linux-kernel - Re: [PATCH 07/31] Add mips-specific parity functions

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Message-ID: <56F968EE.1000307@gmail.com>
Date:	Mon, 28 Mar 2016 10:25:02 -0700
From:	David Daney <ddaney.cavm@...il.com>
To:	"zhaoxiu.zeng" <zhaoxiu.zeng@...il.com>
CC:	Ralf Baechle <ralf@...ux-mips.org>,
	Leonid Yegoshin <Leonid.Yegoshin@...tec.com>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
Subject: Re: [PATCH 07/31] Add mips-specific parity functions

On 03/26/2016 11:06 PM, zhaoxiu.zeng wrote:
> From: Zeng Zhaoxiu <zhaoxiu.zeng@...il.com>
>

There is nothing MIPS specific here.  Why not put it in asm-generic or 
some similar place where it can be shared by all architectures?

Also, are you sure __builtin_popcount() is available on all GCC versions 
that are supported for building the kernel?

David Daney


> Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@...il.com>
> ---
>   arch/mips/include/asm/arch_parity.h | 44 +++++++++++++++++++++++++++++++++++++
>   arch/mips/include/asm/bitops.h      |  3 +++
>   2 files changed, 47 insertions(+)
>   create mode 100644 arch/mips/include/asm/arch_parity.h
>
> diff --git a/arch/mips/include/asm/arch_parity.h b/arch/mips/include/asm/arch_parity.h
> new file mode 100644
> index 0000000..23b3c23
> --- /dev/null
> +++ b/arch/mips/include/asm/arch_parity.h
> @@ -0,0 +1,44 @@
> +/*
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + *
> + */
> +#ifndef _ASM_ARCH_PARITY_H
> +#define _ASM_ARCH_PARITY_H
> +
> +#ifdef ARCH_HAS_USABLE_BUILTIN_POPCOUNT
> +
> +#include <asm/types.h>
> +
> +static inline unsigned int __arch_parity32(unsigned int w)
> +{
> +	return __builtin_popcount(w) & 1;
> +}
> +
> +static inline unsigned int __arch_parity16(unsigned int w)
> +{
> +	return __arch_parity32(w & 0xffff);
> +}
> +
> +static inline unsigned int __arch_parity8(unsigned int w)
> +{
> +	return __arch_parity32(w & 0xff);
> +}
> +
> +static inline unsigned int __arch_parity4(unsigned int w)
> +{
> +	return __arch_parity32(w & 0xf);
> +}
> +
> +static inline unsigned int __arch_parity64(__u64 w)
> +{
> +	return (unsigned int)__builtin_popcountll(w) & 1;
> +}
> +
> +#else
> +#include <asm-generic/bitops/arch_hweight.h>
> +#include <asm-generic/bitops/arch_parity.h>
> +#endif
> +
> +#endif /* _ASM_ARCH_PARITY_H */
> diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
> index ce9666c..0b87734 100644
> --- a/arch/mips/include/asm/bitops.h
> +++ b/arch/mips/include/asm/bitops.h
> @@ -626,6 +626,9 @@ static inline int ffs(int word)
>   #include <asm/arch_hweight.h>
>   #include <asm-generic/bitops/const_hweight.h>
>
> +#include <asm/arch_parity.h>
> +#include <asm-generic/bitops/const_parity.h>
> +
>   #include <asm-generic/bitops/le.h>
>   #include <asm-generic/bitops/ext2-atomic.h>
>
>