x86/copy_user_generic: Optimize copy_user_generic with CPU erms feature

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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@intel.com>
Link: http://lkml.kernel.org/r/1337908785-14015-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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Fenghua Yu 2012-05-24 18:19:45 -07:00 • committed by H. Peter Anvin

parent 2f74759056

commit 954e482bde

3 changed files with 70 additions and 16 deletions

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74

arch/x86/include/asm/alternative.h

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11

arch/x86/include/asm/uaccess_64.h

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1

arch/x86/kernel/x8664_ksyms_64.c

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