Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752518AbbKYTHS (ORCPT ); Wed, 25 Nov 2015 14:07:18 -0500 Received: from mail-pa0-f41.google.com ([209.85.220.41]:34128 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751888AbbKYTHM (ORCPT ); Wed, 25 Nov 2015 14:07:12 -0500 Subject: Re: [PATCH v3 0/4] Allow customizable random offset to mmap_base address. To: Andrew Morton References: <1447888808-31571-1-git-send-email-dcashman@android.com> <20151124163907.1a406b79458b1bb0d3519684@linux-foundation.org> Cc: linux-kernel@vger.kernel.org, linux@arm.linux.org.uk, keescook@chromium.org, mingo@kernel.org, linux-arm-kernel@lists.infradead.org, corbet@lwn.net, dzickus@redhat.com, ebiederm@xmission.com, xypron.glpk@gmx.de, jpoimboe@redhat.com, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, mgorman@suse.de, tglx@linutronix.de, rientjes@google.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, salyzyn@android.com, jeffv@google.com, nnk@google.com, catalin.marinas@arm.com, will.deacon@arm.com, hpa@zytor.com, x86@kernel.org, hecmargi@upv.es, bp@suse.de, dcashman@google.com, Ralf Baechle , Benjamin Herrenschmidt , Heiko Carstens , Martin Schwidefsky From: Daniel Cashman Message-ID: <565606DD.2090502@android.com> Date: Wed, 25 Nov 2015 11:07:09 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151124163907.1a406b79458b1bb0d3519684@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1306 Lines: 28 On 11/24/2015 04:39 PM, Andrew Morton wrote: > mips, powerpc and s390 also implement arch_mmap_rnd(). Are there any > special considerations here, or it just a matter of maintainers wiring > it up and testing it? I had not yet looked at those at all, as I had no way to do even a rudimentary "does it boot" test and opted to post v3 first. Upon first glance, it should just be a matter of wiring it up: Mips is divided into 12/16 bits for 32/64 bit (assume baseline 4k page) w/COMPAT kconfig, powerpc is 11/18 w/COMPAT, s390 is 11/11 w/COMPAT. s390 is a bit strange as COMPAT is for a 31-bit address space, although is_32bit_task() is used to determine which mask to use, and the mask itself for 64-bit only introduces 11 bits of entropy, but while still affecting larger chunks of the address space (mask is 0x3ff80, resulting in an effective 0x7ff shift of PAGE_SIZE + 7 bits). I could go ahead and add these to patchset v4 and as with the previous architectures, rely on feedback from arch-specific maintainers to help tune and test the values. -Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/