Subject: Re: [PATCH v2 09/20] kasan: inline kasan_poison_memory and check_invalid_free

From: Marco Elver <[email-masked]>
Date: Wed, 11 Nov 2020 18:50:38 +0100

On Tue, Nov 10, 2020 at 11:20PM +0100, 'Andrey Konovalov' via kasan-dev wrote:
> Using kasan_poison_memory() or check_invalid_free() currently results in
> function calls. Move their definitions to mm/kasan/kasan.h and turn them
> into static inline functions for hardware tag-based mode to avoid
> unneeded function calls.
> 
> Signed-off-by: Andrey Konovalov <[email-masked]>
> Reviewed-by: Dmitry Vyukov <[email-masked]>
> Link: https://linux-review.googlesource.com/id/Ia9d8191024a12d1374675b3d27197f10193f50bb
> ---
>  mm/kasan/hw_tags.c | 15 ---------------
>  mm/kasan/kasan.h   | 28 ++++++++++++++++++++++++----
>  2 files changed, 24 insertions(+), 19 deletions(-)

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

> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index 1476ac07666e..0303e49904b4 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -30,27 +30,12 @@ void kasan_init_hw_tags(void)
>  	pr_info("KernelAddressSanitizer initialized\n");
>  }
>  
> -void kasan_poison_memory(const void *address, size_t size, u8 value)
> -{
> -	hw_set_mem_tag_range(kasan_reset_tag(address),
> -			round_up(size, KASAN_GRANULE_SIZE), value);
> -}
> -
>  void kasan_unpoison_memory(const void *address, size_t size)
>  {
>  	hw_set_mem_tag_range(kasan_reset_tag(address),
>  			round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
>  }
>  
> -bool check_invalid_free(void *addr)
> -{
> -	u8 ptr_tag = get_tag(addr);
> -	u8 mem_tag = hw_get_mem_tag(addr);
> -
> -	return (mem_tag == KASAN_TAG_INVALID) ||
> -		(ptr_tag != KASAN_TAG_KERNEL && ptr_tag != mem_tag);
> -}
> -
>  void kasan_set_free_info(struct kmem_cache *cache,
>  				void *object, u8 tag)
>  {
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 7498839a15d3..ab7314418604 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -153,8 +153,6 @@ struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
>  struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
>  						const void *object);
>  
> -void kasan_poison_memory(const void *address, size_t size, u8 value);
> -
>  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>  
>  static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
> @@ -194,8 +192,6 @@ void print_tags(u8 addr_tag, const void *addr);
>  static inline void print_tags(u8 addr_tag, const void *addr) { }
>  #endif
>  
> -bool check_invalid_free(void *addr);
> -
>  void *find_first_bad_addr(void *addr, size_t size);
>  const char *get_bug_type(struct kasan_access_info *info);
>  void metadata_fetch_row(char *buffer, void *row);
> @@ -279,6 +275,30 @@ static inline u8 random_tag(void)
>  }
>  #endif
>  
> +#ifdef CONFIG_KASAN_HW_TAGS
> +
> +static inline void kasan_poison_memory(const void *address, size_t size, u8 value)
> +{
> +	hw_set_mem_tag_range(kasan_reset_tag(address),
> +			round_up(size, KASAN_GRANULE_SIZE), value);
> +}
> +
> +static inline bool check_invalid_free(void *addr)
> +{
> +	u8 ptr_tag = get_tag(addr);
> +	u8 mem_tag = hw_get_mem_tag(addr);
> +
> +	return (mem_tag == KASAN_TAG_INVALID) ||
> +		(ptr_tag != KASAN_TAG_KERNEL && ptr_tag != mem_tag);
> +}
> +
> +#else /* CONFIG_KASAN_HW_TAGS */
> +
> +void kasan_poison_memory(const void *address, size_t size, u8 value);
> +bool check_invalid_free(void *addr);
> +
> +#endif /* CONFIG_KASAN_HW_TAGS */
> +
>  /*
>   * Exported functions for interfaces called from assembly or from generated
>   * code. Declarations here to avoid warning about missing declarations.
> -- 
> 2.29.2.222.g5d2a92d10f8-goog
> 
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