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=-3.8 required=3.0 tests=BAYES_00, 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 D75EDC433EF for ; Wed, 8 Sep 2021 10:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF3B961132 for ; Wed, 8 Sep 2021 10:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347972AbhIHKXP convert rfc822-to-8bit (ORCPT ); Wed, 8 Sep 2021 06:23:15 -0400 Received: from mail-vs1-f43.google.com ([209.85.217.43]:40846 "EHLO mail-vs1-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345299AbhIHKXD (ORCPT ); Wed, 8 Sep 2021 06:23:03 -0400 Received: by mail-vs1-f43.google.com with SMTP id d6so1546877vsr.7; Wed, 08 Sep 2021 03:21:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=8g1MXx8tPZJgEtHuWN2FTujyN4+VHT0fVsMeMam6ogc=; b=kcED//ERt5trE8d7hnPV7Qcgck0m/iuCWcHpc8bGLMS5U7rj1GS0G+dB5xUN33P+Dt jo5kdiQKuznjnOMk8wn3lyATBtPRBT03MC7a1UfFCGQH+p0Nyh08OmpYUPwcWeJ4sKG8 StdQKQkc3Dy0eBgek3n/WD6ctZ899CyH0mNLp1ncbtBAgMbFuNfHKEiUV6/mQmgNJenR TGRiGi/DO2Q2FQl8bOnjJ5BNJhP4XpeHqz9VaUMSurXjp/EyNQO0IfPWvGliSrjWpYxt ChQV9S6YKeUi2smrMgNVClWNYDF6giiXl8mgp0xcuQpxFyMVL72l9/NdNv/GiJ8oYYE8 lalw== X-Gm-Message-State: AOAM532RL6BbbMVs+PIcHWTwMsnWTM+bKrTCs7V65oxMY80af1s230Mg JMLhuEbODwlNX6qpglBHydd8X5PgQQl7wPiFk6c= X-Google-Smtp-Source: ABdhPJwesct4erqU/THhxBqimdnSW2qDvyqSXH/Z9bFCp2dBvUaImTAJYv/+9mlsSscBCDOvzxRNjcaQ/XqI3i97b5g= X-Received: by 2002:a05:6102:b10:: with SMTP id b16mr1287001vst.41.1631096515454; Wed, 08 Sep 2021 03:21:55 -0700 (PDT) MIME-Version: 1.0 References: <20210906142615.GA1917503@roeck-us.net> <20210906234921.GA1394069@roeck-us.net> <20210908042838.GA2585993@roeck-us.net> In-Reply-To: From: Geert Uytterhoeven Date: Wed, 8 Sep 2021 12:21:44 +0200 Message-ID: Subject: Re: [PATCH] Enable '-Werror' by default for all kernel builds To: Arnd Bergmann Cc: Guenter Roeck , Al Viro , Linus Torvalds , "David S. Miller" , Dmitry Torokhov , Christian Koenig , Huang Rui , Linux Kernel Mailing List , linux-sparc , Martin Sebor Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 8, 2021 at 11:50 AM Arnd Bergmann wrote: > On Wed, Sep 8, 2021 at 9:49 AM Geert Uytterhoeven wrote: > > On Wed, Sep 8, 2021 at 7:16 AM Guenter Roeck wrote: > > > On 9/7/21 9:48 PM, Al Viro wrote: > > > > On Tue, Sep 07, 2021 at 09:28:38PM -0700, Guenter Roeck wrote: > > > >> memcpy(eth_addr, sanitize_address((void *) 0xfffc1f2c), ETH_ALEN); > > > >> > > > >> but that just seems weird. Is there a better solution ? > > > > > > > > (char (*)[ETH_ALEN])? Said that, shouldn't that be doing something like > > > > ioremap(), rather than casting explicit constants? > > > > > > Typecasts or even assigning the address to a variable does not help. > > > The sanitizer function can not be static either. > > > > So it can only be fixed by obfuscating the constant address in a > > chain of out-of-line functions... > > How is this compiler to be used for bare-metal programming? > > I reported this as a gcc bug when I first saw it back in March: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 > > Martin Sebor suggested marking the pointer as 'volatile' as a workaround, > which is probably fine for bare-metal programming, but I would consider > that bad style for the kernel boot arguments. The RELOC_HIDE trick is probably > fine here, as there are only a couple of instances, and for the network > driver, using volatile is probably appropriate as well. A related one, I guess, is: arch/m68k/include/asm/string.h:72:25: error: argument 2 null where non-null expected [-Werror=nonnull] 72 | #define memcpy(d, s, n) __builtin_memcpy(d, s, n) | ^~~~~~~~~~~~~~~~~~~~~~~~~ drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:387:4: note: in expansion of macro ‘memcpy’ 387 | memcpy((char *)kmap(pages[0]) + | ^~~~~~ Seen with my sun3-allmodconfig build. As NO_DMA=y, dmam_alloc_coherent() returns NULL, and the compiler discovers that g_fragments_base is never assigned to and thus must be NULL. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds