[PATCH] uaccess: Add __copy_from_kernel_inatomic() primitive

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> Yeah, so what I missed here are those nops: placeholders for the 
> STAC/CLAC instructions on x86... and this is what Linus mentioned 
> about the clac() overhead.
> 
> But this could be solved I think: by adding a 
> copy_from_kernel_inatomic() primitive which simply leaves out the 
> STAC/CLAC sequence: as these are always guaranteed to be kernel 
> addresses, the SMAP fault should not be generated.

So the first step would be to introduce a generic 
__copy_from_kernel_inatomic() primitive as attached below.

The next patch will implement efficient __copy_from_kernel_inatomic() 
for x86.

Thanks,

	Ingo

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