linux-kernel - Re: [PATCH 33/35] x86, 64bit, mm: hibernate use generic mapping

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Date:	Thu, 24 Jan 2013 23:50:41 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kiszka <jan.kiszka@....de>,
	Jason Wessel <jason.wessel@...driver.com>,
	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	Pavel Machek <pavel@....cz>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 33/35] x86, 64bit, mm: hibernate use generic mapping_init

On Thursday, January 24, 2013 12:20:14 PM Yinghai Lu wrote:
> We should set mappings only for usable memory ranges under max_pfn
> Otherwise causes same problem that is fixed by
> 
> 	x86, mm: Only direct map addresses that are marked as E820_RAM
> 
> Make it only map range in pfn_mapped array.

Well.

While I don't have fundamental objections, I can't really ACK the patch,
because I haven't been following arch/x86 development for several months
and I can't really say how this is supposed to work after the change.

Thanks,
Rafael


> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Rafael J. Wysocki <rjw@...k.pl>
> Cc: linux-pm@...r.kernel.org
> ---
>  arch/x86/power/hibernate_64.c |   66 ++++++++++++++---------------------------
>  1 file changed, 22 insertions(+), 44 deletions(-)
> 
> diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
> index 460f314..a0fde91 100644
> --- a/arch/x86/power/hibernate_64.c
> +++ b/arch/x86/power/hibernate_64.c
> @@ -11,6 +11,8 @@
>  #include <linux/gfp.h>
>  #include <linux/smp.h>
>  #include <linux/suspend.h>
> +
> +#include <asm/init.h>
>  #include <asm/proto.h>
>  #include <asm/page.h>
>  #include <asm/pgtable.h>
> @@ -39,41 +41,21 @@ pgd_t *temp_level4_pgt;
>  
>  void *relocated_restore_code;
>  
> -static int res_phys_pud_init(pud_t *pud, unsigned long address, unsigned long end)
> +static void *alloc_pgt_page(void *context)
>  {
> -	long i, j;
> -
> -	i = pud_index(address);
> -	pud = pud + i;
> -	for (; i < PTRS_PER_PUD; pud++, i++) {
> -		unsigned long paddr;
> -		pmd_t *pmd;
> -
> -		paddr = address + i*PUD_SIZE;
> -		if (paddr >= end)
> -			break;
> -
> -		pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
> -		if (!pmd)
> -			return -ENOMEM;
> -		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
> -		for (j = 0; j < PTRS_PER_PMD; pmd++, j++, paddr += PMD_SIZE) {
> -			unsigned long pe;
> -
> -			if (paddr >= end)
> -				break;
> -			pe = __PAGE_KERNEL_LARGE_EXEC | paddr;
> -			pe &= __supported_pte_mask;
> -			set_pmd(pmd, __pmd(pe));
> -		}
> -	}
> -	return 0;
> +	return (void *)get_safe_page(GFP_ATOMIC);
>  }
>  
>  static int set_up_temporary_mappings(void)
>  {
> -	unsigned long start, end, next;
> -	int error;
> +	struct x86_mapping_info info = {
> +		.alloc_pgt_page	= alloc_pgt_page,
> +		.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,
> +		.kernel_mapping = true,
> +	};
> +	unsigned long mstart, mend;
> +	int result;
> +	int i;
>  
>  	temp_level4_pgt = (pgd_t *)get_safe_page(GFP_ATOMIC);
>  	if (!temp_level4_pgt)
> @@ -84,21 +66,17 @@ static int set_up_temporary_mappings(void)
>  		init_level4_pgt[pgd_index(__START_KERNEL_map)]);
>  
>  	/* Set up the direct mapping from scratch */
> -	start = (unsigned long)pfn_to_kaddr(0);
> -	end = (unsigned long)pfn_to_kaddr(max_pfn);
> -
> -	for (; start < end; start = next) {
> -		pud_t *pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> -		if (!pud)
> -			return -ENOMEM;
> -		next = start + PGDIR_SIZE;
> -		if (next > end)
> -			next = end;
> -		if ((error = res_phys_pud_init(pud, __pa(start), __pa(next))))
> -			return error;
> -		set_pgd(temp_level4_pgt + pgd_index(start),
> -			mk_kernel_pgd(__pa(pud)));
> +	for (i = 0; i < nr_pfn_mapped; i++) {
> +		mstart = pfn_mapped[i].start << PAGE_SHIFT;
> +		mend   = pfn_mapped[i].end << PAGE_SHIFT;
> +
> +		result = kernel_ident_mapping_init(&info, temp_level4_pgt,
> +						   mstart, mend);
> +
> +		if (result)
> +			return result;
>  	}
> +
>  	return 0;
>  }
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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