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Lu" Date: Wed, 28 Apr 2021 07:56:38 -0700 Message-ID: Subject: Re: [PATCH v26 0/9] Control-flow Enforcement: Indirect Branch Tracking To: Andy Lutomirski Cc: David Laight , Yu-cheng Yu , "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 , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , 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 , Weijiang Yang , Pengfei Xu , Haitao Huang Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 7023A40002C4 X-Stat-Signature: 4awej6w3hfjdonbhn1xk3akpbdhfo8os X-Rspamd-Server: rspam02 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=mail-oi1-f178.google.com; client-ip=209.85.167.178 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619621805-80199 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 Wed, Apr 28, 2021 at 7:52 AM Andy Lutomirski wrote: > > On Wed, Apr 28, 2021 at 7:48 AM David Laight wrote: > > > > From: Yu-cheng Yu > > > Sent: 27 April 2021 21:47 > > > > > > Control-flow Enforcement (CET) is a new Intel processor feature that blocks > > > return/jump-oriented programming attacks. Details are in "Intel 64 and > > > IA-32 Architectures Software Developer's Manual" [1]. > > ... > > > > Does this feature require that 'binary blobs' for out of tree drivers > > be compiled by a version of gcc that adds the ENDBRA instructions? > > > > If enabled for userspace, what happens if an old .so is dynamically > > loaded? CET will be disabled by ld.so in this case. > > Or do all userspace programs and libraries have to have been compiled > > with the ENDBRA instructions? Correct. ld and ld.so check this. > If you believe that the userspace tooling for the legacy IBT table > actually works, then it should just work. Yu-cheng, etc: how well > tested is it? > Legacy IBT bitmap isn't unused since it doesn't cover legacy codes generated by legacy JITs. -- H.J.