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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 097BAC433F5 for ; Wed, 10 Nov 2021 11:10:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE2CF61205 for ; Wed, 10 Nov 2021 11:10:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231338AbhKJLM4 (ORCPT ); Wed, 10 Nov 2021 06:12:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231303AbhKJLMv (ORCPT ); Wed, 10 Nov 2021 06:12:51 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BB2FC061766; Wed, 10 Nov 2021 03:10:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=mdgITkPzF3BfO5swYkj+ahlZhGOLnl+VYeMvWBp1Ch4=; b=EappGx8ZWfi3BFVE5kdMMssiRI RAPxCdQEQpxd3HLCOpE1gxzkECX37cIvJggFAp9Yoz4EINko63XKWYdbyhyoazkXQICH615rleJ3n qfJ8pNOKk630tpnY89QPK5wgx8KXfPxuR+dXqQ2tF1ttKN6HvGNiTDTm0eCIqwhVAnv5q006Luufe BGutNG5xEx3HYbFgRY78TEMZ9xHzbpEQ8bKGCjzc+OVpXCeUNGYd2oPb0yvtq7FaMMq3UcqjPY5FS Xkr+dz5ARAZK3ZBHgf5ehFgjUPc5K0O4hwy2ttPWcOx2Mw5Zp30iWMINbuiU6vBSKCTKpDBiagrru LdNbIFPw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mklUH-001oJL-GX; Wed, 10 Nov 2021 11:09:54 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id CE2B33000A3; Wed, 10 Nov 2021 12:09:53 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id BAF012C799836; Wed, 10 Nov 2021 12:09:53 +0100 (CET) Date: Wed, 10 Nov 2021 12:09:53 +0100 From: Peter Zijlstra To: David Laight Cc: Nick Desaulniers , Bill Wendling , Josh Poimboeuf , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "mark.rutland@arm.com" , "dvyukov@google.com" , "seanjc@google.com" , "pbonzini@redhat.com" , "mbenes@suse.cz" , "llvm@lists.linux.dev" , "linux-toolchains@vger.kernel.org" Subject: Re: [PATCH 20/22] x86,word-at-a-time: Remove .fixup usage Message-ID: References: <20211105171023.989862879@infradead.org> <20211105171821.654356149@infradead.org> <20211108164711.mr2cqdcvedin2lvx@treble> <20211109210736.GV174703@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 10, 2021 at 10:46:42AM +0000, David Laight wrote: > From: Peter Zijlstra > > Sent: 09 November 2021 21:08 > ... > > > > GCC does the same, but I wanted to have the exception stuff be in > > .text.cold, but alas it doesn't do that. I left the attribute because of > > it's descriptive value. > > > > > Unless the cold attribute is helping move > > > ("shrink-wrap"?) the basic block to a whole other section > > > (.text.cold.)? > > > > I was hoping it would do that, but it doesn't on gcc-11. > > Wouldn't moving part of a function to .text.cold (or .text.unlikely) > generate the same problems with the stack backtrace code as the > .text.fixup section you are removing had?? GCC can already split a function into func and func.cold today (or worse: func, func.isra.N, func.cold, func.isra.N.cold etc..). I'm assuming reliable unwind and livepatch know how to deal with this.