Re: [PATCH mm v3 08/19] kasan: inline random_tag for HW_TAGS

From: Dmitry Vyukov <dvyukov@google.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Marco Elver <elver@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Alexander Potapenko <glider@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH mm v3 08/19] kasan: inline random_tag for HW_TAGS
Date: Tue, 17 Nov 2020 11:58:01 +0100	[thread overview]
Message-ID: <CACT4Y+aYcegV8ZqxYGa0PuK-J97Lh5jXoVyciHW0fuEJPzZBvA@mail.gmail.com> (raw)
In-Reply-To: <d42cdd23c59501ccc4ab91cf4e04dd134be57277.1605305978.git.andreyknvl@google.com>

On Fri, Nov 13, 2020 at 11:20 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> Using random_tag() currently results in a function call. Move its
> definition to mm/kasan/kasan.h and turn it into a static inline function
> for hardware tag-based mode to avoid uneeded function calls.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Reviewed-by: Marco Elver <elver@google.com>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

> Link: https://linux-review.googlesource.com/id/Iac5b2faf9a912900e16cca6834d621f5d4abf427
> ---
>  mm/kasan/hw_tags.c |  5 -----
>  mm/kasan/kasan.h   | 31 ++++++++++++++-----------------
>  2 files changed, 14 insertions(+), 22 deletions(-)
>
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index a34476764f1d..3cdd87d189f6 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -51,11 +51,6 @@ void unpoison_range(const void *address, size_t size)
>                         round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
>  }
>
> -u8 random_tag(void)
> -{
> -       return hw_get_random_tag();
> -}
> -
>  bool check_invalid_free(void *addr)
>  {
>         u8 ptr_tag = get_tag(addr);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 5e8cd2080369..7876a2547b7d 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -190,6 +190,12 @@ static inline bool addr_has_metadata(const void *addr)
>
>  #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> +void print_tags(u8 addr_tag, const void *addr);
> +#else
> +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);
> @@ -225,23 +231,6 @@ static inline void quarantine_reduce(void) { }
>  static inline void quarantine_remove_cache(struct kmem_cache *cache) { }
>  #endif
>
> -#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> -
> -void print_tags(u8 addr_tag, const void *addr);
> -
> -u8 random_tag(void);
> -
> -#else
> -
> -static inline void print_tags(u8 addr_tag, const void *addr) { }
> -
> -static inline u8 random_tag(void)
> -{
> -       return 0;
> -}
> -
> -#endif
> -
>  #ifndef arch_kasan_set_tag
>  static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
>  {
> @@ -281,6 +270,14 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
>
>  #endif /* CONFIG_KASAN_HW_TAGS */
>
> +#ifdef CONFIG_KASAN_SW_TAGS
> +u8 random_tag(void);
> +#elif defined(CONFIG_KASAN_HW_TAGS)
> +static inline u8 random_tag(void) { return hw_get_random_tag(); }
> +#else
> +static inline u8 random_tag(void) { return 0; }
> +#endif
> +
>  /*
>   * Exported functions for interfaces called from assembly or from generated
>   * code. Declarations here to avoid warning about missing declarations.
> --
> 2.29.2.299.gdc1121823c-goog
>

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