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| author | Michael Cree <mcree@orcon.net.nz> | 2012-08-19 04:40:58 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-08-19 17:41:18 +0200 |
| commit | f2db633d301b4b50f5f93de0e8314cc81e9bc7de (patch) | |
| tree | aafa01b17e83221ca92ee58e66d7e6783808a224 /arch/alpha/Kconfig | |
| parent | alpha: Wire up cross memory attach syscalls (diff) | |
| download | linux-f2db633d301b4b50f5f93de0e8314cc81e9bc7de.tar.xz linux-f2db633d301b4b50f5f93de0e8314cc81e9bc7de.zip | |
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/Kconfig | 2 |
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, |