From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3060BC10F0B for ; Thu, 18 Apr 2019 06:09:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 087F9205C9 for ; Thu, 18 Apr 2019 06:09:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725876AbfDRGJQ (ORCPT ); Thu, 18 Apr 2019 02:09:16 -0400 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:51853 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725773AbfDRGJQ (ORCPT ); Thu, 18 Apr 2019 02:09:16 -0400 X-Originating-IP: 79.86.19.127 Received: from [192.168.0.11] (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 0791E240008; Thu, 18 Apr 2019 06:09:08 +0000 (UTC) Subject: Re: [PATCH v3 11/11] riscv: Make mmap allocation top-down by default To: Kees Cook Cc: Andrew Morton , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Luis Chamberlain , LKML , linux-arm-kernel , linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, "linux-fsdevel@vger.kernel.org" , Linux-MM References: <20190417052247.17809-1-alex@ghiti.fr> <20190417052247.17809-12-alex@ghiti.fr> From: Alex Ghiti Message-ID: <23d2a38d-363a-929c-5296-c2f8c3b7d1b4@ghiti.fr> Date: Thu, 18 Apr 2019 02:09:08 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: sv-FI Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 4/18/19 1:31 AM, Kees Cook wrote: > On Wed, Apr 17, 2019 at 12:34 AM Alexandre Ghiti wrote: >> In order to avoid wasting user address space by using bottom-up mmap >> allocation scheme, prefer top-down scheme when possible. >> >> Before: >> root@qemuriscv64:~# cat /proc/self/maps >> 00010000-00016000 r-xp 00000000 fe:00 6389 /bin/cat.coreutils >> 00016000-00017000 r--p 00005000 fe:00 6389 /bin/cat.coreutils >> 00017000-00018000 rw-p 00006000 fe:00 6389 /bin/cat.coreutils >> 00018000-00039000 rw-p 00000000 00:00 0 [heap] >> 1555556000-155556d000 r-xp 00000000 fe:00 7193 /lib/ld-2.28.so >> 155556d000-155556e000 r--p 00016000 fe:00 7193 /lib/ld-2.28.so >> 155556e000-155556f000 rw-p 00017000 fe:00 7193 /lib/ld-2.28.so >> 155556f000-1555570000 rw-p 00000000 00:00 0 >> 1555570000-1555572000 r-xp 00000000 00:00 0 [vdso] >> 1555574000-1555576000 rw-p 00000000 00:00 0 >> 1555576000-1555674000 r-xp 00000000 fe:00 7187 /lib/libc-2.28.so >> 1555674000-1555678000 r--p 000fd000 fe:00 7187 /lib/libc-2.28.so >> 1555678000-155567a000 rw-p 00101000 fe:00 7187 /lib/libc-2.28.so >> 155567a000-15556a0000 rw-p 00000000 00:00 0 >> 3fffb90000-3fffbb1000 rw-p 00000000 00:00 0 [stack] >> >> After: >> root@qemuriscv64:~# cat /proc/self/maps >> 00010000-00016000 r-xp 00000000 fe:00 6389 /bin/cat.coreutils >> 00016000-00017000 r--p 00005000 fe:00 6389 /bin/cat.coreutils >> 00017000-00018000 rw-p 00006000 fe:00 6389 /bin/cat.coreutils >> 00018000-00039000 rw-p 00000000 00:00 0 [heap] >> 3ff7eb6000-3ff7ed8000 rw-p 00000000 00:00 0 >> 3ff7ed8000-3ff7fd6000 r-xp 00000000 fe:00 7187 /lib/libc-2.28.so >> 3ff7fd6000-3ff7fda000 r--p 000fd000 fe:00 7187 /lib/libc-2.28.so >> 3ff7fda000-3ff7fdc000 rw-p 00101000 fe:00 7187 /lib/libc-2.28.so >> 3ff7fdc000-3ff7fe2000 rw-p 00000000 00:00 0 >> 3ff7fe4000-3ff7fe6000 r-xp 00000000 00:00 0 [vdso] >> 3ff7fe6000-3ff7ffd000 r-xp 00000000 fe:00 7193 /lib/ld-2.28.so >> 3ff7ffd000-3ff7ffe000 r--p 00016000 fe:00 7193 /lib/ld-2.28.so >> 3ff7ffe000-3ff7fff000 rw-p 00017000 fe:00 7193 /lib/ld-2.28.so >> 3ff7fff000-3ff8000000 rw-p 00000000 00:00 0 >> 3fff888000-3fff8a9000 rw-p 00000000 00:00 0 [stack] >> >> Signed-off-by: Alexandre Ghiti >> Reviewed-by: Christoph Hellwig > Reviewed-by: Kees Cook Thank you very much for all your comments, Alex > > -Kees > >> --- >> arch/riscv/Kconfig | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >> index eb56c82d8aa1..f5897e0dbc1c 100644 >> --- a/arch/riscv/Kconfig >> +++ b/arch/riscv/Kconfig >> @@ -49,6 +49,17 @@ config RISCV >> select GENERIC_IRQ_MULTI_HANDLER >> select ARCH_HAS_PTE_SPECIAL >> select HAVE_EBPF_JIT if 64BIT >> + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU >> + select HAVE_ARCH_MMAP_RND_BITS >> + >> +config ARCH_MMAP_RND_BITS_MIN >> + default 18 >> + >> +# max bits determined by the following formula: >> +# VA_BITS - PAGE_SHIFT - 3 >> +config ARCH_MMAP_RND_BITS_MAX >> + default 33 if 64BIT # SV48 based >> + default 18 >> >> config MMU >> def_bool y >> -- >> 2.20.1 >> >