linux-kernel - Re: [PATCH 0/7] x86: remove always-defined CONFIG_AS

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Message-ID: <CAK7LNAQgKgKgOpQ2bgHrB5h=LTffs2khbYRrBhrxFM44gS88KQ@mail.gmail.com>
Date:   Tue, 24 Mar 2020 07:03:50 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     X86 ML <x86@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Allison Randal <allison@...utok.net>,
        Armijn Hemel <armijn@...ldur.nl>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ingo Molnar <mingo@...hat.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Song Liu <songliubraving@...com>,
        Zhengyuan Liu <liuzhengyuan@...inos.cn>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH 0/7] x86: remove always-defined CONFIG_AS_* options

Hi Jason,

On Mon, Mar 23, 2020 at 3:53 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
>
> On Mon, Mar 23, 2020 at 12:36 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > Hi Jason,
> >
> > On Mon, Mar 23, 2020 at 1:28 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> > >
> > > Hi again,
> > >
> > > I've consolidated your patches and rebased mine on top, and
> > > incorporated your useful binutils comments. The result lives here:
> > >
> > > https://git.zx2c4.com/linux-dev/log/?h=jd/kconfig-assembler-support
> > >
> > > I can submit all of those to the list, if you want, or maybe you can
> > > just pull them out of there, include them in your v2, and put them in
> > > your tree for 5.7? However you want is fine with me.
> >
> >
> > Your series does not work correctly.
> >
> > I will comment why later.
>
> Bummer, okay. Looking forward to learning what's up. Also, if some
> parts of it are useful (like the resorting and organizing of
> arch/x86/crypto/Makefile), feel free to cannibalize it, keeping what's
> useful and discarding what's not.
>


The answer is mostly in my previous reply to Linus:
https://lkml.org/lkml/2020/3/13/27


I think this problem would happen
for CONFIG_AS_CFI and CONFIG_AS_ADX
since the register in instruction code
is machine-bit dependent.

The former is OK wince we are planning to
remove it.

We need to handle -m64 for the latter.
Otherwise, a problem like commit
3a7c733165a4799fa1 would happen.


So, I think we should merge this
https://lore.kernel.org/patchwork/patch/1214332/
then, fix-up CONFIG_AS_ADX on top of it.

(Or, if we do not need to rush,
we can delete CONFIG_AS_ADX entirely after
we bump the binutils version to 2.23)

Thanks.

-- 
Best Regards
Masahiro Yamada