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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 BC42AC4360C for ; Thu, 26 Sep 2019 15:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CBD6222C6 for ; Thu, 26 Sep 2019 15:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727389AbfIZPvx (ORCPT ); Thu, 26 Sep 2019 11:51:53 -0400 Received: from foss.arm.com ([217.140.110.172]:53482 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727216AbfIZPvx (ORCPT ); Thu, 26 Sep 2019 11:51:53 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DCE1028; Thu, 26 Sep 2019 08:51:50 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DA1793F534; Thu, 26 Sep 2019 08:51:49 -0700 (PDT) Date: Thu, 26 Sep 2019 16:51:47 +0100 From: Catalin Marinas To: Vincenzo Frascino Cc: Ard Biesheuvel , Nick Desaulniers , LKML , Thomas Gleixner , Will Deacon , Linux ARM Subject: Re: [PATCH] arm64: Allow disabling of the compat vDSO Message-ID: <20190926155147.GL9689@arrakis.emea.arm.com> References: <20190925130926.50674-1-catalin.marinas@arm.com> <20190925170838.GK7042@arrakis.emea.arm.com> <20190926074717.GA26802@iMac.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190926074717.GA26802@iMac.local> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 26, 2019 at 08:47:18AM +0100, Catalin Marinas wrote: > On Thu, Sep 26, 2019 at 01:06:50AM +0100, Vincenzo Frascino wrote: > > On 9/25/19 6:08 PM, Catalin Marinas wrote: > > > On Wed, Sep 25, 2019 at 09:53:16AM -0700, Nick Desaulniers wrote: > > >> On Wed, Sep 25, 2019 at 6:09 AM Catalin Marinas wrote: > > >>> - clean up the headers includes; vDSO should not include kernel-only > > >>> headers that may even contain code patched at run-time > > >> > > >> This is a big one; Clang validates the inline asm constraints for > > >> extended inline assembly, GCC does not for dead code. So Clang chokes > > >> on the inclusion of arm64 headers using extended inline assembly when > > >> being compiled for arm-linux-gnueabi. > > > > > > Whether clang or gcc, I'd like this fixed anyway. At some point we may > > > inadvertently rely on some code which is patched at boot time for the > > > kernel code but not for the vDSO. > > > > Do we have any code of this kind in header files? > > > > The vDSO library uses only a subset of the headers (mainly Macros) hence all the > > unused symbols should be compiled out. Is your concern only theoretical or do > > you have an example on where this could be happening? > > At the moment it's rather theoretical. Actually, it's not. The moment the compat vdso Makefile needs the line below, we are doing it wrong: VDSO_CFLAGS += -D__uint128_t='void*' -- Catalin