From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752105AbdBPByM (ORCPT ); Wed, 15 Feb 2017 20:54:12 -0500 Received: from mail-pg0-f51.google.com ([74.125.83.51]:32907 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbdBPByK (ORCPT ); Wed, 15 Feb 2017 20:54:10 -0500 From: Stephen Boyd To: Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Laura Abbott , Mark Rutland Subject: [PATCH] arm64: print a fault message when attempting to write RO memory Date: Wed, 15 Feb 2017 17:54:08 -0800 Message-Id: <20170216015408.12933-1-stephen.boyd@linaro.org> X-Mailer: git-send-email 2.10.0.297.gf6727b0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a page is marked read only we should print out that fact, instead of printing out that there was a page fault. Right now we get a cryptic error message that something went wrong with an unhandled fault, but we don't evaluate the esr to figure out that it was a read/write permission fault. Instead of seeing: Unable to handle kernel paging request at virtual address ffff000008e460d8 pgd = ffff800003504000 [ffff000008e460d8] *pgd=0000000083473003, *pud=0000000083503003, *pmd=0000000000000000 Internal error: Oops: 9600004f [#1] PREEMPT SMP we'll see: Internal error: Attempting to write read-only memory: 9600004f [#1] PREEMPT SMP Cc: Laura Abbott Cc: Mark Rutland Signed-off-by: Stephen Boyd --- arch/arm64/mm/fault.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 156169c6981b..752507fa80ec 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -331,6 +331,11 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, if (!search_exception_tables(regs->pc)) die("Accessing user space memory outside uaccess.h routines", regs, esr); + } else if (is_permission_fault(esr, regs)) { + if (esr & ESR_ELx_WNR) + die("Attempting to write read-only memory", regs, esr); + else + die("Attempting to read unreadable memory", regs, esr); } /* -- 2.10.0.297.gf6727b0