From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753678AbdBJUKi (ORCPT ); Fri, 10 Feb 2017 15:10:38 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:34033 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174AbdBJUKh (ORCPT ); Fri, 10 Feb 2017 15:10:37 -0500 Date: Fri, 10 Feb 2017 21:10:30 +0100 (CET) From: Thomas Gleixner To: Borislav Petkov cc: Dmitry Safonov , linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com, Ingo Molnar , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov , x86@kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions In-Reply-To: <20170209135525.qlwrmlo7njk3fsaq@pd.tnic> Message-ID: References: <20170130120432.6716-1-dsafonov@virtuozzo.com> <20170130120432.6716-2-dsafonov@virtuozzo.com> <20170209135525.qlwrmlo7njk3fsaq@pd.tnic> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Feb 2017, Borislav Petkov wrote: > I can't say that I'm thrilled about the ifdeffery this is adding. > > But I can't think of a cleaner approach at a quick glance, though - > that's generic and arch-specific code intertwined muck. Sad face. It's trivial enough to do .... Thanks, tglx --- arch/x86/mm/mmap.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size()) #define MAX_GAP (TASK_SIZE/6*5) +#ifndef CONFIG_COMPAT +# define mmap_rnd_compat_bits mmap_rnd_bits +#endif + static int mmap_is_legacy(void) { if (current->personality & ADDR_COMPAT_LAYOUT) @@ -66,20 +70,14 @@ static int mmap_is_legacy(void) return sysctl_legacy_va_layout; } -unsigned long arch_mmap_rnd(void) +static unsigned long arch_rnd(unsigned int rndbits) { - unsigned long rnd; - - if (mmap_is_ia32()) -#ifdef CONFIG_COMPAT - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); -#else - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); -#endif - else - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); + return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT; +} - return rnd << PAGE_SHIFT; +unsigned long arch_mmap_rnd(void) +{ + return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits); } static unsigned long mmap_base(unsigned long rnd)