Re: Grab the physical address of a label

[Zeinab Alebouyeh <z.alebouyeh@gmail.com>]

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On Wed, Jun 6, 2012 at 11:31 PM, Ian Campbell <Ian.Campbell@citrix.com>wrote:

> Please don't top post, it makes it hard to follow the flow of the
> conversation.
>
> You might also find it useful to read
> http://wiki.xen.org/wiki/Asking_Xen_Devel_Questions
>
> On Thu, 2012-06-07 at 05:29 +0100, Zeinab Alebouyeh wrote:
> > Thanks but I think if I find the base physical address of xen image I
> > can convert virtual address to physical address
>
> I'm not sure what this has to do with taking the address of a label,
> like you originally asked, but...
>
> There are macros to convert a xenheap virtual address into a physical
> one and back, see __pa and __va. (Note that these only work for xenheap
> addresses).
>
> > I'm working in xen4 and my platform is: Processor AMD 64 and Centos 6
> > i386 with 8G of RAM
>
> Are you using a 32-bit or 64-bit hypervisor?
>
> I strongly recommend basing all future x86 work on 64-bit Xen, even if
> you are using a 32 bit dom0.
>
> > Can anyone tell me The physical address that xen image load in it?
> > This physical address depends on platform?
>
> Yes, Xen will relocate itself at start of day. You should be able to
> figure out the details from the implementation of __pa and __va.
>
> It might be helpful if you described what you are actually trying to
> achieve here -- what is your end goal?
>
> Ian.
>

Hi
Because currently I'm not in lab I don't know my hypervisor is 32b or 64
bit.
I'm working in a security project. for improve security of applications
running in virtualized environment. I want to use the security instruction
of AMD SVM named SKINIT.
because this instruction must run in ring0, I add a hypercall in xen and
write my codes in my hypercall function.
The skinit instruction takes the physical address of a block as an input
operand( in the eax register) and establish a secure execution environment
for a software component(block)
I have a label in my hypercall function that is the start of my block. In
order to use skinit I want grab the physical address of my label to save in
eax register.

Thanks if anyone help me.

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