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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 26 Jul 2016 09:22:42 +1000
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Subject: Re: [Qemu-devel] TCG problem with cpu_{st,ld}x_data ?
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Richard Henderson <rth@twiddle.net>, QEMU Developers <qemu-devel@nongnu.org>, Paolo Bonzini <pbonzini@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>

On Tue, 2016-07-26 at 08:42 +1000, Benjamin Herrenschmidt wrote:

> We do something a bit different on ppc where we store the access type
> before every access, however the DSISR case is special in that on
> older
> CPUs, it's expected to contains a whole subset of the opcode which is
> quite a bit more info than what you want here...
> 
> I'm thinking maybe we should use a form of load that returns an error
> instead of longjmp'ing, and if we do error out, flush the tb for that
> instruction and replay which should cause the translate path to
> reload
> the TLB for it but it's still fishy.

I have a better idea !

This is only a problem for alignment interrupts, and those are very
rare, we only generate them in some cases of broken forms like
trying to do a ll/sc on an unaligned address.

So I'm thinking I'm just going to pass the opcode to the helper
in the error_code field.

Cheers,
Ben.