linux-kernel - Re: [PATCH v5 02/21] modpost: remove fromsym info in __ex

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Date:   Wed, 17 May 2023 11:53:07 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nathan Chancellor <nathan@...nel.org>,
        Nicolas Pitre <npitre@...libre.com>,
        Nicolas Schier <nicolas@...sle.eu>
Subject: Re: [PATCH v5 02/21] modpost: remove fromsym info in __ex_table
 section mismatch warning

On Sun, May 14, 2023 at 8:27 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> report_extable_warnings() prints "from" in a pretty form, but we know
> it is always located in the __ex_table section, i.e. a collection of
> struct exception_table_entry.

Would it still be helpful to have "from __ex_table" somewhere in the
error string that may be shown to developers?

>
> It is very likely to fail to get the symbol name and ends up with
> meaningless message:
>
>   ... in reference from the (unknown reference) (unknown) to ...
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
>  scripts/mod/modpost.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index ba4577aa4f1d..bbe066f7adbc 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1297,23 +1297,16 @@ static void report_extable_warnings(const char* modname, struct elf_info* elf,
>                                     Elf_Rela* r, Elf_Sym* sym,
>                                     const char* fromsec, const char* tosec)
>  {
> -       Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec);
> -       const char* fromsym_name = sym_name(elf, fromsym);
>         Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym);
>         const char* tosym_name = sym_name(elf, tosym);
> -       const char* from_pretty_name;
> -       const char* from_pretty_name_p;
>         const char* to_pretty_name;
>         const char* to_pretty_name_p;
>
> -       get_pretty_name(is_function(fromsym),
> -                       &from_pretty_name, &from_pretty_name_p);
>         get_pretty_name(is_function(tosym),
>                         &to_pretty_name, &to_pretty_name_p);
>
> -       warn("%s(%s+0x%lx): Section mismatch in reference from the %s %s%s to the %s %s:%s%s\n",
> -            modname, fromsec, (long)r->r_offset, from_pretty_name,
> -            fromsym_name, from_pretty_name_p,
> +       warn("%s(%s+0x%lx): Section mismatch in reference to the %s %s:%s%s\n",
> +            modname, fromsec, (long)r->r_offset,
>              to_pretty_name, tosec, tosym_name, to_pretty_name_p);
>
>         if (!match(tosec, mismatch->bad_tosec) &&
> --
> 2.39.2
>


-- 
Thanks,
~Nick Desaulniers