Re: [Xen-devel] [PATCH 3/3] xen: arm: handle thumb mode guest in continuations

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2015-03-25 at 23:33 +0000, Julien Grall wrote:
> Hi Ian,
> 
> On 25/03/2015 15:34, Ian Campbell wrote:
> > PC only needs adjusting by 2, otherwise we rerun the instruction prior
> > to the hvc as well.
> 
> I don't understand why you have to adjust PC by 2 for thumb.
> The spec encodes the HVC thumb instruction on 32 bits (i.e 4 bytes).

I was confused by Encoding T1 in the ARMv7 ARM B9.3.4 which has a 15 at
the left most column, but actually it is 15..0,15..0, doh!

So we are fine here. I'll drop this patch and pull the regs->pc frobbing
in the previous patch back out of the if into the common bit.

Ian.


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