2020-11-13 22:23:39

by Andrey Konovalov

Subject: [PATCH mm v3 09/19] kasan: open-code kasan_unpoison_slab

There's the external annotation kasan_unpoison_slab() that is currently
defined as static inline and uses kasan_unpoison_range(). Open-code this
function in mempool.c. Otherwise with an upcoming change this function
will result in an unnecessary function call.

Signed-off-by: Andrey Konovalov <[email protected]>
Link: https://linux-review.googlesource.com/id/Ia7c8b659f79209935cbaab3913bf7f082cc43a0e
---
include/linux/kasan.h | 6 ------
mm/mempool.c | 2 +-
2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 1594177f86bb..872bf145ddde 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -106,11 +106,6 @@ struct kasan_cache {
int free_meta_offset;
};

-size_t __ksize(const void *);
-static inline void kasan_unpoison_slab(const void *ptr)
-{
- kasan_unpoison_range(ptr, __ksize(ptr));
-}
size_t kasan_metadata_size(struct kmem_cache *cache);

bool kasan_save_enable_multi_shot(void);
@@ -166,7 +161,6 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
return false;
}

-static inline void kasan_unpoison_slab(const void *ptr) { }
static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }

#endif /* CONFIG_KASAN */
diff --git a/mm/mempool.c b/mm/mempool.c
index f473cdddaff0..583a9865b181 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -112,7 +112,7 @@ static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
static void kasan_unpoison_element(mempool_t *pool, void *element)
{
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
- kasan_unpoison_slab(element);
+ kasan_unpoison_range(element, __ksize(element));
else if (pool->alloc == mempool_alloc_pages)
kasan_alloc_pages(element, (unsigned long)pool->pool_data);
}
--
2.29.2.299.gdc1121823c-goog

2020-11-16 15:09:58

by Marco Elver

Subject: Re: [PATCH mm v3 09/19] kasan: open-code kasan_unpoison_slab

On Fri, Nov 13, 2020 at 11:19PM +0100, Andrey Konovalov wrote:
> There's the external annotation kasan_unpoison_slab() that is currently
> defined as static inline and uses kasan_unpoison_range(). Open-code this
> function in mempool.c. Otherwise with an upcoming change this function
> will result in an unnecessary function call.
>
> Signed-off-by: Andrey Konovalov <[email protected]>
> Link: https://linux-review.googlesource.com/id/Ia7c8b659f79209935cbaab3913bf7f082cc43a0e

Reviewed-by: Marco Elver <[email protected]>

Thank you!

I also think this change made the code more readable, as
kasan_unpoison_slab() made me think it's unpoisoning the *whole* slab,
which is clearly not the case.

> ---
> include/linux/kasan.h | 6 ------
> mm/mempool.c | 2 +-
> 2 files changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 1594177f86bb..872bf145ddde 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -106,11 +106,6 @@ struct kasan_cache {
> int free_meta_offset;
> };
>
> -size_t __ksize(const void *);
> -static inline void kasan_unpoison_slab(const void *ptr)
> -{
> - kasan_unpoison_range(ptr, __ksize(ptr));
> -}
> size_t kasan_metadata_size(struct kmem_cache *cache);
>
> bool kasan_save_enable_multi_shot(void);
> @@ -166,7 +161,6 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
> return false;
> }
>
> -static inline void kasan_unpoison_slab(const void *ptr) { }
> static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
>
> #endif /* CONFIG_KASAN */
> diff --git a/mm/mempool.c b/mm/mempool.c
> index f473cdddaff0..583a9865b181 100644
> --- a/mm/mempool.c
> +++ b/mm/mempool.c
> @@ -112,7 +112,7 @@ static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
> static void kasan_unpoison_element(mempool_t *pool, void *element)
> {
> if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
> - kasan_unpoison_slab(element);
> + kasan_unpoison_range(element, __ksize(element));
> else if (pool->alloc == mempool_alloc_pages)
> kasan_alloc_pages(element, (unsigned long)pool->pool_data);
> }
> --
> 2.29.2.299.gdc1121823c-goog
>