Re: [PATCH v7 2/5] x86/KASLR: Handle the memory regions specified in kaslr_mem

[Baoquan He]

On 01/17/18 at 06:53pm, Chao Fan wrote:
> If no 'kaslr_mem=' specified, just handle the e820/efi entries directly
> as before. Otherwise, limit kernel to memory regions specified in
> 'kaslr_mem=' commandline.
> 
> Rename process_mem_region to slots_count to match
> slots_fetch_random, and name new function as process_mem_region.
> 
> Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
> ---
>  arch/x86/boot/compressed/kaslr.c | 64 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 53 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index b21741135673..b200a7ceafc1 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -548,9 +548,9 @@ static unsigned long slots_fetch_random(void)
>  	return 0;
>  }

Looks good, ack.

Acked-by: Baoquan He <bhe@xxxxxxxxxx>

>  
> -static void process_mem_region(struct mem_vector *entry,
> -			       unsigned long minimum,
> -			       unsigned long image_size)
> +static void slots_count(struct mem_vector *entry,
> +			unsigned long minimum,
> +			unsigned long image_size)
>  {
>  	struct mem_vector region, overlap;
>  	struct slot_area slot_area;
> @@ -627,6 +627,52 @@ static void process_mem_region(struct mem_vector *entry,
>  	}
>  }
>  
> +static bool process_mem_region(struct mem_vector region,
> +			       unsigned long long minimum,
> +			       unsigned long long image_size)
> +{
> +	/*
> +	 * If kaslr_mem= specified, walk all the regions, and
> +	 * filter the intersection to slots_count.
> +	 */
> +	if (num_usable_region > 0) {
> +		int i;
> +
> +		for (i = 0; i < num_usable_region; i++) {
> +			struct mem_vector entry;
> +			unsigned long long start, end, entry_end, region_end;
> +
> +			start = mem_usable[i].start;
> +			end = start + mem_usable[i].size;
> +			region_end = region.start + region.size;
> +
> +			entry.start = clamp(region.start, start, end);
> +			entry_end = clamp(region_end, start, end);
> +
> +			if (entry.start < entry_end) {
> +				entry.size = entry_end - entry.start;
> +				slots_count(&entry, minimum, image_size);
> +			}
> +
> +			if (slot_area_index == MAX_SLOT_AREA) {
> +				debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");
> +				return 1;
> +			}
> +		}
> +		return 0;
> +	}
> +
> +	/*
> +	 * If no kaslr_mem stored, use region directly
> +	 */
> +	slots_count(&region, minimum, image_size);
> +	if (slot_area_index == MAX_SLOT_AREA) {
> +		debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");
> +		return 1;
> +	}
> +	return 0;
> +}
> +
>  #ifdef CONFIG_EFI
>  /*
>   * Returns true if mirror region found (and must have been processed
> @@ -692,11 +738,9 @@ 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 (process_mem_region(region, minimum, image_size))
>  			break;
> -		}
>  	}
>  	return true;
>  }
> @@ -723,11 +767,9 @@ 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 (process_mem_region(region, minimum, image_size))
>  			break;
> -		}
>  	}
>  }
>  
> -- 
> 2.14.3
> 
> 
>