linux-kernel - Re: [PATCH v4 10/14] kbuild: check static EXPORT

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Date:   Tue, 10 May 2022 22:53:40 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nicolas Schier <nicolas@...sle.eu>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-modules <linux-modules@...r.kernel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: Re: [PATCH v4 10/14] kbuild: check static EXPORT_SYMBOL* by script
 instead of modpost

On Tue, May 10, 2022 at 3:05 AM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@...glegroups.com> wrote:
>
> On Sun, May 8, 2022 at 12:10 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > diff --git a/scripts/check-local-export b/scripts/check-local-export
> > new file mode 100755
> > index 000000000000..d1721fa63057
> > --- /dev/null
> > +++ b/scripts/check-local-export
> > @@ -0,0 +1,48 @@
> > +#!/bin/bash
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +#
> > +# Copyright (C) 2022 Masahiro Yamada
> > +
> > +set -e
> > +set -o pipefail
> > +
> > +declare -A symbol_types
> > +declare -a export_symbols
> > +
> > +exit_code=0
> > +
> > +while read value type name
> > +do
> > +       # to avoid error for clang LTO; $name may be empty
> > +       if [[ $value = -* && -z $name ]]; then
> > +               continue
> > +       fi
> > +
> > +       # The first field (value) may be empty. If so, fix it up.
> > +       if [[ -z $name ]]; then
> > +          name=${type}
> > +          type=${value}
> > +       fi
>
> Consider adding examples of output from NM as comments where you're
> handling special cases.
>
> Aren't BOTH from LTO?  The first case is:
>
> ---------------- T strncpy


For LTO, I see

---------------- t

in the llvm-nm output.



>
> while the second is
>
>                  U strncpy

Right, this happens for all unresolved symbols.
The address part is empty.


I will add the output example in the comment block.





> IIUC?
>
> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
> --
> Thanks,
> ~Nick Desaulniers
>
> --
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-- 
Best Regards
Masahiro Yamada