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Re: [Qemu-devel] TCG sar UB (fwd)
From: |
malc |
Subject: |
Re: [Qemu-devel] TCG sar UB (fwd) |
Date: |
Wed, 7 Sep 2011 20:04:41 +0400 (MSD) |
User-agent: |
Alpine 2.00 (LNX 1167 2008-08-23) |
On Sun, 4 Sep 2011, malc wrote:
> On Sun, 4 Sep 2011, Richard Henderson wrote:
>
> > On 09/03/2011 03:47 PM, malc wrote:
> > > Doesn't make much sense to me, guest clearly asked for 0 and not -1,
> > > besides -1 violates TCG's sar constraints and PPC obliges by emiting
> > > illegal instruction in this case.
> >
> > The shift that the guest asked for was completely folded away.
> >
> > The -1 comes from gen_shift_rm_T1 in the computation of the new
> > flags value. This could instead be moved inside the test for != 0,
> > which is the only place that value is actually used anyway.
> >
> > Try this. Lightly tested.
>
> Now i either get hosts illegal instruction or (with logging enabled) a
> guest kenrnel panic.
Actually i was habitually testing i386-softmmu/qemu.. And after trying
the "properly" named binary things do work.. Want to provide a comment
so i can push that?
[..snip..]
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