Re: [Xen-devel] [PATCH 25/45] xen: arm: separate guest user regs from internal guest state.

[Tim Deegan <tim@xxxxxxx>]

At 14:40 +0000 on 14 Feb (1360852832), Ian Campbell wrote:
> Subject: [PATCH] xen: arm: separate guest user regs from internal guest state.
> 
> struct cpu_user_regs is currently used as both internal state
> (specifically at the base of the stack) and a guest/toolstack
> visible API (via struct vcpu_guest_context used by
> XEN_DOMCTL_{g,s}etvcpucontext and VCPUOP_initialise).
> 
> This causes problems when we want to make the API 64-bit clean since
> we don't really want to change the size of the on-stack struct.
> 
> So split into vcpu_guest_core_regs which is the API facing struct
> and keep cpu_user_regs purely internal, translate between the two.
> 
> In the user API arrange for both 64- and 32-bit registers to be
> included in a layout which does not differ depending on toolstack
> architecture. Also switch to using the more formal banked register
> names (e.g. with the _usr suffix) for clarity.
> 
> This is an ABI change. Note that the kernel doesn't currently use
> this data structure so it affects the tools interface only.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
> v2: Allow 32-bit to see 64-bit register names too, this is needed so that
>     32-bit toolstacks can access/control 64-bit guests.

Acked-by: Tim Deegan <tim@xxxxxxx>


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