Re: [PATCH v3 dwarves 0/8] dwarves: support encoding of optimized-out parameters, removal of inconsistent static functions

[Jiri Olsa <olsajiri@gmail.com>]

On Wed, Feb 08, 2023 at 01:50:27PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Feb 08, 2023 at 01:20:39PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Tue, Feb 07, 2023 at 05:14:54PM +0000, Alan Maguire escreveu:
> > > At optimization level -O2 or higher in gcc, static functions may be
> > > optimized such that they have suffixes like .isra.0, .constprop.0 etc.
> > > These represent 
> > >     
> > > - constant propagation (.constprop.0);
> > > - interprocedural scalar replacement of aggregates, removal of
> > >   unused parameters and replacement of parameters passed by
> > >   reference by parameters passed by value (.isra.0)
> > 
> > Initial test, without using the new options:
> > 
> > [acme@pumpkin ~]$ pfunct /sys/kernel/btf/vmlinux  | sort | uniq -c | sort -n | tail
> >       3 start_show
> >       3 timeout_show
> >       3 uuid_show
> >       4 m_next
> >       4 parse_options
> >       4 sk_diag_fill
> >       4 state_show
> >       4 state_store
> >       5 status_show
> >       6 type_show
> > [acme@pumpkin ~]$
> > 
> > Now I'll use --skip_encoding_btf_inconsistent_proto and --btf_gen_optimized
> 
> With:
> 
> ⬢[acme@toolbox linux]$ git diff
> diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh
> index 1f1f1d397c399afe..9dd185fb1ff1fc3b 100755
> --- a/scripts/pahole-flags.sh
> +++ b/scripts/pahole-flags.sh
> @@ -21,7 +21,7 @@ if [ "${pahole_ver}" -ge "122" ]; then
>  fi
>  if [ "${pahole_ver}" -ge "124" ]; then
>         # see PAHOLE_HAS_LANG_EXCLUDE
> -       extra_paholeopt="${extra_paholeopt} --lang_exclude=rust"
> +       extra_paholeopt="${extra_paholeopt} --lang_exclude=rust --btf_gen_optimized --skip_encoding_btf_inconsistent_proto"
>  fi
> 
>  echo ${extra_paholeopt}
> ⬢[acme@toolbox linux]$
> 
> I get:
> 
> [acme@pumpkin ~]$ pfunct /sys/kernel/btf/vmlinux  | sort | uniq -c | sort -n | tail
>       1 zswap_writeback_entry
>       1 zswap_zpool_param_set
>       1 zs_zpool_create
>       1 zs_zpool_destroy
>       1 zs_zpool_free
>       1 zs_zpool_malloc
>       1 zs_zpool_map
>       1 zs_zpool_shrink
>       1 zs_zpool_total_size
>       1 zs_zpool_unmap
> [acme@pumpkin ~]$
> 
> No functions with more than one entry:
> 
> [acme@pumpkin ~]$ pfunct /sys/kernel/btf/vmlinux  | sort | uniq -c | sort -n | grep -v ' 1 '
> [acme@pumpkin ~]$ pfunct /sys/kernel/btf/vmlinux  | sort | uniq -c | sort -n | grep ' 1 ' | wc -l
> 54558
> [acme@pumpkin ~]$ pfunct /sys/kernel/btf/vmlinux  | wc -l
> 54558
> [acme@pumpkin ~]$
> 
> So I'll bump the release as we did in the past when testing features
> that we need to test against a release on the pahole-flags.sh script so
> that we can do further tests.

I did similar test and ran bpf selftests built with new pahole,
all looks good

Acked/Tested-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka