linux-kernel - Re: [PATCH 2/4] kaslr: select the memory region in immovable node to process

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 20 Oct 2017 14:05:13 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Chao Fan <fanc.fnst@...fujitsu.com>
CC:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bhe@...hat.com>,
        <keescook@...omium.org>, <indou.takao@...fujitsu.com>,
        <caoj.fnst@...fujitsu.com>
Subject: Re: [PATCH 2/4] kaslr: select the memory region in immovable node to
 process

Hi Chao,

At 10/20/2017 11:41 AM, Chao Fan wrote:
> On Fri, Oct 20, 2017 at 11:17:26AM +0800, Dou Liyang wrote:
>> Hi Chao
>>
> Hi Dou-san,
>
>> At 10/19/2017 06:02 PM, Chao Fan wrote:
>>> Since the interrelationship between e820 or efi entries and memory
>>> region in immovable_mem is different:
>>> One memory region in one node may contain several entries of e820 or
>>> efi sometimes, and one entry of e820 or efi may contain the memory in
>>> different nodes sometimes. So select the intersection as a region to
>>> process_mem_region. It may split one node or one entry to several regions.
>>>
>>> Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
>>> ---
>>>  arch/x86/boot/compressed/kaslr.c | 72 ++++++++++++++++++++++++++++++++--------
>>>  1 file changed, 58 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
>>> index 3c1f5204693b..22330cbe8515 100644
>>> --- a/arch/x86/boot/compressed/kaslr.c
>>> +++ b/arch/x86/boot/compressed/kaslr.c
>>> @@ -563,6 +563,7 @@ static void process_mem_region(struct mem_vector *entry,
>>>  	end = min(entry->size + entry->start, mem_limit);
>>>  	if (entry->start >= end)
>>>  		return;
>>> +
>>>  	cur_entry.start = entry->start;
>>>  	cur_entry.size = end - entry->start;
>>
>> Above code has nothing to do with this patch. remove it.
>>
>>>
>>> @@ -621,6 +622,52 @@ static void process_mem_region(struct mem_vector *entry,
>>>  	}
>>>  }
>>>
>>> +static bool select_immovable_node(unsigned long long start,
>>> +				  unsigned long long size,
>>> +				  unsigned long long minimum,
>>> +				  unsigned long long image_size)
>>> +{
>>> +	struct mem_vector region;
>>> +	int i;
>>> +
>>> +	if (num_immovable_region == 0) {
>>
>> Seems it more better:
>>
>> #ifdef CONFIG_MEMORY_HOTPLUG
>> for (i = 0; i < num_immovable_region; i++) {
>>  ...
>> }
>> #else
>> ...
>> process_mem_region(&region, minimum, image_size);
>> ...
>> #endif
>
> No, if we set CONFIG_MEMORY_HOTPLUG=y(the default is y in fedora), but we do not
> use movable_node, we should go to process_mem_region straight, right?

Yes, Indeed, you are right! ;-).

> But in your change, we still go to the for(...), even if
> num_immovable_region == 0.
> So if num_immovable_region is 0, it includes the situation of
> CONFIG_MEMORY_HOTPLUG=n
>
>>
>>> +		region.start = start;
>>> +		region.size = size;
>>> +		process_mem_region(&region, minimum, image_size);
>>> +
>>> +		if (slot_area_index == MAX_SLOT_AREA) {
>>> +			debug_putstr("Aborted memmap scan (slot_areas full)!\n");
>>> +			return 1;
>>> +		}
>>> +	} else {
>>> +		for (i = 0; i < num_immovable_region; i++) {
>>> +			unsigned long long end, select_end;
>>> +			unsigned long long region_start, region_end;
>>> +
>>> +			end = start + size - 1;
>>> +			region_start = immovable_mem[i].start;
>>> +			region_end = region_start + immovable_mem[i].size - 1;
>>> +
>>> +			if (end < region_start || start > region_end)
>>> +				continue;
>>> +
>>> +			region.start = start > region_start ?
>>> +				       start : region_start;
>>> +			select_end = end > region_end ? region_end : end;
>>> +
>>> +			region.size = select_end - region.start + 1;
>>> +
>>> +			process_mem_region(&region, minimum, image_size);
>>> +
>>> +			if (slot_area_index == MAX_SLOT_AREA) {
>>> +				debug_putstr("Aborted memmap scan (slot_areas full)!\n");
>>> +				return 1;
>>> +			}
>>> +		}
>>> +	}
>>> +	return 0;
>>> +}
>>> +
>>>  #ifdef CONFIG_EFI
>>>  /*
>>>   * Returns true if mirror region found (and must have been processed
>>> @@ -631,7 +678,6 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
>>>  {
>>>  	struct efi_info *e = &boot_params->efi_info;
>>>  	bool efi_mirror_found = false;
>>> -	struct mem_vector region;
>>>  	efi_memory_desc_t *md;
>>>  	unsigned long pmap;
>>>  	char *signature;
>>> @@ -664,6 +710,8 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
>>>  	}
>>>
>>>  	for (i = 0; i < nr_desc; i++) {
>>> +		unsigned long long start, size;
>>> +
>>>  		md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i);
>>>
>>>  		/*
>>> @@ -684,13 +732,11 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
>>>  		    !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
>>>  			continue;
>>>
>>> -		region.start = md->phys_addr;
>>> -		region.size = md->num_pages << EFI_PAGE_SHIFT;
>>> -		process_mem_region(&region, minimum, image_size);
>>> -		if (slot_area_index == MAX_SLOT_AREA) {
>>> -			debug_putstr("Aborted EFI scan (slot_areas full)!\n");
>>> +		start = md->phys_addr;
>>> +		size = md->num_pages << EFI_PAGE_SHIFT;
>>> +
>>> +		if (select_immovable_node(start, size, minimum, image_size))
>>
>> Why you replace the region with two parameters? Just use region.
>>
>
> You can see the commit message, we may splite one entry to more regions,
> so there will be region.start compared with memory region in
> immovable_mem and then fill more new regions if we use region here.
> The code will look strange.
>
> Start and size will be more clear.

OK, Understood!

Thanks,
	dou.