From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f175.google.com (mail-pf0-f175.google.com [209.85.192.175]) by kanga.kvack.org (Postfix) with ESMTP id 5033C6B0257 for ; Mon, 7 Dec 2015 05:26:26 -0500 (EST) Received: by pfdd184 with SMTP id d184so63026599pfd.3 for ; Mon, 07 Dec 2015 02:26:26 -0800 (PST) Received: from hqemgate15.nvidia.com (hqemgate15.nvidia.com. [216.228.121.64]) by mx.google.com with ESMTPS id eo16si8218719pab.209.2015.12.07.02.26.25 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 07 Dec 2015 02:26:25 -0800 (PST) Subject: Re: [PATCH v5 3/4] arm64: mm: support ARCH_MMAP_RND_BITS. References: <1449000658-11475-1-git-send-email-dcashman@android.com> <1449000658-11475-2-git-send-email-dcashman@android.com> <1449000658-11475-3-git-send-email-dcashman@android.com> <1449000658-11475-4-git-send-email-dcashman@android.com> From: Jon Hunter Message-ID: <56655EC8.6030905@nvidia.com> Date: Mon, 7 Dec 2015 10:26:16 +0000 MIME-Version: 1.0 In-Reply-To: <1449000658-11475-4-git-send-email-dcashman@android.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Cashman , linux-kernel@vger.kernel.org Cc: dcashman@google.com, linux-doc@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, linux-mm@kvack.org, hpa@zytor.com, mingo@kernel.org, aarcange@redhat.com, linux@arm.linux.org.uk, corbet@lwn.net, xypron.glpk@gmx.de, x86@kernel.org, hecmargi@upv.es, mgorman@suse.de, rientjes@google.com, bp@suse.de, nnk@google.com, dzickus@redhat.com, keescook@chromium.org, arnd@arndb.de, jpoimboe@redhat.com, tglx@linutronix.de, n-horiguchi@ah.jp.nec.com, linux-arm-kernel@lists.infradead.org, salyzyn@android.com, ebiederm@xmission.com, jeffv@google.com, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com On 01/12/15 20:10, Daniel Cashman wrote: > From: dcashman >=20 > arm64: arch_mmap_rnd() uses STACK_RND_MASK to generate the > random offset for the mmap base address. This value represents a > compromise between increased ASLR effectiveness and avoiding > address-space fragmentation. Replace it with a Kconfig option, which > is sensibly bounded, so that platform developers may choose where to > place this compromise. Keep default values as new minimums. >=20 > Signed-off-by: Daniel Cashman > --- > arch/arm64/Kconfig | 31 +++++++++++++++++++++++++++++++ > arch/arm64/mm/mmap.c | 8 ++++++-- > 2 files changed, 37 insertions(+), 2 deletions(-) [snip] > diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c > index ed17747..af461b9 100644 > --- a/arch/arm64/mm/mmap.c > +++ b/arch/arm64/mm/mmap.c > @@ -51,8 +51,12 @@ unsigned long arch_mmap_rnd(void) > { > unsigned long rnd; > =20 > - rnd =3D (unsigned long)get_random_int() & STACK_RND_MASK; > - > +ifdef CONFIG_COMPAT > + if (test_thread_flag(TIF_32BIT)) > + rnd =3D (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits); > + else > +#endif > + rnd =3D (unsigned long)get_random_int() % (1 << mmap_rnd_bits); > return rnd << PAGE_SHIFT; > } The above is causing a build failure on -next today. commit 42a6c8953112a9856dd09148c3d6a2cc106b6003 Author: Jon Hunter Date: Mon Dec 7 10:15:47 2015 +0000 ARM64: mm: Fix build failure caused by invalid ifdef statement =20 Commit 2e4614190421 ("arm64-mm-support-arch_mmap_rnd_bits-v4") caused t= he following build failure due to a missing "#". Fix this. =20 arch/arm64/mm/mmap.c: In function =91arch_mmap_rnd=92: arch/arm64/mm/mmap.c:54:1: error: =91ifdef=92 undeclared (first use in = this function) ifdef CONFIG_COMPAT ^ Signed-off-by: Jon Hunter diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index af461b935137..e59a75a308bc 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -51,7 +51,7 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; =20 -ifdef CONFIG_COMPAT +#ifdef CONFIG_COMPAT if (test_thread_flag(TIF_32BIT)) rnd =3D (unsigned long)get_random_int() % (1 << mmap_rnd_co= mpat_bits); else Cheers Jon -- 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