indeed triggers a rebuild of > libbpf. On my laptop where I was running into this it didn't. I would suspect > a potential diff in make's behavior (not seen in GNU Make 4.3, seen in GNU > Make 4.2.1, fwiw). Anyway, for this niche case, manual rebuild of tools/lib/bpf > does it ... given it's neither seen in your case nor on newer uspace, I took > it in, lets see how it goes. Thanks! Yeah, thanks! Please let me know if you do run into this again somewhere, though. > > > Honestly, hard to tell how this happens without being able to repro > > this. So far everything seems to be working for me. I've tried with > > and without the KBUILD_OUTPUT envvar set. I also tried O=<path>. > > > >>> > >>> Thanks, > >>> Daniel >
