Re: [PATCH] Documentation/changes: Raise minimum supported binutils version to 2.23

From: Masahiro Yamada <masahiroy@kernel.org>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Kees Cook <keescook@chromium.org>, Borislav Petkov <bp@alien8.de>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
	Linux Kernel Mailing List <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
Date: Wed, 25 Mar 2020 02:31:17 +0900	[thread overview]
Message-ID: <CAK7LNAQeeUt6L7xkk2UHE3v6b0e+iD1cx6_JSrZKEYxt2bEhHQ@mail.gmail.com> (raw)
In-Reply-To: <20200324153847.GA2870597@rani.riverdale.lan>

On Wed, Mar 25, 2020 at 12:38 AM Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> On Tue, Mar 24, 2020 at 06:12:01PM +0900, Masahiro Yamada wrote:
> > On Tue, Mar 24, 2020 at 6:02 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > Hi.
> > >
> > >
> > >
> > > On Tue, Mar 24, 2020 at 5:51 AM Kees Cook <keescook@chromium.org> wrote:
> > > >
> > > > 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
> >
> >
> > This seems to be also related to
> > 7883a14339299773b2ce08dcfd97c63c199a9289
> >
> >
> > I had noticed the symbol "_text"
> > was absolute on binutils <= 2.22,
> > but I was not sure whether it was a bug of the tool.
> >
> > I applied the fix.
> > Perhaps, it was unneeded given that
> > we require the binutils 2.23
> >
>
> Which architecture? x86 at least doesn't even build with <= 2.22, but
> adding workarounds for that shows _text as section-relative (T in nm
> output).

The reporter found this for PowerPC,
but I think this could happen on any architecture.

https://patchwork.kernel.org/patch/11430243/

-- 
Best Regards
Masahiro Yamada