Re: [PATCH 1/2] kasan: Cleanup the __HAVE_ARCH_SHADOW_MAP usage

[WANG Xuerui]

Hi,

On 9/9/23 19:54, Huacai Chen wrote:
> As Linus suggested, __HAVE_ARCH_XYZ is stupid and only for historical
> uses. So cleanup the __HAVE_ARCH_SHADOW_MAP usage and use self-defined

For the first sentence, I suggest adding quotation marks to make the 
opinion expression clearer. And paraphrasing a bit:

> As Linus suggested, __HAVE_ARCH_XYZ is "stupid" and "having 
historical uses of it doesn't make it good".

What do you think?

> macros instead.
"self-defined macro" doesn't really make sense, at least to me. I'd 
suggest something like "migrate __HAVE_ARCH_SHADOW_MAP to separate 
macros named after the respective functions", what about this one?
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---
>   arch/loongarch/include/asm/kasan.h | 10 ++++++++--
>   include/linux/kasan.h              |  2 +-
>   mm/kasan/kasan.h                   |  8 +++-----
>   3 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/kasan.h b/arch/loongarch/include/asm/kasan.h
> index deeff8158f45..a12ecab37da7 100644
> --- a/arch/loongarch/include/asm/kasan.h
> +++ b/arch/loongarch/include/asm/kasan.h
> @@ -10,8 +10,6 @@
>   #include <asm/io.h>
>   #include <asm/pgtable.h>
>   
> -#define __HAVE_ARCH_SHADOW_MAP
> -
>   #define KASAN_SHADOW_SCALE_SHIFT 3
>   #define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
>   
> @@ -68,6 +66,7 @@ static __always_inline bool kasan_arch_is_ready(void)
>   	return !kasan_early_stage;
>   }
>   
> +#define kasan_mem_to_shadow kasan_mem_to_shadow
>   static inline void *kasan_mem_to_shadow(const void *addr)
>   {
>   	if (!kasan_arch_is_ready()) {
> @@ -97,6 +96,7 @@ static inline void *kasan_mem_to_shadow(const void *addr)
>   	}
>   }
>   
> +#define kasan_shadow_to_mem kasan_shadow_to_mem
>   static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>   {
>   	unsigned long addr = (unsigned long)shadow_addr;
> @@ -119,6 +119,12 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>   	}
>   }
>   
> +#define addr_has_metadata addr_has_metadata
> +static __always_inline bool addr_has_metadata(const void *addr)
> +{
> +	return (kasan_mem_to_shadow((void *)addr) != NULL);
Drop the outermost pair of parens that's not necessary? It's only a 
simple comparison after all (although the left hand side is a bit "heavy").
> +}
> +
>   void kasan_init(void);
>   asmlinkage void kasan_early_init(void);
>   
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 3df5499f7936..842623d708c2 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -54,7 +54,7 @@ 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
> +#ifndef kasan_mem_to_shadow
>   static inline void *kasan_mem_to_shadow(const void *addr)
>   {
>   	return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index f70e3d7a602e..d37831b8511c 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -291,7 +291,7 @@ struct kasan_stack_ring {
>   
>   #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>   
> -#ifndef __HAVE_ARCH_SHADOW_MAP
> +#ifndef kasan_shadow_to_mem
>   static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>   {
>   	return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
> @@ -299,15 +299,13 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>   }
>   #endif
>   
> +#ifndef addr_has_metadata
>   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
>   }
> +#endif
>   
>   /**
>    * kasan_check_range - Check memory region, and report if invalid access.

The other parts look mechanical and okay to me. With the minor nits 
addressed (or justified):

Reviewed-by: WANG Xuerui <git@xxxxxxxxxx>

--
WANG "xen0n" Xuerui

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