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authorMichael Cree <mcree@orcon.net.nz>2012-08-19 14:40:58 +1200
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-19 08:41:18 -0700
commitf2db633d301b4b50f5f93de0e8314cc81e9bc7de (patch)
treeaafa01b17e83221ca92ee58e66d7e6783808a224 /arch/alpha/Kconfig
parentd8d5da129857bfd54b603771fca5409062167392 (diff)
downloadlinux-sh-f2db633d301b4b50f5f93de0e8314cc81e9bc7de.tar.gz
alpha: Use new generic strncpy_from_user() and strnlen_user()
Similar to x86/sparc/powerpc implementations except: 1) we implement an extremely efficient has_zero()/find_zero() sequence with both prep_zero_mask() and create_zero_mask() no-operations. 2) Our output from prep_zero_mask() differs in that only the lowest eight bits are used to represent the zero bytes nevertheless it can be safely ORed with other similar masks from prep_zero_mask() and forms input to create_zero_mask(), the two fundamental properties prep_zero_mask() must satisfy. Tests on EV67 and EV68 CPUs revealed that the generic code is essentially as fast (to within 0.5% of CPU cycles) of the old Alpha specific code for large quadword-aligned strings, despite the 30% extra CPU instructions executed. In contrast, the generic code for unaligned strings is substantially slower (by more than a factor of 3) than the old Alpha specific code. Signed-off-by: Michael Cree <mcree@orcon.net.nz> Acked-by: Matt Turner <mattst88@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/alpha/Kconfig')
-rw-r--r--arch/alpha/Kconfig2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index d5b9b5e645cc..9944dedee5b1 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -18,6 +18,8 @@ config ALPHA
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_SMP_IDLE_THREAD
select GENERIC_CMOS_UPDATE
+ select GENERIC_STRNCPY_FROM_USER
+ select GENERIC_STRNLEN_USER
help
The Alpha is a 64-bit general-purpose processor designed and
marketed by the Digital Equipment Corporation of blessed memory,