From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Date: Fri, 08 Jul 2016 08:46:39 +0000 Subject: Re: [PATCH 0/9] mm: Hardened usercopy Message-Id: <20160708084639.GA4562@gmail.com> List-Id: References: <1467843928-29351-1-git-send-email-keescook@chromium.org> In-Reply-To: <1467843928-29351-1-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Kees Cook Cc: linux-kernel@vger.kernel.org, Rik van Riel , Casey Schaufler , PaX Team , Brad Spengler , Russell King , Catalin Marinas , Will Deacon , Ard Biesheuvel , Benjamin Herrenschmidt , Michael Ellerman , Tony Luck , Fenghua Yu , "David S. Miller" , x86@kernel.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Andy Lutomirski , Borislav Petkov , Mathias Krause , Jan Kara , Vitaly Wool , Andrea Arcangeli , Dmitry Vyukov , Laura Abbott , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, Linus Torvalds , Thomas Gleixner , "H. Peter Anvin" , Peter Zijlstra * Kees Cook wrote: > - I couldn't detect a measurable performance change with these features > enabled. Kernel build times were unchanged, hackbench was unchanged, > etc. I think we could flip this to "on by default" at some point. Could you please try to find some syscall workload that does many small user copies and thus excercises this code path aggressively? If that measurement works out fine then I'd prefer to enable these security checks by default. Thaks, Ingo