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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 1169BC0044D for ; Mon, 16 Mar 2020 11:22:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B366820719 for ; Mon, 16 Mar 2020 11:22:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="S5Dism4Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B366820719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=paNrQHmLJN1DLSDGKEqHK+bW/LYenZ4gU64PWQdQigo=; b=S5Dism4QJ8O1hb ogjCsnGI1ydzj2v4AjKpQS8/x16FpfjMFTWBEKhneHmB/Uk87UdZj7+DtOcp0fo7lRXhttxCiZC9J zG2um0126WE/S1jb3YC4LLH5vAbGzca79C6oPMpmyR6jEEmIDalXFxvi8Yus52kuyJxzGIhaZQoi/ 9Yo4haJSMn8UHyDW1vQ1W6b9OD0x1PGbmWePhStWVgEpWWSvw8L1Nqq6Rj9xG4TBxgPKXp7dYsI31 xFhezVufFZCq3R1QBeU6cNODl0z2SK7jUFyxFxVQ0aSATNWaEs/+G3EN9y6Hy03kHl7fIge5eNq+c 3wNGcv/c38giPzLS2GhA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDnp0-0003pP-UZ; Mon, 16 Mar 2020 11:22:14 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDnoy-0003ot-FD for linux-arm-kernel@lists.infradead.org; Mon, 16 Mar 2020 11:22:13 +0000 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 A8FC430E; Mon, 16 Mar 2020 04:22:11 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8238C3F52E; Mon, 16 Mar 2020 04:22:08 -0700 (PDT) Date: Mon, 16 Mar 2020 11:22:06 +0000 From: Catalin Marinas To: Vincenzo Frascino Subject: Re: [PATCH v3 18/26] arm64: Introduce asm/vdso/processor.h Message-ID: <20200316112205.GE3005@mbp> References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-19-vincenzo.frascino@arm.com> <20200315182950.GB32205@mbp> <20200316103437.GD3005@mbp> <77a2e91a-58f4-3ba3-9eef-42d6a8faf859@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <77a2e91a-58f4-3ba3-9eef-42d6a8faf859@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200316_042212_554469_15AC53E4 X-CRM114-Status: GOOD ( 18.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Dmitry Safonov <0x7f454c46@gmail.com>, linux-mips@vger.kernel.org, Will Deacon , linux-arch@vger.kernel.org, Marc Zyngier , x86@kernel.org, Russell King , clang-built-linux@googlegroups.com, Ingo Molnar , Kees Cook , Arnd Bergmann , Will Deacon , Borislav Petkov , Andy Lutomirski , Thomas Gleixner , Peter Collingbourne , linux-arm-kernel@lists.infradead.org, Andrei Vagin , Stephen Boyd , Nick Desaulniers , linux-kernel@vger.kernel.org, Mark Salyzyn , Paul Burton Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 16, 2020 at 10:55:00AM +0000, Vincenzo Frascino wrote: > On 3/16/20 10:34 AM, Catalin Marinas wrote: > >> I tried to fine grain the headers as much as I could in order to avoid > >> unneeded/unwanted inclusions: > >> * TASK_SIZE_32 is used to verify ABI consistency on vdso32 (please refer to > >> arch/arm64/kernel/vdso32/vgettimeofday.c). > > > > I see. But the test is probably useless. With 4K pages, TASK_SIZE_32 is > > 1UL << 32, so you can't have a u32 greater than this. So I'd argue that > > the ABI compatibility here doesn't matter. > > > > With 16K or 64K pages, TASK_SIZE_32 is slightly smaller but arm32 never > > supported it. > > > > What's the side-effect of dropping this check altogether? > > The main side-effect is that arm32 and arm64 compat have a different behavior, > that it is what we want to avoid. > > The vdsotest [1] I am using, verifies all the side conditions with respect to > the ABI, which we are now compatible with. Removing those checks would break > this condition. As I said above, I don't see how removing 'if ((u32)ts >= (1UL << 32))' makes any difference. This check was likely removed by the compiler already. Also, userspace doesn't have a trivial way to figure out TASK_SIZE and I can't see anything that tests this in the vdsotest (though I haven't spent that much time looking). If it's hard-coded, note that arm32 TASK_SIZE is different from TASK_SIZE_32 on arm64. Can you tell what actually is failing in vdsotest if you remove the TASK_SIZE_32 checks in the arm64 compat vdso? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel