Re: xen: Fix possible page fault in fifo events

From: David Vrabel
Date: Mon Jul 28 2014 - 08:55:12 EST


On 15/07/14 14:48, Frediano Ziglio wrote:
> sync_test_bit function require a long* read access to pointer.
> This is a problem if the you are using last entry in the page causing
> an access to next page. If this page is not readable you get a memory
> access failure (page fault).
> All other x64 bit functions access memory using 32 bit operations.
> For processors different than x64 long aligned operations are used.

I think we should implement a set of 32-bit bit ops. We fudged around
it for the arm64 problem but this second problem shows we need a better
solution.

David

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