On Fri, Aug 18, 2017 at 01:34:45PM -0700, Eric Anholt wrote: > Daniel Vetter <dan...@ffwll.ch> writes: > > > On Fri, Aug 18, 2017 at 10:41:21AM -0700, Eric Anholt wrote: > >> Noralf Trønnes <nor...@tronnes.org> writes: > >> > Den 18.08.2017 09.46, skrev Daniel Vetter: > >> >> On Thu, Aug 17, 2017 at 06:21:30PM +0200, Noralf Trønnes wrote: > >> >>> Reject mapping an imported dma-buf since is's an invalid use-case. > >> >>> > >> >>> Cc: Philipp Zabel <p.za...@pengutronix.de> > >> >>> Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com> > >> >>> Cc: Sean Paul <seanp...@chromium.org> > >> >>> Cc: Daniel Vetter <daniel.vet...@ffwll.ch> > >> >>> Signed-off-by: Noralf Trønnes <nor...@tronnes.org> > >> >> I think acks from someone using mali would be good too. amdgpu already > >> >> has > >> >> such checks, so I think on the desktop side we're ok. > >> >> > >> >> Acked-by: Daniel Vetter <daniel.vet...@ffwll.ch> > >> >> > >> >> But I think this one here definitely needs a few more acks. I could > >> >> break > >> >> uabi if we're unlucky, so let's not rush it. > >> > > >> > Ok, I've CC'ed the affected parties to increase the odds that they look > >> > at this. These are the drivers using drm_gem_dumb_map_offset() > >> > (hopefully I got the list right): > >> > >> If I understand the affected path right, this would break the PL111+VC4 > >> combination: PL111 makes (dumb) buffers for scanout, and VC4 imports > >> them and uses them for rendering. A vc4 glReadPixels of the window > >> system buffer would map it and fail. > > > > It only rejects the map call on dumb buffers, and mmap on imported dma-buf > > tends to not really work well, or at least break a few abstractions. Are > > you sure this works currently? > > OK, that's right -- vc4 would be doing its "native" map call (the same > code), not dumb map. > > Furthermore, I had it backwards (I had written things both ways at > different points, iirc). We have VC4 making the buffers and PL111 > dma-buf importing them. I don't see X11 mapping those buffers if glamor > is enabled, so this should be OK for vc4. > > GBM's dumb mapping looks safe to me. X11 does some dumb maps, but I > don't think any of those would be on imports.
Yeah the idea is only to lock down the dumb mmap and make sure abi abuse (which might work on a specific combo of exporters/kms drivers) is caught for this generic interface. dumb really should only be used for unaccelarated rendering on exactly that driver. So ack from you? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
