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,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 18734C282C8 for ; Mon, 28 Jan 2019 16:52:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB4F92173C for ; Mon, 28 Jan 2019 16:52:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548694366; bh=smksVjHmBgGlBWiX3aftH5cmLjUKG7JYTo/oSFQbUcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HvihX3/95Qv+QevzLMW5VMvwprd2W+IUCDyukdjx1J4TwquUYzml4Ajx3QYeWdo+J 5d6M4YJaJax7+eWiTYJ2n1ekRCgc0BO/c2G8KT/DoOje5oTs0WNTxeDtDyCkvKGtA/ 9TOv+IlQJhf2i4BeyKvgU/hCPpAhk46kisaOwkjA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388444AbfA1QSf (ORCPT ); Mon, 28 Jan 2019 11:18:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:52880 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388427AbfA1QSb (ORCPT ); Mon, 28 Jan 2019 11:18:31 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BB1632177E; Mon, 28 Jan 2019 16:18:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548692310; bh=smksVjHmBgGlBWiX3aftH5cmLjUKG7JYTo/oSFQbUcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vYFWw2o3wF93cwIaESiUhfzWsY7kL6E4jne0Yfst7KIdMCuBccz3VyrbF+BqbPat2 f8Al7jRtLSKmON7+piCicl+h3kvEc7IgXTGCz4D5ucnf7XelRVjxsImR2TFw0eL3i8 zuh5yN7FSM/5rAdBDFrZlTZI07UU5661MzOfsh1A= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Anton Ivanov , Richard Weinberger , Sasha Levin , linux-um@lists.infradead.org Subject: [PATCH AUTOSEL 4.14 148/170] um: Avoid marking pages with "changed protection" Date: Mon, 28 Jan 2019 11:11:38 -0500 Message-Id: <20190128161200.55107-148-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128161200.55107-1-sashal@kernel.org> References: <20190128161200.55107-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Anton Ivanov [ 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