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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 14718CCF9F8 for ; Thu, 6 Nov 2025 16:10:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7e79lIR0MUUagRf25jA//CylembXpgfk5oULi2Sh4yk=; b=ZNj8971gB4x1/bKu422A02Rblo pO/uWxo01hnef3nF3D+oOWPTNbbH9RBtt9kIbHOAbuFNv7JbIVWxt2zKWFJ/pV6QRY8ip38XTi0m7 bqPAPlA0xCqB4fAHBmz5Y6qfJCJrn4FuN42em6n0d54ZS6e4gYIgVWO5GrupeLEYtSLiUJnlnt769 Ix695MsTnkrIJ6t5fTlB0W0FDZK1By9h3QFlHBmkb/pE93IiTEi3iN+IiODDvozO1m9hSMC2Eq9kP 3vGf3T+TDhsOrDtM9fVToC6SAUaIUK114xsRgZUd55tTkRgRl2cQ9zWZ+a/7jWPwljQNMdM+5i2xo YxggtlWA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vH2Yo-0000000Fsr9-3zPi; Thu, 06 Nov 2025 16:10:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vH2Yj-0000000FsmF-0cze for linux-arm-kernel@lists.infradead.org; Thu, 06 Nov 2025 16:10:02 +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 D8D7C15A1; Thu, 6 Nov 2025 08:09:52 -0800 (PST) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E69B3F66E; Thu, 6 Nov 2025 08:09:59 -0800 (PST) From: Ryan Roberts To: catalin.marinas@arm.com, will@kernel.org, yang@os.amperecomputing.com, david@redhat.com, ardb@kernel.org, dev.jain@arm.com, scott@os.amperecomputing.com, cl@gentwo.org Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, David Hildenbrand Subject: [PATCH v2 3/3] arm64: mm: Tidy up force_pte_mapping() Date: Thu, 6 Nov 2025 16:09:43 +0000 Message-ID: <20251106160945.3182799-4-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251106160945.3182799-1-ryan.roberts@arm.com> References: <20251106160945.3182799-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251106_081001_327235_962B8811 X-CRM114-Status: GOOD ( 17.50 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Tidy up the implementation of force_pte_mapping() to make it easier to read and introduce the split_leaf_mapping_possible() helper to reduce code duplication in split_kernel_leaf_mapping() and arch_kfence_init_pool(). Suggested-by: David Hildenbrand (Red Hat) Signed-off-by: Ryan Roberts --- arch/arm64/mm/mmu.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 652bb8c14035..2ba01dc8ef82 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -710,12 +710,26 @@ static int split_kernel_leaf_mapping_locked(unsigned long addr) static inline bool force_pte_mapping(void) { - bool bbml2 = system_capabilities_finalized() ? + const bool bbml2 = system_capabilities_finalized() ? system_supports_bbml2_noabort() : cpu_supports_bbml2_noabort(); - return (!bbml2 && (rodata_full || arm64_kfence_can_set_direct_map() || - is_realm_world())) || - debug_pagealloc_enabled(); + if (debug_pagealloc_enabled()) + return true; + if (bbml2) + return false; + return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world(); +} + +static inline bool split_leaf_mapping_possible(void) +{ + /* + * !BBML2_NOABORT systems should never run into scenarios where we would + * have to split. So exit early and let calling code detect it and raise + * a warning. + */ + if (!system_supports_bbml2_noabort()) + return false; + return !force_pte_mapping(); } static DEFINE_MUTEX(pgtable_split_lock); @@ -725,22 +739,11 @@ int split_kernel_leaf_mapping(unsigned long start, unsigned long end) int ret; /* - * !BBML2_NOABORT systems should not be trying to change permissions on - * anything that is not pte-mapped in the first place. Just return early - * and let the permission change code raise a warning if not already - * pte-mapped. - */ - if (!system_supports_bbml2_noabort()) - return 0; - - /* - * If the region is within a pte-mapped area, there is no need to try to - * split. Additionally, CONFIG_DEBUG_PAGEALLOC and CONFIG_KFENCE may - * change permissions from atomic context so for those cases (which are - * always pte-mapped), we must not go any further because taking the - * mutex below may sleep. + * Exit early if the region is within a pte-mapped area or if we can't + * split. For the latter case, the permission change code will raise a + * warning if not already pte-mapped. */ - if (force_pte_mapping() || is_kfence_address((void *)start)) + if (!split_leaf_mapping_possible() || is_kfence_address((void *)start)) return 0; /* @@ -1039,7 +1042,7 @@ bool arch_kfence_init_pool(void) int ret; /* Exit early if we know the linear map is already pte-mapped. */ - if (!system_supports_bbml2_noabort() || force_pte_mapping()) + if (!split_leaf_mapping_possible()) return true; /* Kfence pool is already pte-mapped for the early init case. */ -- 2.43.0