From mboxrd@z Thu Jan  1 00:00:00 1970
From: Waiman Long <longman@redhat.com>
Subject: Re: [PATCH v2] x86/paravirt: Don't make vcpu_is_preempted() a
	callee-save function
Date: Tue, 14 Feb 2017 09:46:17 -0500
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To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arch@vger.kernel.org, Juergen Gross <jgross@suse.com>, Jeremy Fitzhardinge <jeremy@goop.org>, x86@kernel.org, kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Chris Wright <chrisw@sous-sol.org>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, xen-devel@lists.xenproject.org, Alok Kataria <akataria@vmware.com>, Thomas Gleixner <tglx@linutronix.de>
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On 02/14/2017 04:39 AM, Peter Zijlstra wrote:
> On Mon, Feb 13, 2017 at 05:34:01PM -0500, Waiman Long wrote:
>> It is the address of &steal_time that will exceed the 32-bit limit.
> That seems extremely unlikely. That would mean we have more than 4G
> worth of per-cpu variables declared in the kernel.

I have some doubt about if the compiler is able to properly use
RIP-relative addressing for this. Anyway, it seems like constraints
aren't allowed for asm() when not in the function context, at least for
the the compiler that I am using (4.8.5). So it is a moot point.

Cheers,
Longman