lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 22 Apr 2022 14:42:06 +0100 From: Catalin Marinas <catalin.marinas@....com> To: Mark Brown <broonie@...nel.org> Cc: Peter Collingbourne <pcc@...gle.com>, Will Deacon <will@...nel.org>, Jonathan Corbet <corbet@....net>, linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] arm64: document the boot requirements for MTE On Tue, Apr 05, 2022 at 09:04:04AM +0100, Mark Brown wrote: > On Mon, Apr 04, 2022 at 02:18:58PM -0700, Peter Collingbourne wrote: > > > + For CPUs with the Memory Tagging Extension feature: > > + > > + - If EL3 is present: > > + > > + - SCR_EL3.ATA (bit 26) must be initialised to 0b1. > > + > > + - If the kernel is entered at EL1 and EL2 is present: > > + > > + - HCR_EL2.ATA (bit 56) must be initialised to 0b1. > > Very nitpicky but this is only required for FEAT_MTE2 and above, plain > FEAT_MTE doesn't have these traps. I don't know that this is a thing > that anyone's actually implemented I think that's a valid point. CPUs may implement FEAT_MTE2 but downgrade it to FEAT_MTE if the SoC does not provide allocation tag storage. So we should make it clear here that only from FEAT_MTE2 we should set those bits (ID_AA64PFR1_EL1.MTE >= 2), otherwise they should be 0 or hyp/firmware risks the OS triggering random external aborts. > and from v8.7 on it's not permitted but the above isn't strictly true > if someone did for some reason have the most basic version. The wording is tricky: "This feature is mandatory from Armv8.7 when FEAT_MTE2 is implemented". So one can still implement FEAT_MTE (or none at all). -- Catalin
Powered by blists - more mailing lists