From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id 83BCB6B03B0 for ; Tue, 14 Feb 2017 13:40:25 -0500 (EST) Received: by mail-oi0-f72.google.com with SMTP id a194so203336348oib.5 for ; Tue, 14 Feb 2017 10:40:25 -0800 (PST) Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-db5eur01on0106.outbound.protection.outlook.com. [104.47.2.106]) by mx.google.com with ESMTPS id e196si3650532ita.89.2017.02.14.10.40.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 14 Feb 2017 10:40:24 -0800 (PST) From: Dmitry Safonov Subject: [PATCHv5 1/5] x86/mm: introduce arch_rnd() to compute 32/64 mmap rnd Date: Tue, 14 Feb 2017 21:36:17 +0300 Message-ID: <20170214183621.2537-2-dsafonov@virtuozzo.com> In-Reply-To: <20170214183621.2537-1-dsafonov@virtuozzo.com> References: <20170214183621.2537-1-dsafonov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: 0x7f454c46@gmail.com, Dmitry Safonov , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov , x86@kernel.org, linux-mm@kvack.org, Cyrill Gorcunov To fix 32-bit mmap() syscall returning pointer higher than 4Gb in 64-bit binaries, two mmap bases will be used: one for mapping with 32-bit syscalls and another for 64-bit syscall. To correctly place those two bases, introduce arch_rnd() function, which will return the random factor independently of mmap_is_ia32(). Suggested-by: Thomas Gleixner Signed-off-by: Dmitry Safonov --- arch/x86/mm/mmap.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index d2dc0438d654..9f3ac019e51c 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -54,6 +54,14 @@ static unsigned long stack_maxrandom_size(void) #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size()) #define MAX_GAP (TASK_SIZE/6*5) +#ifdef CONFIG_64BIT +# define mmap32_rnd_bits mmap_rnd_compat_bits +# define mmap64_rnd_bits mmap_rnd_bits +#else +# define mmap32_rnd_bits mmap_rnd_bits +# define mmap64_rnd_bits mmap_rnd_bits +#endif + static int mmap_is_legacy(void) { if (current->personality & ADDR_COMPAT_LAYOUT) @@ -65,20 +73,14 @@ 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() ? mmap32_rnd_bits : mmap64_rnd_bits); } static unsigned long mmap_base(unsigned long rnd) -- 2.11.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org