Hi Paul
Am Fr., 15. Mai 2020 um 12:12 Uhr schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:
>
> Hi Christian,
>
> Le ven. 15 mai 2020 à 12:09, Christian Gmeiner
> <christian.gmeiner@xxxxxxxxx> a écrit :
> > Am Mo., 11. Mai 2020 um 14:38 Uhr schrieb Christian Gmeiner
> > <christian.gmeiner@xxxxxxxxx>:
> >>
> >> 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@xxxxxxxxxxxxxxx>
> >> Tested-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >> Fixes: ed1dd899baa3 ("drm/etnaviv: rework perfmon query
> >> infrastructure")
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> Signed-off-by: Christian Gmeiner <christian.gmeiner@xxxxxxxxx>
> >> ---
> >> 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..35f7171e779a 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 ((meta->nr_domains - 1) < (index - offset)) {
> >> offset += meta->nr_domains;
> >> continue;
> >> }
> >> --
> >> 2.26.2
> >>
> >
> > ping
>
> I'll merge it tomorrow if there's no further feedback.
>
Works for me too.. as far as Lucas (the maintainer) is happy with it.
--
greets
--
Christian Gmeiner, MSc
https://christian-gmeiner.info/privacypolicy
