linux-kernel - Re: [PATCH 13/18] powerpc/uaccess: fix sparse errors

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Message-ID: <1418601906.5111.37.camel@kernel.crashing.org>
Date:	Mon, 15 Dec 2014 11:05:06 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	linux-arch@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 13/18] powerpc/uaccess: fix sparse errors

On Sun, 2014-12-14 at 18:52 +0200, Michael S. Tsirkin wrote:
> virtio wants to read bitwise types from userspace using get_user.  At the
> moment this triggers sparse errors, since the value is passed through an
> integer.
> 
> Fix that up using __force.

You mean bitfields ? Argh ... we should just remove them from the
compiler and be done with it :-(

Ben.

> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---
>  arch/powerpc/include/asm/uaccess.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
> index 9485b43..a0c071d 100644
> --- a/arch/powerpc/include/asm/uaccess.h
> +++ b/arch/powerpc/include/asm/uaccess.h
> @@ -284,7 +284,7 @@ do {								\
>  	if (!is_kernel_addr((unsigned long)__gu_addr))		\
>  		might_fault();					\
>  	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
> -	(x) = (__typeof__(*(ptr)))__gu_val;			\
> +	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
>  	__gu_err;						\
>  })
>  #endif /* __powerpc64__ */
> @@ -297,7 +297,7 @@ do {								\
>  	might_fault();							\
>  	if (access_ok(VERIFY_READ, __gu_addr, (size)))			\
>  		__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
> -	(x) = (__typeof__(*(ptr)))__gu_val;				\
> +	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
>  	__gu_err;							\
>  })
>  
> @@ -308,7 +308,7 @@ do {								\
>  	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
>  	__chk_user_ptr(ptr);					\
>  	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
> -	(x) = (__typeof__(*(ptr)))__gu_val;			\
> +	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
>  	__gu_err;						\
>  })
>  


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