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Subject: Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit
To: Andy Lutomirski <luto@amacapital.net>,
        Andrew Cooper <andrew.cooper3@citrix.com>
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Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        xen-devel <xen-devel@lists.xen.org>, Borislav Petkov <bp@alien8.de>,
        David Vrabel <david.vrabel@citrix.com>,
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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Date: Tue, 17 Nov 2015 14:37:02 -0500
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On 11/17/2015 02:16 PM, Andy Lutomirski wrote:
>>> Looks good to me.  Does Xen have any sysexit/sysret32 equivalent to
>>> return to 32-bit user mode?  If so, it could be worth trying to wire
>>> it up by patching the jz instead of the test instruction.

We can actually make patching a little bit more efficient by replacing 
the test instruction with 'xor %eax,%eax'. That way we won't need any 
'nop's.


-boris