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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 95C96C43603 for ; Mon, 9 Dec 2019 18:16:14 +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 6469A206D3 for ; Mon, 9 Dec 2019 18:16:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZEukncdt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6469A206D3 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+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:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=7zZZSm8brlm3jgNztC7zuGxGzz58VDZlarX5y60k9C0=; b=ZEukncdtTQkkVM lEKdVKOb4odmlplujadRDdJj7QLz1rPpvmKvACN/ODn66UYMDUtbyiCOFRZwfhn7mf55zTIMWhmp2 39g1gUipKjAPd9DLR3bLmuXz1ZIYnKnlsSoKJpr7QkWGs2IDEShVjsovozOcZH2kYxlUTqpiyIuuv mkJQn6kq8Anjrh03MGTzQSAOKOw+quA8+DKkOXaS0Z0Wu9KhOL2SeVu2NZSWXW7w04e1QxkvmWrMc bhlBgq/t/eHWgEuCJfUK4ljogkLmaR6lsIK95HRdD5crecmIDw4hX/GCO5q0gVLw9p7CAEWy3IEOR ARevVnka7pUD4xv2qwtA==; 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 1ieNZq-0001Xw-66; Mon, 09 Dec 2019 18:16:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ieNWF-00054Q-0a for linux-arm-kernel@lists.infradead.org; Mon, 09 Dec 2019 18:12:31 +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 CC992113E; Mon, 9 Dec 2019 10:12:25 -0800 (PST) Received: from localhost (unknown [10.37.6.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4B6013F6CF; Mon, 9 Dec 2019 10:12:25 -0800 (PST) From: Mark Brown To: Will Deacon , Catalin Marinas , Suzuki K Poulose Subject: [PATCH v9 2/4] arm64: Factor out checks for KASLR in KPTI code into separate function Date: Mon, 9 Dec 2019 18:12:15 +0000 Message-Id: <20191209181217.44890-3-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191209181217.44890-1-broonie@kernel.org> References: <20191209181217.44890-1-broonie@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191209_101227_263536_EA84D55A X-CRM114-Status: GOOD ( 18.41 ) 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: Mark Brown , 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 In preparation for integrating E0PD support with KASLR factor out the checks for interaction between KASLR and KPTI done in boot context into a new function kaslr_requires_kpti(), in the process clarifying the distinction between what we do in boot context and what we do at runtime. Signed-off-by: Mark Brown Reviewed-by: Suzuki K Poulose --- arch/arm64/include/asm/mmu.h | 62 ++++++++++++++++++++++++---------- arch/arm64/kernel/cpufeature.c | 2 +- 2 files changed, 46 insertions(+), 18 deletions(-) diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index f217e3292919..2a93d34cc0ca 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -35,10 +35,46 @@ static inline bool arm64_kernel_unmapped_at_el0(void) cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0); } -static inline bool arm64_kernel_use_ng_mappings(void) +/* + * This check is triggered during the early boot before the cpufeature + * is initialised. Checking the status on the local CPU allows the boot + * CPU to detect the need for non-global mappings and thus avoiding a + * pagetable re-write after all the CPUs are booted. This check will be + * anyway run on individual CPUs, allowing us to get the consistent + * state once the SMP CPUs are up and thus make the switch to non-global + * mappings if required. + */ +static inline bool kaslr_requires_kpti(void) { bool tx1_bug; + if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + return false; + + /* + * Systems affected by Cavium erratum 24756 are incompatible + * with KPTI. + */ + 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); + } + if (tx1_bug) + return false; + + return kaslr_offset() > 0; +} + +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 +88,21 @@ 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(); } typedef void (*bp_hardening_cb_t)(void); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9d578e720168..88aa5ab02926 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1009,7 +1009,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, } /* Useful for KASLR robustness */ - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0) { + if (kaslr_requires_kpti()) { if (!__kpti_forced) { str = "KASLR"; __kpti_forced = 1; -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel