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=-5.8 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 CF206C433E0 for ; Tue, 12 Jan 2021 11:55:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6D6B23107 for ; Tue, 12 Jan 2021 11:55:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731732AbhALLzE (ORCPT ); Tue, 12 Jan 2021 06:55:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728330AbhALLzD (ORCPT ); Tue, 12 Jan 2021 06:55:03 -0500 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21C0AC061575 for ; Tue, 12 Jan 2021 03:54:23 -0800 (PST) Received: from zn.tnic (p200300ec2f0e8c0026b5c8bc02f060b7.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:8c00:26b5:c8bc:2f0:60b7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 976E11EC05BC; Tue, 12 Jan 2021 12:54:21 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1610452461; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=pbmP+Y+nQ4eRzxNH1AOZNvl8RJ+TeM4Bs8STiGzFims=; b=pso3UWjE71pnIktyfAqh8a4iKQWMqXdCxGwupp93WFtRRiMrxRa0pmHb16sqi0kbG75jqJ GmV2CPiHdfDWYkk5eW8vTwt+HVpWq1gCS0fdv0iTmD4qzzrjc7BFYeZZTZTRhGQxyo0zj3 5wl6mAOok6jfuAxx95rUQijpbJMiyx4= Date: Tue, 12 Jan 2021 12:54:21 +0100 From: Borislav Petkov To: Josh Poimboeuf Cc: Nick Desaulniers , =?utf-8?B?RsSBbmctcnXDrCBTw7JuZw==?= , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , X86 ML , "H. Peter Anvin" , Nathan Chancellor , LKML , clang-built-linux Subject: Re: [PATCH v3] x86/entry: emit a symbol for register restoring thunk Message-ID: <20210112115421.GB13086@zn.tnic> References: <20210106015810.5p6crnh7jqtmjtv4@treble> <20210111203807.3547278-1-ndesaulniers@google.com> <20210112003839.GL25645@zn.tnic> <20210112010010.GA8239@zn.tnic> <20210112015952.jdystnwkvuxsrwa2@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210112015952.jdystnwkvuxsrwa2@treble> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 11, 2021 at 07:59:52PM -0600, Josh Poimboeuf wrote: > Right. In the vast majority of cases, .L symbols are totally fine. > > The limitation now being imposed by objtool (due to these assembler > changes) is that all code must be contained in an ELF symbol. And .L > symbols don't create such symbols. > > So basically, you can use an .L symbol *inside* a function or a code > segment, you just can't use the .L symbol to contain the code using a > SYM_*_START/END annotation pair. > > It only affects a tiny fraction of all .L usage. Just a handful of code > sites I think. @Nick, this belongs into the commit message too pls. Also, Documentation/asm-annotations.rst include/linux/linkage.h would need some of that blurb added explaining to users *why* they should not use .L local symbols as SYM_* macro arguments. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette