On 2018-06-15 22:33:47 [+0200], Jason A. Donenfeld wrote: > On Fri, Jun 15, 2018 at 8:32 PM Andy Lutomirski <l...@kernel.org> wrote: > > quite in the form you imagined. The idea that we've tossed around is > > to restore FPU state on return to user mode. Roughly, we'd introduce > > a new thread flag TIF_FPU_UNLOADED (name TBD). > > prepare_exit_to_usermode() would notice this flag, copy the fpstate to > > fpregs, and clear the flag. (Or maybe exit_to_usermode_loop() -- No > > one has quite thought it through, but I think it should be outside the > > loop.) We'd update all the FPU accessors to understand the flag. > > Yes! This is exactly what I was thinking. Then those calls to begin() > and end() could be placed as close to the actual FPU usage as > possible.
I was thinking about this myself. Did anyone try to hack something in the meantime? I might want to look into this, too :) Sebastian
