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

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Date:   Fri, 20 Oct 2017 11:17:26 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Chao Fan <fanc.fnst@...fujitsu.com>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bhe@...hat.com>,
        <keescook@...omium.org>
CC:     <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 10/19/2017 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

> +		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.

>  			break;
> -		}
>  	}
>  	return true;
>  }
> @@ -706,22 +752,20 @@ static void process_e820_entries(unsigned long minimum,
>  				 unsigned long image_size)
>  {
>  	int i;
> -	struct mem_vector region;
>  	struct boot_e820_entry *entry;
>
>  	/* Verify potential e820 positions, appending to slots list. */
>  	for (i = 0; i < boot_params->e820_entries; i++) {
> +		unsigned long long start, size;
>  		entry = &boot_params->e820_table[i];
>  		/* Skip non-RAM entries. */
>  		if (entry->type != E820_TYPE_RAM)
>  			continue;
> -		region.start = entry->addr;
> -		region.size = entry->size;
> -		process_mem_region(&region, minimum, image_size);
> -		if (slot_area_index == MAX_SLOT_AREA) {
> -			debug_putstr("Aborted e820 scan (slot_areas full)!\n");
> +		start = entry->addr;
> +		size = entry->size;
> +
> +		if (select_immovable_node(start, size, minimum, image_size))
ditto

Thanks,
	dou.
>  			break;
> -		}
>  	}
>  }
>
>