From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id E88D76B0285 for ; Fri, 23 Mar 2018 14:26:51 -0400 (EDT) Received: by mail-io0-f200.google.com with SMTP id t9so11129365ioa.9 for ; Fri, 23 Mar 2018 11:26:51 -0700 (PDT) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id s14-v6sor4627512iti.41.2018.03.23.11.26.50 for (Google Transport Security); Fri, 23 Mar 2018 11:26:50 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20180323174447.55F35636@viggo.jf.intel.com> References: <20180323174447.55F35636@viggo.jf.intel.com> From: Linus Torvalds Date: Fri, 23 Mar 2018 11:26:49 -0700 Message-ID: Subject: Re: [PATCH 00/11] Use global pages with PTI Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Linux Kernel Mailing List , linux-mm , Andrea Arcangeli , Andrew Lutomirski , Kees Cook , Hugh Dickins , =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , the arch/x86 maintainers , namit@vmware.com On Fri, Mar 23, 2018 at 10:44 AM, Dave Hansen wrote: > > This adds one major change from the last version of the patch set > (present in the last patch). It makes all kernel text global for non- > PCID systems. This keeps kernel data protected always, but means that > it will be easier to find kernel gadgets via meltdown on old systems > without PCIDs. This heuristic is, I think, a reasonable one and it > keeps us from having to create any new pti=foo options Sounds sane. The patches look reasonable, but I hate seeing a patch series like this where the only ostensible reason is performance, and there are no performance numbers anywhere.. Linus