From mboxrd@z Thu Jan 1 00:00:00 1970 From: phil@raspberrypi.org (Phil Elwell) Date: Wed, 10 May 2017 09:42:43 +0100 Subject: [PATCH] staging: vc04_services: Fix bulk cache maintenance In-Reply-To: <139394270.264573.1493920270267@email.1und1.de> References: <139394270.264573.1493920270267@email.1und1.de> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/05/2017 18:51, Stefan Wahren wrote: > >> Phil Elwell 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 > > Reported-by: Stefan Wahren > Tested-by: Stefan Wahren > > 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. Phil