Re: [PATCH v2 06/21] arm64: KVM: VHE: Patch out use of HVC

[Ard Biesheuvel]

On 1 February 2016 at 17:20, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> On 01/02/16 15:36, Catalin Marinas wrote:
>> 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]
>>
>
> Ah, fair enough. I'll fold that in.
>

Since we're micro-reviewing: what's wrong with

str lr, [sp, #-16]!

?