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x86/asm: Enable fast 32-bit put_user_64() for copy_to_user() 

For fixed sized copies, copy_to_user() will utilize
__put_user_size() fastpaths. However, it is missing the
translation for 64-bit 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.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1429091486-11443-1-git-send-email-chris@chris-wilson.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Chris Wilson 2015-04-15 10:51:26 +01:00 committed by Ingo Molnar
parent c0f6feba78
commit 6a907738ab
1 changed files with 4 additions and 0 deletions
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4
arch/x86/include/asm/uaccess_32.h
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@ -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);