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Re: [Xen-devel] Xen on ARM: Read SP_usr and SP_svc in HYP mode

On 25/08/15 05:43, harry wrote:
> Hi,


> Now I want to implement some functions in other hypervisor, so I need to
> read SP_usr and SP_svc in HYP mode. I know Xen has implemented this
> function. But I use it with regs->sp_usr/svc to achieve this. But I
> don't know how to achieve it. I have read the entry.S file and get the
> process to save the regs, but some definition is not clear. I want to
> know if there is some asm command to achieve this? Or do I need to
> switch the mode manually to read it?

Please reach out the mailing list related to the hypervisor you want to
modify to know whether they have handy helpers to access SP_usr/SP_svc.

If not, I would advice you to read the ARM ARM in order to know how to
access banked registers, particularly the section "Encoding and use of
Banked register transfer instructions".


Julien Grall

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