Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752298AbdLGEQt (ORCPT ); Wed, 6 Dec 2017 23:16:49 -0500 Received: from mail.cn.fujitsu.com ([183.91.158.132]:47138 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752129AbdLGEQs (ORCPT ); Wed, 6 Dec 2017 23:16:48 -0500 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="30790581" Subject: Re: [PATCH v3 1/4] kaslr: add immovable_mem=nn[KMG]@ss[KMG] to specify extracting memory To: Chao Fan , Baoquan He CC: , , , , , , , , 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> From: Dou Liyang Message-ID: Date: Thu, 7 Dec 2017 12:16:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171207035621.GE28884@localhost.localdomain> Content-Type: text/plain; charset="gbk"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.106] X-yoursite-MailScanner-ID: 94950486A778.A8720 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: douly.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7853 Lines: 243 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? } ... > 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 >>>>> >>>>> >>>>> >>>> >>>> >>> >>> >> >> >