From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id A8F076B0009 for ; Fri, 23 Mar 2018 13:46:50 -0400 (EDT) Received: by mail-pl0-f72.google.com with SMTP id bd8-v6so8079089plb.20 for ; Fri, 23 Mar 2018 10:46:50 -0700 (PDT) Received: from mga03.intel.com (mga03.intel.com. [134.134.136.65]) by mx.google.com with ESMTPS id q4-v6si8710399plr.365.2018.03.23.10.46.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Mar 2018 10:46:49 -0700 (PDT) Subject: [PATCH 00/11] Use global pages with PTI From: Dave Hansen Date: Fri, 23 Mar 2018 10:44:47 -0700 Message-Id: <20180323174447.55F35636@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Dave Hansen , aarcange@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, jgross@suse.com, x86@kernel.org, namit@vmware.com The later verions of the KAISER pathces (pre-PTI) allowed the user/kernel shared areas to be GLOBAL. The thought was that this would reduce the TLB overhead of keeping two copies of these mappings. During the switch over to PTI, we seem to have lost our ability to have GLOBAL mappings. This adds them back. 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 Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: Juergen Gross Cc: x86@kernel.org Cc: Nadav Amit