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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 74DF5C561F8 for ; Wed, 21 Oct 2020 09:08:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FF8321D6C for ; Wed, 21 Oct 2020 09:08:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="rtIa9spk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437242AbgJUJIs (ORCPT ); Wed, 21 Oct 2020 05:08:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437186AbgJUJIr (ORCPT ); Wed, 21 Oct 2020 05:08:47 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85279C0613CE; Wed, 21 Oct 2020 02:08:47 -0700 (PDT) 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=eb1OL+P4JmUK1jhG+vTVWpbKbq0qkyHl8thry52FTQA=; b=rtIa9spk+eGaALa7gNwT0CJsKK NjlQ0TaZClui6FNLaSH6sH410ckUEAUgWngz6KlxlBPFXfRsleXkZnz6ehdTlmAjGEDZ54LCQKjzW mVkO6Qrz9t1ONh71M5vaOQ5etGEYUyqKkVWOoiOoxp1OWMTTQymeYA9Bq+58R1K92TY9eQDNJBhMo j3j5B91C/arUdOUsfw/WJeofsIebuUbqnXHmWhjxv5BqEQh/x/dq8CROgLXRvJ7hEs8U3WUEjTr3U sxRZjkXGtDIhLFLuspHPnxp/ilX5Zbg6Dkuh7PJ6uq/ocHYjHiAPX19862wtZObxjvIsngNw8WzZa ycCtxeZA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVA6W-00026P-MZ; Wed, 21 Oct 2020 09:08:21 +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 7B5E2304BAE; Wed, 21 Oct 2020 11:08:17 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6997B2BB99C35; Wed, 21 Oct 2020 11:08:17 +0200 (CEST) Date: Wed, 21 Oct 2020 11:08:17 +0200 From: Peter Zijlstra To: Sami Tolvanen Cc: Josh Poimboeuf , Jann Horn , the arch/x86 maintainers , Masahiro Yamada , Steven Rostedt , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux , Kernel Hardening , linux-arch , Linux ARM , linux-kbuild , kernel list , linux-pci@vger.kernel.org Subject: Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps Message-ID: <20201021090817.GU2651@hirez.programming.kicks-ass.net> References: <20201013003203.4168817-1-samitolvanen@google.com> <20201013003203.4168817-23-samitolvanen@google.com> <20201015102216.GB2611@hirez.programming.kicks-ass.net> <20201015203942.f3kwcohcwwa6lagd@treble> <20201020185217.ilg6w5l7ujau2246@treble> <20201021085606.GZ2628@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201021085606.GZ2628@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, Oct 21, 2020 at 10:56:06AM +0200, Peter Zijlstra wrote: > The "falls through to next function" seems to be limited to things like: > > warning: objtool: setup_vq() falls through to next function setup_vq.cold() > warning: objtool: e1000_xmit_frame() falls through to next function e1000_xmit_frame.cold() > > So something's weird with the .cold thing on vmlinux.o runs. Shiny, check this: $ nm defconfig-build/vmlinux.o | grep setup_vq 00000000004d33a0 t setup_vq 00000000004d4c20 t setup_vq 000000000001edcc t setup_vq.cold 000000000001ee31 t setup_vq.cold 00000000004d3dc0 t vp_setup_vq $ nm defconfig-build/vmlinux.o | grep e1000_xmit_frame 0000000000741490 t e1000_xmit_frame 0000000000763620 t e1000_xmit_frame 000000000002f579 t e1000_xmit_frame.cold 0000000000032b6e t e1000_xmit_frame.cold $ nm defconfig-build/vmlinux.o | grep e1000_diag_test 000000000074c220 t e1000_diag_test 000000000075eb70 t e1000_diag_test 000000000002fc2a t e1000_diag_test.cold 0000000000030880 t e1000_diag_test.cold I guess objtool goes sideways when there's multiple symbols with the same name in a single object file. This obvously never happens on single TU .o files. Not sure what to do about that.