Re: [Xen-devel] Stack switching in a PV guest

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.12.13 at 14:50, Simon Martin <furryfuttock@xxxxxxxxx> wrote:
> I  have  checked  using gdb and when it gets to the iretq statement in
> HYPERVISOR_iret the stack is as follows
> 
> %rsp    -> valid instruction pointer
> %rsp+8  -> same CS as the original stack frame.
> %rsp+16 -> 0 (initial rFLAGS)

%rsp+24 -> ???
%rsp+32 -> ???

Those two are the crucial fields when you're having stack issues.

Furthermore, the guest's kernel stack wants to be switched via
__HYPERVISOR_stack_switch, or else the next interrupt/exception
would end up still using the old stack.

Jan


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