Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 17 Oct 2016 16:30:47 -0700 | Subject | Re: [PATCH RFC 1/3] fpu/x86: add make_fpregs_active(_newstate) helper functions |
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On Mon, Oct 17, 2016 at 4:04 PM, Yu-cheng Yu <yu-cheng.yu@intel.com> wrote: > 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?
Rik wants to add a different form of FPU laziness, and it would be simpler if we could just always copy from a kernel buffer. Does code to do that exist in the tree?
--Andy
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