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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,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 F32F9C432C0 for ; Tue, 3 Dec 2019 22:52:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0A4220866 for ; Tue, 3 Dec 2019 22:52:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413552; bh=qoWiZmhKyc5U9nJDESFCNNEjuf4zfvI/EeR6LBTUUF4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FZXnfxfmVZi3Fs1JR4oR5kTPDqU7w5jwhJIwtAjI+iuoIm4OKPYwgmzd/CECbEFbk ecGva5Wmr3j4jslz1rNmvn/4O6ClNUleqiFsKO115WSrRc8P5OFqV3uiGn5rrHqpPI VtpJykT94eSU8c7BDwuoeFQ3UX48qqT3x3S8BUmQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729435AbfLCWwb (ORCPT ); Tue, 3 Dec 2019 17:52:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:45206 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730009AbfLCWw1 (ORCPT ); Tue, 3 Dec 2019 17:52:27 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 50A8920865; Tue, 3 Dec 2019 22:52:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413546; bh=qoWiZmhKyc5U9nJDESFCNNEjuf4zfvI/EeR6LBTUUF4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FVOzbKG2cUfbALM37wMXot3bgdLTW7qgUiAWIzVE4ocGkAsrEGHSXwep0ovBAT/my ckfmfHTfpw3SPBhkD7PjPymvRzMGnmi8T/wWoIqNhQ/QuCsSPGHexD3lazAeZ0gXQp HkCav+roZhMiyJdZn71Q14TBpwVSjXwQPYu9DjD4= 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 4.19 167/321] powerpc/mm: Make NULL pointer deferences explicit on bad page faults. Date: Tue, 3 Dec 2019 23:33:53 +0100 Message-Id: <20191203223435.824668480@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203223427.103571230@linuxfoundation.org> References: <20191203223427.103571230@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christophe Leroy [ Upstream commit 49a502ea23bf9dec47f8f3c3960909ff409cd1bb ] As several other arches including x86, this patch makes it explicit that a bad page fault is a NULL pointer dereference when the fault address is lower than PAGE_SIZE In the mean time, this page makes all bad_page_fault() messages shorter so that they remain on one single line. And it prefixes them by "BUG: " so that they get easily grepped. Signed-off-by: Christophe Leroy [mpe: Avoid pr_cont()] Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/mm/fault.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 365526ee29b88..6e0ff8b600ced 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -633,21 +633,22 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) switch (TRAP(regs)) { case 0x300: case 0x380: - printk(KERN_ALERT "Unable to handle kernel paging request for " - "data at address 0x%08lx\n", regs->dar); + pr_alert("BUG: %s at 0x%08lx\n", + regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : + "Unable to handle kernel data access", regs->dar); break; case 0x400: case 0x480: - printk(KERN_ALERT "Unable to handle kernel paging request for " - "instruction fetch\n"); + pr_alert("BUG: Unable to handle kernel instruction fetch%s", + regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n"); break; case 0x600: - printk(KERN_ALERT "Unable to handle kernel paging request for " - "unaligned access at address 0x%08lx\n", regs->dar); + pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n", + regs->dar); break; default: - printk(KERN_ALERT "Unable to handle kernel paging request for " - "unknown fault\n"); + pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n", + regs->dar); break; } printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n", -- 2.20.1