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,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 3DE45C4151A for ; Mon, 28 Jan 2019 16:28:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01DE521848 for ; Mon, 28 Jan 2019 16:28:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548692881; bh=lPpeBdvlEi5K53r279FLupuF1kFAcelkdBboUZd/qYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZrEn0FcZ/rRgPs1v4hvn1ZTClOlNLmR1y5fL6RS7BF8nS9iI3mMx2ybmah+A/nOhm C4CuJFwf/YTRZOlciDE+CkQ4eov/ElmRzgxObuUcb5l6GoVJjb+yfWu5AephEJoCmS +4lq+HBk83g0ANcMPBV8EJTGChPyjXHr1PB3yYZA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390525AbfA1Q17 (ORCPT ); Mon, 28 Jan 2019 11:27:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:38356 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390509AbfA1Q15 (ORCPT ); Mon, 28 Jan 2019 11:27:57 -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 6245620879; Mon, 28 Jan 2019 16:27:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548692876; bh=lPpeBdvlEi5K53r279FLupuF1kFAcelkdBboUZd/qYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pN5xuZ1Dbo/Q6C1Hnoebt+mrjGUKhRDMRYYeWc2tKMJ2I+Mo4qicR43ShEAy026Sx j3nVyhBkdskxQII9s7OrlsKpLPK0Ksqrf/2DmMavhQSyncEcKzpsRTTN68zXfC2mVt M4ZHif9vlh3aQZsJHTLHkvNC0q0qIbVTmAnMvfS8= 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 3.18 52/61] um: Avoid marking pages with "changed protection" Date: Mon, 28 Jan 2019 11:26:14 -0500 Message-Id: <20190128162623.59854-52-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128162623.59854-1-sashal@kernel.org> References: <20190128162623.59854-1-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 bf974f712af7..e75fa226f08a 100644 --- a/arch/um/include/asm/pgtable.h +++ b/arch/um/include/asm/pgtable.h @@ -210,12 +210,17 @@ 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)); } @@ -234,6 +239,8 @@ 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