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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 98034C43334 for ; Thu, 6 Sep 2018 18:32:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F72020844 for ; Thu, 6 Sep 2018 18:32:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jtrwReKQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F72020844 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730460AbeIFXI6 (ORCPT ); Thu, 6 Sep 2018 19:08:58 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:45108 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727640AbeIFXI6 (ORCPT ); Thu, 6 Sep 2018 19:08:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=EaTQRWH92bKkiyrNh9+noUJ6tLv7LImLaL95HpCzMPw=; b=jtrwReKQniX2UadwV3/dwisazu CioeYKnXos3NJEJu7xhow+B897MCwX46oXeXqzJ+21vScFYhCLRF5/lHpFZLRdzab5/Fznc1ScNFk 0XzD1ZuAjKQF9LVJYqn2XrLKtkoV8CejHrauNj8u4BFSMvJ6xKaaOtc4/LLv70qQ6v7dhyt2VvyBZ lK9Sa1e50SFxF1WPZs5FvOvYuBttOv9K9NOoS9q7FEAXDZPZgy9UlToGB3+G765njq508Ho8eN5Ge uuhAdobIMt/XWI+f+l3ww1WN0kYQ86XXeNuYE2IEHVTEKbB2o4oogRwEctyv151yOgWprOmYG6L68 CrII+zxQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fxz4W-0007cM-WC; Thu, 06 Sep 2018 18:32:05 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D7DDA2018BF7D; Thu, 6 Sep 2018 20:31:57 +0200 (CEST) Date: Thu, 6 Sep 2018 20:31:57 +0200 From: Peter Zijlstra To: Andy Lutomirski Cc: Nadav Amit , Thomas Gleixner , LKML , Ingo Molnar , X86 ML , Arnd Bergmann , linux-arch , Dave Hansen , Jiri Kosina , Andy Lutomirski , Masami Hiramatsu , Kees Cook Subject: Re: [PATCH v2 0/6] x86/alternatives: text_poke() fixes Message-ID: <20180906183157.GK24106@hirez.programming.kicks-ass.net> References: <20180902173224.30606-1-namit@vmware.com> <20180905185617.GC24082@hirez.programming.kicks-ass.net> <8D3CE999-6D3A-4984-934A-634BDD8AC25A@vmware.com> <6B256AB7-0158-47DF-B2D5-4C835579F3A3@vmware.com> <20180906081300.GF24082@hirez.programming.kicks-ass.net> <20180906101641.GG24142@hirez.programming.kicks-ass.net> <6703CD9F-2D84-4449-A423-A4DC24677673@vmware.com> <20180906171754.GJ24106@hirez.programming.kicks-ass.net> <9AF220A3-D783-442E-8E5B-AD0150628347@vmware.com> <32902EEE-FF64-4C12-A043-1848CC927C88@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <32902EEE-FF64-4C12-A043-1848CC927C88@amacapital.net> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 06, 2018 at 11:09:23AM -0700, Andy Lutomirski wrote: > > On Sep 6, 2018, at 10:58 AM, Nadav Amit wrote: > > It depends what security you want. Some may consider even the short > > time-window in which the kernel code is writable from other cores as > > insufficient for security. > > > > In addition, the set removes the need for remote TLB shootdowns that > > text_poke() - with this fix - requires. > > > > I’m personally in favor of not needing a global broadcast flush to install kprobes. That's fine. But at that point its an optimization, not a correctness issue.