Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754055AbbGWQFJ (ORCPT ); Thu, 23 Jul 2015 12:05:09 -0400 Received: from mail-la0-f41.google.com ([209.85.215.41]:33740 "EHLO mail-la0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753591AbbGWQE7 (ORCPT ); Thu, 23 Jul 2015 12:04:59 -0400 MIME-Version: 1.0 In-Reply-To: <20150723120125.7c6d74d3@gandalf.local.home> References: <1287f683e32f1bbe7fc545bff675f30dcda8d5c1.1437665045.git.luto@kernel.org> <20150723120125.7c6d74d3@gandalf.local.home> From: Andy Lutomirski Date: Thu, 23 Jul 2015 09:04:38 -0700 Message-ID: Subject: Re: [PATCH 2/5] x86/entry/64, entry: Set up a valid sysenter stack and prepare for 32-bit merge To: Steven Rostedt Cc: Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Willy Tarreau , Borislav Petkov , Thomas Gleixner , Peter Zijlstra , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1174 Lines: 27 On Thu, Jul 23, 2015 at 9:01 AM, Steven Rostedt wrote: > On Thu, 23 Jul 2015 08:31:40 -0700 > Andy Lutomirski wrote: > >> Oddly, 64-bit kernels already allocate a percpu sysenter stack, but >> they don't enable it. Enable the stack and tweak the rest of the >> sysenter setup code to be similar to the 32-bit version. > > I'm curious. Did you do any investigation into the 64bit code to why it > wasn't set? Do you know if that was just overlooked with some of the > merging between i386 and x86_64 systems? > > I'm not asking you to do it if you have not, but if you have, I think > it would be more comforting to know that it was just overlooked than > there being some other subtle reason. I think it's just that it was never necessary. #DB has always used IST on x86_64 (IIRC it was like that in the very first commit), so the sysenter stack was never actually referenced. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/