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,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 2AB2FC282CE for ; Mon, 11 Feb 2019 14:51:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E7F3C20700 for ; Mon, 11 Feb 2019 14:51:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549896661; bh=riK/t8jYSLfxkyuJCCIj0BB8e1xI/crnjLWQ3XqU6BU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=brXNsANkWitHF0gvVBrV1FHVn+rLg2E4EAssA8yxFVIIRqCoq7BSop5ogIEgQCXa+ 3l13mDgurfJ79sMpClPnOgQhVidYwmUmR2fng+c/2VqqkbPyisGDHuU1v/72LFUbql x5Iu76QC5UNz8SPfZhvAq57lRwIf7rrgupb7kYxQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388188AbfBKOu7 (ORCPT ); Mon, 11 Feb 2019 09:50:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:36914 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387765AbfBKOuz (ORCPT ); Mon, 11 Feb 2019 09:50:55 -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 D85CC20700; Mon, 11 Feb 2019 14:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549896655; bh=riK/t8jYSLfxkyuJCCIj0BB8e1xI/crnjLWQ3XqU6BU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XIoGl9UAWeKz5n3sGebDNd8DckJ+3fWJIMoODFWZuTHIT2VM2sFuMiFHQjqc6eybx PBkZq1SKBp7Bbsw9kwbuN1lUGGsS6FikhKQf+Mc3+6JWJLANsvSww0YwTlgGlWQrKI 5xm1UmUpWS8IDarFmEZVW5V7u2/K/wHwmMAbCr3U= 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 4.19 219/313] um: Avoid marking pages with "changed protection" Date: Mon, 11 Feb 2019 15:18:19 +0100 Message-Id: <20190211141907.797518104@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141852.749630980@linuxfoundation.org> References: <20190211141852.749630980@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 4.19-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