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ARM: 7449/1: use generic strnlen_user and strncpy_from_user functions

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This patch implements the word-at-a-time interface for ARM using the
same algorithm as x86. We use the fls macro from ARMv5 onwards, where
we have a clz instruction available which saves us a mov instruction
when targetting Thumb-2. For older CPUs, we use the magic 0x0ff0001
constant. Big-endian configurations make use of the implementation from
asm-generic.

With this implemented, we can replace our byte-at-a-time strnlen_user
and strncpy_from_user functions with the optimised generic versions.

Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon
2012-07-06 15:45:39 +01:00
committed by Russell King
parent 4295b898f5
commit 8c56cc8be5
7 changed files with 63 additions and 109 deletions
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4
arch/arm/kernel/armksyms.c
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@@ -87,10 +87,6 @@ EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memchr);
EXPORT_SYMBOL(__memzero);
/* user mem (segment) */
EXPORT_SYMBOL(__strnlen_user);
EXPORT_SYMBOL(__strncpy_from_user);
#ifdef CONFIG_MMU
EXPORT_SYMBOL(copy_page);