From: Keir Fraser <keir@xen.org>
To: Tim Deegan <tim@xen.org>
Cc: xen-devel@lists.xensource.com, David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH] x86: emulate lea with two register operands correctly
Date: Thu, 05 Jan 2012 19:03:09 +0000 [thread overview]
Message-ID: <CB2BA46D.36EF5%keir@xen.org> (raw)
In-Reply-To: <20120105160641.GB87519@ocelot.phlegethon.org>
On 05/01/2012 16:06, "Tim Deegan" <tim@xen.org> wrote:
> At 15:49 +0000 on 05 Jan (1325778595), Keir Fraser wrote:
>> On 05/01/2012 15:03, "David Vrabel" <david.vrabel@citrix.com> wrote:
>>
>>> An lea instruction with two register operands should raise an
>>> undefined instruction exception.
>>>
>>> Skype does such a instruction and will crash when starting if it does
>>> not get the exception.
>>
>> Thanks. I think it is a little nicer to check ea.type != OP_MEM, so I made
>> that change before committing this patch. It's now in xen-unstable staging.
>>
>> It's a bit concerning that we're emulating LEA at all, perhaps. I wonder if
>> a pagetable page has been reused as a code page and we didn't notice yet? Or
>> is there some other reason that skype is getting emulated? :-)
>
> #UD exceptions in HVM are passed to the emulator (IIRC as part of the
> cross-vendor migration patches, so SYSENTER & friends could be managed).
Duh, good point.
-- Keir
> Tim.
next prev parent reply other threads:[~2012-01-05 19:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-05 15:03 [PATCH] x86: emulate lea with two register operands correctly David Vrabel
2012-01-05 15:49 ` Keir Fraser
2012-01-05 16:06 ` Tim Deegan
2012-01-05 19:03 ` Keir Fraser [this message]
2012-01-05 16:17 ` David Vrabel
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