From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH v3 09/27] x86/acpi: Adapt assembly for PIE support
Date: Fri, 25 May 2018 11:14:47 +0200
Message-ID: <20180525091447.GC9666@amd>
References: <20180523195421.180248-1-thgarnie@google.com>
 <20180523195421.180248-10-thgarnie@google.com>
 <20180524110306.GA20225@amd>
 <CAJcbSZFJ84+VC5xDQZGHctupdqwmMBgqzLzFRqCTBpi5t-2Gvw@mail.gmail.com>
Mime-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
	protocol="application/pgp-signature"; boundary="iFRdW5/EC4oqxDHL"
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	"David S . Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Yonghong Song <yhs@fb.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Kees Cook <keescook@chromium.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Borislav Petkov <bp@alien8.de>, Borislav Petkov <bp@suse.de>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>, Juergen Gross <jgro
To: Thomas Garnier <thgarnie@google.com>
Return-path: <kernel-hardening-return-13391-glkh-kernel-hardening=m.gmane.org@lists.openwall.com>
List-Post: <mailto:kernel-hardening@lists.openwall.com>
List-Help: <mailto:kernel-hardening-help@lists.openwall.com>
List-Unsubscribe: <mailto:kernel-hardening-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:kernel-hardening-subscribe@lists.openwall.com>
Content-Disposition: inline
In-Reply-To: <CAJcbSZFJ84+VC5xDQZGHctupdqwmMBgqzLzFRqCTBpi5t-2Gvw@mail.gmail.com>
List-Id: linux-crypto.vger.kernel.org


--iFRdW5/EC4oqxDHL
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Thu 2018-05-24 09:35:42, Thomas Garnier wrote:
> On Thu, May 24, 2018 at 4:03 AM Pavel Machek <pavel@ucw.cz> wrote:
>=20
> > On Wed 2018-05-23 12:54:03, Thomas Garnier wrote:
> > > Change the assembly code to use only relative references of symbols f=
or
> the
> > > kernel to be PIE compatible.
> > >
> > > Position Independent Executable (PIE) support will allow to extended =
the
> > > KASLR randomization range below the -2G memory limit.
>=20
> > What testing did this get?
>=20
> Tested boot, hibernation and performance on qemu and dedicated machine.

Well, this is suspend, not hibernation code.

So "sudo pm-suspend" or "echo mem > /sys/power/state" would be good
way to test this.

Thanks,
							Pavel

> > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S
> b/arch/x86/kernel/acpi/wakeup_64.S
> > > index 50b8ed0317a3..472659c0f811 100644
> > > --- a/arch/x86/kernel/acpi/wakeup_64.S
> > > +++ b/arch/x86/kernel/acpi/wakeup_64.S
> > > @@ -14,7 +14,7 @@
> > >        * Hooray, we are in Long 64-bit mode (but still running in low
> memory)
> > >        */
> > >  ENTRY(wakeup_long64)
> > > -     movq    saved_magic, %rax
> > > +     movq    saved_magic(%rip), %rax
> > >       movq    $0x123456789abcdef0, %rdx
> > >       cmpq    %rdx, %rax
> > >       jne     bogus_64_magic
>=20
> > Because, as comment says, this is rather tricky code.
>=20
> I agree, I think maintainers feedback is very important for this patchset.


--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

--iFRdW5/EC4oqxDHL
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iEYEARECAAYFAlsH1AcACgkQMOfwapXb+vJkPACgivHlv4yQvMmSVj7Gzzlmfl2d
K+EAnRZbTIvGxmfjC1t3r7e5toAEUioW
=2wkA
-----END PGP SIGNATURE-----

--iFRdW5/EC4oqxDHL--