Re: [PATCH v2] kbuild: allow symbol whitelisting with TRIM_UNUSED_KSYMS

[Matthias Maennich]

On Fri, Jan 31, 2020 at 05:40:55PM +0000, Quentin Perret wrote:
> On Friday 31 Jan 2020 at 13:15:08 (+0000), 'Matthias Maennich' via kernel-team wrote:
> > On Wed, Jan 29, 2020 at 06:15:41PM +0000, Quentin Perret wrote:
> > > diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
> > > index a904bf1f5e67..8e1b7f70e800 100755
> > > --- a/scripts/adjust_autoksyms.sh
> > > +++ b/scripts/adjust_autoksyms.sh
> > > @@ -48,6 +48,7 @@ cat > "$new_ksyms_file" << EOT
> > > EOT
> > > sed 's/ko$/mod/' modules.order |
> > > xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
> > > +cat - "${CONFIG_UNUSED_KSYMS_WHITELIST:-/dev/null}" |
> >
> > This handles absolute paths very well. I wonder whether we can make this
> > more useful for folks that want to maintain such a whitelist in their
> > copy of the tree. Lets say, I have in my sources
> > arch/x86/configs/x86_64_symbol_whitelist and in my config I have
> > CONFIG_UNUSED_KSYMS_WHITELIST="arch/x86/configs/x86_64_symbol_whitelist".
> >
> > If I see it correctly, UNUSED_KSYMS_WHITELIST is currently either an
> > absolute path or a relative path to the current build directory. I would
> > prefer if relative paths would be relative to the source directory to
> > support the above use case. (Note, that scenario above works if I build
> > directly in the sources, but fails if I build O=/somewhere/else.)
>
> Right, that is an interesting use case. I suppose something like the
> below should work (with appropriate documentation of the config option).
>
> ---8<---
> diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
> index 8e1b7f70e800..d37803fd75ce 100755
> --- a/scripts/adjust_autoksyms.sh
> +++ b/scripts/adjust_autoksyms.sh
> @@ -38,6 +38,12 @@ esac
> # We need access to CONFIG_ symbols
> . include/config/auto.conf
>
> +ksym_wl="${CONFIG_UNUSED_KSYMS_WHITELIST:-/dev/null}"
> +# If the path is relative, it must be relative to the source tree
> +if [ "$ksym_wl" == "${ksym_wl#/}" ]; then
> +       ksym_wl="$abs_srctree/$ksym_wl"
> +fi
> +
> # Generate a new ksym list file with symbols needed by the current
> # set of modules.
> cat > "$new_ksyms_file" << EOT
> @@ -48,7 +54,7 @@ cat > "$new_ksyms_file" << EOT
> EOT
> sed 's/ko$/mod/' modules.order |
> xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
> -cat - "${CONFIG_UNUSED_KSYMS_WHITELIST:-/dev/null}" |
> +cat - "$ksym_wl" |
> sort -u |
> sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$new_ksyms_file"
> --->8---
>
> Thoughts ?

That definitely looks like I would expect that config option to work.
Thanks for looking into that!

Cheers,
Matthias

> Thanks,
> Quentin