linux-kernel - Re: [PATCH v4 RESEND 4/11] x86/asm: Fix pud/pmd interfaces to handle large PAT bit

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Message-ID: <56411FFB.80104@oracle.com>
Date:	Mon, 9 Nov 2015 17:36:43 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
Cc:	Toshi Kani <toshi.kani@....com>, hpa@...or.com, tglx@...utronix.de,
	mingo@...hat.com, akpm@...ux-foundation.org, bp@...en8.de,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, x86@...nel.org,
	jgross@...e.com, konrad.wilk@...cle.com, elliott@....com
Subject: Re: [PATCH v4 RESEND 4/11] x86/asm: Fix pud/pmd interfaces to handle
 large PAT bit

On 11/09/2015 03:47 PM, Kirill A. Shutemov wrote:
> On Mon, Nov 09, 2015 at 02:39:31PM -0500, Boris Ostrovsky wrote:
>> On 11/09/2015 02:16 PM, Toshi Kani wrote:
>>> On Mon, 2015-11-09 at 13:06 -0500, Boris Ostrovsky wrote:
>>>> On 09/17/2015 02:24 PM, Toshi Kani wrote:
>>>>> Now that we have pud/pmd mask interfaces, which handle pfn & flags
>>>>> mask properly for the large PAT bit.
>>>>>
>>>>> Fix pud/pmd pfn & flags interfaces by replacing PTE_PFN_MASK and
>>>>> PTE_FLAGS_MASK with the pud/pmd mask interfaces.
>>>>>
>>>>> Suggested-by: Juergen Gross <jgross@...e.com>
>>>>> Signed-off-by: Toshi Kani <toshi.kani@....com>
>>>>> Cc: Juergen Gross <jgross@...e.com>
>>>>> Cc: Konrad Wilk <konrad.wilk@...cle.com>
>>>>> Cc: Thomas Gleixner <tglx@...utronix.de>
>>>>> Cc: H. Peter Anvin <hpa@...or.com>
>>>>> Cc: Ingo Molnar <mingo@...hat.com>
>>>>> Cc: Borislav Petkov <bp@...en8.de>
>>>>> ---
>>>>>    arch/x86/include/asm/pgtable.h       |   14 ++++++++------
>>>>>    arch/x86/include/asm/pgtable_types.h |    4 ++--
>>>>>    2 files changed, 10 insertions(+), 8 deletions(-)
>>>>>
>>>> Looks like this commit is causing this splat for 32-bit kernels. I am
>>>> attaching my config file, just in case.
>>> Thanks for the report!  I'd like to reproduce the issue since I am not sure how
>>> this change caused it...
>>>
>>> I tried to build a kernel with the attached config file, and got the following
>>> error.  Not sure what I am missing.
>>>
>>> ----
>>> $ make -j24 ARCH=i386
>>>     :
>>>    LD      drivers/built-in.o
>>>    LINK    vmlinux
>>> ./.config: line 44: $'\r': command not found
>> I wonder whether my email client added ^Ms to the file that I send. It
>> shouldn't have.
>>
>>> Makefile:929: recipe for target 'vmlinux' failed
>>> make: *** [vmlinux] Error 127
>>> ----
>>>
>>> Do you have steps to reproduce the issue?  Or do you see it during boot-time?
>> This always happens just after system has booted, it may still be going over
>> init scripts. I am booting with ramdisk, don't know whether it has anything
>> to do with this problem.
>>
>> FWIW, it looks like pmd_pfn_mask() inline is causing this. Reverting it
>> alone makes this crash go away.
> Could you check the patch below?


I does fix the problem on baremetal, thanks. My 32-bit Xen guests still 
fail which I thought was the same issue but now that I looked at it more 
carefully it has different signature.

-boris


>
> diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> index dd5b0aa9dd2f..c1e797266ce9 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -279,17 +279,14 @@ static inline pmdval_t native_pmd_val(pmd_t pmd)
>   static inline pudval_t pud_pfn_mask(pud_t pud)
>   {
>   	if (native_pud_val(pud) & _PAGE_PSE)
> -		return PUD_PAGE_MASK & PHYSICAL_PAGE_MASK;
> +		return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
>   	else
>   		return PTE_PFN_MASK;
>   }
>   
>   static inline pudval_t pud_flags_mask(pud_t pud)
>   {
> -	if (native_pud_val(pud) & _PAGE_PSE)
> -		return ~(PUD_PAGE_MASK & (pudval_t)PHYSICAL_PAGE_MASK);
> -	else
> -		return ~PTE_PFN_MASK;
> +	return ~pud_pfn_mask(pud);
>   }
>   
>   static inline pudval_t pud_flags(pud_t pud)
> @@ -300,17 +297,14 @@ static inline pudval_t pud_flags(pud_t pud)
>   static inline pmdval_t pmd_pfn_mask(pmd_t pmd)
>   {
>   	if (native_pmd_val(pmd) & _PAGE_PSE)
> -		return PMD_PAGE_MASK & PHYSICAL_PAGE_MASK;
> +		return ~((1ULL << PMD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
>   	else
>   		return PTE_PFN_MASK;
>   }
>   
>   static inline pmdval_t pmd_flags_mask(pmd_t pmd)
>   {
> -	if (native_pmd_val(pmd) & _PAGE_PSE)
> -		return ~(PMD_PAGE_MASK & (pmdval_t)PHYSICAL_PAGE_MASK);
> -	else
> -		return ~PTE_PFN_MASK;
> +	return ~pmd_pfn_mask(pmd);
>   }
>   
>   static inline pmdval_t pmd_flags(pmd_t pmd)

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