Re: [PATCH v5 1/2] kasan: split kasan_*enabled() functions into a separate header

[Andrey Konovalov <andreyknvl@gmail.com>]

On Sat, Feb 19, 2022 at 2:30 AM Peter Collingbourne <pcc@google.com> wrote:
>
> In an upcoming commit we are going to need to call
> kasan_hw_tags_enabled() from arch/arm64/include/asm/mte.h. This
> would create a circular dependency between headers if KASAN_GENERIC
> or KASAN_SW_TAGS is enabled: linux/kasan.h -> linux/pgtable.h ->
> asm/pgtable.h -> asm/mte.h -> linux/kasan.h. Break the cycle
> by introducing a new header linux/kasan-enabled.h with the
> kasan_*enabled() functions that can be included from asm/mte.h.
>
> Link: https://linux-review.googlesource.com/id/I5b0d96c6ed0026fc790899e14d42b2fac6ab568e
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> ---
>  include/linux/kasan-enabled.h | 33 +++++++++++++++++++++++++++++++++
>  include/linux/kasan.h         | 23 +----------------------
>  2 files changed, 34 insertions(+), 22 deletions(-)
>  create mode 100644 include/linux/kasan-enabled.h
>
> diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> new file mode 100644
> index 000000000000..4b6615375022
> --- /dev/null
> +++ b/include/linux/kasan-enabled.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_KASAN_ENABLED_H
> +#define _LINUX_KASAN_ENABLED_H
> +
> +#ifdef CONFIG_KASAN_HW_TAGS
> +
> +DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
> +
> +static __always_inline bool kasan_enabled(void)
> +{
> +       return static_branch_likely(&kasan_flag_enabled);
> +}
> +
> +static inline bool kasan_hw_tags_enabled(void)
> +{
> +       return kasan_enabled();
> +}
> +
> +#else /* CONFIG_KASAN_HW_TAGS */
> +
> +static inline bool kasan_enabled(void)
> +{
> +       return IS_ENABLED(CONFIG_KASAN);
> +}
> +
> +static inline bool kasan_hw_tags_enabled(void)
> +{
> +       return false;
> +}
> +
> +#endif /* CONFIG_KASAN_HW_TAGS */
> +
> +#endif /* LINUX_KASAN_ENABLED_H */
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 4a45562d8893..b6a93261c92a 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -3,6 +3,7 @@
>  #define _LINUX_KASAN_H
>
>  #include <linux/bug.h>
> +#include <linux/kasan-enabled.h>
>  #include <linux/kernel.h>
>  #include <linux/static_key.h>
>  #include <linux/types.h>
> @@ -83,33 +84,11 @@ static inline void kasan_disable_current(void) {}
>
>  #ifdef CONFIG_KASAN_HW_TAGS
>
> -DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
> -
> -static __always_inline bool kasan_enabled(void)
> -{
> -       return static_branch_likely(&kasan_flag_enabled);
> -}
> -
> -static inline bool kasan_hw_tags_enabled(void)
> -{
> -       return kasan_enabled();
> -}
> -
>  void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags);
>  void kasan_free_pages(struct page *page, unsigned int order);
>
>  #else /* CONFIG_KASAN_HW_TAGS */
>
> -static inline bool kasan_enabled(void)
> -{
> -       return IS_ENABLED(CONFIG_KASAN);
> -}
> -
> -static inline bool kasan_hw_tags_enabled(void)
> -{
> -       return false;
> -}
> -
>  static __always_inline void kasan_alloc_pages(struct page *page,
>                                               unsigned int order, gfp_t flags)
>  {
> --
> 2.35.1.473.g83b2b277ed-goog
>

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>