From: Lucas Stach <l.stach@pengutronix.de>
To: Christian Gmeiner <christian.gmeiner@gmail.com>,
linux-kernel@vger.kernel.org
Cc: Paul Cercueil <paul@crapouillou.net>,
stable@vger.kernel.org,
Russell King <linux+etnaviv@armlinux.org.uk>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2] drm/etnaviv: fix perfmon domain interation
Date: Tue, 19 May 2020 12:48:35 +0200 [thread overview]
Message-ID: <074a3a7c83c87f5265eec69c150f8f993bd787da.camel@pengutronix.de> (raw)
In-Reply-To: <20200519053019.48376-1-christian.gmeiner@gmail.com>
Am Dienstag, den 19.05.2020, 07:30 +0200 schrieb Christian Gmeiner:
> The GC860 has one GPU device which has a 2d and 3d core. In this case
> we want to expose perfmon information for both cores.
>
> The driver has one array which contains all possible perfmon domains
> with some meta data - doms_meta. Here we can see that for the GC860
> two elements of that array are relevant:
>
> doms_3d: is at index 0 in the doms_meta array with 8 perfmon domains
> doms_2d: is at index 1 in the doms_meta array with 1 perfmon domain
>
> The userspace driver wants to get a list of all perfmon domains and
> their perfmon signals. This is done by iterating over all domains and
> their signals. If the userspace driver wants to access the domain with
> id 8 the kernel driver fails and returns invalid data from doms_3d with
> and invalid offset.
>
> This results in:
> Unable to handle kernel paging request at virtual address 00000000
>
> On such a device it is not possible to use the userspace driver at all.
>
> The fix for this off-by-one error is quite simple.
>
> Reported-by: Paul Cercueil <paul@crapouillou.net>
> Tested-by: Paul Cercueil <paul@crapouillou.net>
> Fixes: ed1dd899baa3 ("drm/etnaviv: rework perfmon query infrastructure")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Thanks, applied to etnaviv/fixes.
Regards,
Lucas
> ---
> drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> index e6795bafcbb9..75f9db8f7bec 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> @@ -453,7 +453,7 @@ static const struct etnaviv_pm_domain *pm_domain(const struct etnaviv_gpu *gpu,
> if (!(gpu->identity.features & meta->feature))
> continue;
>
> - if (meta->nr_domains < (index - offset)) {
> + if (index - offset >= meta->nr_domains) {
> offset += meta->nr_domains;
> continue;
> }
prev parent reply other threads:[~2020-05-19 10:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 5:30 [PATCH v2] drm/etnaviv: fix perfmon domain interation Christian Gmeiner
2020-05-19 10:48 ` Lucas Stach [this message]
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