Re: Building perf with BUILD_BPF_SKEL=1 by default

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Sun, Dec 05, 2021 at 10:06:42AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Dec 03, 2021 at 07:32:34PM +0000, Song Liu escreveu:
> > 
> > 
> > > On Dec 3, 2021, at 5:10 AM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > > 
> > > Hi Song,
> > > 
> > > 	So I'm changing all my containers to build with BUILD_BPF_SKEL=1
> > > to then make this the default, so far older containers fail either
> > > because the clang available is too old, so I've added a NO_BUILD_BPF_SKEL=1
> > > env var to disable that in those containers and then there is this other
> > > case where clang is recent enough but:
> > > 
> > >    util/bpf_skel/bperf_leader.bpf.c:13:20: error: use of undeclared identifier 'BPF_F_PRESERVE_ELEMS'
> > >            __uint(map_flags, BPF_F_PRESERVE_ELEMS);
> > > 
> > > Because the system's /usr/include/linux/bpf.h doesn't have that
> > > BPF_F_PRESERVE_ELEMS enum entry.
> > > 
> > > These are enums to make them available via BTF, but then I can't use
> > > the:
> > > 
> > > #ifdef BPF_F_PRESERVE_ELEMS
> > > #define BPF_F_PRESERVE_ELEMS (1U << 11)
> > > #endif
> > > 
> > > approach.
> > > 
> > > But then we _have_ it in the tools/include/uapi/linux/bpf.h we ship:
> > > 
> > > $ grep BPF_F_PRESERVE_ELEMS tools/include/uapi/linux/bpf.h
> > > 	BPF_F_PRESERVE_ELEMS	= (1U << 11),
> > > $
> > > 
> > > so we need to switch to using it somehow, this way we can build in more
> > > systems and make bperf and other BPF enabled features.
> > > 
> > > From a quick look I couldn't find where to add
> > > $(sourcedir)/tools/include/uapi/ to the include path used to build
> > > util/bpf_skel/bperf_leader.bpf.c, should be easy, can you take a look?
> > > 
> > > Thanks,
> > > 
> > > - Arnaldo
> > 
> > I think the following should fix it
> 
> I'm trying this now and tentatively sticking a Signed-off-by: you to it,
> ok?

Fixed these as well (debian:11, debian:experimental, some recent
ubuntus):

In file included from util/bpf_skel/bperf_follower.bpf.c:3:
In file included from /usr/include/linux/bpf.h:11:
In file included from /usr/include/linux/types.hutil/bpf_skel/bperf_leader.bpf.c::5In file included from :3util/bpf_skel/bpf_prog_profiler.bpf.c10:
::In file included from 3 /usr/include/linux/bpf.h:
:In file included from 11/usr/include/linux/bpf.h:
fatal error:: 11/usr/include/linux/types.h:
:'asm/types.h' file not found5:/usr/include/linux/types.h10
::5 :10: fatal errorfatal error: : 'asm/types.h' file not found'asm/types.h' file not found#include <asm/types.h>


         ^~~~~~~~~~~~~
#include <asm/types.h>#include <asm/types.h>

         ^~~~~~~~~~~~~         ^~~~~~~~~~~~~

1 error generated.
1 error generated.
1 error generated.
make[2]: *** [Makefile.perf:1072: /tmp/build/perf/util/bpf_skel/.tmp/bperf_follower.bpf.o] Error 1