[tip:x86/asm] x86/asm: Enable fast 32-bit put_user_64() for copy_to_user()
From: tip-bot for Chris Wilson
Date: Thu Apr 16 2015 - 12:17:03 EST
Commit-ID: 6a907738ab9840ca3d71c22cd28fba4cbae7f7ce
Gitweb: http://git.kernel.org/tip/6a907738ab9840ca3d71c22cd28fba4cbae7f7ce
Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 15 Apr 2015 10:51:26 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 16 Apr 2015 12:08:21 +0200
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@xxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1429091486-11443-1-git-send-email-chris@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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 3c03a5d..0ed5504 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);
--
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