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=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 30877C169C4 for ; Mon, 11 Feb 2019 15:57:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB14A21B18 for ; Mon, 11 Feb 2019 15:57:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549900677; bh=J4zK+wuGlmBjQ7i7sehrwEICdZa3OottXBU/BN69jls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CpGHqr+0aPtV1BnwuKVD7i1WEXlWXv6t7zq+lrOzH+MOgq/v6GcR+L5aycA1tGPOx khKl3ThWbABAOurqcs9kAnPqyzBZKFiN9TQDcDCHLajiX0pR/0I/ZvdqzcAzqcrHyK G+FK4SGcP8asY91vMqLOhV3EoQKrKNi+PeelBUKM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727691AbfBKOdX (ORCPT ); Mon, 11 Feb 2019 09:33:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:40994 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730624AbfBKOdS (ORCPT ); Mon, 11 Feb 2019 09:33:18 -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 058D920675; Mon, 11 Feb 2019 14:33:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549895597; bh=J4zK+wuGlmBjQ7i7sehrwEICdZa3OottXBU/BN69jls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Px6Kr0YnSIdCk6+QDyxBrFNe9vOQwJ1M2O3uSDvwWQzhWHYF/ZBfDgYTlVIrdType 1iwe0WQALWiMyI8L8ot/Dg77+FfM9P5FXCHrIZf90A4QZ1ae4EygUVUB5tS8KfoPSQ dDxwMIYIgVPlJXmdIu6aJ0nwtJRTPzflVGfIeUK8= 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 4.20 259/352] um: Avoid marking pages with "changed protection" Date: Mon, 11 Feb 2019 15:18:06 +0100 Message-Id: <20190211141903.552540891@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141846.543045703@linuxfoundation.org> References: <20190211141846.543045703@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: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.20-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