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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A1BEC433EF for ; Wed, 24 Nov 2021 13:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354781AbhKXNxE (ORCPT ); Wed, 24 Nov 2021 08:53:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:37488 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354062AbhKXNsp (ORCPT ); Wed, 24 Nov 2021 08:48:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DCEF76334A; Wed, 24 Nov 2021 13:02:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637758941; bh=CEcvv+vzt12RPoJlIolDN3gbYICVproW8INlvGSj9bM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W2vH4ZPWRDq6YUgNIEXOgjGT1tOfnLxq9PYa/ITzYmaj5CAylYdvtq6akjZi2poph qTf48XTboRQsCpMcloWi7pw3YtHufd4+scvxV/4xAMhE+wLQ5SbLqceP5jVt0x6IdS Ik6jt0IZM4tY5eEB8GU7TuOPkbUVxjtXod3KHJG0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christophe Leroy , Michael Ellerman , Sasha Levin Subject: [PATCH 5.15 079/279] powerpc/8xx: Fix Oops with STRICT_KERNEL_RWX without DEBUG_RODATA_TEST Date: Wed, 24 Nov 2021 12:56:06 +0100 Message-Id: <20211124115721.440034581@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115718.776172708@linuxfoundation.org> References: <20211124115718.776172708@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christophe Leroy [ Upstream commit c12ab8dbc492b992e1ea717db933cee568780c47 ] Until now, all tests involving CONFIG_STRICT_KERNEL_RWX were done with DEBUG_RODATA_TEST to check the result. But now that CONFIG_STRICT_KERNEL_RWX is selected by default, it came without CONFIG_DEBUG_RODATA_TEST and led to the following Oops [ 6.830908] Freeing unused kernel image (initmem) memory: 352K [ 6.840077] BUG: Unable to handle kernel data access on write at 0xc1285200 [ 6.846836] Faulting instruction address: 0xc0004b6c [ 6.851745] Oops: Kernel access of bad area, sig: 11 [#1] [ 6.857075] BE PAGE_SIZE=16K PREEMPT CMPC885 [ 6.861348] SAF3000 DIE NOTIFICATION [ 6.864830] CPU: 0 PID: 1 Comm: swapper Not tainted 5.15.0-rc5-s3k-dev-02255-g2747d7b7916f #451 [ 6.873429] NIP: c0004b6c LR: c0004b60 CTR: 00000000 [ 6.878419] REGS: c902be60 TRAP: 0300 Not tainted (5.15.0-rc5-s3k-dev-02255-g2747d7b7916f) [ 6.886852] MSR: 00009032 CR: 53000335 XER: 8000ff40 [ 6.893564] DAR: c1285200 DSISR: 82000000 [ 6.893564] GPR00: 0c000000 c902bf20 c20f4000 08000000 00000001 04001f00 c1800000 00000035 [ 6.893564] GPR08: ff0001ff c1280000 00000002 c0004b60 00001000 00000000 c0004b1c 00000000 [ 6.893564] GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 6.893564] GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1060000 [ 6.932034] NIP [c0004b6c] kernel_init+0x50/0x138 [ 6.936682] LR [c0004b60] kernel_init+0x44/0x138 [ 6.941245] Call Trace: [ 6.943653] [c902bf20] [c0004b60] kernel_init+0x44/0x138 (unreliable) [ 6.950022] [c902bf30] [c001122c] ret_from_kernel_thread+0x5c/0x64 [ 6.956135] Instruction dump: [ 6.959060] 48ffc521 48045469 4800d8cd 3d20c086 89295fa0 2c090000 41820058 480796c9 [ 6.966890] 4800e48d 3d20c128 39400002 3fe0c106 <91495200> 3bff8000 4806fa1d 481f7d75 [ 6.974902] ---[ end trace 1e397bacba4aa610 ]--- 0xc1285200 corresponds to 'system_state' global var that the kernel is trying to set to SYSTEM_RUNNING. This var is above the RO/RW limit so it shouldn't Oops. It oopses because the dirty bit is missing. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/3d5800b0bbcd7b19761b98f50421358667b45331.1635520232.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin --- arch/powerpc/kernel/head_8xx.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 9bdb95f5694f7..2d596881b70e7 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -755,7 +755,7 @@ _GLOBAL(mmu_pin_tlb) cmplw r6, r9 bdnzt lt, 2b -4: LOAD_REG_IMMEDIATE(r8, 0xf0 | _PAGE_SPS | _PAGE_SH | _PAGE_PRESENT) +4: LOAD_REG_IMMEDIATE(r8, 0xf0 | _PAGE_DIRTY | _PAGE_SPS | _PAGE_SH | _PAGE_PRESENT) 2: ori r0, r6, MD_EVALID mtspr SPRN_MD_CTR, r5 mtspr SPRN_MD_EPN, r0 -- 2.33.0