Date: Mon, 13 Oct 2008 18:42:25 +0000 (UTC) From: Rafal Jaworowski <raj@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/arm/arm pmap.c Message-ID: <200810131842.m9DIgWwc055245@repoman.freebsd.org>
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raj 2008-10-13 18:42:25 UTC
FreeBSD src repository
Modified files:
sys/arm/arm pmap.c
Log:
SVN rev 183836 on 2008-10-13 18:42:25Z by raj
Do not use cached page for temporary mapping in pmap_zero_page_generic()
The physical page which we clear is accessed via additional temp kernel
mapping for the period of zeroing operation. However in systems with virtual
d-cache (most ARMs) when write-allocate feature is enabled, we can have
modified but unflushed content pertaining to this physical page still in the
d-cache due to its primary (pre-existing) mapping. In such scenario that
cached content upon flush is likely to overwrite [portions of] the physical
page we want to zero here..
This is a general problem with multiple virtual mappings covering the same
physical page with write-allocate and virtual d-cache: there is inherent
potential for corruptions of this kind, which are not easily resolved; it is
best policy that such multiple mappings be not allowed.
Obtained from: Marvell, Semihalf
Revision Changes Path
1.103 +8 -10 src/sys/arm/arm/pmap.c
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