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=-7.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 04375C49ED9 for ; Thu, 12 Sep 2019 05:43:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C936A20856 for ; Thu, 12 Sep 2019 05:43:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="eoTwfksJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727050AbfILFnI (ORCPT ); Thu, 12 Sep 2019 01:43:08 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:41191 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726222AbfILFnI (ORCPT ); Thu, 12 Sep 2019 01:43:08 -0400 Received: by mail-wr1-f66.google.com with SMTP id h7so25951293wrw.8 for ; Wed, 11 Sep 2019 22:43:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=WMphAgSBPHIKk4SYSy5DiphCnKasXaVbpOhSBFsQlZM=; b=eoTwfksJpQP/aJRoNnP2I9L/oxf3rt3+WUiVHu018iFRgwNVhSNaUJpczvueG0VVpT 5UEajxPI1yyue6jILtHZ4Kq5JOv9RXWRwYs15GdqZnOPsvDSa0f5yVHZ7Oo+O5aXi26m oQq7bwa9VoCOJF8JJKk4SjzgOBDJo8oP18VvIm2DTTr8LiwkPxPmVDTgtfSQ7FJQtLBK SGMEj3OK2F0Om8P6F4VnepcY1ikk45GKvDALgQjx1815zBpUrFtUa/TvWVNAy0lgINtc ax8vt0u8nqR2rWCzu8I6d+CP/bhYa86aqRoue8PpNtZDlCpYbWeyeIWu+YeL+ZLTLFdR ZU1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=WMphAgSBPHIKk4SYSy5DiphCnKasXaVbpOhSBFsQlZM=; b=ic+3aDA3rADDAhf5iOUR7YQEg8c3btGhS1oUlsEDrrXZzRf7bcOoGC6G8USeHfZ8on GbqDbTeecmUXaSec3jfWmLn5foQT6LcM3YeANLafz7Mt3T37hKkacoCg27W+gT1UdhyT FoTdmU8YhaQhBXT0NK37d5jnnm5URoT/K+yLRstgyBipT3hYduT+1ehccsvENmPy215z 8FdvlNNzScQJ6jTm+TMOmbJxTyLPlEiPf4eF6dmAzjFbirwsL+4TWSD8lJ02eZZQBUi4 NTbc+o2+rwLKPgsfpX2xiPUhF2fXW1Ctx7snshC0bsXKf3vhNi+/2rnSdT2tspWQIqbt GXvQ== X-Gm-Message-State: APjAAAX4JjDmeGlzOaagZDWiAoHnmDN9rb6ImQ9X48ov8sCgVW2g+lMp Fnwyn2zQaECErrFEdV+zUh8= X-Google-Smtp-Source: APXvYqx8qHpVyMNgn+KXK4Ga99H83IyvN+gu/U0zu34xNKGN69+bZpzqlo+n/fuamwALPdtHuD1b7w== X-Received: by 2002:a5d:54cd:: with SMTP id x13mr9856547wrv.12.1568266986685; Wed, 11 Sep 2019 22:43:06 -0700 (PDT) Received: from archlinux-threadripper ([2a01:4f8:222:2f1b::2]) by smtp.gmail.com with ESMTPSA id b194sm11035883wmg.46.2019.09.11.22.43.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Sep 2019 22:43:05 -0700 (PDT) Date: Wed, 11 Sep 2019 22:43:04 -0700 From: Nathan Chancellor To: Nick Desaulniers Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev , LKML , clang-built-linux Subject: Re: [PATCH v3 3/3] powerpc/prom_init: Use -ffreestanding to avoid a reference to bcmp Message-ID: <20190912054304.GA103826@archlinux-threadripper> References: <20190911182049.77853-1-natechancellor@gmail.com> <20190911182049.77853-4-natechancellor@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 11, 2019 at 02:01:59PM -0700, Nick Desaulniers wrote: > On Wed, Sep 11, 2019 at 11:21 AM Nathan Chancellor > wrote: > > > > r370454 gives LLVM the ability to convert certain loops into a reference > > to bcmp as an optimization; this breaks prom_init_check.sh: > > > > CALL arch/powerpc/kernel/prom_init_check.sh > > Error: External symbol 'bcmp' referenced from prom_init.c > > make[2]: *** [arch/powerpc/kernel/Makefile:196: prom_init_check] Error 1 > > > > bcmp is defined in lib/string.c as a wrapper for memcmp so this could be > > added to the whitelist. However, commit 450e7dd4001f ("powerpc/prom_init: > > don't use string functions from lib/") copied memcmp as prom_memcmp to > > avoid KASAN instrumentation so having bcmp be resolved to regular memcmp > > would break that assumption. Furthermore, because the compiler is the > > one that inserted bcmp, we cannot provide something like prom_bcmp. > > > > To prevent LLVM from being clever with optimizations like this, use > > -ffreestanding to tell LLVM we are not hosted so it is not free to make > > transformations like this. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/647 > > Link: https://github.com/llvm/llvm-project/commit/5c9f3cfec78f9e9ae013de9a0d092a68e3e79e002 > > The above link doesn't work for me (HTTP 404). PEBKAC? > https://github.com/llvm/llvm-project/commit/5c9f3cfec78f9e9ae013de9a0d092a68e3e79e002 Not really sure how an extra 2 got added on the end of that... Must have screwed up in vim somehow. Link: https://github.com/llvm/llvm-project/commit/5c9f3cfec78f9e9ae013de9a0d092a68e3e79e00 I can resend unless the maintainer is able to fix that up when it gets applied. Cheers, Nathan