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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 C10A5C169C4 for ; Mon, 11 Feb 2019 15:01:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FCE921773 for ; Mon, 11 Feb 2019 15:01:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549897266; bh=gPmJKA67Ch26ua1Pp3F+3LHqTv1tS85PVDPrISh5BtA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=RLFpWl2aY7yLkDTzlpxMGtk0577AEBBLZFpk5yI67C2/xrTjow9zaOVNi/k+nzP+F WJzz0ZhHSx3pZApUNE89Th6ehQBPiaTBVNmF5IDAJlZQYt4MBzWZwcqLx36yg0QxLV 1sbAdGgAXGKniQAN09pelTrVqSS5XmfN2GYHDh1w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390117AbfBKPBF (ORCPT ); Mon, 11 Feb 2019 10:01:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:49006 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390097AbfBKPBD (ORCPT ); Mon, 11 Feb 2019 10:01:03 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (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 20F5A222A7; Mon, 11 Feb 2019 15:01:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549897262; bh=gPmJKA67Ch26ua1Pp3F+3LHqTv1tS85PVDPrISh5BtA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u46jTm7r+s80rfwsFPegg2plA5sbsvadJv3kuNhnHuhCYmCFVWCgPB4Y3AUbs7EYn nO0/+oQpcZ83EJWTs+t6s3M7Ngj6gBXRRMUYmgapTaKKBhhWRASqjroz0TokQS4ZlJ e8bi8bN1VyW08+9NRjKN077T6vz411qzJG5bFWdw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anton Ivanov , Richard Weinberger , Sasha Levin Subject: [PATCH 4.14 143/205] um: Avoid marking pages with "changed protection" Date: Mon, 11 Feb 2019 15:19:01 +0100 Message-Id: <20190211141837.720534756@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141827.214852402@linuxfoundation.org> References: <20190211141827.214852402@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 8892d8545f2d0342b9c550defbfb165db237044b ] Changing protection is a very high cost operation in UML because in addition to an extra syscall it also interrupts mmap merge sequences generated by the tlb. While the condition is not particularly common it is worth avoiding. Signed-off-by: Anton Ivanov Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- arch/um/include/asm/pgtable.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h index 7485398d0737..9c04562310b3 100644 --- a/arch/um/include/asm/pgtable.h +++ b/arch/um/include/asm/pgtable.h @@ -197,12 +197,17 @@ static inline pte_t pte_mkold(pte_t pte) static inline pte_t pte_wrprotect(pte_t pte) { - pte_clear_bits(pte, _PAGE_RW); + if (likely(pte_get_bits(pte, _PAGE_RW))) + pte_clear_bits(pte, _PAGE_RW); + else + return pte; return(pte_mknewprot(pte)); } static inline pte_t pte_mkread(pte_t pte) { + if (unlikely(pte_get_bits(pte, _PAGE_USER))) + return pte; pte_set_bits(pte, _PAGE_USER); return(pte_mknewprot(pte)); } @@ -221,6 +226,8 @@ static inline pte_t pte_mkyoung(pte_t pte) static inline pte_t pte_mkwrite(pte_t pte) { + if (unlikely(pte_get_bits(pte, _PAGE_RW))) + return pte; pte_set_bits(pte, _PAGE_RW); return(pte_mknewprot(pte)); } -- 2.19.1