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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 5183BCA9EA1 for ; Fri, 18 Oct 2019 12:01:20 +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 2088021897 for ; Fri, 18 Oct 2019 12:01:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ABkJPZOh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2088021897 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=/lFp21wlyXK9x+dlAiD4d4ms9I3zCpOFtjHNZRAWMOQ=; b=ABkJPZOh4VFc6U g2hIH7a1Mne6QYprpxEGwp+qsaSmWMizGGZ2R1ad9bcq0zp0Q+RpdFL9uko8IBT4rmb/ovisS1itX QQAh8BhtCTN8QQjyI4H/Bm6Hx42tjO+voUTHVcUJI8KqmlVWsi4ge8Ymgx5+raGNLLFynuaslvSMq C5F2R/sWAhX+wr28biT7J6b8AoQvuEt1Yms2fRyqFe0AUb0eEdLrix7Ri+38KPjhn32fSSFuepz8A nHKAmMywA84XX54Ax/mMTKhxlQupE3rN/SZb3ZED3mmbgJVJjSEdAGO5kE29JolsqWSI5k0CFGnvc rU5SgD3I0ZgQCzfdYTow==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLQwZ-0000Pe-BJ; Fri, 18 Oct 2019 12:01:19 +0000 Received: from [217.140.110.172] (helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLQwW-0000OZ-Bq for linux-arm-kernel@lists.infradead.org; Fri, 18 Oct 2019 12:01:17 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 64211CA3; Fri, 18 Oct 2019 05:01:05 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.197.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CD3653F6C4; Fri, 18 Oct 2019 05:01:04 -0700 (PDT) Date: Fri, 18 Oct 2019 13:01:02 +0100 From: Catalin Marinas To: Mark Brown Subject: Re: [PATCH v3 1/3] arm64: Factor out checks for KASLR in KPTI code into separate function Message-ID: <20191018120102.GA55431@arrakis.emea.arm.com> References: <20191016151421.27708-1-broonie@kernel.org> <20191016151421.27708-2-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191016151421.27708-2-broonie@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-20191018_050116_447358_4CF9D7FA X-CRM114-Status: GOOD ( 15.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 16, 2019 at 04:14:19PM +0100, Mark Brown wrote: > +static inline bool arm64_kernel_use_ng_mappings(void) > +{ > /* What's a kpti? Use global mappings if we don't know. */ > if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) > return false; > @@ -52,29 +79,21 @@ static inline bool arm64_kernel_use_ng_mappings(void) > if (arm64_kernel_unmapped_at_el0()) > return true; > > - if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) > + /* > + * Once we are far enough into boot for capabilities to be > + * ready we will have confirmed if we are using non-global > + * mappings so don't need to consider anything else here. > + */ > + if (static_branch_likely(&arm64_const_caps_ready)) > return false; > > /* > * KASLR is enabled so we're going to be enabling kpti on non-broken > * CPUs regardless of their susceptibility to Meltdown. Rather > * than force everybody to go through the G -> nG dance later on, > - * just put down non-global mappings from the beginning. > + * just put down non-global mappings from the beginning > */ > - if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) { > - tx1_bug = false; > -#ifndef MODULE > - } else if (!static_branch_likely(&arm64_const_caps_ready)) { > - extern const struct midr_range cavium_erratum_27456_cpus[]; > - > - tx1_bug = is_midr_in_range_list(read_cpuid_id(), > - cavium_erratum_27456_cpus); > -#endif > - } else { > - tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456); > - } > - > - return !tx1_bug && kaslr_offset() > 0; > + return kaslr_requires_kpti(); > } While that's a step in the right direction, I'd like to see {PTE,PMD}_MAYBE_NG move away from the current use of arm64_kernel_use_ng_mappings(). These macros are used during early during boot and we seem to rely on cpu_hwcaps not being populated yet (arm64_kernel_unmapped_at_el0() checking it via cpus_have_const_cap()). Could we have a global variable (boot or a pgtable attr type) which we populate during early boot and subsequently use in the PTE_MAYBE_NG macro? Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel