kasan: introduce kasan_get_alloc_track

Add a kasan_get_alloc_track() helper that fetches alloc_track for a slab
object and use this helper in the common reporting code.

For now, the implementations of this helper are the same for the Generic
and tag-based modes, but they will diverge later in the series.

This change hides references to alloc_meta from the common reporting code.
This is desired as only the Generic mode will be using per-object
metadata after this series.

Link: https://lkml.kernel.org/r/0c365a35f4a833fff46f9d42c3212b32f7166556.1662411799.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/generic.c

@@ -381,6 +381,18 @@ void kasan_save_free_info(struct kmem_cache *cache,
 	*(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREETRACK;
 }
 
+struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
+						void *object)
+{
+	struct kasan_alloc_meta *alloc_meta;
+
+	alloc_meta = kasan_get_alloc_meta(cache, object);
+	if (!alloc_meta)
+		return NULL;
+
+	return &alloc_meta->alloc_track;
+}
+
 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 						void *object, u8 tag)
 {

mm/kasan/kasan.h

@@ -283,6 +283,8 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc);
 void kasan_set_track(struct kasan_track *track, gfp_t flags);
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags);
 void kasan_save_free_info(struct kmem_cache *cache, void *object, u8 tag);
+struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
+						void *object);
 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 						void *object, u8 tag);
 

mm/kasan/report.c

@@ -255,12 +255,12 @@ static void describe_object_addr(struct kmem_cache *cache, void *object,
 static void describe_object_stacks(struct kmem_cache *cache, void *object,
 					const void *addr, u8 tag)
 {
-	struct kasan_alloc_meta *alloc_meta;
+	struct kasan_track *alloc_track;
 	struct kasan_track *free_track;
 
-	alloc_meta = kasan_get_alloc_meta(cache, object);
-	if (alloc_meta) {
-		print_track(&alloc_meta->alloc_track, "Allocated");
+	alloc_track = kasan_get_alloc_track(cache, object);
+	if (alloc_track) {
+		print_track(alloc_track, "Allocated");
 		pr_err("\n");
 	}
 

mm/kasan/tags.c

@@ -38,6 +38,18 @@ void kasan_save_free_info(struct kmem_cache *cache,
 	kasan_set_track(&alloc_meta->free_track, GFP_NOWAIT);
 }
 
+struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
+						void *object)
+{
+	struct kasan_alloc_meta *alloc_meta;
+
+	alloc_meta = kasan_get_alloc_meta(cache, object);
+	if (!alloc_meta)
+		return NULL;
+
+	return &alloc_meta->alloc_track;
+}
+
 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 						void *object, u8 tag)
 {