| Subject | Re: [patch 11/41] x86/fpu: Get rid of copy_supervisor_to_kernel() | From | Andy Lutomirski <> | Date | Fri, 11 Jun 2021 12:42:22 -0700 |
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On 6/11/21 9:15 AM, Thomas Gleixner wrote: > If the fast path of restoring the FPU state on sigreturn fails or is not > taken and the current task's FPU is active then the FPU has to be > deactivated for the slow path to allow a safe update of the tasks FPU > memory state. > > With supervisor states enabled, this requires to save the supervisor state > in the memory state first. Supervisor states require XSAVES so saving only > the supervisor state requires to reshuffle the memory buffer because XSAVES > uses the compacted format and therefore stores the supervisor states at the > beginning of the memory state. That's just an overengineered optimization. > > Get rid of it and save the full state for this case.
Hallelujah.
Reviewed-by: Andy Lutomirski <luto@kernel.org>
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