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=-17.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D3EC7C4743C for ; Mon, 21 Jun 2021 11:20:33 +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 918F761059 for ; Mon, 21 Jun 2021 11:20:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 918F761059 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com 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:MIME-Version:References:In-Reply-To: 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: List-Owner; bh=5lqCzel6OhOaSOi/1fGwdvKI1mEL5GS1EWk2JyZ1u+A=; b=N7frKzsS4Ag4j8 Ggp/I0rTaK5yKx4XSDAJg4frXbexuOLn7EtmAvIfybmUYd6dPNAfdATlbfKcjfwbWj8AHV4IO3xe4 qBscSFHfqa3XO4lQUTR2ZbO7YMyOHq17VhcLxsstSlRbA95Zc5IXIpfXBT7mqDaKAUorDs7dIuWW0 Ook/n/BeZp+cPZ9UtEzsWKDCBJJ4wVfZDJKw82iFpNxr79yfmjoYcS4njgXLhbtwnqXJyUQw5Vadx r+IaKJlMPoxfd8ummsJYeBBrwegdLBTD7nFXD23illjmzs5WNCjBFIgh8BFpdboSIuZQ3WT8YP0jn s5xKQn9qMJEz31GaVt6Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvHwz-003GfD-Es; Mon, 21 Jun 2021 11:18:45 +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 1lvHwl-003GcU-V7 for linux-arm-kernel@lists.infradead.org; Mon, 21 Jun 2021 11:18:33 +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 6C687D6E; Mon, 21 Jun 2021 04:18:30 -0700 (PDT) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AE5C93F718; Mon, 21 Jun 2021 04:18:27 -0700 (PDT) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Cc: Steven Price , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Mark Rutland , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Andrew Jones Subject: [PATCH v17 1/6] arm64: mte: Sync tags for pages where PTE is untagged Date: Mon, 21 Jun 2021 12:17:11 +0100 Message-Id: <20210621111716.37157-2-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210621111716.37157-1-steven.price@arm.com> References: <20210621111716.37157-1-steven.price@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210621_041832_137692_6162239E X-CRM114-Status: GOOD ( 20.29 ) 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 A KVM guest could store tags in a page even if the VMM hasn't mapped the page with PROT_MTE. So when restoring pages from swap we will need to check to see if there are any saved tags even if !pte_tagged(). However don't check pages for which pte_access_permitted() returns false as these will not have been swapped out. Reviewed-by: Catalin Marinas Signed-off-by: Steven Price --- arch/arm64/include/asm/mte.h | 4 ++-- arch/arm64/include/asm/pgtable.h | 22 +++++++++++++++++++--- arch/arm64/kernel/mte.c | 18 +++++++++++++----- 3 files changed, 34 insertions(+), 10 deletions(-) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index bc88a1ced0d7..347ef38a35f7 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -37,7 +37,7 @@ void mte_free_tag_storage(char *storage); /* track which pages have valid allocation tags */ #define PG_mte_tagged PG_arch_2 -void mte_sync_tags(pte_t *ptep, pte_t pte); +void mte_sync_tags(pte_t old_pte, pte_t pte); void mte_copy_page_tags(void *kto, const void *kfrom); void mte_thread_init_user(void); void mte_thread_switch(struct task_struct *next); @@ -53,7 +53,7 @@ int mte_ptrace_copy_tags(struct task_struct *child, long request, /* unused if !CONFIG_ARM64_MTE, silence the compiler */ #define PG_mte_tagged 0 -static inline void mte_sync_tags(pte_t *ptep, pte_t pte) +static inline void mte_sync_tags(pte_t old_pte, pte_t pte) { } static inline void mte_copy_page_tags(void *kto, const void *kfrom) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 0b10204e72fc..db5402168841 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -314,9 +314,25 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte)) __sync_icache_dcache(pte); - if (system_supports_mte() && - pte_present(pte) && pte_tagged(pte) && !pte_special(pte)) - mte_sync_tags(ptep, pte); + /* + * If the PTE would provide user space access to the tags associated + * with it then ensure that the MTE tags are synchronised. Although + * pte_access_permitted() returns false for exec only mappings, they + * don't expose tags (instruction fetches don't check tags). + */ + if (system_supports_mte() && pte_access_permitted(pte, false) && + !pte_special(pte)) { + pte_t old_pte = READ_ONCE(*ptep); + /* + * We only need to synchronise if the new PTE has tags enabled + * or if swapping in (in which case another mapping may have + * set tags in the past even if this PTE isn't tagged). + * (!pte_none() && !pte_present()) is an open coded version of + * is_swap_pte() + */ + if (pte_tagged(pte) || (!pte_none(old_pte) && !pte_present(old_pte))) + mte_sync_tags(old_pte, pte); + } __check_racy_pte_update(mm, ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 125a10e413e9..69b3fde8759e 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -32,10 +32,9 @@ DEFINE_STATIC_KEY_FALSE(mte_async_mode); EXPORT_SYMBOL_GPL(mte_async_mode); #endif -static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) +static void mte_sync_page_tags(struct page *page, pte_t old_pte, + bool check_swap, bool pte_is_tagged) { - pte_t old_pte = READ_ONCE(*ptep); - if (check_swap && is_swap_pte(old_pte)) { swp_entry_t entry = pte_to_swp_entry(old_pte); @@ -43,6 +42,9 @@ static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) return; } + if (!pte_is_tagged) + return; + page_kasan_tag_reset(page); /* * We need smp_wmb() in between setting the flags and clearing the @@ -55,16 +57,22 @@ static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) mte_clear_page_tags(page_address(page)); } -void mte_sync_tags(pte_t *ptep, pte_t pte) +void mte_sync_tags(pte_t old_pte, pte_t pte) { struct page *page = pte_page(pte); long i, nr_pages = compound_nr(page); bool check_swap = nr_pages == 1; + bool pte_is_tagged = pte_tagged(pte); + + /* Early out if there's nothing to do */ + if (!check_swap && !pte_is_tagged) + return; /* if PG_mte_tagged is set, tags have already been initialised */ for (i = 0; i < nr_pages; i++, page++) { if (!test_and_set_bit(PG_mte_tagged, &page->flags)) - mte_sync_page_tags(page, ptep, check_swap); + mte_sync_page_tags(page, old_pte, check_swap, + pte_is_tagged); } } -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel