linux-kernel - Re: [PATCH] x86/copy_user_generic: Optimize copy_user

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Date:	Wed, 6 Jun 2012 11:52:01 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Fenghua Yu <fenghua.yu@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	H Peter Anvin <hpa@...or.com>,
	Andi Kleen <andi@...stfloor.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH] x86/copy_user_generic: Optimize copy_user_generic with
 CPU erms feature


* Fenghua Yu <fenghua.yu@...el.com> wrote:

> From: Fenghua Yu <fenghua.yu@...el.com>
> 
> According to Intel 64 and IA-32 SDM and Optimization Reference Manual, beginning
> with Ivybridge, REG string operation using MOVSB and STOSB can provide both
> flexible and high-performance REG string operations in cases like memory copy.
> Enhancement availability is indicated by CPUID.7.0.EBX[9] (Enhanced REP MOVSB/
> STOSB).
> 
> If CPU erms feature is detected, patch copy_user_generic with enhanced fast
> string version of copy_user_generic.
> 
> A few new macros are defined to reduce duplicate code in ALTERNATIVE and
> ALTERNATIVE_2.
> 
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> ---
> checkpatch.pl reports two errors in alternative_call_2() definition. I think
> the errors are invalid and should be ignored:
> ERROR: Macros with complex values should be enclosed in parenthesis
> ERROR: space prohibited before open square bracket '['

ok.

> 
>  arch/x86/include/asm/alternative.h |   74 ++++++++++++++++++++++++++++-------
>  arch/x86/include/asm/uaccess_64.h  |   11 +++++-
>  arch/x86/kernel/x8664_ksyms_64.c   |    1 +
>  3 files changed, 70 insertions(+), 16 deletions(-)

Looks good to me. Peter, Thomas, any objections?

Thanks,

	Ingo
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