linux-kernel - Re: [PATCH v1 02/15] powerpc/uaccess: Define ___get_user

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Date:   Tue, 02 Mar 2021 09:20:11 +1100
From:   Daniel Axtens <dja@...ens.net>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 02/15] powerpc/uaccess: Define ___get_user_instr() for ppc32

Hi Christophe,

> +#else /* !CONFIG_PPC64 */
> +#define ___get_user_instr(gu_op, dest, ptr)				\
> +	gu_op((dest).val, (u32 __user *)(ptr))
> +#endif /* CONFIG_PPC64 */
>  
>  #define get_user_instr(x, ptr) \
>  	___get_user_instr(get_user, x, ptr)
> @@ -91,18 +95,6 @@ static inline bool __access_ok(unsigned long addr, unsigned long size)
>  #define __get_user_instr_inatomic(x, ptr) \
>  	___get_user_instr(__get_user_inatomic, x, ptr)
>  
> -#else /* !CONFIG_PPC64 */
> -#define get_user_instr(x, ptr) \
> -	get_user((x).val, (u32 __user *)(ptr))
> -
> -#define __get_user_instr(x, ptr) \
> -	__get_user_nocheck((x).val, (u32 __user *)(ptr), sizeof(u32), true)
> -
> -#define __get_user_instr_inatomic(x, ptr) \
> -	__get_user_nosleep((x).val, (u32 __user *)(ptr), sizeof(u32))
> -
> -#endif /* CONFIG_PPC64 */

The previous version of __get_user_instr called __get_user_nocheck,
this version calls __get_user. Likewise __get_user_instr_inatomic called
__get_user_nosleep and now it calls __get_user_inatomic. I was confused
by this until I chased the macro definitions and realised that both
names refer to the same thing:

#define __get_user(x, ptr) \
	__get_user_nocheck((x), (ptr), sizeof(*(ptr)), true)

#define __get_user_inatomic(x, ptr) \
	__get_user_nosleep((x), (ptr), sizeof(*(ptr)))

(I don't think you need to do anything here, I'm just documenting what I
considered while reviewing your patch.)

As such:
Reviewed-by: Daniel Axtens <dja@...ens.net>

Kind regards,
Daniel


> -
>  extern long __put_user_bad(void);
>  
>  #define __put_user_size(x, ptr, size, retval)			\
> -- 
> 2.25.0