On Tue, Apr 4, 2023 at 10:43 AM Qing Zhang <zhangqing@xxxxxxxxxxx> wrote:
>
> Like the LoongArch, which has many holes between different segments
> and valid address space(256T available) is insufficient to map all
> these segments to kasan shadow memory with the common formula provided
> by kasan core, We need architecture specific mapping formula,different
> segments are mapped individually, and only limited length of space of
> that specific segment is mapped to shadow.
>
> Therefore, when the incoming address is converted to a shadow, we need
> to add a condition to determine whether it is valid.
>
> Signed-off-by: Qing Zhang <zhangqing@xxxxxxxxxxx>
> ---
> include/linux/kasan.h | 2 ++
> mm/kasan/kasan.h | 6 ++++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index f7ef70661ce2..3b91b941873d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -54,11 +54,13 @@ extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
> int kasan_populate_early_shadow(const void *shadow_start,
> const void *shadow_end);
>
> +#ifndef __HAVE_ARCH_SHADOW_MAP
> static inline void *kasan_mem_to_shadow(const void *addr)
> {
> return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
> + KASAN_SHADOW_OFFSET;
> }
> +#endif
>
> int kasan_add_zero_shadow(void *start, unsigned long size);
> void kasan_remove_zero_shadow(void *start, unsigned long size);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index a61eeee3095a..033335c13b25 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -291,16 +291,22 @@ struct kasan_stack_ring {
>
> #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>
> +#ifndef __HAVE_ARCH_SHADOW_MAP
> static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
> {
> return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
> << KASAN_SHADOW_SCALE_SHIFT);
> }
> +#endif
>
> static __always_inline bool addr_has_metadata(const void *addr)
> {
> +#ifdef __HAVE_ARCH_SHADOW_MAP
> + return (kasan_mem_to_shadow((void *)addr) != NULL);
> +#else
> return (kasan_reset_tag(addr) >=
> kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> +#endif
> }
>
> /**
> --
> 2.20.1
>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Thanks!
