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SubjectRe: [PATCH v2 06/21] arm64: KVM: VHE: Patch out use of HVC
On Mon, Feb 01, 2016 at 01:34:16PM +0000, Marc Zyngier wrote:
> On 01/02/16 13:16, Christoffer Dall wrote:
> > On Mon, Jan 25, 2016 at 03:53:40PM +0000, Marc Zyngier wrote:
> >> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> >> index 93e8d983..9e0683f 100644
> >> --- a/arch/arm64/kvm/hyp/hyp-entry.S
> >> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> >> @@ -38,6 +38,32 @@
> >> ldp x0, x1, [sp], #16
> >> .endm
> >>
> >> +.macro do_el2_call
> >> + /*
> >> + * Shuffle the parameters before calling the function
> >> + * pointed to in x0. Assumes parameters in x[1,2,3].
> >> + */
> >> + stp lr, xzr, [sp, #-16]!
> >
> > remind me why this pair isn't just doing "str" instead of "stp" with the
> > xzr ?
>
> Because SP has to be aligned on a 16 bytes boundary at all times.

You could do something like:

sub sp, sp, #16
str lr, [sp]

--
Catalin

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