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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/ | ||||||||||||
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