gpu: host1x: Forbid relocation address shifting in the firewall

Incorrectly shifted relocation address will cause a lower memory
corruption and likely a hang on a write or a read of an arbitrary data
in case of IOMMU absence. As of now, there is no known use for the
address shifting and adding a proper shifts / sizes validation is a much
more work. Let's forbid shifts in the firewall till a proper validation
is implemented.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Erik Faye-Lund <kusmabite@gmail.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/host1x/job.c

@@ -330,6 +330,10 @@ static bool check_reloc(struct host1x_reloc *reloc, struct host1x_bo *cmdbuf,
 	if (reloc->cmdbuf.bo != cmdbuf || reloc->cmdbuf.offset != offset)
 		return false;
 
+	/* relocation shift value validation isn't implemented yet */
+	if (reloc->shift)
+		return false;
+
 	return true;
 }