I ran into the same issue
DESCEND objtool
DESCEND bpf/resolve_btfids
CALL scripts/atomic/check-atomics.sh
CALL scripts/checksyscalls.sh
CHK include/generated/compile.h
CC kernel/rseq.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[2]: *** [scripts/Makefile.build:540: kernel/bpf/preload] Error 2
make[1]: *** [scripts/Makefile.build:540: kernel/bpf] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:1872: kernel] Error 2
make: *** Waiting for unfinished jobs....
And I tried `make clean` in tools/lib/bpf , which didn't solve the
issue, had to do a full clean. To me it seems we should add
"libbpf_version.h" along with LIBBPF_A in kernel/bpf/preload/Makefile
Cheers.
On Thu, Sep 9, 2021 at 6:48 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> 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
> >
