From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id B26AC6B038E for ; Mon, 6 Mar 2017 09:21:23 -0500 (EST) Received: by mail-io0-f199.google.com with SMTP id 20so25712310iod.2 for ; Mon, 06 Mar 2017 06:21:23 -0800 (PST) Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-db5eur01on0131.outbound.protection.outlook.com. [104.47.2.131]) by mx.google.com with ESMTPS id 70si8500204ioo.245.2017.03.06.06.21.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 06 Mar 2017 06:21:22 -0800 (PST) From: Dmitry Safonov Subject: [PATCHv6 1/5] x86/mm: introduce arch_rnd() to compute 32/64 mmap rnd Date: Mon, 6 Mar 2017 17:17:17 +0300 Message-ID: <20170306141721.9188-2-dsafonov@virtuozzo.com> In-Reply-To: <20170306141721.9188-1-dsafonov@virtuozzo.com> References: <20170306141721.9188-1-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 , "Kirill A. Shutemov" 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 7940166c799b..f31ed7097d0b 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -55,6 +55,14 @@ 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_COMPAT +# 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) @@ -66,20 +74,14 @@ 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