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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A2DCC6FA83 for ; Sun, 11 Sep 2022 15:27:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229572AbiIKP1H (ORCPT ); Sun, 11 Sep 2022 11:27:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229547AbiIKP1F (ORCPT ); Sun, 11 Sep 2022 11:27:05 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E2521F602; Sun, 11 Sep 2022 08:27:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=dA4KVJ9n+xFH+aRdTmGiWAtvnpKz/8BixrIpwCUxjkc=; b=OG6BVIJB3q4yCM/NV+izRXyJ0q 99gfi9l91m0kKaaSLo2cgsOK8Z5HjaKHAYH1h/5TTrdLQwPzb7H3iOZHTUSQEAf23oiUFiLc2e4aP NnrSBGBfcAiCUYl6BMaN9BeaGaV0Ihx2lwfguVQ6OLR/dECX+C5xicUpuPz1y5VKZATM90hHHyXxS qLRYbz90DMY+9MEPiGsU/vKcdgNBG87EOhGBxQ8Qwmna9GtL7PVEGEkcpz8nyzlu3ywVU267V0mu7 Uv+pZBF8a2hKkIgV0jita7HVD8Q6/qhWJKn6WhHQ7vlKWMVgIeuG/kWID7ROjFI7Lw3tBtqrZ5cKD QFKs5rbg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oXOqj-00Bbqh-3b; Sun, 11 Sep 2022 15:26:21 +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 (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 831F030008D; Sun, 11 Sep 2022 17:26:18 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5CEEE2B16575A; Sun, 11 Sep 2022 17:26:18 +0200 (CEST) Date: Sun, 11 Sep 2022 17:26:18 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: linux-toolchains@vger.kernel.org, Indu Bhagat , Nick Desaulniers , linux-kernel@vger.kernel.org, "Jose E. Marchesi" , Miroslav Benes , Mark Rutland , Will Deacon , x86@kernel.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ard Biesheuvel , Chen Zhongjin , Sathvika Vasireddy , Christophe Leroy , Mark Brown Subject: Re: [RFC] Objtool toolchain proposal: -fannotate-{jump-table,noreturn} Message-ID: References: <20220909180704.jwwed4zhwvin7uyi@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220909180704.jwwed4zhwvin7uyi@treble> Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Fri, Sep 09, 2022 at 11:07:04AM -0700, Josh Poimboeuf wrote: > Alternatives > ------------ > > Another idea which has been floated in the past is for objtool to read > DWARF (or .eh_frame) to help it figure out the control flow. That > hasn't been tried yet, but would be considerably more difficult and > fragile IMO. I though Ard played around with that a bit on ARM64. And yes, given that most toolchains consider DWARF itself best-effort, I'm not holding my breath there. On top of that, building a kernel with DWARFs on is just so much slower..