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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 81AA4C10F11 for ; Wed, 24 Apr 2019 16:45:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56A29206A3 for ; Wed, 24 Apr 2019 16:45:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732785AbfDXQps (ORCPT ); Wed, 24 Apr 2019 12:45:48 -0400 Received: from foss.arm.com ([217.140.101.70]:48864 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726935AbfDXQpq (ORCPT ); Wed, 24 Apr 2019 12:45:46 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6EE3DEBD; Wed, 24 Apr 2019 09:45:45 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4CC813F706; Wed, 24 Apr 2019 09:45:41 -0700 (PDT) Date: Wed, 24 Apr 2019 17:45:38 +0100 From: Will Deacon To: Mathieu Desnoyers Cc: Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Thomas Gleixner , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H . Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , Steven Rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Michael Kerrisk , Joel Fernandes , Shuah Khan , linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH for 5.2 08/10] rseq/selftests: aarch64 code signature: handle big-endian environment Message-ID: <20190424164538.GC18611@fuggles.cambridge.arm.com> References: <20190424152502.14246-1-mathieu.desnoyers@efficios.com> <20190424152502.14246-9-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190424152502.14246-9-mathieu.desnoyers@efficios.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 24, 2019 at 11:25:00AM -0400, Mathieu Desnoyers wrote: > Handle compiling with -mbig-endian on aarch64, which generates binaries > with mixed code vs data endianness (little endian code, big endian > data). > > Else mismatch between code endianness for the generated signatures and > data endianness for the RSEQ_SIG parameter passed to the rseq > registration will trigger application segmentation faults when the > kernel try to abort rseq critical sections. > > Signed-off-by: Mathieu Desnoyers > CC: Peter Zijlstra > CC: Thomas Gleixner > CC: Joel Fernandes > CC: Catalin Marinas > CC: Dave Watson > CC: Will Deacon > CC: Shuah Khan > CC: Andi Kleen > CC: linux-kselftest@vger.kernel.org > CC: "H . Peter Anvin" > CC: Chris Lameter > CC: Russell King > CC: Michael Kerrisk > CC: "Paul E . McKenney" > CC: Paul Turner > CC: Boqun Feng > CC: Josh Triplett > CC: Steven Rostedt > CC: Ben Maurer > CC: linux-api@vger.kernel.org > CC: Andy Lutomirski > CC: Andrew Morton > CC: Linus Torvalds > --- > tools/testing/selftests/rseq/rseq-arm64.h | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/rseq/rseq-arm64.h b/tools/testing/selftests/rseq/rseq-arm64.h > index b41a2a48e965..200dae9e4208 100644 > --- a/tools/testing/selftests/rseq/rseq-arm64.h > +++ b/tools/testing/selftests/rseq/rseq-arm64.h > @@ -6,7 +6,20 @@ > * (C) Copyright 2018 - Will Deacon > */ > > -#define RSEQ_SIG 0xd428bc00 /* BRK #0x45E0 */ > +/* > + * aarch64 -mbig-endian generates mixed endianness code vs data: > + * little-endian code and big-endian data. Ensure the RSEQ_SIG signature > + * matches code endianness. > + */ > +#define RSEQ_SIG_CODE 0xd428bc00 /* BRK #0x45E0. */ > + > +#ifdef __AARCH64EB__ > +#define RSEQ_SIG_DATA 0x00bc28d4 /* BRK #0x45E0. */ It would be neater to implement swab32 and use that with RSEQ_SIG_CODE, but either way: Acked-by: Will Deacon Will