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 Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EACEC433F5 for ; Wed, 2 Mar 2022 17:11:39 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B29EB40D26; Wed, 2 Mar 2022 12:11:38 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GlvegVM7t+Bv; Wed, 2 Mar 2022 12:11:37 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8632140C1B; Wed, 2 Mar 2022 12:11:37 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id EBAB340C1B for ; Wed, 2 Mar 2022 12:11:35 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id O+-4BZ+EL3CD for ; Wed, 2 Mar 2022 12:11:34 -0500 (EST) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id B580740B03 for ; Wed, 2 Mar 2022 12:11:34 -0500 (EST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F1BEAB82109; Wed, 2 Mar 2022 17:11:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE8DEC340ED; Wed, 2 Mar 2022 17:11:28 +0000 (UTC) Date: Wed, 2 Mar 2022 17:11:25 +0000 From: Catalin Marinas To: Mark Brown Subject: Re: [PATCH v12 22/40] arm64/sme: Implement ptrace support for streaming mode SVE registers Message-ID: References: <20220225165923.1474372-1-broonie@kernel.org> <20220225165923.1474372-23-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220225165923.1474372-23-broonie@kernel.org> Cc: Basant Kumar Dwivedi , Will Deacon , Luis Machado , Szabolcs Nagy , Marc Zyngier , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, Alan Hayward , Shuah Khan , kvmarm@lists.cs.columbia.edu, Salil Akerkar X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, Feb 25, 2022 at 04:59:05PM +0000, Mark Brown wrote: > The streaming mode SVE registers are represented using the same data > structures as for SVE but since the vector lengths supported and in use > may not be the same as SVE we represent them with a new type NT_ARM_SSVE. > Unfortunately we only have a single 16 bit reserved field available in > the header so there is no space to fit the current and maximum vector > length for both standard and streaming SVE mode without redefining the > structure in a way the creates a complicatd and fragile ABI. Since FFR > is not present in streaming mode it is read and written as zero. > > Setting NT_ARM_SSVE registers will put the task into streaming mode, > similarly setting NT_ARM_SVE registers will exit it. Reads that do not > correspond to the current mode of the task will return the header with > no register data. For compatibility reasons on write setting no flag for > the register type will be interpreted as setting SVE registers, though > users can provide no register data as an alternative mechanism for doing > so. > > Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm