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 --- 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; }