From: Eugene Surovegin <ebs@ebshome.net>
To: Bryan Rittmeyer <bryan@staidm.org>
Cc: linux-kernel@vger.kernel.org,
linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
Paul Mackerras <paulus@samba.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH] ppc32 copy_to_user dcbt fixup
Date: Sat, 13 Mar 2004 01:11:10 -0800 [thread overview]
Message-ID: <20040313091110.GA30393@gate.ebshome.net> (raw)
In-Reply-To: <20040313041547.GB11512@staidm.org>
On Fri, Mar 12, 2004 at 08:15:47PM -0800, Bryan Rittmeyer wrote:
> copy_tofrom_user and copy_page use dcbt to prefetch source data [1].
> Since at least 2.4.17, these functions have been prefetching
> beyond the end of the source buffer, leading to two problems:
>
> 1. Subtly broken software cache coherency. If the area following src
> was invalidate_dcache_range'd prior to submitting for DMA,
> an out-of-bounds dcbt from copy_to_user of a separate slab object
> may read in the area before DMA completion. When the DMA does complete,
> data will not be loaded from RAM because stale data is already in cache.
> Thus you get a corrupt network packet, bogus audio capture, etc.
>
I reported this problem on -embedded list half a year ago.
This is already fixed in 2.4 tree, not sure about 2.6
Eugene.
next prev parent reply other threads:[~2004-03-13 9:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-13 4:15 Bryan Rittmeyer
2004-03-13 4:50 ` Benjamin Herrenschmidt
2004-03-13 7:49 ` Bryan Rittmeyer
2004-03-13 8:36 ` Benjamin Herrenschmidt
2004-03-15 8:38 ` Segher Boessenkool
2004-03-13 9:11 ` Eugene Surovegin [this message]
2004-03-16 1:59 ` Bryan Rittmeyer
[not found] <1z8Na-5hH-1@gated-at.bofh.it>
2004-03-13 14:39 ` Danjel McGougan
2004-03-14 22:35 ` Bryan Rittmeyer
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