Re: [PATCH v8 14/46] x86, mm: use pfn_range_is_mapped() with reserve_initrd

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Nov 16, 2012 at 07:38:51PM -0800, Yinghai Lu wrote:
> We are going to map ram only, so under max_low_pfn_mapped,
> between 4g and max_pfn_mapped does not mean mapped at all.
> 
> Use pfn_range_is_mapped() to find out if range is mapped for initrd.
> 
> That could happen bootloader put initrd in range but user could
                   ^- 'if the'                              ^^^^^-'used'

> use memmap to carve some of range out.
  ^^^-> get rid of that.       ^^^^->'ranges'

> 
> Also during copying need to use early_memmap to map original initrd
> for accessing.
> 
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> ---
>  arch/x86/kernel/setup.c |   52 +++++++++++++++++++++++++---------------------
>  1 files changed, 28 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d85cbd9..bd52f9d 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -317,20 +317,19 @@ static void __init relocate_initrd(void)
>  	u64 ramdisk_image = boot_params.hdr.ramdisk_image;
>  	u64 ramdisk_size  = boot_params.hdr.ramdisk_size;
>  	u64 area_size     = PAGE_ALIGN(ramdisk_size);
> -	u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
>  	u64 ramdisk_here;
>  	unsigned long slop, clen, mapaddr;
>  	char *p, *q;
>  
> -	/* We need to move the initrd down into lowmem */
> -	ramdisk_here = memblock_find_in_range(0, end_of_lowmem, area_size,
> -					 PAGE_SIZE);
> +	/* We need to move the initrd down into directly mapped mem */
> +	ramdisk_here = memblock_find_in_range(0, PFN_PHYS(max_low_pfn_mapped),
> +						 area_size, PAGE_SIZE);
>  
>  	if (!ramdisk_here)
>  		panic("Cannot find place for new RAMDISK of size %lld\n",
>  			 ramdisk_size);
>  
> -	/* Note: this includes all the lowmem currently occupied by
> +	/* Note: this includes all the mem currently occupied by
>  	   the initrd, we rely on that fact to keep the data intact. */
>  	memblock_reserve(ramdisk_here, area_size);
>  	initrd_start = ramdisk_here + PAGE_OFFSET;
> @@ -340,17 +339,7 @@ static void __init relocate_initrd(void)
>  
>  	q = (char *)initrd_start;
>  
> -	/* Copy any lowmem portion of the initrd */
> -	if (ramdisk_image < end_of_lowmem) {
> -		clen = end_of_lowmem - ramdisk_image;
> -		p = (char *)__va(ramdisk_image);
> -		memcpy(q, p, clen);
> -		q += clen;
> -		ramdisk_image += clen;
> -		ramdisk_size  -= clen;
> -	}
> -
> -	/* Copy the highmem portion of the initrd */
> +	/* Copy the initrd */
>  	while (ramdisk_size) {
>  		slop = ramdisk_image & ~PAGE_MASK;
>  		clen = ramdisk_size;
> @@ -364,7 +353,7 @@ static void __init relocate_initrd(void)
>  		ramdisk_image += clen;
>  		ramdisk_size  -= clen;
>  	}
> -	/* high pages is not converted by early_res_to_bootmem */
> +
>  	ramdisk_image = boot_params.hdr.ramdisk_image;
>  	ramdisk_size  = boot_params.hdr.ramdisk_size;
>  	printk(KERN_INFO "Move RAMDISK from [mem %#010llx-%#010llx] to"
> @@ -373,13 +362,27 @@ static void __init relocate_initrd(void)
>  		ramdisk_here, ramdisk_here + ramdisk_size - 1);
>  }
>  
> +static u64 __init get_mem_size(unsigned long limit_pfn)
> +{
> +	int i;
> +	u64 mapped_pages = 0;
> +	unsigned long start_pfn, end_pfn;
> +
> +	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
> +		start_pfn = min_t(unsigned long, start_pfn, limit_pfn);
> +		end_pfn = min_t(unsigned long, end_pfn, limit_pfn);
> +		mapped_pages += end_pfn - start_pfn;
> +	}
> +
> +	return mapped_pages << PAGE_SHIFT;
> +}
>  static void __init reserve_initrd(void)
>  {
>  	/* Assume only end is not page aligned */
>  	u64 ramdisk_image = boot_params.hdr.ramdisk_image;
>  	u64 ramdisk_size  = boot_params.hdr.ramdisk_size;
>  	u64 ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
> -	u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
> +	u64 mapped_size;
>  
>  	if (!boot_params.hdr.type_of_loader ||
>  	    !ramdisk_image || !ramdisk_size)
> @@ -387,18 +390,19 @@ static void __init reserve_initrd(void)
>  
>  	initrd_start = 0;
>  
> -	if (ramdisk_size >= (end_of_lowmem>>1)) {
> +	mapped_size = get_mem_size(max_low_pfn_mapped);
> +	if (ramdisk_size >= (mapped_size>>1))
>  		panic("initrd too large to handle, "
>  		       "disabling initrd (%lld needed, %lld available)\n",
> -		       ramdisk_size, end_of_lowmem>>1);
> -	}
> +		       ramdisk_size, mapped_size>>1);
>  
>  	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n", ramdisk_image,
>  			ramdisk_end - 1);
>  
> -
> -	if (ramdisk_end <= end_of_lowmem) {
> -		/* All in lowmem, easy case */
> +	if (ramdisk_end <= (max_low_pfn_mapped<<PAGE_SHIFT) &&
> +	    pfn_range_is_mapped(PFN_DOWN(ramdisk_image),
> +				PFN_DOWN(ramdisk_end))) {
> +		/* All are mapped, easy case */
>  		/*
>  		 * don't need to reserve again, already reserved early
>  		 * in i386_start_kernel
> -- 
> 1.7.7