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

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