From patchwork Sun Feb 22 11:50:01 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Blanchard X-Patchwork-Id: 23530 X-Patchwork-Delegate: benh@kernel.crashing.org Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 347B35F468 for ; Sun, 22 Feb 2009 23:06:14 +1100 (EST) X-Original-To: linuxppc-dev@ozlabs.org Delivered-To: linuxppc-dev@ozlabs.org Received: by ozlabs.org (Postfix, from userid 1010) id 66194DDDA5; Sun, 22 Feb 2009 23:01:37 +1100 (EST) Resent-From: anton@kryten Resent-Date: Sun, 22 Feb 2009 22:58:55 +1100 Resent-Message-ID: <20090222115855.GE12006@kryten> Resent-To: linuxppc-dev@ozlabs.org Message-Id: <20090222115332.173898755@samba.org> References: <20090222114957.213647384@samba.org> User-Agent: quilt/0.46-1 Date: Sun, 22 Feb 2009 22:50:01 +1100 From: Anton Blanchard To: linuxppc-dev@ozlabs.org Subject: [patch 04/10] powerpc: Randomise mmap start address Content-Disposition: inline; filename=randomise_mmap.patch X-BeenThere: linuxppc-dev@ozlabs.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org Randomise mmap start address - 8MB on 32bit and 1GB on 64bit tasks. Until ppc32 uses the mmap.c functionality, this is ppc64 specific. Before: # ./test & cat /proc/${!}/maps|tail -2|head -1 f75fe000-f7fff000 rw-p f75fe000 00:00 0 f75fe000-f7fff000 rw-p f75fe000 00:00 0 f75fe000-f7fff000 rw-p f75fe000 00:00 0 f75fe000-f7fff000 rw-p f75fe000 00:00 0 f75fe000-f7fff000 rw-p f75fe000 00:00 0 After: # ./test & cat /proc/${!}/maps|tail -2|head -1 f718b000-f7b8c000 rw-p f718b000 00:00 0 f7551000-f7f52000 rw-p f7551000 00:00 0 f6ee7000-f78e8000 rw-p f6ee7000 00:00 0 f74d4000-f7ed5000 rw-p f74d4000 00:00 0 f6e9d000-f789e000 rw-p f6e9d000 00:00 0 Similar for 64bit, but with 1GB of scatter: # ./test & cat /proc/${!}/maps|tail -2|head -1 fffb97b5000-fffb97b6000 rw-p fffb97b5000 00:00 0 fffce9a3000-fffce9a4000 rw-p fffce9a3000 00:00 0 fffeaaf2000-fffeaaf3000 rw-p fffeaaf2000 00:00 0 fffd88ac000-fffd88ad000 rw-p fffd88ac000 00:00 0 fffbc62e000-fffbc62f000 rw-p fffbc62e000 00:00 0 Signed-off-by: Anton Blanchard Index: linux-2.6/arch/powerpc/mm/mmap.c =================================================================== --- linux-2.6.orig/arch/powerpc/mm/mmap.c 2009-02-20 13:46:35.000000000 +1100 +++ linux-2.6/arch/powerpc/mm/mmap.c 2009-02-20 13:47:23.000000000 +1100 @@ -24,6 +24,7 @@ #include #include +#include #include /* @@ -45,6 +46,20 @@ return sysctl_legacy_va_layout; } +static unsigned long mmap_rnd(void) +{ + unsigned long rnd = 0; + + if (current->flags & PF_RANDOMIZE) { + /* 8MB for 32bit, 1GB for 64bit */ + if (is_32bit_task()) + rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT))); + else + rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT))); + } + return rnd << PAGE_SHIFT; +} + static inline unsigned long mmap_base(void) { unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur; @@ -54,7 +69,7 @@ else if (gap > MAX_GAP) gap = MAX_GAP; - return TASK_SIZE - (gap & PAGE_MASK); + return PAGE_ALIGN(TASK_SIZE - gap - mmap_rnd()); } /*