[RFC PATCH] uprobes: copy to user-space xol page with proper cache flushing

[Russell King - ARM Linux]

On Fri, Apr 11, 2014 at 05:32:49PM +0200, Peter Zijlstra wrote:
> On Fri, Apr 11, 2014 at 05:22:07PM +0200, Oleg Nesterov wrote:
> > And I am just curious, why arm's copy_to_user_page() disables premption
> > before memcpy?
> 
> Without looking, I suspect its because the VIVT caches, they need to get
> shot down on every context switch.

So... let's think about that for a moment... if we have a preemption event,
then that's a context switch, which means...

No, this is obviously not the reason, because such an event on a fully
VIVT system would result in the caches being flushed, meaning that we
wouldn't need to do anything if we could be predicably preempted at that
point.

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