drm/prime: split array import functions v4

Mapping the imported pages of a DMA-buf into an userspace process
doesn't work as expected.

But we have reoccurring requests on this approach, so split the
functions for this and  document that dma_buf_mmap() needs to be used
instead.

v2: split it into two functions
v3: rebased on latest changes
v4: update commit message a bit
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/403838/

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -918,7 +918,7 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_bo_device *bdev,
 		goto release_sg;
 
 	/* convert SG to linear array of pages and dma addresses */
-	drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL, gtt->ttm.dma_address,
+	drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
 				       ttm->num_pages);
 
 	return 0;
@@ -1264,8 +1264,7 @@ static int amdgpu_ttm_tt_populate(struct ttm_bo_device *bdev,
 			ttm->sg = sgt;
 		}
 
-		drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
-						 gtt->ttm.dma_address,
+		drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
 					       ttm->num_pages);
 		return 0;
 	}

drivers/gpu/drm/drm_prime.c

@@ -978,44 +978,58 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 EXPORT_SYMBOL(drm_gem_prime_import);
 
 /**
- * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
+ * drm_prime_sg_to_page_array - convert an sg table into a page array
  * @sgt: scatter-gather table to convert
- * @pages: optional array of page pointers to store the page array in
- * @addrs: optional array to store the dma bus address of each page
- * @max_entries: size of both the passed-in arrays
+ * @pages: array of page pointers to store the pages in
+ * @max_entries: size of the passed-in array
  *
- * Exports an sg table into an array of pages and addresses. This is currently
- * required by the TTM driver in order to do correct fault handling.
+ * Exports an sg table into an array of pages.
  *
- * Drivers can use this in their &drm_driver.gem_prime_import_sg_table
- * implementation.
+ * This function is deprecated and strongly discouraged to be used.
+ * The page array is only useful for page faults and those can corrupt fields
+ * in the struct page if they are not handled by the exporting driver.
  */
-int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
-				     dma_addr_t *addrs, int max_entries)
+int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
+					    struct page **pages,
+					    int max_entries)
 {
-	struct sg_dma_page_iter dma_iter;
 	struct sg_page_iter page_iter;
 	struct page **p = pages;
-	dma_addr_t *a = addrs;
 
-	if (pages) {
 	for_each_sgtable_page(sgt, &page_iter, 0) {
 		if (WARN_ON(p - pages >= max_entries))
 			return -1;
 		*p++ = sg_page_iter_page(&page_iter);
 	}
-	}
-	if (addrs) {
+	return 0;
+}
+EXPORT_SYMBOL(drm_prime_sg_to_page_array);
+
+/**
+ * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
+ * @sgt: scatter-gather table to convert
+ * @addrs: array to store the dma bus address of each page
+ * @max_entries: size of both the passed-in arrays
+ *
+ * Exports an sg table into an array of addresses.
+ *
+ * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
+ * implementation.
+ */
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+				   int max_entries)
+{
+	struct sg_dma_page_iter dma_iter;
+	dma_addr_t *a = addrs;
+
 	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
 		if (WARN_ON(a - addrs >= max_entries))
 			return -1;
 		*a++ = sg_page_iter_dma_address(&dma_iter);
 	}
-	}
-
 	return 0;
 }
-EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
+EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
 
 /**
  * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

@@ -135,8 +135,7 @@ struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,
 		goto fail;
 	}
 
-	ret = drm_prime_sg_to_page_addr_arrays(sgt, etnaviv_obj->pages,
-					       NULL, npages);
+	ret = drm_prime_sg_to_page_array(sgt, etnaviv_obj->pages, npages);
 	if (ret)
 		goto fail;
 

drivers/gpu/drm/mediatek/mtk_drm_gem.c

@@ -260,7 +260,7 @@ int mtk_drm_gem_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 		return -ENOMEM;
 	}
 
-	drm_prime_sg_to_page_addr_arrays(sgt, mtk_gem->pages, NULL, npages);
+	drm_prime_sg_to_page_array(sgt, mtk_gem->pages, npages);
 
 	mtk_gem->kvaddr = vmap(mtk_gem->pages, npages, VM_MAP,
 			       pgprot_writecombine(PAGE_KERNEL));

drivers/gpu/drm/msm/msm_gem.c

@@ -1180,7 +1180,7 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
 		goto fail;
 	}
 
-	ret = drm_prime_sg_to_page_addr_arrays(sgt, msm_obj->pages, NULL, npages);
+	ret = drm_prime_sg_to_page_array(sgt, msm_obj->pages, npages);
 	if (ret) {
 		mutex_unlock(&msm_obj->lock);
 		goto fail;

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -1235,8 +1235,7 @@ nouveau_ttm_tt_populate(struct ttm_bo_device *bdev,
 		return 0;
 
 	if (slave && ttm->sg) {
-		drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
-						 ttm_dma->dma_address,
+		drm_prime_sg_to_dma_addr_array(ttm->sg, ttm_dma->dma_address,
 					       ttm->num_pages);
 		return 0;
 	}

drivers/gpu/drm/omapdrm/omap_gem.c

@@ -1324,8 +1324,7 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
 		}
 
 		omap_obj->pages = pages;
-		ret = drm_prime_sg_to_page_addr_arrays(sgt, pages, NULL,
-						       npages);
+		ret = drm_prime_sg_to_page_array(sgt, pages, npages);
 		if (ret) {
 			omap_gem_free_object(obj);
 			obj = ERR_PTR(-ENOMEM);

drivers/gpu/drm/radeon/radeon_ttm.c

@@ -395,7 +395,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_bo_device *bdev, struct ttm_tt *
 	if (r)
 		goto release_sg;
 
-	drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL, gtt->ttm.dma_address,
+	drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
 				       ttm->num_pages);
 
 	return 0;
@@ -574,8 +574,7 @@ static int radeon_ttm_tt_populate(struct ttm_bo_device *bdev,
 	}
 
 	if (slave && ttm->sg) {
-		drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
-						 gtt->ttm.dma_address,
+		drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
 					       ttm->num_pages);
 		return 0;
 	}

drivers/gpu/drm/vgem/vgem_drv.c

@@ -356,8 +356,7 @@ static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev,
 	}
 
 	obj->pages_pin_count++; /* perma-pinned */
-	drm_prime_sg_to_page_addr_arrays(obj->table, obj->pages, NULL,
-					npages);
+	drm_prime_sg_to_page_array(obj->table, obj->pages, npages);
 	return &obj->base;
 }
 

drivers/gpu/drm/xen/xen_drm_front_gem.c

@@ -220,8 +220,8 @@ xen_drm_front_gem_import_sg_table(struct drm_device *dev,
 
 	xen_obj->sgt_imported = sgt;
 
-	ret = drm_prime_sg_to_page_addr_arrays(sgt, xen_obj->pages,
-					       NULL, xen_obj->num_pages);
+	ret = drm_prime_sg_to_page_array(sgt, xen_obj->pages,
+					 xen_obj->num_pages);
 	if (ret < 0)
 		return ERR_PTR(ret);
 

include/drm/drm_prime.h

@@ -105,8 +105,9 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 
 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg);
 
-int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
-				     dma_addr_t *addrs, int max_pages);
-
+int drm_prime_sg_to_page_array(struct sg_table *sgt, struct page **pages,
+			       int max_pages);
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+				   int max_pages);
 
 #endif /* __DRM_PRIME_H__ */