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[134.134.136.20]) by mx.google.com with ESMTPS id v32si3031193plg.3.2019.06.07.12.31.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jun 2019 12:31:50 -0700 (PDT) Received-SPF: pass (google.com: domain of yu-cheng.yu@intel.com designates 134.134.136.20 as permitted sender) client-ip=134.134.136.20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yu-cheng.yu@intel.com designates 134.134.136.20 as permitted sender) smtp.mailfrom=yu-cheng.yu@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Jun 2019 12:31:49 -0700 X-ExtLoop1: 1 Received: from yyu32-desk1.sc.intel.com ([143.183.136.147]) by orsmga005.jf.intel.com with ESMTP; 07 Jun 2019 12:31:48 -0700 Message-ID: <997ef050c13e3654dee6a862d810cffcafce249b.camel@intel.com> Subject: Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function From: Yu-cheng Yu To: Dave Hansen , 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 , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin Date: Fri, 07 Jun 2019 12:23:46 -0700 In-Reply-To: References: <20190606200926.4029-1-yu-cheng.yu@intel.com> <20190606200926.4029-4-yu-cheng.yu@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit 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 Fri, 2019-06-07 at 12:03 -0700, Dave Hansen wrote: > On 6/6/19 1:09 PM, Yu-cheng Yu wrote: > > + modify_fpu_regs_begin(); > > + rdmsrl(MSR_IA32_U_CET, r); > > + r |= (MSR_IA32_CET_LEG_IW_EN | bitmap); > > + wrmsrl(MSR_IA32_U_CET, r); > > + modify_fpu_regs_end(); > > Isn't there a bunch of other stuff in this MSR? It seems like the > bitmap value would allow overwriting lots of bits in the MSR that have > nothing to do with the bitmap... in a prctl() that's supposed to only be > dealing with the bitmap. Yes, the bitmap address should have been masked, although it is checked for page alignment (which has the same effect). I will fix it. Yu-cheng