| Date | Tue, 13 Jan 2015 17:19:38 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH 05/11] x86,fpu: ensure FPU state is reloaded from memory if task is traced |
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On 01/11, riel@redhat.com wrote: > > @@ -412,8 +412,14 @@ static inline void switch_fpu_prepare(struct task_struct *old, struct task_struc > bool preload = tsk_used_math(new) && (use_eager_fpu() || > new->thread.fpu_counter > 5); > if (__thread_has_fpu(old)) { > - if (!__save_init_fpu(old)) > + /* > + * Make sure the FPU state is restored from memory next time, > + * if the task has an FPU exception pending, or the task's in > + * memory FPU state could be changed by a debugger. > + */ > + if (!__save_init_fpu(old) || task_is_stopped_or_traced(old)) > cpu = ~0;
Well, if debugger wants to change FPU state, it should call init_fpu() which resets .last_cpu ?
Plus "is_stopped" is not needed, ptracer no longer can do STOPPED -> TRACED transition.
Oleg.
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