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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id y20-20020aa78f34000000b005617c676344sm2649775pfr.89.2022.10.03.21.54.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 21:54:27 -0700 (PDT) Date: Mon, 3 Oct 2022 21:54:26 -0700 From: Kees Cook To: Dave Hansen , "Gustavo A. R. Silva" , Nathan Chancellor , Nick Desaulniers Cc: Rick Edgecombe , x86@kernel.org, "H . 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 , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , 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, Tom Lendacky , "Moger, Babu" Subject: Re: [PATCH v2 33/39] x86/cpufeatures: Limit shadow stack to Intel CPUs Message-ID: <202210032147.ED1310CEA8@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-34-rick.p.edgecombe@intel.com> <202210031656.23FAA3195@keescook> <559f937f-cab4-d408-6d95-fc85b4809aa9@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <559f937f-cab4-d408-6d95-fc85b4809aa9@intel.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664859269; 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=0foMv+yNCzUvsFibuuhT0xJMSn3BsckwqQnYwsSpG6c=; b=ERSa0C3BX6F4zAE3QCmlCcYJfsCvnXYZm81WIC5arZeo9oy+c73cbakaqMz3myr9nWH2As 1JxgkbHXeNxuo05B1uTvtRIpOJrjnyr1Beni9Z5kOyR2cuo78kgywRV+baLSYgRonBckbH WASJyB3TvO0sfkVyJO9FMes9CyjP07I= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=kP2DU18O; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf05.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.44 as permitted sender) smtp.mailfrom=keescook@chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664859269; a=rsa-sha256; cv=none; b=ufBWh+f3ywu1lR1pvTJZ9AJSpHhziS2oxtSnIuCeFzYK/vmUTzNqI7ZLq2Fmrbtis59YET q3h9SMUUb55W/qTKn3kd64s/jvBlqDLF3b2bWubxCo7vQPcpL+LJLPSYk8qBGj42k34yHg +whjX/2QSvI9yN1hBQ0KkW9+rI3/ocY= X-Rspam-User: X-Stat-Signature: 4e83xdmui7hpui58egud68cnpxnhpt3c X-Rspamd-Queue-Id: A1324100011 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=kP2DU18O; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf05.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.44 as permitted sender) smtp.mailfrom=keescook@chromium.org X-Rspamd-Server: rspam01 X-HE-Tag: 1664859269-601289 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: On Mon, Oct 03, 2022 at 05:09:04PM -0700, Dave Hansen wrote: > On 10/3/22 16:57, Kees Cook wrote: > > On Thu, Sep 29, 2022 at 03:29:30PM -0700, Rick Edgecombe wrote: > >> Shadow stack is supported on newer AMD processors, but the kernel > >> implementation has not been tested on them. Prevent basic issues from > >> showing up for normal users by disabling shadow stack on all CPUs except > >> Intel until it has been tested. At which point the limitation should be > >> removed. > >> > >> Signed-off-by: Rick Edgecombe > > So running the selftests on an AMD system is sufficient to drop this > > patch? > > Yes, that's enough. > > I _thought_ the AMD folks provided some tested-by's at some point in the > past. But, maybe I'm confusing this for one of the other shared > features. Either way, I'm sure no tested-by's were dropped on purpose. > > I'm sure Rick is eager to trim down his series and this would be a great > patch to drop. Does anyone want to make that easy for Rick? > > Hey Gustavo, Nathan, or Nick! I know y'all have some fancy AMD testing rigs. Got a moment to spin up this series and run the selftests? :) -- Kees Cook