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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 78BD2C74A21 for ; Wed, 10 Jul 2019 13:43:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 573DE20651 for ; Wed, 10 Jul 2019 13:43:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727566AbfGJNm7 (ORCPT ); Wed, 10 Jul 2019 09:42:59 -0400 Received: from foss.arm.com ([217.140.110.172]:33560 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726080AbfGJNm6 (ORCPT ); Wed, 10 Jul 2019 09:42:58 -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 DB6732B; Wed, 10 Jul 2019 06:42:57 -0700 (PDT) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 152993F71F; Wed, 10 Jul 2019 06:42:54 -0700 (PDT) Subject: Re: [PATCH] arm64: vdso: Fix ABI regression in compat vdso To: Will Deacon Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-kselftest@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, arnd@arndb.de, linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com, daniel.lezcano@linaro.org, tglx@linutronix.de, salyzyn@android.com, pcc@google.com, shuah@kernel.org, 0x7f454c46@gmail.com, linux@rasmusvillemoes.dk, huw@codeweavers.com, sthotton@marvell.com, andre.przywara@arm.com, luto@kernel.org, john.stultz@linaro.org References: <20190621095252.32307-11-vincenzo.frascino@arm.com> <20190710130452.44111-1-vincenzo.frascino@arm.com> <20190710132532.r27yryvt25ex76xk@willie-the-truck> From: Vincenzo Frascino Message-ID: <4ea8fd8a-c50d-0cb7-af56-5bb90b0e50f8@arm.com> Date: Wed, 10 Jul 2019 14:42:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190710132532.r27yryvt25ex76xk@willie-the-truck> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2019 14:25, Will Deacon wrote: > On Wed, Jul 10, 2019 at 02:04:52PM +0100, Vincenzo Frascino wrote: >> Prior to the introduction of Unified vDSO support and compat layer for >> vDSO on arm64, AT_SYSINFO_EHDR was not defined for compat tasks. >> In the current implementation, AT_SYSINFO_EHDR is defined even if the >> compat vdso layer is not built and this causes a regression in the >> expected behavior of the ABI. >> >> Restore the ABI behavior making sure that AT_SYSINFO_EHDR for compat >> tasks is defined only when CONFIG_GENERIC_COMPAT_VDSO and >> CONFIG_COMPAT_VDSO are enabled. > > I think you could do a better job in the changelog of explaining what's > actually going on here. The problem seems to be that you're advertising > the presence of a non-existent vDSO to userspace. > >> Reported-by: John Stultz >> Signed-off-by: Vincenzo Frascino >> --- >> arch/arm64/include/asm/elf.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h >> index 3c7037c6ba9b..b7992bb9d414 100644 >> --- a/arch/arm64/include/asm/elf.h >> +++ b/arch/arm64/include/asm/elf.h >> @@ -202,7 +202,7 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG]; >> ({ \ >> set_thread_flag(TIF_32BIT); \ >> }) >> -#ifdef CONFIG_GENERIC_COMPAT_VDSO >> +#if defined(CONFIG_COMPAT_VDSO) && defined(CONFIG_GENERIC_COMPAT_VDSO) > > Can't this just be #ifdef CONFIG_COMPAT_VDSO ? > Yes, I realized it after I pushed the patch that CONFIG_GENERIC_COMPAT_VDSO can be removed. Posting v2 shortly. > John -- can you give this a whirl, please? > > Cheers, > > Will > -- Regards, Vincenzo