From patchwork Mon Jan 9 05:28:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 13093059 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 06F11C54EBD for ; Mon, 9 Jan 2023 05:29:43 +0000 (UTC) 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:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=iRr8PN6a+kamZisYm7/KCI5nWXDHvAFE8Z675JeYJIk=; b=GOY0TLIPVNDN5+ bm9Aop6kOHQQRwsuv4rGJjJ04AgD2AewStxmdEUwHDE4tzjZ8boy4h2ouIQb6r62DvIPmfydVDcwq nZqt6tgY55z/0WbOSc6aadWKZDgGYxtxFJWCslV8MyA+FzLzaG1xWjI0aZi73jz5koKYkynoX4WJi 78dNrtvEARRLCkvRt1MKQfBnaIK/hvbUmIOLgJJdSzgkoH0aKOkXAbscMAZynJCDiB744yVghwyhc 3hFxeGX83GNstSa1PB7hYjxD2M8DwBHZ7/yAiGtu3Z4Wtw0LPcF6N6VxYFP0SwaddZmvTR8l+VFEV 8bVposPVqoETeF04BWNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pEki5-00HSGb-BS; Mon, 09 Jan 2023 05:28:37 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pEki0-00HSDy-Hj for linux-arm-kernel@lists.infradead.org; Mon, 09 Jan 2023 05:28:34 +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 C2F151042; Sun, 8 Jan 2023 21:29:08 -0800 (PST) Received: from a077893.blr.arm.com (unknown [10.162.40.15]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5923C3F71A; Sun, 8 Jan 2023 21:28:24 -0800 (PST) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com Cc: Anshuman Khandual , Mark Rutland , Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH V2] arm64/mm: Intercept pfn changes in set_pte_at() Date: Mon, 9 Jan 2023 10:58:16 +0530 Message-Id: <20230109052816.405335-1-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230108_212832_723666_04AB60EA X-CRM114-Status: GOOD ( 14.33 ) 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 Changing pfn on a user page table mapped entry, without first going through break-before-make (BBM) procedure is unsafe. This just updates set_pte_at() to intercept such changes, via an updated pgattr_change_is_safe(). This new check happens via __check_racy_pte_update(), which has now been renamed as __check_safe_pte_update(). Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Cc: Andrew Morton Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual Acked-by: Mark Rutland --- This applies on v6.2-rc3. This patch had some test time on an internal CI system without any issues being reported. Changes in V1: https://lore.kernel.org/all/20221116031001.292236-1-anshuman.khandual@arm.com/ arch/arm64/include/asm/pgtable.h | 8 ++++++-- arch/arm64/mm/mmu.c | 8 +++++++- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index b4bbeed80fb6..832c9c8fb58f 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -275,6 +275,7 @@ static inline void set_pte(pte_t *ptep, pte_t pte) } extern void __sync_icache_dcache(pte_t pteval); +bool pgattr_change_is_safe(u64 old, u64 new); /* * PTE bits configuration in the presence of hardware Dirty Bit Management @@ -292,7 +293,7 @@ extern void __sync_icache_dcache(pte_t pteval); * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) */ -static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep, +static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte) { pte_t old_pte; @@ -318,6 +319,9 @@ static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep, VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx", __func__, pte_val(old_pte), pte_val(pte)); + VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)), + "%s: unsafe attribute change: 0x%016llx -> 0x%016llx", + __func__, pte_val(old_pte), pte_val(pte)); } static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, @@ -346,7 +350,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, mte_sync_tags(old_pte, pte); } - __check_racy_pte_update(mm, ptep, pte); + __check_safe_pte_update(mm, ptep, pte); set_pte(ptep, pte); } diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 14c87e8d69d8..a1d16b35c4f6 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -133,7 +133,7 @@ static phys_addr_t __init early_pgtable_alloc(int shift) return phys; } -static bool pgattr_change_is_safe(u64 old, u64 new) +bool pgattr_change_is_safe(u64 old, u64 new) { /* * The following mapping attributes may be updated in live @@ -145,6 +145,12 @@ static bool pgattr_change_is_safe(u64 old, u64 new) if (old == 0 || new == 0) return true; + /* If old and new ptes are valid, pfn should not change */ + if (pte_valid(__pte(old)) && pte_valid(__pte(new))) { + if (pte_pfn(__pte(old)) != pte_pfn(__pte(new))) + return false; + } + /* live contiguous mappings may not be manipulated at all */ if ((old | new) & PTE_CONT) return false;