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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 85DDBC33C9E for ; Wed, 8 Jan 2020 01:26:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 48D48207E0 for ; Wed, 8 Jan 2020 01:26:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hQnK0UEw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48D48207E0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D1F498E0005; Tue, 7 Jan 2020 20:26:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CCFD18E0001; Tue, 7 Jan 2020 20:26:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE63B8E0005; Tue, 7 Jan 2020 20:26:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0051.hostedemail.com [216.40.44.51]) by kanga.kvack.org (Postfix) with ESMTP id A841C8E0001 for ; Tue, 7 Jan 2020 20:26:08 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 5F3A14DBD for ; Wed, 8 Jan 2020 01:26:08 +0000 (UTC) X-FDA: 76352726016.03.dust68_6fc3106b7c33d X-HE-Tag: dust68_6fc3106b7c33d X-Filterd-Recvd-Size: 3773 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Wed, 8 Jan 2020 01:26:07 +0000 (UTC) Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 BD66D20692; Wed, 8 Jan 2020 01:26:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578446767; bh=7zxvCiU+gHGR4GRmG1cvHE0RiTtR7+LpexvhzNKlKpg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hQnK0UEw9ZlsNOsV4p4QPfA2+YF/whGABIKaCI7XlawRupGhk/Mkt2NS1qgLRIuwl +2hmKYHnJRmWHztA9m8vO4s1qy3dEmoZ5zxn+9PHUx5R+YDvUYho5ff9p0npuOPG7+ 5qfTN85lMMl+a+GnuaL4uIGUj5KP+pRnt80ceECI= Date: Wed, 8 Jan 2020 10:26:02 +0900 From: Masami Hiramatsu To: Arnd Bergmann Cc: Andrew Morton , Oleksandr Natalenko , linux-mm@kvack.org, Arnaldo Carvalho de Melo , Will Deacon , Masami Hiramatsu , Song Liu , Alexey Dobriyan , Marc Zyngier , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH] kallsyms: work around bogus -Wrestrict warning Message-Id: <20200108102602.43d4c5433eb495cdbf387e9b@kernel.org> In-Reply-To: <20200107214042.855757-1-arnd@arndb.de> References: <20200107214042.855757-1-arnd@arndb.de> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Arnd, On Tue, 7 Jan 2020 22:40:26 +0100 Arnd Bergmann wrote: > gcc -O3 produces some really odd warnings for this file: > > kernel/kallsyms.c: In function 'sprint_symbol': > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict] > strcpy(buffer, name); > ^~~~~~~~~~~~~~~~~~~~ > kernel/kallsyms.c: In function 'sprint_symbol_no_offset': > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict] > strcpy(buffer, name); > ^~~~~~~~~~~~~~~~~~~~ > kernel/kallsyms.c: In function 'sprint_backtrace': > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict] > strcpy(buffer, name); > ^~~~~~~~~~~~~~~~~~~~ > > This obviously cannot be since it is preceded by an 'if (name != buffer)' > check. Hmm, this looks like a bug in gcc. > > Using sprintf() instead of strcpy() is a bit wasteful but is > the best workaround I could come up with. > > Fixes: mmtom ("init/Kconfig: enable -O3 for all arches") > Signed-off-by: Arnd Bergmann > --- > kernel/kallsyms.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c > index d812b90f4c86..726b8eeb223e 100644 > --- a/kernel/kallsyms.c > +++ b/kernel/kallsyms.c > @@ -366,7 +366,7 @@ static int __sprint_symbol(char *buffer, unsigned long address, > return sprintf(buffer, "0x%lx", address - symbol_offset); > > if (name != buffer) > - strcpy(buffer, name); > + sprintf(buffer, "%s", name); BTW, this seems not happen. kallsyms_lookup() (and it's subfunctions) always stores the result into buffer unless name == NULL. Maybe we can remove these 2 lines? (and add a comment line for kallsyms_lookup() so that it guarantees the symbol name always stored in namebuf argument) Thank you, -- Masami Hiramatsu