[PATCH RFC v2 20/21] kasan: simplify assign_tag and set_tag calls

[Andrey Konovalov]

set_tag() already ignores the tag for the generic mode, so just call it
as is. Add a check for the generic mode to assign_tag(), and simplify its
call in ____kasan_kmalloc().

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Link: https://linux-review.googlesource.com/id/I18905ca78fb4a3d60e1a34a4ca00247272480438
---
 mm/kasan/common.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 983383ebe32a..3cd56861eb11 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -235,6 +235,9 @@ void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
 static u8 assign_tag(struct kmem_cache *cache, const void *object,
 			bool init, bool keep_tag)
 {
+	if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+		return 0xff;
+
 	/*
 	 * 1. When an object is kmalloc()'ed, two hooks are called:
 	 *    kasan_slab_alloc() and kasan_kmalloc(). We assign the
@@ -277,8 +280,8 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
 		__memset(alloc_meta, 0, sizeof(*alloc_meta));
 	}
 
-	if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
-		object = set_tag(object, assign_tag(cache, object, true, false));
+	/* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
+	object = set_tag(object, assign_tag(cache, object, true, false));
 
 	return (void *)object;
 }
@@ -360,9 +363,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
 				KASAN_GRANULE_SIZE);
 	redzone_end = round_up((unsigned long)object + cache->object_size,
 				KASAN_GRANULE_SIZE);
-
-	if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
-		tag = assign_tag(cache, object, false, keep_tag);
+	tag = assign_tag(cache, object, false, keep_tag);
 
 	/*
 	 * Don't unpoison the object when keeping the tag. Tag is kept for:
-- 
2.29.0.rc1.297.gfa9743e501-goog