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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 C8EA9C31E46 for ; Wed, 12 Jun 2019 17:31:00 +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 96D8B208CA for ; Wed, 12 Jun 2019 17:31:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="CSifTBTi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96D8B208CA 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=Azb+dgQyMvzM59OOF2wxfT3SQYhdzd2I/FeqoMuAYHs=; b=CSifTBTimrCFDW BCZZK8Ib0eNJ5MDb6cmL/4GsjaMTSSrMjpyqB0+YTG7X0XFvtDcvgLJmKLguOOfVGxQFScqc/zsqp ZMcoxOFcm79zPF7T+ZLI0ygp/u9zLpM+m5unwyY0rSbFQNT7CfuO2DvIjlSWSykC++2+fP8Ef52+h UgLx5V20LCaq2OwaGk3rR2sBQMRomPNeIM3PbxcGA7af9bkkyc56bx9+KTcGRwbL+GeTn3uNN+Rh8 eJkaPceNAbWQlrO0iItCSkn7lxz5PUAKQKR+L9QEGbUtgC6zzHG1MaLA7Liiyy++Ah1t2mNaCZSjQ DjnQRpI0vHpBXqrRhEpg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hb75I-00023P-K6; Wed, 12 Jun 2019 17:30:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hb73W-0007Qr-Ib for linux-arm-kernel@lists.infradead.org; Wed, 12 Jun 2019 17:29:04 +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 7801428; Wed, 12 Jun 2019 10:29:00 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3E5FA3F246; Wed, 12 Jun 2019 10:28:59 -0700 (PDT) Date: Wed, 12 Jun 2019 18:28:53 +0100 From: Will Deacon To: Dave Martin Subject: Re: [PATCH v2 1/3] arm64/sve: Fix missing SVE/FPSIMD endianness conversions Message-ID: <20190612172853.GA27039@fuggles.cambridge.arm.com> References: <1560355234-25516-1-git-send-email-Dave.Martin@arm.com> <1560355234-25516-2-git-send-email-Dave.Martin@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1560355234-25516-2-git-send-email-Dave.Martin@arm.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190612_102902_755373_35901096 X-CRM114-Status: GOOD ( 14.07 ) 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: Peter Maydell , gdb@sourceware.org, Alan Hayward , Zhang Lei , Julien Grall , Catalin Marinas , Alex =?iso-8859-1?Q?Benn=E9e?= , linux-arm-kernel@lists.infradead.org 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 Wed, Jun 12, 2019 at 05:00:32PM +0100, Dave Martin wrote: > The in-memory representation of SVE and FPSIMD registers is > different: the FPSIMD V-registers are stored as single 128-bit > host-endian values, whereas SVE registers are stored in an > endianness-invariant byte order. > > This means that the two representations differ when running on a > big-endian host. But we blindly copy data from one representation > to another when converting between the two, resulting in the > register contents being unintentionally byteswapped in certain > situations. Currently this can be triggered by the first SVE > instruction after a syscall, for example (though the potential > trigger points may vary in future). > > So, fix the conversion functions fpsimd_to_sve(), sve_to_fpsimd() > and sve_sync_from_fpsimd_zeropad() to swab where appropriate. > > There is no common swahl128() or swab128() that we could use here. > Maybe it would be worth making this generic, but for now add a > simple local hack. > > Since the byte order differences are exposed in ABI, also clarify > the docuentation. > > Fixes: bc0ee4760364 ("arm64/sve: Core task context handling") > Fixes: 8cd969d28fd2 ("arm64/sve: Signal handling support") > Fixes: 43d4da2c45b2 ("arm64/sve: ptrace and ELF coredump support") > Signed-off-by: Dave Martin Thanks, Dave. I've picked this one up and pushed it out to our fixes branch for 5.2. I assume Catalin will take the other two for 5.3. It's probably worth proposing some generic 128-bit swab functions too, in case there's any interest (in which case we could drop our local implementation later on). Cheers, Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel