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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 F1637C2BCA1 for ; Fri, 7 Jun 2019 15:46:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5B7F21479 for ; Fri, 7 Jun 2019 15:46:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559922382; bh=GnmitQ/FmhUl1iQbeJpEQmDM6jx8+AikL4E/B9gvUfw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2okp3LMjLjZIPEE/TEgTRGib7nAwTsis2+nqem+nH9ajNtp2Fo5X/31z6o8nWN3+m kfb3E/yybkKd5TpF77vNOHhZsvzTu4Oapf3cX/1140dFuquV3n4rVOycgQRzGD1EgQ BjlgZltMu5zvRZinrIIES0Z8D7DIFJJ+Gxse7DXM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731371AbfFGPqS (ORCPT ); Fri, 7 Jun 2019 11:46:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:58322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730632AbfFGPqK (ORCPT ); Fri, 7 Jun 2019 11:46:10 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8CE92212F5; Fri, 7 Jun 2019 15:46:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559922369; bh=GnmitQ/FmhUl1iQbeJpEQmDM6jx8+AikL4E/B9gvUfw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qjm40VFZmaaZzjIQJcCdq6udW1VbiOrM/zD6xxFEN9bvF8xvnVZwM8b8egN/nX0Pc pv47YppUeDnRseXsoP5IlK7HBnvtzAJtkiB1APAcCyMLwpB1NoP1qhEwpMp/xT7pmK +Q0d8CQXfM03VbeUOI5IXAZitWnIhMhRIXP94wf0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Martin Sebor , Nick Desaulniers , Miguel Ojeda , Stefan Agner Subject: [PATCH 4.19 62/73] Compiler Attributes: add support for __copy (gcc >= 9) Date: Fri, 7 Jun 2019 17:39:49 +0200 Message-Id: <20190607153855.885568110@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190607153848.669070800@linuxfoundation.org> References: <20190607153848.669070800@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miguel Ojeda commit c0d9782f5b6d7157635ae2fd782a4b27d55a6013 upstream. >>From the GCC manual: copy copy(function) The copy attribute applies the set of attributes with which function has been declared to the declaration of the function to which the attribute is applied. The attribute is designed for libraries that define aliases or function resolvers that are expected to specify the same set of attributes as their targets. The copy attribute can be used with functions, variables, or types. However, the kind of symbol to which the attribute is applied (either function or variable) must match the kind of symbol to which the argument refers. The copy attribute copies only syntactic and semantic attributes but not attributes that affect a symbol’s linkage or visibility such as alias, visibility, or weak. The deprecated attribute is also not copied. https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html The upcoming GCC 9 release extends the -Wmissing-attributes warnings (enabled by -Wall) to C and aliases: it warns when particular function attributes are missing in the aliases but not in their target, e.g.: void __cold f(void) {} void __alias("f") g(void); diagnoses: warning: 'g' specifies less restrictive attribute than its target 'f': 'cold' [-Wmissing-attributes] Using __copy(f) we can copy the __cold attribute from f to g: void __cold f(void) {} void __copy(f) __alias("f") g(void); This attribute is most useful to deal with situations where an alias is declared but we don't know the exact attributes the target has. For instance, in the kernel, the widely used module_init/exit macros define the init/cleanup_module aliases, but those cannot be marked always as __init/__exit since some modules do not have their functions marked as such. Suggested-by: Martin Sebor Reviewed-by: Nick Desaulniers Signed-off-by: Miguel Ojeda Signed-off-by: Stefan Agner Signed-off-by: Greg Kroah-Hartman --- include/linux/compiler-gcc.h | 4 ++++ include/linux/compiler_types.h | 4 ++++ 2 files changed, 8 insertions(+) --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -201,6 +201,10 @@ #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 #endif +#if GCC_VERSION >= 90100 +#define __copy(symbol) __attribute__((__copy__(symbol))) +#endif + #if !defined(__noclone) #define __noclone /* not needed */ #endif --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -180,6 +180,10 @@ struct ftrace_likely_data { #define __diag_GCC(version, severity, string) #endif +#ifndef __copy +# define __copy(symbol) +#endif + #define __diag_push() __diag(push) #define __diag_pop() __diag(pop)