linux-kernel - Re: [PATCH v2 3/5] drm/v3d: Add support for compute shader dispatch.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87v9zc1eoy.fsf@anholt.net>
Date:   Wed, 17 Apr 2019 14:53:33 -0700
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        david.emett@...adcom.com, thomas.spurden@...adcom.com
Subject: Re: [PATCH v2 3/5] drm/v3d: Add support for compute shader dispatch.

Eric Anholt <eric@...olt.net> writes:

> The compute shader dispatch interface is pretty simple -- just pass in
> the regs that userspace has passed us, with no CLs to run.  However,
> with no CL to run it means that we need to do manual cache flushing of
> the L2 after the HW execution completes (for SSBO, atomic, and
> image_load_store writes that are the output of compute shaders).
>
> This doesn't yet expose the L2 cache's ability to have a region of the
> address space not write back to memory (which could be used for
> shared_var storage).
>
> So far, the Mesa side has been tested on V3D v4.2 simpenrose (passing
> the ES31 tests), and on the kernel side on 7278 (failing atomic
> compswap tests in a way that doesn't reproduce on simpenrose).

Fixed the compswap issue in Mesa.  Looks like cmpxchg needed the TYPE
field set to vec2 instead of 32-bit, since there are two values written
to TMUD.  The spec says the field is ignored, but that doesn't seem to
be the case.

Download attachment "signature.asc" of type "application/pgp-signature" (833 bytes)