[PATCH v3] ARM: mm: support big-endian page tables

[PATCH v3] ARM: mm: support big-endian page tables

[Jianguo Wu]

When enable LPAE and big-endian in a hisilicon board, while specify
mem=384M mem=512M@7680M, will get bad page state:

Freeing unused kernel memory: 180K (c0466000 - c0493000)
BUG: Bad page state in process init  pfn:fa442
page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
page flags: 0x40000400(reserved)
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
[<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
[<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
[<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
[<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
[<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
[<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
[<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
[<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
[<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)

The bad pfn:fa442 is not system memory(mem=384M mem=512M@7680M), after debugging,
I find in page fault handler, will get wrong pfn from pte just after set pte,
as follow:
do_anonymous_page()
{
	...
	set_pte_at(mm, address, page_table, entry);
	
	//debug code
	pfn = pte_pfn(entry);
	pr_info("pfn:0x%lx, pte:0x%llx\n", pfn, pte_val(entry));

	//read out the pte just set
	new_pte = pte_offset_map(pmd, address);
	new_pfn = pte_pfn(*new_pte);
	pr_info("new pfn:0x%lx, new pte:0x%llx\n", pfn, pte_val(entry));
	...
}

pfn:   0x1fa4f5,     pte:0xc00001fa4f575f
new_pfn:0xfa4f5, new_pte:0xc00000fa4f5f5f	//new pfn/pte is wrong.

The bug is happened in cpu_v7_set_pte_ext(ptep, pte):
An LPAE PTE is a 64bit quantity, passed to cpu_v7_set_pte_ext in the r2 and r3 registers.
On an LE kernel, r2 contains the LSB of the PTE, and r3 the MSB.
On a BE kernel, the assignment is reversed.

Unfortunately, the current code always assumes the LE case,
leading to corruption of the PTE when clearing/setting bits.

This patch fixes this issue much like it has been done already in the
cpu_v7_switch_mm case.

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Cc: stable@vger.kernel.org
---
-v2: Refactoring code suggested by Ben Dooks.
-v3: Rewrite commit message suggested by Marc Zyngier.
---
 arch/arm/mm/proc-v7-3level.S |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index 01a719e..22e3ad6 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S
@@ -64,6 +64,14 @@ ENTRY(cpu_v7_switch_mm)
 	mov	pc, lr
 ENDPROC(cpu_v7_switch_mm)
 
+#ifdef __ARMEB__
+#define rl r3
+#define rh r2
+#else
+#define rl r2
+#define rh r3
+#endif
+
 /*
  * cpu_v7_set_pte_ext(ptep, pte)
  *
@@ -73,13 +81,13 @@ ENDPROC(cpu_v7_switch_mm)
  */
 ENTRY(cpu_v7_set_pte_ext)
 #ifdef CONFIG_MMU
-	tst	r2, #L_PTE_VALID
+	tst	rl, #L_PTE_VALID
 	beq	1f
-	tst	r3, #1 << (57 - 32)		@ L_PTE_NONE
-	bicne	r2, #L_PTE_VALID
+	tst	rh, #1 << (57 - 32)		@ L_PTE_NONE
+	bicne	rl, #L_PTE_VALID
 	bne	1f
-	tst	r3, #1 << (55 - 32)		@ L_PTE_DIRTY
-	orreq	r2, #L_PTE_RDONLY
+	tst	rh, #1 << (55 - 32)		@ L_PTE_DIRTY
+	orreq	rl, #L_PTE_RDONLY
 1:	strd	r2, r3, [r0]
 	ALT_SMP(W(nop))
 	ALT_UP (mcr	p15, 0, r0, c7, c10, 1)		@ flush_pte
-- 
1.7.1



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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Marc Zyngier]

On Thu, Apr 17 2014 at 10:31:37 am BST, Jianguo Wu <wujianguo@huawei.com> wrote:
> When enable LPAE and big-endian in a hisilicon board, while specify
> mem=384M mem=512M@7680M, will get bad page state:
>
> Freeing unused kernel memory: 180K (c0466000 - c0493000)
> BUG: Bad page state in process init  pfn:fa442
> page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
> page flags: 0x40000400(reserved)
> Modules linked in:
> CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
> [<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
> [<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
> [<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
> [<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
> [<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
> [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
> [<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
> [<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
> [<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)
>
> The bad pfn:fa442 is not system memory(mem=384M mem=512M@7680M), after debugging,
> I find in page fault handler, will get wrong pfn from pte just after set pte,
> as follow:
> do_anonymous_page()
> {
> 	...
> 	set_pte_at(mm, address, page_table, entry);
> 	
> 	//debug code
> 	pfn = pte_pfn(entry);
> 	pr_info("pfn:0x%lx, pte:0x%llx\n", pfn, pte_val(entry));
>
> 	//read out the pte just set
> 	new_pte = pte_offset_map(pmd, address);
> 	new_pfn = pte_pfn(*new_pte);
> 	pr_info("new pfn:0x%lx, new pte:0x%llx\n", pfn, pte_val(entry));
> 	...
> }
>
> pfn:   0x1fa4f5,     pte:0xc00001fa4f575f
> new_pfn:0xfa4f5, new_pte:0xc00000fa4f5f5f	//new pfn/pte is wrong.
>
> The bug is happened in cpu_v7_set_pte_ext(ptep, pte):
> An LPAE PTE is a 64bit quantity, passed to cpu_v7_set_pte_ext in the r2 and r3 registers.
> On an LE kernel, r2 contains the LSB of the PTE, and r3 the MSB.
> On a BE kernel, the assignment is reversed.
>
> Unfortunately, the current code always assumes the LE case,
> leading to corruption of the PTE when clearing/setting bits.
>
> This patch fixes this issue much like it has been done already in the
> cpu_v7_switch_mm case.
>
> Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
> Cc: stable@vger.kernel.org

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

> ---
> -v2: Refactoring code suggested by Ben Dooks.
> -v3: Rewrite commit message suggested by Marc Zyngier.
> ---
>  arch/arm/mm/proc-v7-3level.S |   18 +++++++++++++-----
>  1 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
> index 01a719e..22e3ad6 100644
> --- a/arch/arm/mm/proc-v7-3level.S
> +++ b/arch/arm/mm/proc-v7-3level.S
> @@ -64,6 +64,14 @@ ENTRY(cpu_v7_switch_mm)
>  	mov	pc, lr
>  ENDPROC(cpu_v7_switch_mm)
>  
> +#ifdef __ARMEB__
> +#define rl r3
> +#define rh r2
> +#else
> +#define rl r2
> +#define rh r3
> +#endif
> +
>  /*
>   * cpu_v7_set_pte_ext(ptep, pte)
>   *
> @@ -73,13 +81,13 @@ ENDPROC(cpu_v7_switch_mm)
>   */
>  ENTRY(cpu_v7_set_pte_ext)
>  #ifdef CONFIG_MMU
> -	tst	r2, #L_PTE_VALID
> +	tst	rl, #L_PTE_VALID
>  	beq	1f
> -	tst	r3, #1 << (57 - 32)		@ L_PTE_NONE
> -	bicne	r2, #L_PTE_VALID
> +	tst	rh, #1 << (57 - 32)		@ L_PTE_NONE
> +	bicne	rl, #L_PTE_VALID
>  	bne	1f
> -	tst	r3, #1 << (55 - 32)		@ L_PTE_DIRTY
> -	orreq	r2, #L_PTE_RDONLY
> +	tst	rh, #1 << (55 - 32)		@ L_PTE_DIRTY
> +	orreq	rl, #L_PTE_RDONLY
>  1:	strd	r2, r3, [r0]
>  	ALT_SMP(W(nop))
>  	ALT_UP (mcr	p15, 0, r0, c7, c10, 1)		@ flush_pte

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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Will Deacon]

Hi Jianguo,

On Thu, Apr 17, 2014 at 10:43:01AM +0100, Marc Zyngier wrote:
> On Thu, Apr 17 2014 at 10:31:37 am BST, Jianguo Wu <wujianguo@huawei.com> wrote:
> > When enable LPAE and big-endian in a hisilicon board, while specify
> > mem=384M mem=512M@7680M, will get bad page state:
> >
> > Freeing unused kernel memory: 180K (c0466000 - c0493000)
> > BUG: Bad page state in process init  pfn:fa442
> > page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
> > page flags: 0x40000400(reserved)
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
> > [<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
> > [<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
> > [<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
> > [<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
> > [<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
> > [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
> > [<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
> > [<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
> > [<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)


[...]

Please can you put this into Russell's patch system? You can also add my
ack:

  Acked-by: Will Deacon <will.deacon@arm.com>

You should also CC stable <stable@vger.kernel.org> in the commit log.

Cheers,

Will

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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Jianguo Wu]

On 2014/4/23 21:20, Will Deacon wrote:

> Hi Jianguo,
> 
> On Thu, Apr 17, 2014 at 10:43:01AM +0100, Marc Zyngier wrote:
>> On Thu, Apr 17 2014 at 10:31:37 am BST, Jianguo Wu <wujianguo@huawei.com> wrote:
>>> When enable LPAE and big-endian in a hisilicon board, while specify
>>> mem=384M mem=512M@7680M, will get bad page state:
>>>
>>> Freeing unused kernel memory: 180K (c0466000 - c0493000)
>>> BUG: Bad page state in process init  pfn:fa442
>>> page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
>>> page flags: 0x40000400(reserved)
>>> Modules linked in:
>>> CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
>>> [<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
>>> [<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
>>> [<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
>>> [<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
>>> [<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
>>> [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
>>> [<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
>>> [<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
>>> [<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)
> 
> 
> [...]
> 
> Please can you put this into Russell's patch system? You can also add my
> ack:
> 
>   Acked-by: Will Deacon <will.deacon@arm.com>
> 
> You should also CC stable <stable@vger.kernel.org> in the commit log.
> 

Hi Will,
I have submit to http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8037/1.

Thanks,
Jianguo Wu.

> Cheers,
> 
> Will
> 
> .
> 



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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Jianguo Wu]

Hi Russell,
Could you please merge this to mainline? Thanks!

Jianguo Wu.

On 2014/4/24 10:51, Jianguo Wu wrote:

> On 2014/4/23 21:20, Will Deacon wrote:
> 
>> Hi Jianguo,
>>
>> On Thu, Apr 17, 2014 at 10:43:01AM +0100, Marc Zyngier wrote:
>>> On Thu, Apr 17 2014 at 10:31:37 am BST, Jianguo Wu <wujianguo@huawei.com> wrote:
>>>> When enable LPAE and big-endian in a hisilicon board, while specify
>>>> mem=384M mem=512M@7680M, will get bad page state:
>>>>
>>>> Freeing unused kernel memory: 180K (c0466000 - c0493000)
>>>> BUG: Bad page state in process init  pfn:fa442
>>>> page:c7749840 count:0 mapcount:-1 mapping:  (null) index:0x0
>>>> page flags: 0x40000400(reserved)
>>>> Modules linked in:
>>>> CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66
>>>> [<c000f5f0>] (unwind_backtrace+0x0/0x11c) from [<c000cbc4>] (show_stack+0x10/0x14)
>>>> [<c000cbc4>] (show_stack+0x10/0x14) from [<c009e448>] (bad_page+0xd4/0x104)
>>>> [<c009e448>] (bad_page+0xd4/0x104) from [<c009e520>] (free_pages_prepare+0xa8/0x14c)
>>>> [<c009e520>] (free_pages_prepare+0xa8/0x14c) from [<c009f8ec>] (free_hot_cold_page+0x18/0xf0)
>>>> [<c009f8ec>] (free_hot_cold_page+0x18/0xf0) from [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8)
>>>> [<c00b5444>] (handle_pte_fault+0xcf4/0xdc8) from [<c00b6458>] (handle_mm_fault+0xf4/0x120)
>>>> [<c00b6458>] (handle_mm_fault+0xf4/0x120) from [<c0013754>] (do_page_fault+0xfc/0x354)
>>>> [<c0013754>] (do_page_fault+0xfc/0x354) from [<c0008400>] (do_DataAbort+0x2c/0x90)
>>>> [<c0008400>] (do_DataAbort+0x2c/0x90) from [<c0008fb4>] (__dabt_usr+0x34/0x40)
>>
>>
>> [...]
>>
>> Please can you put this into Russell's patch system? You can also add my
>> ack:
>>
>>   Acked-by: Will Deacon <will.deacon@arm.com>
>>
>> You should also CC stable <stable@vger.kernel.org> in the commit log.
>>
> 
> Hi Will,
> I have submit to http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8037/1.
> 
> Thanks,
> Jianguo Wu.
> 
>> Cheers,
>>
>> Will
>>
>> .
>>
> 
> 
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
> 



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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Will Deacon]

On Thu, May 29, 2014 at 04:20:57AM +0100, Jianguo Wu wrote:
> Hi Russell,
> Could you please merge this to mainline? Thanks!

Give him a chance, it's not the merge window yet ;) I can see it queued in
his for-next branch.

Will

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Re: [PATCH v3] ARM: mm: support big-endian page tables

[Russell King - ARM Linux]

On Thu, May 29, 2014 at 08:58:38AM +0100, Will Deacon wrote:
> On Thu, May 29, 2014 at 04:20:57AM +0100, Jianguo Wu wrote:
> > Hi Russell,
> > Could you please merge this to mainline? Thanks!
> 
> Give him a chance, it's not the merge window yet ;) I can see it queued in
> his for-next branch.

It's not like it's something that has ever worked in the past - so
it's really a new feature rather than a bug fix, even through we've
been growing BE support in other areas.

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