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Subject: Re: [Qemu-devel] [PATCH v4 12/21] target-arm: A64: Implement DC ZVA
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Rob Herring <rob.herring@linaro.org>, Peter Crosthwaite <peter.crosthwaite@xilinx.com>, Patch Tracking <patches@linaro.org>, Michael Matz <matz@suse.de>, Claudio Fontana <claudio.fontana@huawei.com>, Alexander Graf <agraf@suse.de>, QEMU Developers <qemu-devel@nongnu.org>, Will Newton <will.newton@linaro.org>, Dirk Mueller <dmueller@suse.de>, Laurent Desnogues <laurent.desnogues@gmail.com>, =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>, "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>, Christoffer Dall <christoffer.dall@linaro.org>

On 03/07/2014 07:11 AM, Peter Maydell wrote:
>> > As a bonus, you'll have accurate exceptions should the access throw, so you
>> > don't need to force the save of PC before calling the helper.  Which... I don't
>> > see you doing, so perhaps there's a bug here at the moment.
> Mmm. (In system mode we'll save PC as a side effect of having
> an accessfn defined for the DC_ZVA reginfo.)

Ah, I see it.

I'll note that the GETRA/PC thing can be made to work with any helper.  It's
just a matter of passing down the outermost helper's retaddr to
cpu_restore_state.  C.f. target-alpha's dynamic_excp/arith_excp functions.

So in theory there's no need for the accessfn to require storing the pc first.


r~