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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,LOTS_OF_MONEY,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 36264C4727C for ; Fri, 25 Sep 2020 13:38:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08F862076D for ; Fri, 25 Sep 2020 13:38:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728901AbgIYNi3 (ORCPT ); Fri, 25 Sep 2020 09:38:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728824AbgIYNi2 (ORCPT ); Fri, 25 Sep 2020 09:38:28 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF2A1C0613CE; Fri, 25 Sep 2020 06:38:28 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kLnvY-0062Aw-Sk; Fri, 25 Sep 2020 13:38:21 +0000 Date: Fri, 25 Sep 2020 14:38:20 +0100 From: Al Viro To: Stephen Rothwell Cc: Josh Poimboeuf , Linux Next Mailing List , Linux Kernel Mailing List , "Peter Zijlstra (Intel)" , Thomas Gleixner , Borislav Petkov Subject: Re: linux-next: build failure after merge of the vfs tree Message-ID: <20200925133820.GW3421308@ZenIV.linux.org.uk> References: <20200924183038.3c6da86e@canb.auug.org.au> <20200924200807.GU3421308@ZenIV.linux.org.uk> <20200925220128.1604f09b@canb.auug.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200925220128.1604f09b@canb.auug.org.au> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 25, 2020 at 10:01:28PM +1000, Stephen Rothwell wrote: > $ x86_64-linux-gnu-gcc --version > x86_64-linux-gnu-gcc (Debian 10.2.0-9) 10.2.0 > $ x86_64-linux-gnu-ld --version > GNU ld (GNU Binutils for Debian) 2.35 > > and the gcc plugins don't get built for the allnoconfig builds. > I reverted my Revert commit after I finished linux-next today and built > the x86_64 allnoconfig verion of lib/iov_iter.s: > > $ grep -A 1 '41 "/home/sfr/next/next/arch/x86/include/asm/barrier.h"' lib/iov_iter.s > # 41 "/home/sfr/next/next/arch/x86/include/asm/barrier.h" 1 > cmp $140737488351232,%rdx; sbb %rcx,%rcx; #, uaddr, mask Wait a sec... static inline unsigned long array_index_mask_nospec(unsigned long index, unsigned long size) { unsigned long mask; asm volatile ("cmp %1,%2; sbb %0,%0;" :"=r" (mask) :"g"(size),"r" (index) :"cc"); return mask; } used with large constant size will blow up - "g" is wrong, since cmp allows 64bit arguments to be register or memory ones; immediates can't go past 32bit. Looks like on the configs where it builds we end up with not seeing it's a constant... Josh, any ideas? We could, of course, make it "r"(size), but that would be unpleasant in all existing callers...