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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 03 Aug 2016 19:50:30 +1000
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Subject: Re: [Qemu-devel] [PATCH 2/2] Fix g2h() for 32-bit targets on 64-bit
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>

On Wed, 2016-08-03 at 09:40 +0100, Peter Maydell wrote:
> > index 6eb5fe8..0164535 100644
> > --- a/include/exec/cpu_ldst.h
> > +++ b/include/exec/cpu_ldst.h
> > @@ -49,7 +49,7 @@
> >
> >=C2=A0 #if defined(CONFIG_USER_ONLY)
> >=C2=A0 /* All direct uses of g2h and h2g need to go away for usermode =
softmmu.=C2=A0 */
> > -#define g2h(x) ((void *)((unsigned long)(target_ulong)(x) + guest_ba=
se))
> > +#define g2h(x) ((void *)(guest_base + (unsigned long)(target_ulong)(=
x)))
>=20
> I'm confused. Is this just swapping the order of the operands to '+'?
> I wouldn't expect that to make any difference because typecast has
> higher precedence than '+'...

The typecast to target_ulong which is 32-bits :-)

> > I run 32-bit (ARM) programs on x86-64 a lot so I would be surprised
> if g2h() was broken like this.

I had a pretty clear breakage case, and this along with patch 1 fixed
it.

Cheers,
Ben.