For fixed sized copies, copy_to_user() will utilize __put_user_size fastpaths. However, it is missing the translation for 64bit copies on x86/32. Testing on a Pinetrail Atom, the 64 bit put_user fastpath is substantially faster than the generic copy_to_user() fallback.
Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: [email protected] CC: [email protected] --- arch/x86/include/asm/uaccess_32.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h index 3c03a5de64d3..0ed5504c6060 100644 --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -59,6 +59,10 @@ __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4); return ret; + case 8: + __put_user_size(*(u64 *)from, (u64 __user *)to, + 8, ret, 8); + return ret; } } return __copy_to_user_ll(to, from, n); -- 2.1.4 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
