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

elver
2020-10-01T17:29:12Z

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
>