Re: [PATCH RFC 1/3] fpu/x86: add make_fpregs_active(_newstate) helper functions

[Yu-cheng Yu]

On Mon, Oct 17, 2016 at 01:57:06PM -0700, Andy Lutomirski wrote:
> Dave and/or Yu-cheng: didn't one of you have some code to allow a user
> xstate buffer to be filled from the copy in kernel memory?  If we did
> that, we could avoid this mess entirely.

In copy_fpstate_to_sigframe() (arch/x86/kernel/fpu/signal.c), the 
assumption was we have lazy fpu:

	if (fpregs_active() || we want an #NM exception)
		copy_fpregs_to_sigframe();
	else
		copy kernel buffer to user buffer;

But this is not the true anymore.  Or do you mean something else?

-- Yu-cheng