Re: [PATCH v8 4/4] arm64: vdso32: Implement __vdso_futex_robust_try_unlock()

["André Almeida" <andrealmeid@igalia.com>]

Em 17/09/2026 07:50, Mark Rutland escreveu:
> On Wed, Sep 16, 2026 at 10:11:01PM -0300, André Almeida wrote:
>> Em 16/09/2026 11:28, Mark Rutland escreveu:
>>> On Fri, Aug 21, 2026 at 06:50:45PM -0300, André Almeida wrote:
>>>> Based on aarch64 implementation, provide a 32 bit entry point for
>>>> this vDSO.
>>>>
>>>> In order to keep compatibility with arm64_futex_robust_unlock_get_pop(),
>>>> make sure to store the pop address at r2 and the compare result value
>>>> at r3.
>>>
>>> Before we add this to the compat vdso, we'll need to implement this on
>>> arch/arm/.
>>>
>>> Otherwise, my comments on the patch for the native vdso functions apply
>>> here too.
>>
>> Right, and the compat entry point at arch/arm64/ would point to the
>> __vdso_futex_robust_list32_try_unlock implementation at arch/arm/?
> 
> So far we've had arm64 provide its own copy (which e.g. might use
> sequences relying on ARMv8+ instructions), so I think we'd do the same
> here.
> 
> The key thing is that 32-bit tasks on arm64 should see the same ABI as
> native tasks on 32-bit arm. As there's a risk that 32-bit arm might have
> some ABI quirks (e.g. due to older processors), we don't want to enable
> features for compat tasks on arm64 before that's been implemented on
> 32-bit arm.
Gotcha, makes perfect sense.

Thanks!
	André