Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752035AbdHDCBm (ORCPT ); Thu, 3 Aug 2017 22:01:42 -0400 Received: from [183.91.158.132] ([183.91.158.132]:53976 "EHLO heian.cn.fujitsu.com" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751845AbdHDCBl (ORCPT ); Thu, 3 Aug 2017 22:01:41 -0400 X-IronPort-AV: E=Sophos;i="5.41,318,1498492800"; d="scan'208";a="22198507" Date: Fri, 4 Aug 2017 10:01:31 +0800 From: Chao Fan To: Dou Liyang CC: Baoquan He , , , , , , , , , , , Subject: Re: [PATCH] x86/boot/KASLR: Extend movable_node option for KASLR Message-ID: <20170804020130.GA32462@localhost.localdomain> References: <1501762641-15634-1-git-send-email-douly.fnst@cn.fujitsu.com> <20170803122458.GA5913@localhost.localdomain> <20170803234901.GE1874@x1> <96b436e3-6d48-6a02-5cd4-f23c3a8de240@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <96b436e3-6d48-6a02-5cd4-f23c3a8de240@cn.fujitsu.com> User-Agent: Mutt/1.8.3 (2017-05-23) X-Originating-IP: [10.167.226.75] X-yoursite-MailScanner-ID: EF95E4724E45.AC465 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: fanc.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6276 Lines: 178 On Fri, Aug 04, 2017 at 09:37:14AM +0800, Dou Liyang wrote: >Hi Chao,Baoquan > >At 08/04/2017 07:49 AM, Baoquan He wrote: >> On 08/03/17 at 08:24pm, Chao Fan wrote: >> > It's almost another "mem=". >> > >No, it is different. > >See Documentation/kernel-parameters: > >"mem=" will force usage of a specific amount of memory and kernel will >not see the whole system memory. > >But "movable_node=" will not do that. > > >> Then why not using 'mem=' directly? >> > >Before answer this question, let's first discuss why the users want to >replace "mem=" with "movable_node" when they hope to support NUMA node >hot-plug. > >I guess the real reason is that: > >When booting up the system, We should have the whole memory not just >the un-hotpluggable memory which restrict by "mem=", eg: > >we boot up kernel with 4 node: > >node 0 size: 1024 MB immovable >node 1 size: 1024 MB movable >node 2 size: 1024 MB movable >node 3 size: 1024 MB movable > >If we use "mem=1024M" in the command line, we just can use 1G memory. >But actually, we should have 4G normally. > >Above is also one reason for why not using 'mem=' directly. Following >is other reasons: > Hi Dou, >1). each kernel option has its own role, we'd better misuse them. I guess you mean "we'd better not misuse them" >2). movable_node is used as a boot-time switch to make nodes movable >or not, it should consider any situations, such as KASLR. Yes, then in my understanding, as for this issue, you will leave both "movable_node" and "movable_node=nn[KMG]" in kernel option, right? If so, then what will happen when only "movable_node" specified without "movable_node=nn[KMG]"? If I misunderstand it, please let me know. Thanks, Chao Fan > > >Thanks, > dou. > >> > >> > On Thu, Aug 03, 2017 at 08:17:21PM +0800, Dou Liyang wrote: >> > > movable_node is a boot-time switch to make hot-pluggable memory >> > > NUMA nodes to be movable. This option is based on an assumption >> > > that any node which the kernel resides in is defined as >> > > un-hotpluggable. Linux can allocates memory near the kernel image >> > > to try the best to keep the kernel away from hotpluggable memory >> > > in the same NUMA node. So other nodes can be movable. >> > > >> > > But, KASLR doesn't know which node is un-hotpluggable, the all >> > > hotpluggable memory ranges is recorded in ACPI SRAT table, SRAT >> > > is not parsed. So, KASLR may randomize the kernel in a movable >> > > node which will be immovable. >> > > >> > > Extend movable_node option to restrict kernel to be randomized in >> > > immovable nodes by adding a parameter. this parameter sets up >> > > the boundaries between the movable nodes and immovable nodes. >> > > >> > > Reported-by: Chao Fan >> > > Signed-off-by: Dou Liyang >> > > --- >> > > Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++-- >> > > arch/x86/boot/compressed/kaslr.c | 19 ++++++++++++++++--- >> > > 2 files changed, 25 insertions(+), 5 deletions(-) >> > > >> > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> > > index d9c171c..44c7e33 100644 >> > > --- a/Documentation/admin-guide/kernel-parameters.txt >> > > +++ b/Documentation/admin-guide/kernel-parameters.txt >> > > @@ -2305,7 +2305,8 @@ >> > > mousedev.yres= [MOUSE] Vertical screen resolution, used for devices >> > > reporting absolute coordinates, such as tablets >> > > >> > > - movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter >> > > + movablecore=nn[KMG] >> > > + [KNL,X86,IA-64,PPC] This parameter >> > > is similar to kernelcore except it specifies the >> > > amount of memory used for migratable allocations. >> > > If both kernelcore and movablecore is specified, >> > > @@ -2315,12 +2316,18 @@ >> > > that the amount of memory usable for all allocations >> > > is not too small. >> > > >> > > - movable_node [KNL] Boot-time switch to make hotplugable memory >> > > + movable_node [KNL] Boot-time switch to make hot-pluggable memory >> > > NUMA nodes to be movable. This means that the memory >> > > of such nodes will be usable only for movable >> > > allocations which rules out almost all kernel >> > > allocations. Use with caution! >> > > >> > > + movable_node=nn[KMG] >> > > + [KNL] Extend movable_node to work well with KASLR. This >> > > + parameter is the boundaries between the movable nodes >> > > + and immovable nodes, the memory which exceeds it will >> > > + be regarded as hot-pluggable. >> > > + >> > > MTD_Partition= [MTD] >> > > Format: ,,, >> > > >> > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c >> > > index 91f27ab..7e2351b 100644 >> > > --- a/arch/x86/boot/compressed/kaslr.c >> > > +++ b/arch/x86/boot/compressed/kaslr.c >> > > @@ -89,7 +89,10 @@ struct mem_vector { >> > > static bool memmap_too_large; >> > > >> > > >> > > -/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ >> > > +/* >> > > + * Store memory limit specified by the following situations: >> > > + * "mem=nn[KMG]" or "memmap=nn[KMG]" or "movable_node=nn[KMG]" >> > > + */ >> > > unsigned long long mem_limit = ULLONG_MAX; >> > > >> > > >> > > @@ -212,7 +215,8 @@ static int handle_mem_memmap(void) >> > > char *param, *val; >> > > u64 mem_size; >> > > >> > > - if (!strstr(args, "memmap=") && !strstr(args, "mem=")) >> > > + if (!strstr(args, "memmap=") && !strstr(args, "mem=") && >> > > + !strstr(args, "movable_node=")) >> > > return 0; >> > > >> > > tmp_cmdline = malloc(len + 1); >> > > @@ -247,7 +251,16 @@ static int handle_mem_memmap(void) >> > > free(tmp_cmdline); >> > > return -EINVAL; >> > > } >> > > - mem_limit = mem_size; >> > > + mem_limit = mem_limit > mem_size ? mem_size : mem_limit; >> > > + } else if (!strcmp(param, "movable_node")) { >> > > + char *p = val; >> > > + >> > > + mem_size = memparse(p, &p); >> > > + if (mem_size == 0) { >> > > + free(tmp_cmdline); >> > > + return -EINVAL; >> > > + } >> > > + mem_limit = mem_limit > mem_size ? mem_size : mem_limit; >> > > } >> > > } >> > > >> > > -- >> > > 2.5.5 >> > > >> > >> > >> >> >>