Re: [PATCH v6 03/18] kasan: sw_tags: Use arithmetic shift for shadow computation

[Alexander Potapenko]

> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index b00849ea8ffd..952ade776e51 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -61,8 +61,14 @@ int kasan_populate_early_shadow(const void *shadow_start,
>  #ifndef kasan_mem_to_shadow
>  static inline void *kasan_mem_to_shadow(const void *addr)
>  {
> -       return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
> -               + KASAN_SHADOW_OFFSET;
> +       void *scaled;
> +
> +       if (IS_ENABLED(CONFIG_KASAN_GENERIC))
> +               scaled = (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT);
> +       else
> +               scaled = (void *)((long)addr >> KASAN_SHADOW_SCALE_SHIFT);
> +
> +       return KASAN_SHADOW_OFFSET + scaled;
>  }
>  #endif

As Marco pointed out, this part is reverted in Patch 17. Any reason to do that?