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Date:   Mon, 23 Mar 2020 13:51:18 -0700
From:   Kees Cook <keescook@chromium.org>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     bp@alien8.de, Arvind Sankar <nivedita@alum.mit.edu>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org,
        Thomas Lendacky <Thomas.Lendacky@amd.com>,
        Mauro Rossi <issor.oruam@gmail.com>,
        Michael Matz <matz@suse.de>
Subject: Re: [PATCH] Documentation/changes: Raise minimum supported binutils
 version to 2.23
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On Mon, Mar 23, 2020 at 02:44:54PM -0600, Jason A. Donenfeld wrote:
> On Mon, Mar 16, 2020 at 05:02:59PM +0100, Borislav Petkov wrote:
> > Long overdue patch, see below.
> > 
> > Plan is to queue it after 5.7-rc1.
> > 
> > ---
> > From: Borislav Petkov <bp@suse.de>
> > Date: Mon, 16 Mar 2020 16:28:36 +0100
> > Subject: [PATCH] Documentation/changes: Raise minimum supported binutilsa version to 2.23
> > 
> > The currently minimum-supported binutils version 2.21 has the problem of
> > promoting symbols which are defined outside of a section into absolute.
> > According to Arvind:
> > 
> >   binutils-2.21 and -2.22. An x86-64 defconfig will fail with
> >           Invalid absolute R_X86_64_32S relocation: _etext
> >   and after fixing that one, with
> >           Invalid absolute R_X86_64_32S relocation: __end_of_kernel_reserve
> > 
> > Those two versions of binutils have a bug when it comes to handling
> > symbols defined outside of a section and binutils 2.23 has the proper
> > fix, see: https://sourceware.org/legacy-ml/binutils/2012-06/msg00155.html
> > 
> > Therefore, up to the fixed version directly, skipping the broken ones.
> > 
> > Currently shipping distros already have the fixed binutils version so
> > there should be no breakage resulting from this.
> > 
> > For more details about the whole thing, see the thread in Link.
> 
> That sounds very good to me. Then we'll be able to use ADX instructions
> without ifdefs.
> 
> Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>

Can you send these now and we can land in 5.7 with the doc change?

-Kees

-- 
Kees Cook