lkml.org 
[lkml]   [2004]   [Mar]   [13]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
    /
    DateSat, 13 Mar 2004 01:11:10 -0800
    FromEugene Surovegin <>
    SubjectRe: [PATCH] ppc32 copy_to_user dcbt fixup
    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.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at  http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at  http://www.tux.org/lkml/
    
    
    \
     
     \ /
      Last update: 2005-03-22 14:01    [from the cache]
    ©2003-2008