drm/i915/gt: Replace kmap with its safer kmap_local_page counterpart

kmap_local_page(), unlike kmap(), performs a contextualized
mapping of pages. This means the pages are mapped locally to the
thread that created them, making them invisible outside the
thread and safer to use.

Replace kmap() and kunmap() with kmap_local_page() and
kunmap_local() counterparts for improved safety.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Reviewed-by: Nitin Gote <nitin.r.gote@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250214003437.1311476-1-andi.shyti@linux.intel.com

Author: Andi Shyti

drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c

@@ -749,15 +749,15 @@ static void swizzle_page(struct page *page)
 	char *vaddr;
 	int i;
 
-	vaddr = kmap(page);
+	vaddr = kmap_local_page(page);
 
 	for (i = 0; i < PAGE_SIZE; i += 128) {
 		memcpy(temp, &vaddr[i], 64);
 		memcpy(&vaddr[i], &vaddr[i + 64], 64);
 		memcpy(&vaddr[i + 64], temp, 64);
 	}
 
-	kunmap(page);
+	kunmap_local(vaddr);
 }
 
 /**

drivers/gpu/drm/i915/gt/shmem_utils.c

@@ -108,15 +108,15 @@ static int __shmem_rw(struct file *file, loff_t off,
 		if (IS_ERR(page))
 			return PTR_ERR(page);
 
-		vaddr = kmap(page);
+		vaddr = kmap_local_page(page);
 		if (write) {
 			memcpy(vaddr + offset_in_page(off), ptr, this);
 			set_page_dirty(page);
 		} else {
 			memcpy(ptr, vaddr + offset_in_page(off), this);
 		}
 		mark_page_accessed(page);
-		kunmap(page);
+		kunmap_local(vaddr);
 		put_page(page);
 
 		len -= this;
@@ -143,11 +143,11 @@ int shmem_read_to_iosys_map(struct file *file, loff_t off,
 		if (IS_ERR(page))
 			return PTR_ERR(page);
 
-		vaddr = kmap(page);
+		vaddr = kmap_local_page(page);
 		iosys_map_memcpy_to(map, map_off, vaddr + offset_in_page(off),
 				    this);
 		mark_page_accessed(page);
-		kunmap(page);
+		kunmap_local(vaddr);
 		put_page(page);
 
 		len -= this;