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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 EBAE0C07E99 for ; Mon, 12 Jul 2021 12:26:26 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AB8B361108 for ; Mon, 12 Jul 2021 12:26:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB8B361108 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=2ZUUYKx+FmMdk/GYny2XQJrvoqKZ3LsFBs0jujpN+Bc=; b=FiU2qx92SGit5G w9tJIF664NlnrEen6XxLOP8/b/8BoVWoQrIuNy1G6MNJ0t3bxiGG+epNPOQiYM4vp3uECkHNtGErB vJdP2a9q3EB/9WWFgXmwcf2zCZbwRDTOea/V8+DqdBd2iz+Mk1n1WH5dEMhOHwWx4H8ZhbsTjj23j L+8rVK9A2y6OPtfzxlHoWlZyqCfDXFE9xE0G+nLe+HTTOQfNJWtSWRO58uof21L50Zr1IRTEgk0Ce mg/mTEMC7ykOPh6tTPdZ1NiANSwzaP0uITWYVNDvx6VTfgKVGYhDUHG+rVEpiegg0m46cm8xGDgMi 1SEUCRHUpswQSXndLoYg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m2uzL-007I2x-11; Mon, 12 Jul 2021 12:24:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m2uzH-007I2T-CX for linux-arm-kernel@lists.infradead.org; Mon, 12 Jul 2021 12:24:40 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id D5FA460FF3; Mon, 12 Jul 2021 12:24:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626092679; bh=39UDyHmtvOvV95HVEQniIReLPUgxxMG9Orayrb4XS8s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M8SaYHYX0KXistxYO3gZheS3K/a4uVcqEH2wWVz2vMpyzLtMehlRP79auLe2mEFrB ZMwbOO7bzHqn/qf4AO+Dlp4WuZ2XicziQRZ4iMI7Gp/bNLjVyXoR6bnbbxULDhImhT 5i4afyquJqZ6l/knqLSeWzeYssEL9mYtdBmDH+4Ke5Xdb9LkEmdf38BlpiGURyMoy9 uywuS6JjqM4sPnU4Qq+DFfZavJt3pHR8MBc7vUtYmHzvjhjCSW/EPDdjdnrsyGGNag XkbsOKyJNv91V/Kq7986IYUKdRPxuzWv2KIivt5RQWSYDW0IrX1PQISNXJ6ANlB6YA b2PVVAfIeEIDg== Date: Mon, 12 Jul 2021 13:24:34 +0100 From: Will Deacon To: Nathan Chancellor Cc: Catalin Marinas , Nick Desaulniers , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] arm64: Restrict ARM64_BTI_KERNEL to clang 12.0.0 and newer Message-ID: <20210712122433.GA28536@willie-the-truck> References: <20210709000627.3183718-1-nathan@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210709000627.3183718-1-nathan@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210712_052439_486503_69E0A1B7 X-CRM114-Status: GOOD ( 13.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Nathan, On Thu, Jul 08, 2021 at 05:06:27PM -0700, Nathan Chancellor wrote: > Commit 97fed779f2a6 ("arm64: bti: Provide Kconfig for kernel mode BTI") > disabled CONFIG_ARM64_BTI_KERNEL when CONFIG_GCOV_KERNEL was enabled and > compilign with clang because of warnings that occur because LLVM was not Typo: "compilign" > emitting PAC/BTI instructions for compiler generated functions. > > This was an adequate fix to avoid the warnings with allmodconfig until > commit 51c2ee6d121c ("Kconfig: Introduce ARCH_WANTS_NO_INSTR and > CC_HAS_NO_PROFILE_FN_ATTR"), which prevented CONFIG_GCOV_KERNEL from > being selected with clang 12.0.0 and older because it does not support > the no_profile_instrument_function attribute. As a result, > CONFIG_ARM64_BTI_KERNEL gets enabled and there are more warnings of this > nature. I'm half asleep today, but I'm struggling to follow what GCOV_KERNEL has to do with the warnings here. Prior to 51c2ee6d121c, you could still go and turn that option off and so wouldn't the same warnings be triggered in that configuration? In other words, I think there are two aspects to this patch: 1. Removing the (now useless) !GCOV_KERNEL dependency 2. Requiring Clang >= version 12 but the commit message doesn't really say where these warnings are coming from or why Clang 12 gets rid of them. Thanks, Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel