Re: [PATCH v3 04/39] kasan: shadow declarations only for software modes

From: elver@google.com
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	kasan-dev@googlegroups.com,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Elena Petrova <lenaptr@google.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 04/39] kasan: shadow declarations only for software modes
Date: Thu, 1 Oct 2020 19:29:01 +0200	[thread overview]
Message-ID: <20201001172901.GB4162920@elver.google.com> (raw)
In-Reply-To: <9de4c3b360444c66fcf454e0880fc655c5d80395.1600987622.git.andreyknvl@google.com>

On Fri, Sep 25, 2020 at 12:50AM +0200, Andrey Konovalov 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>

> ---
> Change-Id: I864be75a88b91b443c55e9c2042865e15703e164
> ---
>  include/linux/kasan.h | 44 ++++++++++++++++++++++++++-----------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index bd5b4965a269..44a9aae44138 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -3,16 +3,24 @@
>  #define _LINUX_KASAN_H
>  
>  #include <linux/types.h>
> +#include <asm/kasan.h>
>  
>  struct kmem_cache;
>  struct page;
>  struct vm_struct;
>  struct task_struct;
>  
> -#ifdef CONFIG_KASAN
> +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>  
>  #include <linux/pgtable.h>
> -#include <asm/kasan.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];
> @@ -29,6 +37,23 @@ 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);
>  
> @@ -69,9 +94,6 @@ 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)
>  {
> @@ -137,14 +159,6 @@ 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; }
>  
> @@ -152,8 +166,6 @@ 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);
> @@ -168,8 +180,6 @@ 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);
> -- 
> 2.28.0.681.g6f77f65b4e-goog
>