drm/etnaviv: fix mmap operations for userptr and dma-buf objects

Add an indirect object operations call to allow distinct implementations
of the mmap operation based on the type of the object.

This ensures that the exporter is called to set up the mmap for imported
dma-bufs and disallows mapping of userptr objects through the DRM file,
as this might lead to serious corruption of kernel internal state.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -172,7 +172,7 @@ int etnaviv_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	}
 
 	obj = to_etnaviv_bo(vma->vm_private_data);
-	return etnaviv_gem_mmap_obj(obj, vma);
+	return obj->ops->mmap(obj, vma);
 }
 
 int etnaviv_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
@@ -544,6 +544,7 @@ static const struct etnaviv_gem_ops etnaviv_gem_shmem_ops = {
 	.get_pages = etnaviv_gem_shmem_get_pages,
 	.release = etnaviv_gem_shmem_release,
 	.vmap = etnaviv_gem_vmap_impl,
+	.mmap = etnaviv_gem_mmap_obj,
 };
 
 void etnaviv_gem_free_object(struct drm_gem_object *obj)
@@ -885,10 +886,17 @@ static void etnaviv_gem_userptr_release(struct etnaviv_gem_object *etnaviv_obj)
 	put_task_struct(etnaviv_obj->userptr.task);
 }
 
+static int etnaviv_gem_userptr_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
+		struct vm_area_struct *vma)
+{
+	return -EINVAL;
+}
+
 static const struct etnaviv_gem_ops etnaviv_gem_userptr_ops = {
 	.get_pages = etnaviv_gem_userptr_get_pages,
 	.release = etnaviv_gem_userptr_release,
 	.vmap = etnaviv_gem_vmap_impl,
+	.mmap = etnaviv_gem_userptr_mmap_obj,
 };
 
 int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_file *file,

drivers/gpu/drm/etnaviv/etnaviv_gem.h

@@ -79,6 +79,7 @@ struct etnaviv_gem_ops {
 	int (*get_pages)(struct etnaviv_gem_object *);
 	void (*release)(struct etnaviv_gem_object *);
 	void *(*vmap)(struct etnaviv_gem_object *);
+	int (*mmap)(struct etnaviv_gem_object *, struct vm_area_struct *);
 };
 
 static inline bool is_active(struct etnaviv_gem_object *etnaviv_obj)

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

@@ -84,10 +84,17 @@ static void *etnaviv_gem_prime_vmap_impl(struct etnaviv_gem_object *etnaviv_obj)
 	return dma_buf_vmap(etnaviv_obj->base.import_attach->dmabuf);
 }
 
+static int etnaviv_gem_prime_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
+		struct vm_area_struct *vma)
+{
+	return dma_buf_mmap(etnaviv_obj->base.dma_buf, vma, 0);
+}
+
 static const struct etnaviv_gem_ops etnaviv_gem_prime_ops = {
 	/* .get_pages should never be called */
 	.release = etnaviv_gem_prime_release,
 	.vmap = etnaviv_gem_prime_vmap_impl,
+	.mmap = etnaviv_gem_prime_mmap_obj,
 };
 
 struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,