linux-kernel - Re: [PATCH] kbuild: Parameterize kallsyms generation and correct reporting

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Message-ID: <201908130815.33BA0DE322@keescook>
Date:   Tue, 13 Aug 2019 08:17:06 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH] kbuild: Parameterize kallsyms generation and correct
 reporting

On Wed, Aug 14, 2019 at 12:00:05AM +0900, Masahiro Yamada wrote:
> On Tue, Aug 13, 2019 at 6:49 AM Kees Cook <keescook@...omium.org> wrote:
> >
> > When kallsyms generation happens, temporary vmlinux outputs are linked
> > but the quiet make output doesn't report it, giving the impression that
> > the prior command is taking longer than expected.
> >
> > Instead, report the KSYM step before the temporary linking. While at it,
> > this consolidates the repeated "kallsyms generation step" into a single
> > function and removes the existing copy/pasting.
> >
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> 
> Hmm, I did not notice this.

He either until I was getting link errors from MODINFO :)

> How about showing the link stage explicitly?
> (Is it too verbose?)
> 
>   MODINFO modules.builtin.modinfo
>   LD      .tmp_vmlinux1
>   KSYMS   .tmp_kallsyms1.o
>   LD      .tmp_vmlinux2
>   KSYMS   .tmp_kallsyms2.o
>   LD      vmlinux
>   SORTEX  vmlinux

I'm fine with this -- it's probably the right thing to do since getting
vmlinux link errors fro KSYMS probably doesn't make sense either. ;)

> If this verbosity is OK,
> you can move 'info LD  ${2}' into vmlinux_link()

Done.

> Anyway, I like the clean-ups in this patch.
> 
> This is just my personal preference, but
> may I ask two cosmetic changes?
> 
> [1] Could you move kallsyms_step()
>     between  kallsyms() and mksysmap() ?
>     I want to collect function definitions
>     to the top of the script.
> 
> [2] Could you shorten 'kallsymso_previous'
>     to 'kallsymso_prev' ?

Sounds good. v2 sent.

-- 
Kees Cook