From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48EADFC6194 for ; Wed, 6 Nov 2019 23:06:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16D49217F4 for ; Wed, 6 Nov 2019 23:06:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GgDXazro" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727196AbfKFXGE (ORCPT ); Wed, 6 Nov 2019 18:06:04 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:30744 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727813AbfKFXGE (ORCPT ); Wed, 6 Nov 2019 18:06:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1573081563; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oz3HskjRqxhlPDCGk63+nwo4iuGFQJFiMO6YAWOvkkM=; b=GgDXazro+alhncTZ04jcmsXbIP8uYcyCIuP5+1e0kwKHUg8X/ayFPMAF/EEoFtDqy2qqAH FklH2APBHGq16e98yor7Pbfzn8WC9cPKWELY9lwsv+4C8MAyfgJTGzPMqy2h71VoiRzs6V D3IAAYuhcSSBpx4R5jDKbPX76Yq09hw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-139-EYyaIi7oOz6ejyNGGCbU1Q-1; Wed, 06 Nov 2019 18:06:02 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 52FB4800C73; Wed, 6 Nov 2019 23:06:01 +0000 (UTC) Received: from treble (ovpn-122-162.rdu2.redhat.com [10.10.122.162]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A3ACB60BE0; Wed, 6 Nov 2019 23:05:57 +0000 (UTC) Date: Wed, 6 Nov 2019 17:05:53 -0600 From: Josh Poimboeuf To: Joe Lawrence Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Subject: Re: [PATCH] x86/stacktrace: update kconfig help text for reliable unwinders Message-ID: <20191106230553.wnyltmkzwk5dph4l@treble> References: <20191106224344.8373-1-joe.lawrence@redhat.com> MIME-Version: 1.0 In-Reply-To: <20191106224344.8373-1-joe.lawrence@redhat.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: EYyaIi7oOz6ejyNGGCbU1Q-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: live-patching-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Wed, Nov 06, 2019 at 05:43:44PM -0500, Joe Lawrence wrote: > commit 6415b38bae26 ("x86/stacktrace: Enable HAVE_RELIABLE_STACKTRACE > for the ORC unwinder") marked the ORC unwinder as a "reliable" unwinder. > Update the help text to reflect that change: the frame pointer unwinder > is no longer the only one that provides HAVE_RELIABLE_STACKTRACE. >=20 > Signed-off-by: Joe Lawrence > --- > arch/x86/Kconfig.debug | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) >=20 > diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug > index bf9cd83de777..69cdf0558c13 100644 > --- a/arch/x86/Kconfig.debug > +++ b/arch/x86/Kconfig.debug > @@ -316,10 +316,6 @@ config UNWINDER_FRAME_POINTER > =09 unwinder, but the kernel text size will grow by ~3% and the kernel'= s > =09 overall performance will degrade by roughly 5-10%. > =20 > -=09 This option is recommended if you want to use the livepatch > -=09 consistency model, as this is currently the only way to get a > -=09 reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE). > - > config UNWINDER_GUESS > =09bool "Guess unwinder" > =09depends on EXPERT > @@ -333,6 +329,10 @@ config UNWINDER_GUESS > =09 useful in many cases. Unlike the other unwinders, it has no runtim= e > =09 overhead. > =20 > +=09 This option is not recommended if you want to use the livepatch > +=09 consistency model, as this unwinder cannot guarantee reliable stack > +=09 traces. > + I'm not sure whether this last hunk is helpful. At the very least the wording of "not recommended" might be confusing because it's not even possible to combine UNWINDER_GUESS+HAVE_RELIABLE_STACKTRACE. arch/x86/Kconfig: select HAVE_RELIABLE_STACKTRACE if X86_64 &= & (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION --=20 Josh