Re: [PATCH bpf-next] bpf: add --skip_encoding_btf_inconsistent_proto, --btf_gen_optimized to pahole flags for v1.25

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

Em Wed, Feb 08, 2023 at 05:17:02PM +0000, Alan Maguire escreveu:
> From: Alan Maguire <alan.maguire@oracle.com>
> Date: Thu, 2 Feb 2023 12:26:20 +0000
> Subject: [PATCH bpf-next] bpf: add --skip_encoding_btf_inconsistent_proto,
>  --btf_gen_optimized to pahole flags for v1.25
> 
> v1.25 of pahole supports filtering out functions with multiple
> inconsistent function prototypes or optimized-out parameters
> from the BTF representation.  These present problems because
> there is no additional info in BTF saying which inconsistent
> prototype matches which function instance to help guide
> attachment, and functions with optimized-out parameters can
> lead to incorrect assumptions about register contents.
> 
> So for now, filter out such functions while adding BTF
> representations for functions that have "."-suffixes
> (foo.isra.0) but not optimized-out parameters.
> 
> This patch assumes changes in [1] land and pahole is bumped
> to v1.25.
> 
> [1] https://lore.kernel.org/bpf/1675790102-23037-1-git-send-email-alan.maguire@oracle.com/
> 
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---
>  scripts/pahole-flags.sh | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh
> index 1f1f1d3..728d551 100755
> --- a/scripts/pahole-flags.sh
> +++ b/scripts/pahole-flags.sh
> @@ -23,5 +23,8 @@ if [ "${pahole_ver}" -ge "124" ]; then
>  	# see PAHOLE_HAS_LANG_EXCLUDE
>  	extra_paholeopt="${extra_paholeopt} --lang_exclude=rust"
>  fi
> +if [ "${pahole_ver}" -ge "125" ]; then
> +	extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_inconsistent_proto --btf_gen_optimized"
> +fi
>  
>  echo ${extra_paholeopt}
> -- 
> 1.8.3.1


I applied the patch and it works as advertised using what is in pahole's
'next' branch, that should go to 'master' later today.

Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>

- Arnaldo