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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 17 Mar 2014 12:50:29 +0000
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Subject: Re: [Qemu-devel] [PATCH v4 06/21] target-arm: Provide syndrome
 information for MMU faults
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To: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: Rob Herring <rob.herring@linaro.org>, Patch Tracking <patches@linaro.org>, Michael Matz <matz@suse.de>, Claudio Fontana <claudio.fontana@huawei.com>, Alexander Graf <agraf@suse.de>, "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>, Laurent Desnogues <laurent.desnogues@gmail.com>, Dirk Mueller <dmueller@suse.de>, Will Newton <will.newton@linaro.org>, =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>, "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>, Christoffer Dall <christoffer.dall@linaro.org>, Richard Henderson <rth@twiddle.net>

On 17 March 2014 12:41, Peter Maydell <peter.maydell@linaro.org> wrote:
> On 17 March 2014 03:28, Peter Crosthwaite <peter.crosthwaite@xilinx.com> wrote:
>> On Fri, Mar 7, 2014 at 5:32 AM, Peter Maydell <peter.maydell@linaro.org> wrote:
>>> From: Rob Herring <rob.herring@linaro.org>
>
>>> +    /* Set bit 26 for exceptions with no change in EL */
>>> +    if (arm_current_pl(env)) {
>>> +        syn |= 1 << ARM_EL_EC_SHIFT;
>>> +    }
>>> +
>>
>> Perhaps in internals.h:
>>
>> #define ARM_EL_EC_SAME_LEVEL (1 << ARM_EL_EC_SHIFT)
>>
>> Then this becomes:
>>
>> syn |= ARM_EL_EC_SAME_LEVEL
>>
>> Then in internals.h you can be more self documenting with:
>>
>> EC_BREAKPOINT_SAME_EL = EC_BREAKPOINT | ARM_EL_EC_SAME_LEVEL
>
> Yeah, seems reasonable.

On the other hand you can't define EC_BREAKPOINT_SAME_EL
like that, because the EC_ enum values aren't shifted.

Perhaps it would be better to have the syn_* functions for
the EC values which have SAME_EL versions (currently just
insn abort and data abort, since we don't implement any
of the hardware debug exceptions) have an extra parameter
bool same_el, and have the syn_ function OR in the extra bit.

thanks
-- PMM