1 files changed, 13 insertions, 77 deletions

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 032bf3e98c24..6310a180278b 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -334,14 +334,6 @@ DEFINE_ASAN_SET_SHADOW(f3);
 DEFINE_ASAN_SET_SHADOW(f5);
 DEFINE_ASAN_SET_SHADOW(f8);
 
-/* Only allow cache merging when no per-object metadata is present. */
-slab_flags_t kasan_never_merge(void)
-{
-	if (!kasan_requires_meta())
-		return 0;
-	return SLAB_KASAN;
-}
-
 /*
  * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
  * For larger allocations larger redzones are used.
@@ -370,15 +362,13 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 		return;
 
 	/*
-	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN
-	 * and that thus have per-object metadata.
-	 * Currently this flag is used in two places:
-	 * 1. In slab_ksize() to account for per-object metadata when
-	 *    calculating the size of the accessible memory within the object.
-	 * 2. In slab_common.c via kasan_never_merge() to prevent merging of
-	 *    caches with per-object metadata.
+	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN and
+	 * that thus have per-object metadata. Currently, this flag is used in
+	 * slab_ksize() to account for per-object metadata when calculating the
+	 * size of the accessible memory within the object. Additionally, we use
+	 * SLAB_NO_MERGE to prevent merging of caches with per-object metadata.
 	 */
-	*flags |= SLAB_KASAN;
+	*flags |= SLAB_KASAN | SLAB_NO_MERGE;
 
 	ok_size = *size;
 
@@ -485,16 +475,6 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 	if (alloc_meta) {
 		/* Zero out alloc meta to mark it as invalid. */
 		__memset(alloc_meta, 0, sizeof(*alloc_meta));
-
-		/*
-		 * Prepare the lock for saving auxiliary stack traces.
-		 * Temporarily disable KASAN bug reporting to allow instrumented
-		 * raw_spin_lock_init to access aux_lock, which resides inside
-		 * of a redzone.
-		 */
-		kasan_disable_current();
-		raw_spin_lock_init(&alloc_meta->aux_lock);
-		kasan_enable_current();
 	}
 
 	/*
@@ -506,18 +486,8 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 
 static void release_alloc_meta(struct kasan_alloc_meta *meta)
 {
-	/* Evict the stack traces from stack depot. */
-	stack_depot_put(meta->alloc_track.stack);
-	stack_depot_put(meta->aux_stack[0]);
-	stack_depot_put(meta->aux_stack[1]);
-
-	/*
-	 * Zero out alloc meta to mark it as invalid but keep aux_lock
-	 * initialized to avoid having to reinitialize it when another object
-	 * is allocated in the same slot.
-	 */
-	__memset(&meta->alloc_track, 0, sizeof(meta->alloc_track));
-	__memset(meta->aux_stack, 0, sizeof(meta->aux_stack));
+	/* Zero out alloc meta to mark it as invalid. */
+	__memset(meta, 0, sizeof(*meta));
 }
 
 static void release_free_meta(const void *object, struct kasan_free_meta *meta)
@@ -529,27 +499,10 @@ static void release_free_meta(const void *object, struct kasan_free_meta *meta)
 	if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREE_META)
 		return;
 
-	/* Evict the stack trace from the stack depot. */
-	stack_depot_put(meta->free_track.stack);
-
 	/* Mark free meta as invalid. */
 	*(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREE;
 }
 
-void kasan_release_object_meta(struct kmem_cache *cache, const void *object)
-{
-	struct kasan_alloc_meta *alloc_meta;
-	struct kasan_free_meta *free_meta;
-
-	alloc_meta = kasan_get_alloc_meta(cache, object);
-	if (alloc_meta)
-		release_alloc_meta(alloc_meta);
-
-	free_meta = kasan_get_free_meta(cache, object);
-	if (free_meta)
-		release_free_meta(object, free_meta);
-}
-
 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object)
 {
 	struct kasan_cache *info = &cache->kasan_info;
@@ -574,8 +527,6 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
 	struct kmem_cache *cache;
 	struct kasan_alloc_meta *alloc_meta;
 	void *object;
-	depot_stack_handle_t new_handle, old_handle;
-	unsigned long flags;
 
 	if (is_kfence_address(addr) || !slab)
 		return;
@@ -586,33 +537,18 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
 	if (!alloc_meta)
 		return;
 
-	new_handle = kasan_save_stack(0, depot_flags);
-
-	/*
-	 * Temporarily disable KASAN bug reporting to allow instrumented
-	 * spinlock functions to access aux_lock, which resides inside of a
-	 * redzone.
-	 */
-	kasan_disable_current();
-	raw_spin_lock_irqsave(&alloc_meta->aux_lock, flags);
-	old_handle = alloc_meta->aux_stack[1];
 	alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
-	alloc_meta->aux_stack[0] = new_handle;
-	raw_spin_unlock_irqrestore(&alloc_meta->aux_lock, flags);
-	kasan_enable_current();
-
-	stack_depot_put(old_handle);
+	alloc_meta->aux_stack[0] = kasan_save_stack(0, depot_flags);
 }
 
 void kasan_record_aux_stack(void *addr)
 {
-	return __kasan_record_aux_stack(addr,
-			STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
+	return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC);
 }
 
 void kasan_record_aux_stack_noalloc(void *addr)
 {
-	return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_GET);
+	return __kasan_record_aux_stack(addr, 0);
 }
 
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
@@ -623,7 +559,7 @@ void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
 	if (!alloc_meta)
 		return;
 
-	/* Evict previous stack traces (might exist for krealloc or mempool). */
+	/* Invalidate previous stack traces (might exist for krealloc or mempool). */
 	release_alloc_meta(alloc_meta);
 
 	kasan_save_track(&alloc_meta->alloc_track, flags);
@@ -637,7 +573,7 @@ void kasan_save_free_info(struct kmem_cache *cache, void *object)
 	if (!free_meta)
 		return;
 
-	/* Evict previous stack trace (might exist for mempool). */
+	/* Invalidate previous stack trace (might exist for mempool). */
 	release_free_meta(object, free_meta);
 
 	kasan_save_track(&free_meta->free_track, 0);