linux-kernel - Re: [PATCH v2 2/4] kaslr: select the memory region in immovable node to process

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Date:   Thu, 9 Nov 2017 16:21:32 +0800
From:   Baoquan He <bhe@...hat.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, keescook@...omium.org,
        yasu.isimatu@...il.com, indou.takao@...fujitsu.com,
        caoj.fnst@...fujitsu.com, douly.fnst@...fujitsu.com
Subject: Re: [PATCH v2 2/4] kaslr: select the memory region in immovable node
 to process

Hi Chao,

On 11/01/17 at 07:32pm, Chao Fan wrote:
> Compare the region of memmap entry and immovable_mem, then choose the
> intersection to process_mem_region.
> 
> Since the interrelationship between e820 or efi entries and memory
> region in immovable_mem is different:

Could you paste a bootlog with efi=debug specified in cmdline on the
system you tested? I want to check what kind of intersection between
them. The adding makes code pretty ugly, want to make sure if we have
to do like this.

Thanks
Baoquan

> 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.
> 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 | 60 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 52 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 0a591c0023f1..fcd640fdeaed 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -634,6 +634,54 @@ static void process_mem_region(struct mem_vector *entry,
>  	}
>  }
>  
> +static bool select_immovable_node(struct mem_vector region,
> +				  unsigned long long minimum,
> +				  unsigned long long image_size)
> +{
> +	int i;
> +
> +	/* If no immovable_mem stored, use region directly */
> +	if (num_immovable_region == 0) {
> +		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 {
> +		/*
> +		 * Walk all immovable regions, and filter the intersection
> +		 * to process_mem_region.
> +		 */
> +		for (i = 0; i < num_immovable_region; i++) {
> +			struct mem_vector entry;
> +			unsigned long long start, end, select_end, region_end;
> +
> +			region_end = region.start + region.size - 1;
> +			start = immovable_mem[i].start;
> +			end = start + immovable_mem[i].size - 1;
> +
> +			if (region_end < start || region.start > end)
> +				continue;
> +
> +			/* May split one region to several entries. */
> +			entry.start = start > region.start ?
> +				      start : region.start;
> +			select_end = end > region_end ? region_end : end;
> +
> +			entry.size = select_end - entry.start + 1;
> +
> +			process_mem_region(&entry, 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
> @@ -699,11 +747,9 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
>  
>  		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");
> +
> +		if (select_immovable_node(region, minimum, image_size))
>  			break;
> -		}
>  	}
>  	return true;
>  }
> @@ -730,11 +776,9 @@ static void process_e820_entries(unsigned long minimum,
>  			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");
> +
> +		if (select_immovable_node(region, minimum, image_size))
>  			break;
> -		}
>  	}
>  }
>  
> -- 
> 2.13.6
> 
> 
>