Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751792AbdLGFca (ORCPT ); Thu, 7 Dec 2017 00:32:30 -0500 Received: from mail.cn.fujitsu.com ([183.91.158.132]:39433 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750982AbdLGFc3 (ORCPT ); Thu, 7 Dec 2017 00:32:29 -0500 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="30792411" Date: Thu, 7 Dec 2017 13:31:55 +0800 From: Chao Fan To: Baoquan He CC: Dou Liyang , , , , , , , , , Subject: Re: [PATCH v3 1/4] kaslr: add immovable_mem=nn[KMG]@ss[KMG] to specify extracting memory Message-ID: <20171207053154.GF28884@localhost.localdomain> 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> <20171207045806.GQ15074@x1> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171207045806.GQ15074@x1> User-Agent: Mutt/1.9.1 (2017-09-22) X-Originating-IP: [10.167.225.56] X-yoursite-MailScanner-ID: 615FC486A778.AC078 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: 9471 Lines: 249 On Thu, Dec 07, 2017 at 12:58:06PM +0800, Baoquan He wrote: >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. > Thanks Baoquan and Dou, I will make the new version. Thanks, Chao Fan >> ... >> >> > 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 >> > > > > > >> > > > > > >> > > > > > >> > > > > >> > > > > >> > > > >> > > > >> > > >> > > >> > >> >> > >