linux-kernel - [PATCH 14/32] kasan: only define kasan_metadata

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Date:   Mon, 13 Jun 2022 22:14:05 +0200
From:   andrey.konovalov@...ux.dev
To:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com, Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Florian Mayer <fmayer@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 14/32] kasan: only define kasan_metadata_size for Generic mode

From: Andrey Konovalov <andreyknvl@...gle.com>

KASAN provides a helper for calculating the size of per-object metadata
stored in the redzone.

As now only the Generic mode uses per-object metadata, only define
kasan_metadata_size() for this mode.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 include/linux/kasan.h | 17 ++++++++---------
 mm/kasan/common.c     | 11 -----------
 mm/kasan/generic.c    | 11 +++++++++++
 3 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b092277bf48d..027df7599573 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -150,14 +150,6 @@ static __always_inline void kasan_cache_create_kmalloc(struct kmem_cache *cache)
 		__kasan_cache_create_kmalloc(cache);
 }
 
-size_t __kasan_metadata_size(struct kmem_cache *cache);
-static __always_inline size_t kasan_metadata_size(struct kmem_cache *cache)
-{
-	if (kasan_enabled())
-		return __kasan_metadata_size(cache);
-	return 0;
-}
-
 void __kasan_poison_slab(struct slab *slab);
 static __always_inline void kasan_poison_slab(struct slab *slab)
 {
@@ -282,7 +274,6 @@ static inline void kasan_cache_create(struct kmem_cache *cache,
 				      unsigned int *size,
 				      slab_flags_t *flags) {}
 static inline void kasan_cache_create_kmalloc(struct kmem_cache *cache) {}
-static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 static inline void kasan_poison_slab(struct slab *slab) {}
 static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
 					void *object) {}
@@ -333,6 +324,8 @@ static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
 
 #ifdef CONFIG_KASAN_GENERIC
 
+size_t kasan_metadata_size(struct kmem_cache *cache);
+
 void kasan_cache_shrink(struct kmem_cache *cache);
 void kasan_cache_shutdown(struct kmem_cache *cache);
 void kasan_record_aux_stack(void *ptr);
@@ -340,6 +333,12 @@ void kasan_record_aux_stack_noalloc(void *ptr);
 
 #else /* CONFIG_KASAN_GENERIC */
 
+/* Tag-based KASAN modes do not use per-object metadata. */
+static inline size_t kasan_metadata_size(struct kmem_cache *cache)
+{
+	return 0;
+}
+
 static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
 static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
 static inline void kasan_record_aux_stack(void *ptr) {}
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 8a83ca9ad738..a0ddbf02aa6d 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -138,17 +138,6 @@ void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
 	cache->kasan_info.is_kmalloc = true;
 }
 
-size_t __kasan_metadata_size(struct kmem_cache *cache)
-{
-	if (!kasan_requires_meta())
-		return 0;
-	return (cache->kasan_info.alloc_meta_offset ?
-		sizeof(struct kasan_alloc_meta) : 0) +
-		((cache->kasan_info.free_meta_offset &&
-		  cache->kasan_info.free_meta_offset != KASAN_NO_FREE_META) ?
-		 sizeof(struct kasan_free_meta) : 0);
-}
-
 void __kasan_poison_slab(struct slab *slab)
 {
 	struct page *page = slab_page(slab);
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 5125fad76f70..806ab92032c3 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -427,6 +427,17 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 		__memset(alloc_meta, 0, sizeof(*alloc_meta));
 }
 
+size_t kasan_metadata_size(struct kmem_cache *cache)
+{
+	if (!kasan_requires_meta())
+		return 0;
+	return (cache->kasan_info.alloc_meta_offset ?
+		sizeof(struct kasan_alloc_meta) : 0) +
+		((cache->kasan_info.free_meta_offset &&
+		  cache->kasan_info.free_meta_offset != KASAN_NO_FREE_META) ?
+		 sizeof(struct kasan_free_meta) : 0);
+}
+
 static void __kasan_record_aux_stack(void *addr, bool can_alloc)
 {
 	struct slab *slab = kasan_addr_to_slab(addr);
-- 
2.25.1