[v2,2/2] ARM : change fixmap mapping region to support 32 CPUs

于 2014/4/14 1:34, Nicolas Pitre 写道:
> On Sun, 13 Apr 2014, Liu hua wrote:
> 
>> Hi Nicolas.
>>
>> Sure, your suggestion made my patch looks better. How about that :
>>
>> Thanks,
>> Liu Hua
> 
> There is something else that bothers me.
> 
>> +	unsigned long idx = __virt_to_fix(vaddr);
>> +	idx -= FIX_KMAP_BEGIN;
>> +	return *(fixmap_page_table + idx);
> 
> FIX_KMAP_BEGIN represents the starting point for mapping fixmap indices 
> to page table entries.  So here you should _add_ the 
> FIX_KMAP_BEGIN offset to the page table index not substract it.  
> Currently FIX_KMAP_BEGIN is defined to 0 but still.
> 
>> +}
>> +
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>> -	BUG_ON(!pte_none(get_top_pte(vaddr)));
>> +	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> 
> Ditto here.
> 
> In fact, this FIX_KMAP_BEGIN is only creating more confusing code for 
> nothing as we define it to 0 anyway, and it is not used by non 
> architecture specific code.  So I'd suggest you create a patch to be 
> applied before this one that simply gets rid of FIX_KMAP_BEGIN and 
> FIX_KMAP_END altogether.  We could reintroduce them back if ever they're 
> needed.
> 
> 
> Nicolas
> 
Hi Nicolas,

Yes, it seems that FIX_KMAP_BEGIN and FIX_KMAP_END are not as important for
ARM than that for other architectures (MIPS PowerPC x86), whose FIX_KMAP_BEGIN
is not 0. I will reminder this in my patch. Anyone who need them can get
imformantion there.


Now the new patchs are following. Maybe I sould resend the patch series
with a new tag. If It is time to do that. Can I add this information
"Reviewed-by: Nicolas Pitre <nico@linaro.org>" ?

Thanks,
Liu Hua.

-----------------patch 1-------------------------

Subject: [PATCH 1/2] ARM : fixmap : remove FIX_KMAP_BEGIN and FIX_KMAP_END

It seems that these two variables are not used by non
architecture specific code. And on ARM FIX_KMAP_BEGIN
equals zero; FIX_KMAP_END is totally not used by the
kernel.

This patch removes these two variables. The code will
become clear when I introduce a bugfix on fixmap mapping
region.

Signed-off-by: Liu Hua <sdu.liu@huawei.com>
---
 arch/arm/include/asm/fixmap.h | 12 ++++++++----
 arch/arm/mm/highmem.c         |  6 +++---
 2 files changed, 11 insertions(+), 7 deletions(-)

On Mon, 14 Apr 2014, Liu hua wrote:

> Yes, it seems that FIX_KMAP_BEGIN and FIX_KMAP_END are not as important for
> ARM than that for other architectures (MIPS PowerPC x86), whose FIX_KMAP_BEGIN
> is not 0. I will reminder this in my patch. Anyone who need them can get
> imformantion there.
> 
> 
> Now the new patchs are following. Maybe I sould resend the patch series
> with a new tag. If It is time to do that. Can I add this information
> "Reviewed-by: Nicolas Pitre <nico@linaro.org>" ?
> 
> Thanks,
> Liu Hua.
> 
> -----------------patch 1-------------------------
> 
> Subject: [PATCH 1/2] ARM : fixmap : remove FIX_KMAP_BEGIN and FIX_KMAP_END
> 
> It seems that these two variables are not used by non
> architecture specific code. And on ARM FIX_KMAP_BEGIN
> equals zero; FIX_KMAP_END is totally not used by the
> kernel.
> 
> This patch removes these two variables. The code will
> become clear when I introduce a bugfix on fixmap mapping

s/clear/clearer/

> region.
> 
> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> ---
>  arch/arm/include/asm/fixmap.h | 12 ++++++++----
>  arch/arm/mm/highmem.c         |  6 +++---
>  2 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index bbae919..8675bb9 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -17,9 +17,13 @@
>  #define FIXADDR_TOP		0xfffe0000UL
>  #define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
> 
> -#define FIX_KMAP_BEGIN		0
> -#define FIX_KMAP_END		(FIXADDR_SIZE >> PAGE_SHIFT)
> -
> +/* Notice : FIX_KMAP_END and FIX_KMAP_BEGIN are removed.
> + *
> + * Instead, using FIX_KMAP_NR_PTES to tell the pte number
> + * belonged to fixmap mapping region.
> + *
> + */

Please move this comment to the commit log instead.  This is not 
important enough to occupy that much space in the code.

> +#define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
>  #define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
>  #define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
> 
> @@ -27,7 +31,7 @@ extern void __this_fixmap_does_not_exist(void);
> 
>  static inline unsigned long fix_to_virt(const unsigned int idx)
>  {
> -	if (idx >= FIX_KMAP_END)
> +	if (idx >= FIX_KMAP_NR_PTES)
>  		__this_fixmap_does_not_exist();
>  	return __fix_to_virt(idx);
>  }
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 21b9e1b..e05e8ad 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -63,7 +63,7 @@ void *kmap_atomic(struct page *page)
>  	type = kmap_atomic_idx_push();
> 
>  	idx = type + KM_TYPE_NR * smp_processor_id();
> -	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
> +	vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  	/*
>  	 * With debugging enabled, kunmap_atomic forces that entry to 0.
> @@ -94,7 +94,7 @@ void __kunmap_atomic(void *kvaddr)
>  		if (cache_is_vivt())
>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> +		BUG_ON(vaddr != __fix_to_virt(idx));
>  		set_top_pte(vaddr, __pte(0));
>  #else
>  		(void) idx;  /* to kill a warning */
> @@ -117,7 +117,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
> 
>  	type = kmap_atomic_idx_push();
>  	idx = type + KM_TYPE_NR * smp_processor_id();
> -	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
> +	vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  	BUG_ON(!pte_none(get_top_pte(vaddr)));
>  #endif
> -- 
> 1.9.0

With the above details fixed you may add:

Reviewed-by: Nicolas Pitre <nico@linaro.org>

> -----------------patch 2-------------------------
> 
> 
> 
> Subject: [PATCH 2/2] ARM : change fixmap mapping region to support 32 CPUs
> 
> In 32-bit ARM systems, the fixmap mapping region can support
> no more than 14 CPUs(total: 896k; one CPU: 64K). And we can
> configure NR_CPUS up to 32. So there is a mismatch.
> 
> This patch moves fixmapping region downwards to region
> 0xffc00000-0xffe00000 . Then the fixmap mapping region can
> support up to 32 CPUs
> 
> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> ---
>  Documentation/arm/memory.txt   |  2 +-
>  arch/arm/include/asm/fixmap.h  | 16 ++--------------
>  arch/arm/include/asm/highmem.h |  1 +
>  arch/arm/mm/highmem.c          | 27 +++++++++++++++++++++------
>  arch/arm/mm/mmu.c              |  4 ++++
>  5 files changed, 29 insertions(+), 21 deletions(-)
> 
> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
> index d74e8a5..256c5e0 100644
> --- a/Documentation/arm/memory.txt
> +++ b/Documentation/arm/memory.txt
> @@ -41,7 +41,7 @@ fffe8000	fffeffff	DTCM mapping area for platforms with
>  fffe0000	fffe7fff	ITCM mapping area for platforms with
>  				ITCM mounted inside the CPU.
> 
> -fff00000	fffdffff	Fixmap mapping region.  Addresses provided
> +fffc0000	ffdfffff	Fixmap mapping region.  Addresses provided
>  				by fix_to_virt() will be located here.
> 
>  fee00000	feffffff	Mapping of PCI I/O space. This is a static
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 8675bb9..fb8a5a7 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -1,20 +1,8 @@
>  #ifndef _ASM_FIXMAP_H
>  #define _ASM_FIXMAP_H
> 
> -/*
> - * Nothing too fancy for now.
> - *
> - * On ARM we already have well known fixed virtual addresses imposed by
> - * the architecture such as the vector page which is located at 0xffff0000,
> - * therefore a second level page table is already allocated covering
> - * 0xfff00000 upwards.
> - *
> - * The cache flushing code in proc-xscale.S uses the virtual area between
> - * 0xfffe0000 and 0xfffeffff.
> - */
> -
> -#define FIXADDR_START		0xfff00000UL
> -#define FIXADDR_TOP		0xfffe0000UL
> +#define FIXADDR_START		0xffc00000UL
> +#define FIXADDR_TOP		0xffe00000UL
>  #define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
> 
>  /* Notice : FIX_KMAP_END and FIX_KMAP_BEGIN are removed.
> diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
> index 91b99ab..5355795 100644
> --- a/arch/arm/include/asm/highmem.h
> +++ b/arch/arm/include/asm/highmem.h
> @@ -18,6 +18,7 @@
>  	} while (0)
> 
>  extern pte_t *pkmap_page_table;
> +extern pte_t *fixmap_page_table;
> 
>  extern void *kmap_high(struct page *page);
>  extern void kunmap_high(struct page *page);
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index e05e8ad..45aeaac 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -18,6 +18,21 @@
>  #include <asm/tlbflush.h>
>  #include "mm.h"
> 
> +pte_t *fixmap_page_table;
> +
> +static inline void set_fixmap_pte(int idx, pte_t pte)
> +{
> +	unsigned long vaddr = __fix_to_virt(idx);
> +	set_pte_ext(fixmap_page_table + idx, pte, 0);
> +	local_flush_tlb_kernel_page(vaddr);
> +}
> +
> +static inline pte_t get_fixmap_pte(unsigned long vaddr)
> +{
> +	unsigned long idx = __virt_to_fix(vaddr);
> +	return *(fixmap_page_table + idx);
> +}
> +
>  void *kmap(struct page *page)
>  {
>  	might_sleep();
> @@ -69,14 +84,14 @@ void *kmap_atomic(struct page *page)
>  	 * With debugging enabled, kunmap_atomic forces that entry to 0.
>  	 * Make sure it was indeed properly unmapped.
>  	 */
> -	BUG_ON(!pte_none(get_top_pte(vaddr)));
> +	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>  #endif
>  	/*
>  	 * When debugging is off, kunmap_atomic leaves the previous mapping
>  	 * in place, so the contained TLB flush ensures the TLB is updated
>  	 * with the new mapping.
>  	 */
> -	set_top_pte(vaddr, mk_pte(page, kmap_prot));
> +	set_fixmap_pte(idx, mk_pte(page, kmap_prot));
> 
>  	return (void *)vaddr;
>  }
> @@ -95,7 +110,7 @@ void __kunmap_atomic(void *kvaddr)
>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  		BUG_ON(vaddr != __fix_to_virt(idx));
> -		set_top_pte(vaddr, __pte(0));
> +		set_fixmap_pte(idx, __pte(0));
>  #else
>  		(void) idx;  /* to kill a warning */
>  #endif
> @@ -119,9 +134,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
>  	idx = type + KM_TYPE_NR * smp_processor_id();
>  	vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -	BUG_ON(!pte_none(get_top_pte(vaddr)));
> +	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>  #endif
> -	set_top_pte(vaddr, pfn_pte(pfn, kmap_prot));
> +	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
> 
>  	return (void *)vaddr;
>  }
> @@ -133,5 +148,5 @@ struct page *kmap_atomic_to_page(const void *ptr)
>  	if (vaddr < FIXADDR_START)
>  		return virt_to_page(ptr);
> 
> -	return pte_page(get_top_pte(vaddr));
> +	return pte_page(get_fixmap_pte(vaddr));
>  }
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index b68c6b2..09c0a16 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -35,6 +35,7 @@
>  #include <asm/mach/arch.h>
>  #include <asm/mach/map.h>
>  #include <asm/mach/pci.h>
> +#include <asm/fixmap.h>
> 
>  #include "mm.h"
>  #include "tcm.h"
> @@ -1359,6 +1360,9 @@ static void __init kmap_init(void)
>  #ifdef CONFIG_HIGHMEM
>  	pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
>  		PKMAP_BASE, _PAGE_KERNEL_TABLE);
> +
> +	fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
> +		FIXADDR_START, _PAGE_KERNEL_TABLE);
>  #endif
>  }
> 
> -- 
> 1.9.0

Reviewed-by: Nicolas Pitre <nico@linaro.org>

> 
>

于 2014/4/14 21:50, Nicolas Pitre 写道:
> On Mon, 14 Apr 2014, Liu hua wrote:
> 
>> Yes, it seems that FIX_KMAP_BEGIN and FIX_KMAP_END are not as important for
>> ARM than that for other architectures (MIPS PowerPC x86), whose FIX_KMAP_BEGIN
>> is not 0. I will reminder this in my patch. Anyone who need them can get
>> imformantion there.
>>
>>
>> Now the new patchs are following. Maybe I sould resend the patch series
>> with a new tag. If It is time to do that. Can I add this information
>> "Reviewed-by: Nicolas Pitre <nico@linaro.org>" ?
>>
>> Thanks,
>> Liu Hua.
>>
>> -----------------patch 1-------------------------
>>
>> Subject: [PATCH 1/2] ARM : fixmap : remove FIX_KMAP_BEGIN and FIX_KMAP_END
>>
>> It seems that these two variables are not used by non
>> architecture specific code. And on ARM FIX_KMAP_BEGIN
>> equals zero; FIX_KMAP_END is totally not used by the
>> kernel.
>>
>> This patch removes these two variables. The code will
>> become clear when I introduce a bugfix on fixmap mapping
> 
> s/clear/clearer/
> 
>> region.
>>
>> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
>> ---
>>  arch/arm/include/asm/fixmap.h | 12 ++++++++----
>>  arch/arm/mm/highmem.c         |  6 +++---
>>  2 files changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
>> index bbae919..8675bb9 100644
>> --- a/arch/arm/include/asm/fixmap.h
>> +++ b/arch/arm/include/asm/fixmap.h
>> @@ -17,9 +17,13 @@
>>  #define FIXADDR_TOP		0xfffe0000UL
>>  #define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
>>
>> -#define FIX_KMAP_BEGIN		0
>> -#define FIX_KMAP_END		(FIXADDR_SIZE >> PAGE_SHIFT)
>> -
>> +/* Notice : FIX_KMAP_END and FIX_KMAP_BEGIN are removed.
>> + *
>> + * Instead, using FIX_KMAP_NR_PTES to tell the pte number
>> + * belonged to fixmap mapping region.
>> + *
>> + */
> 
> Please move this comment to the commit log instead.  This is not 
> important enough to occupy that much space in the code.
> 
>> +#define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
>>  #define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
>>  #define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
>>
>> @@ -27,7 +31,7 @@ extern void __this_fixmap_does_not_exist(void);
>>
>>  static inline unsigned long fix_to_virt(const unsigned int idx)
>>  {
>> -	if (idx >= FIX_KMAP_END)
>> +	if (idx >= FIX_KMAP_NR_PTES)
>>  		__this_fixmap_does_not_exist();
>>  	return __fix_to_virt(idx);
>>  }
>> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
>> index 21b9e1b..e05e8ad 100644
>> --- a/arch/arm/mm/highmem.c
>> +++ b/arch/arm/mm/highmem.c
>> @@ -63,7 +63,7 @@ void *kmap_atomic(struct page *page)
>>  	type = kmap_atomic_idx_push();
>>
>>  	idx = type + KM_TYPE_NR * smp_processor_id();
>> -	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>> +	vaddr = __fix_to_virt(idx);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>>  	/*
>>  	 * With debugging enabled, kunmap_atomic forces that entry to 0.
>> @@ -94,7 +94,7 @@ void __kunmap_atomic(void *kvaddr)
>>  		if (cache_is_vivt())
>>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>> -		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
>> +		BUG_ON(vaddr != __fix_to_virt(idx));
>>  		set_top_pte(vaddr, __pte(0));
>>  #else
>>  		(void) idx;  /* to kill a warning */
>> @@ -117,7 +117,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>>
>>  	type = kmap_atomic_idx_push();
>>  	idx = type + KM_TYPE_NR * smp_processor_id();
>> -	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>> +	vaddr = __fix_to_virt(idx);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>>  	BUG_ON(!pte_none(get_top_pte(vaddr)));
>>  #endif
>> -- 
>> 1.9.0
> 
> With the above details fixed you may add:
> 
> Reviewed-by: Nicolas Pitre <nico@linaro.org>
> 
>> -----------------patch 2-------------------------
>>
>>
>>
>> Subject: [PATCH 2/2] ARM : change fixmap mapping region to support 32 CPUs
>>
>> In 32-bit ARM systems, the fixmap mapping region can support
>> no more than 14 CPUs(total: 896k; one CPU: 64K). And we can
>> configure NR_CPUS up to 32. So there is a mismatch.
>>
>> This patch moves fixmapping region downwards to region
>> 0xffc00000-0xffe00000 . Then the fixmap mapping region can
>> support up to 32 CPUs
>>
>> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
>> ---
>>  Documentation/arm/memory.txt   |  2 +-
>>  arch/arm/include/asm/fixmap.h  | 16 ++--------------
>>  arch/arm/include/asm/highmem.h |  1 +
>>  arch/arm/mm/highmem.c          | 27 +++++++++++++++++++++------
>>  arch/arm/mm/mmu.c              |  4 ++++
>>  5 files changed, 29 insertions(+), 21 deletions(-)
>>
>> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
>> index d74e8a5..256c5e0 100644
>> --- a/Documentation/arm/memory.txt
>> +++ b/Documentation/arm/memory.txt
>> @@ -41,7 +41,7 @@ fffe8000	fffeffff	DTCM mapping area for platforms with
>>  fffe0000	fffe7fff	ITCM mapping area for platforms with
>>  				ITCM mounted inside the CPU.
>>
>> -fff00000	fffdffff	Fixmap mapping region.  Addresses provided
>> +fffc0000	ffdfffff	Fixmap mapping region.  Addresses provided
>>  				by fix_to_virt() will be located here.
>>
>>  fee00000	feffffff	Mapping of PCI I/O space. This is a static
>> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
>> index 8675bb9..fb8a5a7 100644
>> --- a/arch/arm/include/asm/fixmap.h
>> +++ b/arch/arm/include/asm/fixmap.h
>> @@ -1,20 +1,8 @@
>>  #ifndef _ASM_FIXMAP_H
>>  #define _ASM_FIXMAP_H
>>
>> -/*
>> - * Nothing too fancy for now.
>> - *
>> - * On ARM we already have well known fixed virtual addresses imposed by
>> - * the architecture such as the vector page which is located at 0xffff0000,
>> - * therefore a second level page table is already allocated covering
>> - * 0xfff00000 upwards.
>> - *
>> - * The cache flushing code in proc-xscale.S uses the virtual area between
>> - * 0xfffe0000 and 0xfffeffff.
>> - */
>> -
>> -#define FIXADDR_START		0xfff00000UL
>> -#define FIXADDR_TOP		0xfffe0000UL
>> +#define FIXADDR_START		0xffc00000UL
>> +#define FIXADDR_TOP		0xffe00000UL
>>  #define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
>>
>>  /* Notice : FIX_KMAP_END and FIX_KMAP_BEGIN are removed.
>> diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
>> index 91b99ab..5355795 100644
>> --- a/arch/arm/include/asm/highmem.h
>> +++ b/arch/arm/include/asm/highmem.h
>> @@ -18,6 +18,7 @@
>>  	} while (0)
>>
>>  extern pte_t *pkmap_page_table;
>> +extern pte_t *fixmap_page_table;
>>
>>  extern void *kmap_high(struct page *page);
>>  extern void kunmap_high(struct page *page);
>> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
>> index e05e8ad..45aeaac 100644
>> --- a/arch/arm/mm/highmem.c
>> +++ b/arch/arm/mm/highmem.c
>> @@ -18,6 +18,21 @@
>>  #include <asm/tlbflush.h>
>>  #include "mm.h"
>>
>> +pte_t *fixmap_page_table;
>> +
>> +static inline void set_fixmap_pte(int idx, pte_t pte)
>> +{
>> +	unsigned long vaddr = __fix_to_virt(idx);
>> +	set_pte_ext(fixmap_page_table + idx, pte, 0);
>> +	local_flush_tlb_kernel_page(vaddr);
>> +}
>> +
>> +static inline pte_t get_fixmap_pte(unsigned long vaddr)
>> +{
>> +	unsigned long idx = __virt_to_fix(vaddr);
>> +	return *(fixmap_page_table + idx);
>> +}
>> +
>>  void *kmap(struct page *page)
>>  {
>>  	might_sleep();
>> @@ -69,14 +84,14 @@ void *kmap_atomic(struct page *page)
>>  	 * With debugging enabled, kunmap_atomic forces that entry to 0.
>>  	 * Make sure it was indeed properly unmapped.
>>  	 */
>> -	BUG_ON(!pte_none(get_top_pte(vaddr)));
>> +	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>>  #endif
>>  	/*
>>  	 * When debugging is off, kunmap_atomic leaves the previous mapping
>>  	 * in place, so the contained TLB flush ensures the TLB is updated
>>  	 * with the new mapping.
>>  	 */
>> -	set_top_pte(vaddr, mk_pte(page, kmap_prot));
>> +	set_fixmap_pte(idx, mk_pte(page, kmap_prot));
>>
>>  	return (void *)vaddr;
>>  }
>> @@ -95,7 +110,7 @@ void __kunmap_atomic(void *kvaddr)
>>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>>  		BUG_ON(vaddr != __fix_to_virt(idx));
>> -		set_top_pte(vaddr, __pte(0));
>> +		set_fixmap_pte(idx, __pte(0));
>>  #else
>>  		(void) idx;  /* to kill a warning */
>>  #endif
>> @@ -119,9 +134,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
>>  	idx = type + KM_TYPE_NR * smp_processor_id();
>>  	vaddr = __fix_to_virt(idx);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>> -	BUG_ON(!pte_none(get_top_pte(vaddr)));
>> +	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>>  #endif
>> -	set_top_pte(vaddr, pfn_pte(pfn, kmap_prot));
>> +	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
>>
>>  	return (void *)vaddr;
>>  }
>> @@ -133,5 +148,5 @@ struct page *kmap_atomic_to_page(const void *ptr)
>>  	if (vaddr < FIXADDR_START)
>>  		return virt_to_page(ptr);
>>
>> -	return pte_page(get_top_pte(vaddr));
>> +	return pte_page(get_fixmap_pte(vaddr));
>>  }
>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>> index b68c6b2..09c0a16 100644
>> --- a/arch/arm/mm/mmu.c
>> +++ b/arch/arm/mm/mmu.c
>> @@ -35,6 +35,7 @@
>>  #include <asm/mach/arch.h>
>>  #include <asm/mach/map.h>
>>  #include <asm/mach/pci.h>
>> +#include <asm/fixmap.h>
>>
>>  #include "mm.h"
>>  #include "tcm.h"
>> @@ -1359,6 +1360,9 @@ static void __init kmap_init(void)
>>  #ifdef CONFIG_HIGHMEM
>>  	pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
>>  		PKMAP_BASE, _PAGE_KERNEL_TABLE);
>> +
>> +	fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
>> +		FIXADDR_START, _PAGE_KERNEL_TABLE);
>>  #endif
>>  }
>>
>> -- 
>> 1.9.0
> 
> Reviewed-by: Nicolas Pitre <nico@linaro.org>
> 
>>
>>
Ok, I will send the patch series with tag "v3". If there is no
bothersome details. you can add "Reviewed-by:" at than time!

Thanks,
Liu Hua