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

Dou Liyang
2017-10-20T06:05:19Z

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@cn.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.