From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from heliosphere.sirena.org.uk ([172.104.155.198]:42732 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389214AbeKGCTn (ORCPT ); Tue, 6 Nov 2018 21:19:43 -0500 Date: Tue, 6 Nov 2018 16:53:29 +0000 From: Mark Brown To: Russell King - ARM Linux Cc: Marc Zyngier , David Long , stable@vger.kernel.org, Florian Fainelli , Tony Lindgren , Mark Rutland , Greg KH Subject: Re: [PATCH 4.9 09/24] ARM: spectre-v2: add firmware based hardening Message-ID: <20181106165329.GD31950@sirena.org.uk> References: <20181031135713.2873-1-dave.long@linaro.org> <20181031135713.2873-10-dave.long@linaro.org> <86y3a6ebfi.wl-marc.zyngier@arm.com> <20181106105500.GZ30658@n2100.armlinux.org.uk> <20181106161932.GB31950@sirena.org.uk> <20181106163044.GJ30658@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="hxkXGo8AKqTJ+9QI" Content-Disposition: inline In-Reply-To: <20181106163044.GJ30658@n2100.armlinux.org.uk> Sender: stable-owner@vger.kernel.org List-ID: --hxkXGo8AKqTJ+9QI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Nov 06, 2018 at 04:30:44PM +0000, Russell King - ARM Linux wrote: > With any missing ENDPROC(), the only way to currently detect it is by > trying to run the code path - building alone does not flag any warnings > or errors. That's because the assembler has no idea whether what is > being assembled is code or data, and the purpose of ENDPROC() is to > mark it as code for the rest of the toolchain, so that it can apply the > bit 0 "fixup" for Thumb2 code. > So, in this case, the only way the error is detectable is to have a > platform where we boot a kernel which makes use of the HVC fixup path. > If that's too much to ask, then we're just going to have to accept that > Thumb2 kernels are going to be more fragile than ARM kernels because > there's no way to be certain that we have the correct annotations > everywhere - so we're going to have to rely on users reporting these > bugs _after_ the changes have hit mainline. Oh, totally - but currently none of the automated stuff is even trying to boot it so if we can do literally anything we'll be better off in terms of coverage even though it doesn't address the fundemental fragility. --hxkXGo8AKqTJ+9QI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlvhxwgACgkQJNaLcl1U h9BJkwf9EayaHV0THIoirRZXc2FDSfOhAVzqRX2ciptHE5aK2wq9+HQRqsRolSlm CtOsDzGdgkgPNLjvrZPZ9UJeDXBfc++u2rHJ7LGn9SkVp+vjRDbJfjO2R+n9Hpxw MYTFdM86lvlYCZvr1A/9jte354BAZfFzxJ4CxA8U0EASL6u9W2gM3+Q4bg8XsDMx eCAUkagMGQPLJb1bXC1yWAWq/697BbPymzLXZk+fH04rhlYF1RGmjHTIKY8ABtfv V8mBSh+zTDzN2vT4712yg2oUmxT7nJTTZf64sEUMf2ZaF92TfK1f7aoFh17Ih3mv lFg2Zoj3gUN2+hlQf+SJwOE0gFeLzg== =oLpC -----END PGP SIGNATURE----- --hxkXGo8AKqTJ+9QI--