Re: [PATCH 2/8] perf bpf filter: Implement event sample filtering

Namhyung Kim
2023-02-22T19:48:58Z

On Sun, Feb 19, 2023 at 8:48 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Sun, Feb 19, 2023 at 3:14 AM Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> >
> > Em Sat, Feb 18, 2023 at 10:13:23PM -0800, Namhyung Kim escreveu:
> > > The BPF program will be attached to a perf_event and be triggered when
> > > it overflows. It'd iterate the filters map and compare the sample
> > > value according to the expression. If any of them fails, the sample
> > > would be dropped.
> > >
> > > Also it needs to have the corresponding sample data for the expression
> > > so it compares data->sample_flags with the given value. To access the
> > > sample data, it uses the bpf_cast_to_kern_ctx() kfunc which was added
> > > in v6.2 kernel.
> >
> > CLANG /tmp/build/perf/util/bpf_skel/.tmp/sample_filter.bpf.o
> > util/bpf_skel/sample_filter.bpf.c:26:19: error: no member named 'sample_flags' in 'struct perf_sample_data'
> > if ((kctx->data->sample_flags & entry->flags) == 0)
> > ~~~~~~~~~~ ^
> > 1 error generated.
> > make[2]: *** [Makefile.perf:1078: /tmp/build/perf/util/bpf_skel/.tmp/sample_filter.bpf.o] Error 1
> > make[1]: *** [Makefile.perf:236: sub-make] Error 2
> > make: *** [Makefile:113: install-bin] Error 2
> > make: Leaving directory '/var/home/acme/git/perf/tools/perf'
> >
> > Performance counter stats for 'make -k BUILD_BPF_SKEL=1 CORESIGHT=1 O=/tmp/build/perf -C tools/perf install-bin':
>
> Hmm.. strange. In the include/linux/perf_event.h, the
> perf_sample_data has sample_flags, but vmlinux.h doesn't.

It looks like the vmlinux.h came from the old kernel image (before v6.1).
Please try again after building the kernel. I'll add a check to prevent
such a build error in v3.

Thanks,
Namhyung