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=-9.1 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 CE578C43381 for ; Mon, 18 Feb 2019 14:03:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9FD0021901 for ; Mon, 18 Feb 2019 14:03:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550498611; bh=9lFSmPBTLREf+u/IAkmAImviphgRRXcC8LwIqAfEDHI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=uJj1C/P1emTZCl6rtUAiOcx+5lQhqs1NxWV5Nc6g1dY18/udzma1/v1SDbxv0Qbcl q84iRKI2DfjLyEyPvvzjop/iQwSckB26rv5Q9z2HREcbCD8pNxU0H8lVgit3DnpTvf NhFE/kKWxweWaYIIdSC8aJzb5CoawCjkuzY4lXHs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389702AbfBRODa (ORCPT ); Mon, 18 Feb 2019 09:03:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:45386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389691AbfBROD1 (ORCPT ); Mon, 18 Feb 2019 09:03:27 -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 4F3B62070D; Mon, 18 Feb 2019 14:03:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550498606; bh=9lFSmPBTLREf+u/IAkmAImviphgRRXcC8LwIqAfEDHI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/0QG9CRkZdV6uB796HoU+89vw+AtXjwmxgTwlM6NL6KtNAbF2bdzCOLrr5wz7qzl aE1zbEpU530dDF9OL07a+IIGScBrZ5SysXuc8aYauH/Yzt9uULeML02OT0YuH2CTLM sI0vDr5M8jfgAZViGS9OL8ulSGtLCqICQLgWJ4x0= 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 4.4 062/143] um: Avoid marking pages with "changed protection" Date: Mon, 18 Feb 2019 14:43:10 +0100 Message-Id: <20190218133531.371720729@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190218133529.099444112@linuxfoundation.org> References: <20190218133529.099444112@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 4.4-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 18eb9924dda3..aeb430212947 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