linux-kernel - Re: [PATCH v2] kbuild: modpost: Explicitly warn about unprototyped symbols

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Date:   Thu, 17 Jun 2021 10:05:44 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] kbuild: modpost: Explicitly warn about unprototyped symbols

On Mon, Jun 7, 2021 at 11:02 PM Mark Brown <broonie@...nel.org> wrote:
>
> One common cause of modpost version generation failures is a failure to
> prototype exported assembly functions - the tooling requires this for
> exported functions even if they are not and should not be called from C
> code in order to do the version mangling for symbols. Unfortunately the
> error message is currently rather abstruse, simply saying that "version
> generation failed" and even diving into the code doesn't directly show
> what's going on since there's several steps between the problem and it
> being observed.
>
> Provide an explicit hint as to the likely cause of a version generation
> failure to help anyone who runs into this in future more readily diagnose
> and fix the problem.
>
> Signed-off-by: Mark Brown <broonie@...nel.org>
> ---

Applied to linux-kbuild. Thanks.


>
> v2:
>  - Reword and reformat error message.
>  - Fix duplicated is.
>
>  scripts/mod/modpost.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 3e623ccc020b..270a7df898e2 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -660,8 +660,11 @@ static void handle_modversion(const struct module *mod,
>         unsigned int crc;
>
>         if (sym->st_shndx == SHN_UNDEF) {
> -               warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n",
> -                    symname, mod->name, mod->is_vmlinux ? "" : ".ko");
> +               warn("EXPORT symbol \"%s\" [%s%s] version ...\n"
> +                    "Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
> +                    symname, mod->name, mod->is_vmlinux ? "" : ".ko",
> +                    symname);
> +
>                 return;
>         }
>
> --
> 2.20.1
>


-- 
Best Regards
Masahiro Yamada