From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753926AbcAVQCw (ORCPT <rfc822;w@1wt.eu>);
	Fri, 22 Jan 2016 11:02:52 -0500
Received: from mx1.redhat.com ([209.132.183.28]:54508 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751588AbcAVQCu (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 22 Jan 2016 11:02:50 -0500
Date: Fri, 22 Jan 2016 10:02:45 -0600
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
        Michal Marek <mmarek@suse.cz>, Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <andi@firstfloor.org>, Pedro Alves <palves@redhat.com>,
        Namhyung Kim <namhyung@gmail.com>,
        Bernd Petrovitsch <bernd@petrovitsch.priv.at>,
        Chris J Arges <chris.j.arges@canonical.com>,
        Andrew Morton <akpm@linux-foundation.org>, Jiri Slaby <jslaby@suse.cz>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Gleb Natapov <gleb@kernel.org>, kvm@vger.kernel.org
Subject: Re: [PATCH 26/33] x86/kvm: Add stack frame dependency to test_cc()
 inline asm
Message-ID: <20160122160245.GD20502@treble.redhat.com>
References: <cover.1453405861.git.jpoimboe@redhat.com>
 <affc672d13100eb0c743b8c7ce88c47a104161bf.1453405861.git.jpoimboe@redhat.com>
 <56A1FED2.50700@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <56A1FED2.50700@redhat.com>
User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Jan 22, 2016 at 11:05:06AM +0100, Paolo Bonzini wrote:
> 
> 
> On 21/01/2016 23:49, Josh Poimboeuf wrote:
> > With some configs, gcc doesn't inline test_cc().  When that happens, it
> > doesn't create a stack frame before inserting the call instruction.
> > This breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled
> > and can result in a bad stack trace.
> > 
> > Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by
> > listing the stack pointer as an output operand for the inline asm
> > statement.
> 
> If an __always_inline allocation works, that would be better.

Yeah, that seems to work.  I'll update the patch.

-- 
Josh