Re: [Xen-devel] [PATCH 1/4] x86: move syscall trampolines off the stack

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 18/05/15 13:46, Jan Beulich wrote:
> This is needed as stacks are going to become non-executable. Use
> separate stub pages (shared among suitable CPUs on the same node)
> instead.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Can you please include a description of how you intend the stubs to
function, and how they are layed out?  Parts of the code look like a
single page per stub, while other bits look like several stubs per page.

(Personally, I would split the stub allocation/mapping/freeing into a
patch separately to moving the syscall trampolines, as each are
moderately complicated changes.)

~Andrew

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