Re: [PATCH v9 05/44] kasan: shadow declarations only for software modes

[Alexander Potapenko <glider@google.com>]

On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> This is a preparatory commit for the upcoming addition of a new hardware
> tag-based (MTE-based) KASAN mode.
>
> Group shadow-related KASAN function declarations and only define them
> for the two existing software modes.
>
> No functional changes for software modes.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>

> ---
> Change-Id: I864be75a88b91b443c55e9c2042865e15703e164
> ---
>  include/linux/kasan.h | 47 ++++++++++++++++++++++++++++---------------
>  1 file changed, 31 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 59538e795df4..26f2ab92e7ca 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -11,7 +11,6 @@ struct task_struct;
>
>  #ifdef CONFIG_KASAN
>
> -#include <linux/pgtable.h>
>  #include <asm/kasan.h>
>
>  /* kasan_data struct is used in KUnit tests for KASAN expected failures */
> @@ -20,6 +19,20 @@ struct kunit_kasan_expectation {
>         bool report_found;
>  };
>
> +#endif
> +
> +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> +
> +#include <linux/pgtable.h>
> +
> +/* Software KASAN implementations use shadow memory. */
> +
> +#ifdef CONFIG_KASAN_SW_TAGS
> +#define KASAN_SHADOW_INIT 0xFF
> +#else
> +#define KASAN_SHADOW_INIT 0
> +#endif
> +
>  extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
>  extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE];
>  extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
> @@ -35,6 +48,23 @@ static inline void *kasan_mem_to_shadow(const void *addr)
>                 + KASAN_SHADOW_OFFSET;
>  }
>
> +int kasan_add_zero_shadow(void *start, unsigned long size);
> +void kasan_remove_zero_shadow(void *start, unsigned long size);
> +
> +#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> +
> +static inline int kasan_add_zero_shadow(void *start, unsigned long size)
> +{
> +       return 0;
> +}
> +static inline void kasan_remove_zero_shadow(void *start,
> +                                       unsigned long size)
> +{}
> +
> +#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> +
> +#ifdef CONFIG_KASAN
> +
>  /* Enable reporting bugs after kasan_disable_current() */
>  extern void kasan_enable_current(void);
>
> @@ -75,9 +105,6 @@ struct kasan_cache {
>         int free_meta_offset;
>  };
>
> -int kasan_add_zero_shadow(void *start, unsigned long size);
> -void kasan_remove_zero_shadow(void *start, unsigned long size);
> -
>  size_t __ksize(const void *);
>  static inline void kasan_unpoison_slab(const void *ptr)
>  {
> @@ -143,14 +170,6 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
>         return false;
>  }
>
> -static inline int kasan_add_zero_shadow(void *start, unsigned long size)
> -{
> -       return 0;
> -}
> -static inline void kasan_remove_zero_shadow(void *start,
> -                                       unsigned long size)
> -{}
> -
>  static inline void kasan_unpoison_slab(const void *ptr) { }
>  static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
>
> @@ -158,8 +177,6 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
>
>  #ifdef CONFIG_KASAN_GENERIC
>
> -#define KASAN_SHADOW_INIT 0
> -
>  void kasan_cache_shrink(struct kmem_cache *cache);
>  void kasan_cache_shutdown(struct kmem_cache *cache);
>  void kasan_record_aux_stack(void *ptr);
> @@ -174,8 +191,6 @@ static inline void kasan_record_aux_stack(void *ptr) {}
>
>  #ifdef CONFIG_KASAN_SW_TAGS
>
> -#define KASAN_SHADOW_INIT 0xFF
> -
>  void kasan_init_tags(void);
>
>  void *kasan_reset_tag(const void *addr);
> --
> 2.29.2.222.g5d2a92d10f8-goog
>


-- 
Alexander Potapenko
Software Engineer

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