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From: davem@davemloft.net (David Miller)
Date: Fri, 11 Apr 2014 14:19:11 -0400 (EDT)
Subject: [RFC PATCH] uprobes: copy to user-space xol page with proper
 cache flushing
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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 11 Apr 2014 11:11:33 -0700

> And quite frankly, using the "vma->vm_flags" sounds potentially
> *incorrect* to me, since it really isn't about the vma. If you change
> a page through a non-executable vma, you'd want to flush the icache
> entry for that page mapped in a totally different vma. So I really get
> the feeling that passing in "vma" is actively *wrong*. The vma
> interface really makes little to no sense.
> 
> Hmm?

The vm_flags check is about "could it have gotten into the I-cache
via this VMA".

If the VMA protections change, we'd do a flush of some sort during
that change.