Messages in this thread | | | Subject | Re: [PATCH] staging: vc04_services: Fix bulk cache maintenance | From | Phil Elwell <> | Date | Wed, 10 May 2017 10:11:04 +0100 |
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On 10/05/2017 10:06, Greg Kroah-Hartman wrote: > On Wed, May 10, 2017 at 09:42:43AM +0100, Phil Elwell wrote: >> On 04/05/2017 18:51, Stefan Wahren wrote: >>> >>>> Phil Elwell <phil@raspberrypi.org> hat am 4. Mai 2017 um 11:58 geschrieben: >>>> >>>> >>>> vchiq_arm supports transfers less than one page and at arbitrary >>>> alignment, using the dma-mapping API to perform its cache maintenance >>>> (even though the VPU drives the DMA hardware). Read (DMA_FROM_DEVICE) >>>> operations use cache invalidation for speed, falling back to >>>> clean+invalidate on partial cache lines, with writes (DMA_TO_DEVICE) >>>> using flushes. >>>> >>>> If a read transfer has ends which aren't page-aligned, performing cache >>>> maintenance as if they were whole pages can lead to memory corruption >>>> since the partial cache lines at the ends (and any cache lines before or >>>> after the transfer area) will be invalidated. This bug was masked until >>>> the disabling of the cache flush in flush_dcache_page(). >>>> >>>> Honouring the requested transfer start- and end-points prevents the >>>> corruption. >>>> >>>> Fixes: cf9caf192988 ("staging: vc04_services: Replace dmac_map_area with dmac_map_sg") >>>> Signed-off-by: Phil Elwell <phil@raspberrypi.org> >>> >>> Reported-by: Stefan Wahren <stefan.wahren@i2se.com> >>> Tested-by: Stefan Wahren <stefan.wahren@i2se.com> >>> >>> In order to clarify the context of this issue: >>> >>> http://lists.infradead.org/pipermail/linux-rpi-kernel/2017-April/006149.html >> >> Thanks, Stefan. >> >> Is there no feedback other on this patch? It's been in the rpi-4.11.y downstream >> branch for a week now with favourable results - see issue >> https://github.com/raspberrypi/linux/issues/1977 and pr >> https://github.com/raspberrypi/linux/pull/1987. > > It's the middle of the merge window, I can't do anything with this > until after 4.12-rc1 comes out. Please be patient...
Yes, of course - that's the kind of feedback I was looking for.
Thanks,
Phil
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