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Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com Subject: Re: [PATCH v2 23/39] x86: Introduce userspace API for CET enabling References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-24-rick.p.edgecombe@intel.com> Date: Mon, 10 Oct 2022 12:56:22 +0200 In-Reply-To: <20220929222936.14584-24-rick.p.edgecombe@intel.com> (Rick Edgecombe's message of "Thu, 29 Sep 2022 15:29:20 -0700") Message-ID: <87v8os0wx5.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665399399; a=rsa-sha256; cv=none; b=LEIow2WW8Dmy6oqta+VyY517IfGOw1lorYwDJX+XYsEqNm0h7XYO4Bzde+LFJ0TMKRxfN0 Nz7qoIMtfKDFZAAi/lBc7rp2in9VJI9HsoO/Wf4v60EVbohfOIp9JmAQL93b8rMg8zBWl5 6Ev/5pCYlT/Vfzk3UMEB3ptlzq+e8sk= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=J1c5DtGn; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf04.hostedemail.com: domain of fweimer@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=fweimer@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665399399; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uZluJ2tPl3X9nnw7yPiBnqn8JoOI7ryP6/Lgd98YHyQ=; b=uQeyIXNvHLfB/QC+6CxhW8JpJoLgBOrzTOnZIbtNCtTKOfCGqKsl6JBYT16DwfS+iOo4dW Sed73sHzpyo1WMDyxHlZnK3fCpMGNUixrJGTG1agS/TV/3xCQf+eaDdn94odSyefxyQKA6 YiFosIo/4d18pEdwcfRD8wtTga0EmJI= X-Rspam-User: X-Stat-Signature: 9jh9p7zo6r5kghipzrdkfpd9378benp7 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: E045B4001D Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=J1c5DtGn; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf04.hostedemail.com: domain of fweimer@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=fweimer@redhat.com X-HE-Tag: 1665399397-926853 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: * Rick Edgecombe: > + /* Only support enabling/disabling one feature at a time. */ > + if (hweight_long(features) > 1) > + return -EINVAL; This means we'll soon need three extra system calls for x86-64 process start: SHSTK, IBT, and switching off vsyscall emulation. (The latter does not need any special CPU support.) Maybe we can do something else instead to make the strace output a little bit cleaner? Thanks, Florian