From mboxrd@z Thu Jan 1 00:00:00 1970 From: gregkh@linuxfoundation.org (Greg Kroah-Hartman) Date: Wed, 10 May 2017 11:06:26 +0200 Subject: [PATCH] staging: vc04_services: Fix bulk cache maintenance In-Reply-To: References: <139394270.264573.1493920270267@email.1und1.de> Message-ID: <20170510090626.GA21141@kroah.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, May 10, 2017 at 09:42:43AM +0100, Phil Elwell wrote: > 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. 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... thanks, greg k-h