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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 14A73C4332B for ; Sat, 21 Mar 2020 12:06:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E26AD20724 for ; Sat, 21 Mar 2020 12:06:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727192AbgCUMGn (ORCPT ); Sat, 21 Mar 2020 08:06:43 -0400 Received: from foss.arm.com ([217.140.110.172]:34740 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726192AbgCUMGm (ORCPT ); Sat, 21 Mar 2020 08:06:42 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 134EC31B; Sat, 21 Mar 2020 05:06:42 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 026A33F52E; Sat, 21 Mar 2020 05:06:38 -0700 (PDT) Date: Sat, 21 Mar 2020 12:06:36 +0000 From: Catalin Marinas To: Stephen Boyd Cc: Vincenzo Frascino , clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, x86@kernel.org, Will Deacon , Arnd Bergmann , Russell King , Paul Burton , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Mark Salyzyn , Kees Cook , Peter Collingbourne , Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Nick Desaulniers , Marc Zyngier , Mark Rutland Subject: Re: [PATCH v5 18/26] arm64: vdso32: Code clean up Message-ID: <20200321120635.GA3052@mbp> References: <20200320145351.32292-1-vincenzo.frascino@arm.com> <20200320145351.32292-19-vincenzo.frascino@arm.com> <158474646622.125146.3263940499372231797@swboyd.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <158474646622.125146.3263940499372231797@swboyd.mtv.corp.google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 20, 2020 at 04:21:06PM -0700, Stephen Boyd wrote: > Quoting Vincenzo Frascino (2020-03-20 07:53:43) > > The compat vdso library had some checks that are not anymore relevant. > > Can we get the information on why they aren't relevant anymore in the > commit text? I'd rather not find this commit three years from now and > have no idea why it was applied. Good point. But I'd rather say that the original reason for adding them was bogus (ABI compatibility between arm64 compat and arm32, when arm32 vdso never got them). There may be some (very hard to justify) reason to add them if we want compatibility between vdso and syscall fallback on addresses greater than TASK_SIZE. The vdso code generates a SIGSEGV or SIGBUS while the syscall returns -EFAULT. However, you'd have similar mismatch on unmapped addresses below TASK_SIZE which cannot be handled by the vdso (not a simple comparison). I think the vdsotest code should be adjusted accordingly. -- Catalin