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Date:   Thu, 12 Dec 2019 09:44:26 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Emese Revfy <re.emese@gmail.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] gcc-plugins: make it possible to disable
 CONFIG_GCC_PLUGINS again
Message-ID: <201912120943.486E507@keescook>
References: <20191211133951.401933-1-arnd@arndb.de>
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 <CAK8P3a1dH+msCgxU-=w4gp30Bw+x3=6Cj473DuFzxun+3dfOcA@mail.gmail.com>
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On Thu, Dec 12, 2019 at 10:59:40AM +0100, Arnd Bergmann wrote:
> On Thu, Dec 12, 2019 at 5:52 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Wed, Dec 11, 2019 at 10:40 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > >
> > > I noticed that randconfig builds with gcc no longer produce a lot of
> > > ccache hits, unlike with clang, and traced this back to plugins
> > > now being enabled unconditionally if they are supported.
> > >
> > > I am now working around this by adding
> > >
> > >    export CCACHE_COMPILERCHECK=/usr/bin/size -A %compiler%
> > >
> > > to my top-level Makefile. This changes the heuristic that ccache uses
> > > to determine whether the plugins are the same after a 'make clean'.
> > >
> > > However, it also seems that being able to just turn off the plugins is
> > > generally useful, at least for build testing it adds noticeable overhead
> > > but does not find a lot of bugs additional bugs, and may be easier for
> > > ccache users than my workaround.
> > >
> > > Fixes: 9f671e58159a ("security: Create "kernel hardening" config area")
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >
> > Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
> 
> On Wed, Dec 11, 2019 at 2:59 PM Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
> >Acked-by: Ard Biesheuvel <ardb@kernel.org>
> 
> Thanks! Who would be the best person to pick up the patch?
> Should I send it to Andrew?

Acked-by: Kees Cook <keescook@chromium.org>

I can take it in my tree, or I'm happy to have Masahiro take it.

-- 
Kees Cook