Re: [Qemu-devel] [PATCH 2/2] Fix g2h() for 32-bit targets on 64-bit hosts

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Wed, 2016-08-03 at 19:50 +1000, Benjamin Herrenschmidt wrote:
> 
> > 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 :-)

But you are right, this isn't the breakage. Patch 1/2 is sufficient
to fix it, though I didn't realize it at first.

"vaddr" is actually a typedef, so the whole tlb_vaddr_to_host() turned
into a cast of guest_base to vaddr...

The g2h part was just me being tired. It's true though that
target_ulong is going to be 32-bits which I don't like but
type promotion makes it work.

So drop that patch and stick to patch 1/2 which is the real fix.

As to why you don't hit the bug on ARM, well, maybe you don't 
many helpers using tlb_vaddr_to_host ? Also address randomization makes
things hit or miss here ...

Cheers,
Ben.