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

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Date:   Sat, 20 May 2023 22:11:26 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
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 Thu, May 18, 2023 at 3:53 AM Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
>
> 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?


See the code.

The variable, 'fromsec' (i.e. "__ex_table") is remaining.

It prints a warning message as you wish.




> >
> > 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



-- 
Best Regards
Masahiro Yamada