x86/fpu: Introduce task_disable_lazy_fpu_restore() helper
Currently there are a few magic assignments sprinkled through the code that disable lazy FPU state restoring, some more effective than others, and all equally mystifying. It would be easier to have a helper to explicitly disable lazy FPU state restoring for a task. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: http://lkml.kernel.org/r/1423252925-14451-6-git-send-email-riel@redhat.com Signed-off-by: Borislav Petkov <bp@suse.de>
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@ -79,6 +79,16 @@ static inline void __cpu_disable_lazy_restore(unsigned int cpu)
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per_cpu(fpu_owner_task, cpu) = NULL;
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}
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/*
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* Used to indicate that the FPU state in memory is newer than the FPU
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* state in registers, and the FPU state should be reloaded next time the
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* task is run. Only safe on the current task, or non-running tasks.
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*/
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static inline void task_disable_lazy_fpu_restore(struct task_struct *tsk)
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{
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tsk->thread.fpu.last_cpu = ~0;
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}
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static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu)
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{
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return new == this_cpu_read_stable(fpu_owner_task) &&
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