Subject: Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit
To: Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@amacapital.net>
References: <1447456706-24347-1-git-send-email-boris.ostrovsky@oracle.com>
 <CALCETrVAEKrPiMX9O43pqkEC=xqc2qJ=VBNsV5iMMvW09W07hQ@mail.gmail.com>
 <56468D24.8030801@oracle.com>
 <CALCETrWD+=vj_rL-4Ng8fj_oOEs8Q6wftFg9hDDm1HiiEmu2FA@mail.gmail.com>
 <564A0371.2040104@oracle.com>
 <CALCETrUc+dbVY4JRUOqTCZpXndz7OJkchMU7nfc8QNyjgRxY2w@mail.gmail.com>
 <20151116195906.GB20137@pd.tnic>
 <CALCETrW3vehf-BRatCYL8TS-xF8MPDeEYtUEwfuayGrt_FO0vg@mail.gmail.com>
 <20151116202232.GC20137@pd.tnic>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        xen-devel <xen-devel@lists.xen.org>,
        David Vrabel <david.vrabel@citrix.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
From: "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <564A50C3.1000200@zytor.com>
Date: Mon, 16 Nov 2015 13:55:15 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <20151116202232.GC20137@pd.tnic>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 718
Lines: 29

On 11/16/15 12:22, Borislav Petkov wrote:
> 
> Huh, so what's wrong with a jump:
> 
> 	jmp 1f
> 	swapgs
> 	1:
> 

What is the point of that jump?

>> If it would make you feel better, it could be X86_BUG_XENPV :-p
> 
> That doesn't matter - I just don't want to open the flood gates on
> pseudo feature bits.
> 
> hpa, what do you think?

Pseudo feature bits are fine, we already have plenty of them.  They make
sense as they let us reuse a lot of infrastructure.

	-hpa


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/