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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 201A7C64E7B for ; Tue, 1 Dec 2020 09:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A20ED20809 for ; Tue, 1 Dec 2020 09:06:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="UwuZ2gLU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388241AbgLAJF4 (ORCPT ); Tue, 1 Dec 2020 04:05:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:40836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388716AbgLAJDn (ORCPT ); Tue, 1 Dec 2020 04:03:43 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5DC5F2067D; Tue, 1 Dec 2020 09:02:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1606813377; bh=k5DVzzqjaDSJoLUEeJg5gBxnwWjkgZXI9Cmyy6Ji0BI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UwuZ2gLU6vYA2qfpS1cdbAEhgjdusfsh+WLijXqmGIBnNtFPvCnDQRwEip1cg4nBF h0gcvHK0cOPl3ISrpypQDKJd9hp0E7i69p5QxwR2mBNW2fZ9xY0pft4T1seVQzHbQY dNuK8Cj12IGW9YMmpjjhgurAw2f4EgscrasMCVRY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yu Zhao , Minchan Kim , Catalin Marinas , Will Deacon Subject: [PATCH 5.4 19/98] arm64: pgtable: Fix pte_accessible() Date: Tue, 1 Dec 2020 09:52:56 +0100 Message-Id: <20201201084655.160489931@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201201084652.827177826@linuxfoundation.org> References: <20201201084652.827177826@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Will Deacon commit 07509e10dcc77627f8b6a57381e878fe269958d3 upstream. pte_accessible() is used by ptep_clear_flush() to figure out whether TLB invalidation is necessary when unmapping pages for reclaim. Although our implementation is correct according to the architecture, returning true only for valid, young ptes in the absence of racing page-table modifications, this is in fact flawed due to lazy invalidation of old ptes in ptep_clear_flush_young() where we elide the expensive DSB instruction for completing the TLB invalidation. Rather than penalise the aging path, adjust pte_accessible() to return true for any valid pte, even if the access flag is cleared. Cc: Fixes: 76c714be0e5e ("arm64: pgtable: implement pte_accessible()") Reported-by: Yu Zhao Acked-by: Yu Zhao Reviewed-by: Minchan Kim Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20201120143557.6715-2-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/pgtable.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -98,8 +98,6 @@ extern unsigned long empty_zero_page[PAG #define pte_valid(pte) (!!(pte_val(pte) & PTE_VALID)) #define pte_valid_not_user(pte) \ ((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID) -#define pte_valid_young(pte) \ - ((pte_val(pte) & (PTE_VALID | PTE_AF)) == (PTE_VALID | PTE_AF)) #define pte_valid_user(pte) \ ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) @@ -107,9 +105,12 @@ extern unsigned long empty_zero_page[PAG * Could the pte be present in the TLB? We must check mm_tlb_flush_pending * so that we don't erroneously return false for pages that have been * remapped as PROT_NONE but are yet to be flushed from the TLB. + * Note that we can't make any assumptions based on the state of the access + * flag, since ptep_clear_flush_young() elides a DSB when invalidating the + * TLB. */ #define pte_accessible(mm, pte) \ - (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid_young(pte)) + (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte)) /* * p??_access_permitted() is true for valid user mappings (subject to the