linux-kernel - Re: [PATCH v4 02/16] x86/asm: Introduce inline memcpy and memset

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Message-ID: <20240711081317.GD4587@noisy.programming.kicks-ass.net>
Date: Thu, 11 Jul 2024 10:13:17 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
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	Xiongwei Song <xiongwei.song@...driver.com>,
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	Brijesh Singh <brijesh.singh@....com>,
	Michael Roth <michael.roth@....com>,
	Tony Luck <tony.luck@...el.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Alexey Kardashevskiy <aik@....com>,
	Jonathan Corbet <corbet@....net>,
	Sohil Mehta <sohil.mehta@...el.com>, Ingo Molnar <mingo@...nel.org>,
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Subject: Re: [PATCH v4 02/16] x86/asm: Introduce inline memcpy and memset

On Wed, Jul 10, 2024 at 07:06:38PM +0300, Alexander Shishkin wrote:
> From: Peter Zijlstra <peterz@...radead.org>
> 
> Provide inline memcpy and memset functions that can be used instead of
> the GCC builtins whenever necessary.
> 
> Code posted by Peter Zijlstra <peterz@...radead.org>.

We haz a tag for that:

Originally-by: Peter Zijlstra <peterz@...radead.org>

> Link: https://lore.kernel.org/lkml/Y759AJ%2F0N9fqwDED@hirez.programming.kicks-ass.net/
> [Missing Signed-off-by from PeterZ]

There, lemme fix that for you:

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

> Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> ---
>  arch/x86/include/asm/string.h | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/arch/x86/include/asm/string.h b/arch/x86/include/asm/string.h
> index c3c2c1914d65..9cb5aae7fba9 100644
> --- a/arch/x86/include/asm/string.h
> +++ b/arch/x86/include/asm/string.h
> @@ -1,6 +1,32 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_X86_STRING_H
> +#define _ASM_X86_STRING_H
> +
>  #ifdef CONFIG_X86_32
>  # include <asm/string_32.h>
>  #else
>  # include <asm/string_64.h>
>  #endif
> +
> +static __always_inline void *__inline_memcpy(void *to, const void *from, size_t len)
> +{
> +	void *ret = to;
> +
> +	asm volatile("rep movsb"
> +		     : "+D" (to), "+S" (from), "+c" (len)
> +		     : : "memory");
> +	return ret;
> +}
> +
> +static __always_inline void *__inline_memset(void *s, int v, size_t n)
> +{
> +	void *ret = s;
> +
> +	asm volatile("rep stosb"
> +		     : "+D" (s), "+c" (n)
> +		     : "a" ((uint8_t)v)
> +		     : "memory");
> +	return ret;
> +}
> +
> +#endif /* _ASM_X86_STRING_H */
> -- 
> 2.43.0
>