Commit 576c930e authored by Boris Brezillon's avatar Boris Brezillon Committed by Steven Price
Browse files

drm/panthor: Flush shmem writes before mapping buffers CPU-uncached 



The shmem layer zeroes out the new pages using cached mappings, and if
we don't CPU-flush we might leave dirty cachelines behind, leading to
potential data leaks and/or asynchronous buffer corruption when dirty
cachelines are evicted.

Fixes: 8a1cc075 ("drm/panthor: Add GEM logical block")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Reviewed-by: default avatarLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: default avatarSteven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20251107171214.1186299-1-boris.brezillon@collabora.com
parent eef295a8

drivers/gpu/drm/panthor/panthor_gem.c

+18 −0
Original line number Diff line number Diff line
@@ -288,6 +288,23 @@ panthor_gem_create_with_handle(struct drm_file *file, 


	panthor_gem_debugfs_set_usage_flags(bo, 0);



	/* If this is a write-combine mapping, we query the sgt to force a CPU

	 * cache flush (dma_map_sgtable() is called when the sgt is created).

	 * This ensures the zero-ing is visible to any uncached mapping created

	 * by vmap/mmap.

	 * FIXME: Ideally this should be done when pages are allocated, not at

	 * BO creation time.

	 */

	if (shmem->map_wc) {

		struct sg_table *sgt;



		sgt = drm_gem_shmem_get_pages_sgt(shmem);

		if (IS_ERR(sgt)) {

			ret = PTR_ERR(sgt);

			goto out_put_gem;

		}

	}



	/*

	 * Allocate an id of idr table where the obj is registered

	 * and handle has the id what user can see.
@@ -296,6 +313,7 @@ panthor_gem_create_with_handle(struct drm_file *file, 
	if (!ret)

		*size = bo->base.base.size;



out_put_gem:

	/* drop reference from allocate - handle holds it now. */

	drm_gem_object_put(&shmem->base);