linux-kernel - Re: [PATCH kernel v8 09/31] powerpc/powernv: Do not set "read" flag if direction==DMA

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 15 Apr 2015 17:17:10 +1000
From:	David Gibson <david@...son.dropbear.id.au>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernel v8 09/31] powerpc/powernv: Do not set "read" flag
 if direction==DMA_NONE

On Fri, Apr 10, 2015 at 04:30:51PM +1000, Alexey Kardashevskiy wrote:
> Normally a bitmap from the iommu_table is used to track what TCE entry
> is in use. Since we are going to use iommu_table without its locks and
> do xchg() instead, it becomes essential not to put bits which are not
> implied in the direction flag.

It's not clear to me from this why lack of locking implies the need to
not put extra bits in.

> This adds iommu_direction_to_tce_perm() (its counterpart is there already)
> and uses it for powernv's pnv_tce_build().
> 
> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>

I have no objection to the patch though, so

Reviewed-by: David Gibson <david@...son.dropbear.id.au>

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Content of type "application/pgp-signature" skipped