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[23.128.96.18]) by mx.google.com with ESMTP id n11si2587884ejh.543.2020.06.18.14.44.17; Thu, 18 Jun 2020 14:44:43 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=VDPQQlHk; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729918AbgFRSIq (ORCPT + 99 others); Thu, 18 Jun 2020 14:08:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:38262 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726960AbgFRSIp (ORCPT ); Thu, 18 Jun 2020 14:08:45 -0400 Received: from mail-wr1-f52.google.com (mail-wr1-f52.google.com [209.85.221.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A319320EDD for ; Thu, 18 Jun 2020 18:08:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592503724; bh=VDvkimlQQCU+ioG4SXcIgHDcfTL7wrOO5MqRdGAfTEc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=VDPQQlHkkM5i7l2kUKNI3MZru9Hp/OEKTgL7dxlE68FMj9Xzb952t7xKajdZ5SW1F 67v8OG9mr/+GMjo/Iez1PiQZGTTLLHWmcny1nYd5LUyvWZ/cfnvPhUjeOJSxWs9mGn RTCRHkEvdwbjk8Afg+JbzEO44IrmsOmHtKs/MCQ0= Received: by mail-wr1-f52.google.com with SMTP id r7so7064633wro.1 for ; Thu, 18 Jun 2020 11:08:44 -0700 (PDT) X-Gm-Message-State: AOAM531hNxGw5xj2tvIIadH30u2+xiXuF1hBpAZlgoINiqJeFrpM5QhF G/juBfCrmdQnGnf/qoY9Qzt97VJKBG/wRU+ooRe76w== X-Received: by 2002:a5d:49c5:: with SMTP id t5mr6061347wrs.18.1592503723269; Thu, 18 Jun 2020 11:08:43 -0700 (PDT) MIME-Version: 1.0 References: <20200528201402.1708239-1-sashal@kernel.org> <874kr8cv9i.fsf@nanos.tec.linutronix.de> In-Reply-To: <874kr8cv9i.fsf@nanos.tec.linutronix.de> From: Andy Lutomirski Date: Thu, 18 Jun 2020 11:08:31 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v13 00/16] Enable FSGSBASE instructions To: Thomas Gleixner Cc: Sasha Levin , Andrew Lutomirski , Andi Kleen , Jonathan Corbet , Ingo Molnar , Borislav Petkov , X86 ML , Shuah Khan , Greg KH , Tony Luck , "Bae, Chang Seok" , Dave Hansen , Peter Zijlstra , "open list:DOCUMENTATION" , LKML , Jarkko Sakkinen Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 18, 2020 at 7:18 AM Thomas Gleixner wrote: > > Sasha, > > Sasha Levin writes: > > Changes from v12: > > - Reformat the series to be closer to the reverted codebase for easier > > review. > > - Drop a few of the changes introduced in v8 and v9. > > I've pushed the lot out to > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/fsgsbase > > Thanks for taking this up! > Is there a plan to deal with: /* * This function has some ABI oddities. * * A 32-bit ptracer probably expects that writing FS or GS will change * FSBASE or GSBASE respectively. In the absence of FSGSBASE support, * this code indeed has that effect. When FSGSBASE is added, this * will require a special case. * * For existing 64-bit ptracers, writing FS or GS *also* currently * changes the base if the selector is nonzero the next time the task * is run. This behavior may? not be needed, and trying to preserve it * when FSGSBASE is added would be complicated at best. */ in arch/x86/kernel/ptrace.c?