From patchwork Mon Jan 25 18:39:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 371302 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 52F55C433E6 for ; Tue, 26 Jan 2021 21:15:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25EFC22B3F for ; Tue, 26 Jan 2021 21:15:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728516AbhAZEum (ORCPT ); Mon, 25 Jan 2021 23:50:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:33826 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726633AbhAYSqc (ORCPT ); Mon, 25 Jan 2021 13:46:32 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C23042067B; Mon, 25 Jan 2021 18:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611600370; bh=BAAw2el7VSWzS5NnVOyyghdQ4oO7R+bR8fqn+CNmSew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=icRjoLSar/LBBYWwMfBpJnhWhc1rZGZF/Wno/icVTk7aSCFZrYDAGlasAPRCf7nQm MAObiq7PEuGIG4HbZpIdgpVYb4L2bFNLp6w5JgxZq3KWYOKaUWSZmCvp4KSPYBW1I7 OAEohwi5aNwL548pzgZAlR+GfVYErs+BTj0GA5V0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ariel Marcovitch , Christophe Leroy , Michael Ellerman , Sasha Levin Subject: [PATCH 5.4 45/86] powerpc: Fix alignment bug within the init sections Date: Mon, 25 Jan 2021 19:39:27 +0100 Message-Id: <20210125183202.970095454@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210125183201.024962206@linuxfoundation.org> References: <20210125183201.024962206@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ariel Marcovitch [ Upstream commit 2225a8dda263edc35a0e8b858fe2945cf6240fde ] This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch Reviewed-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/vmlinux.lds.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index f9081724d6910..a4e576019d79c 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -210,6 +210,12 @@ SECTIONS .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { _sinittext = .; INIT_TEXT + + /* + *.init.text might be RO so we must ensure this section ends on + * a page boundary. + */ + . = ALIGN(PAGE_SIZE); _einittext = .; #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); @@ -223,6 +229,8 @@ SECTIONS EXIT_TEXT } + . = ALIGN(PAGE_SIZE); + INIT_DATA_SECTION(16) . = ALIGN(8);