Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752305AbdLGE6V (ORCPT ); Wed, 6 Dec 2017 23:58:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54928 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752132AbdLGE6U (ORCPT ); Wed, 6 Dec 2017 23:58:20 -0500 Date: Thu, 7 Dec 2017 12:58:06 +0800 From: Baoquan He To: Dou Liyang Cc: Chao Fan , linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, keescook@chromium.org, yasu.isimatu@gmail.com, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com Subject: Re: [PATCH v3 1/4] kaslr: add immovable_mem=nn[KMG]@ss[KMG] to specify extracting memory Message-ID: <20171207045806.GQ15074@x1> References: <20171205085200.9528-1-fanc.fnst@cn.fujitsu.com> <20171205085200.9528-2-fanc.fnst@cn.fujitsu.com> <20171206093557.GL15074@x1> <20171207025356.GD28884@localhost.localdomain> <20171207030924.GO15074@x1> <20171207035621.GE28884@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.0 (2016-08-17) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 07 Dec 2017 04:58:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9094 Lines: 239 On 12/07/17 at 12:16pm, Dou Liyang wrote: > Hi All, > > At 12/07/2017 11:56 AM, Chao Fan wrote: > > On Thu, Dec 07, 2017 at 11:09:24AM +0800, Baoquan He wrote: > > > On 12/07/17 at 10:53am, Chao Fan wrote: > > > > On Wed, Dec 06, 2017 at 05:35:57PM +0800, Baoquan He wrote: > > > > > Hi Chao, > > > > > > > > > > Yes, now the code looks much better than the last version. > > > > > > > > > > On 12/05/17 at 04:51pm, Chao Fan wrote: > > > > > > In current code, kaslr may choose the memory region in movable > > > > > > nodes to extract kernel, which will make the nodes can't be hot-removed. > > > > > > To solve it, we can specify the memory region in immovable node. > > > > > > Create immovable_mem to store the regions in immovable_mem, where should > > > > > > be chosen by kaslr. > > > > > > > > > > > > Multiple regions can be specified, comma delimited. > > > > > > Considering the usage of memory, only support for 4 regions. > > > > > > 4 regions contains 2 nodes at least, enough for kernel to extract. > > > > > > > > > > > > Also change the "handle_mem_memmap" to "handle_mem_filter", since > > > > > > it will not only handle memmap parameter now. > > > > > > > > > > One concern is whether it will fail to do KASLR if only specify > > > > > > > > Sorry, I think I have not understood your point. > > > > So if there is something wrong, please let me know. > > > > > > What I meant is whether we need check 'movable_node' and > > > 'immovable_mem=' being specified together. If only specify 'movable_node', > > > we may need to return and do not do kaslr or do not do physical kaslr > > > since kernel could be located on movable mem region. > > > Indeed. > > If *immovable_mem* is valid only when Kernel supports both > KASLR and Node hotplug(movable_node). we need check them together: > > ... > else if (!strcmp(param, "movable_node")) { > if (!strcmp(param, "immovable_mem")) > parse_immovable_mem_regions(val); > else > //no KASLR or no node hotplug? > > } Yes, I meant this. We can skip kernel physical address randomization, the virtual address can still be randomized. > ... > > > I think both are OK and have reasons, and I tend to not return. > > Because if there is a parameter can solve the problem, but not specified. > > It's a problem of user-level. > > How do you think? > > > > Seems we should clarify the scope of 'immovable_mem=' and document it. > > Thanks, > dou > > > Thanks, > > Chao Fan > > > > > > > > Otherwise it will do physical kaslr anyway, memory hotplug will be > > > impacted later. > > > > > > > > > > > I don't think if only specify "movable_node" will fail KASLR. > > > > Since in this patchset(3/4), only disable kernel mirror. KASLR in > > > > current upstream code didn't parse "movable_node". > > > > > > > > > "movable_node". Surely in this case it won't fail system, just hotplug > > > > > memory might be impacted if kernel is located on that, will FJ mind > > > > > > > > Yes, it's the reason why I make this patchset. > > > > In my personal understanding, "movable_node" is a beginning why I make > > > > this patchset, but not the whole reason. > > > > Only "movable_node" specified might cause hotplug memory can't be > > > > removed if kernel is located on that, so we need the help of > > > > "immovable_mem=". "movable_node" help hotplug memory can be removed, and > > > > "immovable_mem=" works for the same target, but just in kaslr. > > > > So up to now, there is not a very tight coupling between "movable_node" > > > > and "immovable_mem=". The independence of "immovable_mem=" is that, > > > > help kaslr selects the right regions, avoid the memory in hotpluggable > > > > NUMA nodes, which causes the memory can't removed. It's a independent > > > > reason why we need a parameter like "immovable_mem=". > > > > So I think we should also handle it if only specify "immovable_mem=" > > > > without "movable_node". > > > > > > > > Thanks, > > > > Chao Fan > > > > > > > > > this? And what if only specify 'immovable_mem=' but without 'movable_node'? > > > > > > > > > > Thanks > > > > > Baoquan > > > > > > > > > > > > > > > > > Signed-off-by: Chao Fan > > > > > > --- > > > > > > arch/x86/boot/compressed/kaslr.c | 80 ++++++++++++++++++++++++++++++++++++++-- > > > > > > 1 file changed, 77 insertions(+), 3 deletions(-) > > > > > > > > > > > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c > > > > > > index a63fbc25ce84..0bbbaf5f6370 100644 > > > > > > --- a/arch/x86/boot/compressed/kaslr.c > > > > > > +++ b/arch/x86/boot/compressed/kaslr.c > > > > > > @@ -108,6 +108,15 @@ enum mem_avoid_index { > > > > > > static struct mem_vector mem_avoid[MEM_AVOID_MAX]; > > > > > > +/* Only supporting at most 4 immovable memory regions with kaslr */ > > > > > > +#define MAX_IMMOVABLE_MEM 4 > > > > > > + > > > > > > +/* Store the memory regions in immovable node */ > > > > > > +static struct mem_vector immovable_mem[MAX_IMMOVABLE_MEM]; > > > > > > + > > > > > > +/* The immovable regions user specify, not more than 4 */ > > > > > > +static int num_immovable_region; > > > > > > + > > > > > > static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two) > > > > > > { > > > > > > /* Item one is entirely before item two. */ > > > > > > @@ -168,6 +177,38 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size) > > > > > > return -EINVAL; > > > > > > } > > > > > > +static int parse_immovable_mem(char *p, > > > > > > + unsigned long long *start, > > > > > > + unsigned long long *size) > > > > > > +{ > > > > > > + char *oldp; > > > > > > + > > > > > > + if (!p) > > > > > > + return -EINVAL; > > > > > > + > > > > > > + oldp = p; > > > > > > + *size = memparse(p, &p); > > > > > > + if (p == oldp) > > > > > > + return -EINVAL; > > > > > > + > > > > > > + /* We support nn[KMG]@ss[KMG] and nn[KMG]. */ > > > > > > + switch (*p) { > > > > > > + case '@': > > > > > > + *start = memparse(p + 1, &p); > > > > > > + return 0; > > > > > > + default: > > > > > > + /* > > > > > > + * If w/o offset, only size specified, immovable_mem=nn[KMG] > > > > > > + * has the same behaviour as immovable_mem=nn[KMG]@0. It means > > > > > > + * the region starts from 0. > > > > > > + */ > > > > > > + *start = 0; > > > > > > + return 0; > > > > > > + } > > > > > > + > > > > > > + return -EINVAL; > > > > > > +} > > > > > > + > > > > > > static void mem_avoid_memmap(char *str) > > > > > > { > > > > > > static int i; > > > > > > @@ -207,7 +248,37 @@ static void mem_avoid_memmap(char *str) > > > > > > memmap_too_large = true; > > > > > > } > > > > > > -static int handle_mem_memmap(void) > > > > > > +#ifdef CONFIG_MEMORY_HOTPLUG > > > > > > +static void parse_immovable_mem_regions(char *str) > > > > > > +{ > > > > > > + static int i; > > > > > > + > > > > > > + while (str && (i < MAX_IMMOVABLE_MEM)) { > > > > > > + int rc; > > > > > > + unsigned long long start, size; > > > > > > + char *k = strchr(str, ','); > > > > > > + > > > > > > + if (k) > > > > > > + *k++ = 0; > > > > > > + > > > > > > + rc = parse_immovable_mem(str, &start, &size); > > > > > > + if (rc < 0) > > > > > > + break; > > > > > > + str = k; > > > > > > + > > > > > > + immovable_mem[i].start = start; > > > > > > + immovable_mem[i].size = size; > > > > > > + i++; > > > > > > + } > > > > > > + num_immovable_region = i; > > > > > > +} > > > > > > +#else > > > > > > +static inline void parse_immovable_mem_regions(char *str) > > > > > > +{ > > > > > > +} > > > > > > +#endif > > > > > > + > > > > > > +static int handle_mem_filter(void) > > > > > > { > > > > > > char *args = (char *)get_cmd_line_ptr(); > > > > > > size_t len = strlen((char *)args); > > > > > > @@ -215,7 +286,8 @@ 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, "immovable_mem=")) > > > > > > return 0; > > > > > > tmp_cmdline = malloc(len + 1); > > > > > > @@ -240,6 +312,8 @@ static int handle_mem_memmap(void) > > > > > > if (!strcmp(param, "memmap")) { > > > > > > mem_avoid_memmap(val); > > > > > > + } else if (!strcmp(param, "immovable_mem")) { > > > > > > + parse_immovable_mem_regions(val); > > > > > > } else if (!strcmp(param, "mem")) { > > > > > > char *p = val; > > > > > > @@ -379,7 +453,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size, > > > > > > /* We don't need to set a mapping for setup_data. */ > > > > > > /* Mark the memmap regions we need to avoid */ > > > > > > - handle_mem_memmap(); > > > > > > + handle_mem_filter(); > > > > > > #ifdef CONFIG_X86_VERBOSE_BOOTUP > > > > > > /* Make sure video RAM can be used. */ > > > > > > -- > > > > > > 2.14.3 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >