Split the core fpu state restoration out into __math_state_restore, which
assumes that cr0.TS is clear and that the fpu context has been initialized.
This will be used during context switch. There are two reasons this is
desireable:
- There's a small clarification. When __switch_to() calls math_state_restore,
it relies on the fact that tsk_used_math() returns true, and so will
never do a blocking init_fpu(). __math_state_restore() does not have
(or need) that logic, so the question never arises.
- It allows the clts() to be moved earler in __switch_to() so it can be performed
while cpu context updates are batched (will be done in a later patch).
[ Impact: refactor code to make reuse cleaner; no functional change ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
e6e9cac8c3