From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>, kvm list <kvm@vger.kernel.org>,
xen-devel <Xen-devel@lists.xen.org>
Subject: Re: [Xen-devel] Does __KERNEL_DS serve a purpose?
Date: Fri, 8 Apr 2016 09:01:19 +0100 [thread overview]
Message-ID: <5707654F.1060407@citrix.com> (raw)
In-Reply-To: <CALCETrWHHUsd=VXUXQvdeODFFBEDr9EUQQTJ3oWbtO8aHgd3Xw@mail.gmail.com>
On 08/04/2016 01:24, Andy Lutomirski wrote:
> I can't see any reason that we need the __KERNEL_DS segment at all --
> I think that everything that uses __KERNEL_DS could use __USER_DS
> instead. Am I missing anything? This has been bugging me for a
> while.
>
> I mulled over this a bit when trying to understand the sysret_ss_attrs
> bug and then forgot about it.
Linux doesn't have a separate __KERNEL_SS. For the plain data segments,
the dpl is not interesting.
However, %ss is also loaded with __KERNEL_DS, and %ss.dpl is somewhat
important.
~Andrew
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>, kvm list <kvm@vger.kernel.org>,
xen-devel <Xen-devel@lists.xen.org>
Subject: Re: Does __KERNEL_DS serve a purpose?
Date: Fri, 8 Apr 2016 09:01:19 +0100 [thread overview]
Message-ID: <5707654F.1060407@citrix.com> (raw)
In-Reply-To: <CALCETrWHHUsd=VXUXQvdeODFFBEDr9EUQQTJ3oWbtO8aHgd3Xw@mail.gmail.com>
On 08/04/2016 01:24, Andy Lutomirski wrote:
> I can't see any reason that we need the __KERNEL_DS segment at all --
> I think that everything that uses __KERNEL_DS could use __USER_DS
> instead. Am I missing anything? This has been bugging me for a
> while.
>
> I mulled over this a bit when trying to understand the sysret_ss_attrs
> bug and then forgot about it.
Linux doesn't have a separate __KERNEL_SS. For the plain data segments,
the dpl is not interesting.
However, %ss is also loaded with __KERNEL_DS, and %ss.dpl is somewhat
important.
~Andrew
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next prev parent reply other threads:[~2016-04-08 8:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 0:24 Does __KERNEL_DS serve a purpose? Andy Lutomirski
2016-04-08 8:01 ` Andrew Cooper [this message]
2016-04-08 8:01 ` Andrew Cooper
2016-04-08 16:00 ` Andy Lutomirski
2016-04-08 16:00 ` [Xen-devel] " Andy Lutomirski
2016-04-08 17:12 ` Paolo Bonzini
2016-04-08 22:06 ` Andy Lutomirski
2016-04-08 22:06 ` [Xen-devel] " Andy Lutomirski
2016-04-08 22:32 ` Andrew Cooper
2016-04-08 22:32 ` Andrew Cooper
2016-04-08 17:12 ` Paolo Bonzini
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