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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 9BCCEC43331 for ; Fri, 3 Apr 2020 17:18:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 584D0206F5 for ; Fri, 3 Apr 2020 17:18:43 +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="OO/FqPH7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404222AbgDCRSm (ORCPT ); Fri, 3 Apr 2020 13:18:42 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:60742 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727998AbgDCRSm (ORCPT ); Fri, 3 Apr 2020 13:18:42 -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-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=dx9pi5qloDON5sT21yKIuo+5buti9mt8VDPr2oqHge0=; b=OO/FqPH7EVVlBiTMJcVr+rZ4K7 lNSuHxSFpfPkIkLW2/9LL0/FtfFVTMLXaaZVIFwUP9u/fBrMnShHsTG7T2Meuu3eIed0SBH8UNGpS XestdDvUTO+vTbWa6eMQGOgNRUvmLqzx0p68U5fA1WjXkHwPgyMHiywNmxKfEvzX/SAVaLJWdmBTz oOPgT8yZVIvW1Xp8ktZNym9XV4tYlDNzsXaPw4pyKM6RUwWgpy5vD7vhrJDuAsI9J1FdSvqVi1HeI RXkC1Flq5lDkCIj0U/8OU9Q6Tx+7K6h7GwST8E3GGr7yg74igzlElwF5I+OL0VcPKsL+Szcw2Ss1J OWVykH0A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jKPxn-0003Ci-B6; Fri, 03 Apr 2020 17:18:39 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 284FB3060FD; Fri, 3 Apr 2020 19:18:37 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0A1A22B125212; Fri, 3 Apr 2020 19:18:37 +0200 (CEST) Date: Fri, 3 Apr 2020 19:18:36 +0200 From: Peter Zijlstra To: Alexandre Chartre Cc: Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org, jthierry@redhat.com, tglx@linutronix.de Subject: Re: [PATCH 5/7] x86/speculation: Annotate intra-function calls Message-ID: <20200403171836.GB20730@hirez.programming.kicks-ass.net> References: <20200402082220.808-1-alexandre.chartre@oracle.com> <20200402082220.808-6-alexandre.chartre@oracle.com> <20200403160538.qwu237amhanr6pyi@treble> <20200403161607.jxz6duaz7dud22wf@treble> <2c615bae-6002-80b7-493d-b24ec48f69c9@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c615bae-6002-80b7-493d-b24ec48f69c9@oracle.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 03, 2020 at 10:14:49AM -0700, Alexandre Chartre wrote: > So that means that any alternative that does a stack manipulation isn't > currently supported? It's fundamentally impossible to correctly unwind through. Instructions before and after the alternative need to have the same stack layout irrespective of the alternative chosen. What we need in this case though is only a different stack layout inside the alternative, and that is doable.