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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 9BF1FC432C3 for ; Sat, 16 Nov 2019 16:22:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 737BB21479 for ; Sat, 16 Nov 2019 16:22:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573921377; bh=JBQjh57E1Ndhk4dCtXRsycP+umjDUfzghAGmYQhFalo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Z8jce0bmdT+WKGNBiMep4l3O3FltoaEN8dJ1Q/ylgzbdRF63nKsAGW/7KvIavUs7Y BRYqqUsTh29vsttr2B1+a/0BvbITh4v+YMI6QnxgTDQ0fMsLVJNHCULVVwt/UwnGRC YvLV5cP5epVzIYHTkMwtSVD20EXZ8YFLRYoO8csw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731189AbfKPQW4 (ORCPT ); Sat, 16 Nov 2019 11:22:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:46996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728589AbfKPPnI (ORCPT ); Sat, 16 Nov 2019 10:43:08 -0500 Received: from sasha-vm.mshome.net (unknown [50.234.116.4]) (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 4365B2073B; Sat, 16 Nov 2019 15:43:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573918987; bh=JBQjh57E1Ndhk4dCtXRsycP+umjDUfzghAGmYQhFalo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DiCle8aVQ1+TFNBe0ZGRZPqYP4/raLrYW0l2u6KLVSQl0cp1rmn2Uf7DCsgz8WU8J wjmdOfT2XldSn1JGK88lG8dt+yAhEkTISCLTQauaM4XLaHDdS0XITE9kzUO752iy/S NHwOo+QPdJuqMIr6dgH2vzTMoSLjx7OAushChkzw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Michael Ellerman , Sasha Levin , linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.19 093/237] powerpc/mm/radix: Fix overuse of small pages in splitting logic Date: Sat, 16 Nov 2019 10:38:48 -0500 Message-Id: <20191116154113.7417-93-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116154113.7417-1-sashal@kernel.org> References: <20191116154113.7417-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review 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: Michael Ellerman [ Upstream commit 3b5657ed5b4e27ccf593a41ff3c5aa27dae8df18 ] When we have CONFIG_STRICT_KERNEL_RWX enabled, we want to split the linear mapping at the text/data boundary so we can map the kernel text read only. But the current logic uses small pages for the entire text section, regardless of whether a larger page size would fit. eg. with the boundary at 16M we could use 2M pages, but instead we use 64K pages up to the 16M boundary: Mapped 0x0000000000000000-0x0000000001000000 with 64.0 KiB pages Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages This is because the test is checking if addr is < __init_begin and addr + mapping_size is >= _stext. But that is true for all pages between _stext and __init_begin. Instead what we want to check is if we are crossing the text/data boundary, which is at __init_begin. With that fixed we see: Mapped 0x0000000000000000-0x0000000000e00000 with 2.00 MiB pages Mapped 0x0000000000e00000-0x0000000001000000 with 64.0 KiB pages Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages ie. we're correctly using 2MB pages below __init_begin, but we still drop down to 64K pages unnecessarily at the boundary. Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/mm/pgtable-radix.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c index 24a2eadc8c21a..b387c7b917b7e 100644 --- a/arch/powerpc/mm/pgtable-radix.c +++ b/arch/powerpc/mm/pgtable-radix.c @@ -295,14 +295,14 @@ static int __meminit create_physical_mapping(unsigned long start, if (split_text_mapping && (mapping_size == PUD_SIZE) && (addr < __pa_symbol(__init_begin)) && - (addr + mapping_size) >= __pa_symbol(_stext)) { + (addr + mapping_size) >= __pa_symbol(__init_begin)) { max_mapping_size = PMD_SIZE; goto retry; } if (split_text_mapping && (mapping_size == PMD_SIZE) && (addr < __pa_symbol(__init_begin)) && - (addr + mapping_size) >= __pa_symbol(_stext)) { + (addr + mapping_size) >= __pa_symbol(__init_begin)) { mapping_size = PAGE_SIZE; psize = mmu_virtual_psize; } -- 2.20.1