[PATCH v2 0/2] change ARM linux memory layout to support 32 CPUs

[PATCH v2 0/2] change ARM linux memory layout to support 32 CPUs

[Liu Hua]

Hi Nicolas or Russell,

This patch series change fixmap mapping region to suppport 32 CPUs.
Because the "top_pmd" covers 0xfffe0000 - 0xffffffff(2M). And part 
is used by vector table. So I move this region down to 0xffc00000
 - 0xffdffff. 


I have tested the patches on arma9(2 CPUs) and arma15(16 CPUs) platforms

BTW, As we know we can configure NR_CPUS up to 32. So we need 2048K 
at most. But for ARM systems with less cpus, there is a waste 
of virtual address. So should we change its size according to
NR_CPUS, as what MIPS linux does ?

Changes from v1:
---------------
- changed documentation for ARM linux memory layout.
- moved fixmap mapping region, not just extended.

Liu Hua (2):
  ARM : DMA : remove useless information about DMA
  ARM : extend fixmap mapping region to support 32 CPUs

 Documentation/arm/memory.txt   |  8 ++------
 arch/arm/include/asm/fixmap.h  |  4 ++--
 arch/arm/include/asm/highmem.h |  1 +
 arch/arm/include/asm/memory.h  |  2 --
 arch/arm/mm/highmem.c          | 10 +++++-----
 arch/arm/mm/mm.h               |  7 +++++++
 arch/arm/mm/mmu.c              |  4 ++++
 mm/highmem.c                   |  1 +
 8 files changed, 22 insertions(+), 15 deletions(-)

-- 
1.9.0

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Liu Hua]

Because commit e9da6e9905e6 has remove custom consistent dma
region. So the related variable and document should be removed

Signed-off-by: Liu Hua <sdu.liu@huawei.com>
---
 Documentation/arm/memory.txt  | 4 ----
 arch/arm/include/asm/memory.h | 2 --
 2 files changed, 6 deletions(-)

diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
index 4bfb9ff..8a361c0 100644
--- a/Documentation/arm/memory.txt
+++ b/Documentation/arm/memory.txt
@@ -44,10 +44,6 @@ fffe0000	fffe7fff	ITCM mapping area for platforms with
 fff00000	fffdffff	Fixmap mapping region.  Addresses provided
 				by fix_to_virt() will be located here.
 
-ffc00000	ffefffff	DMA memory mapping region.  Memory returned
-				by the dma_alloc_xxx functions will be
-				dynamically mapped here.
-
 ff000000	ffbfffff	Reserved for future expansion of DMA
 				mapping region.
 
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 02fa255..2b75146 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -83,8 +83,6 @@
  */
 #define IOREMAP_MAX_ORDER	24
 
-#define CONSISTENT_END		(0xffe00000UL)
-
 #else /* CONFIG_MMU */
 
 /*
-- 
1.9.0

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Marek Szyprowski]

Hello,

On 2014-04-11 10:00, Liu Hua wrote:
> Because commit e9da6e9905e6 has remove custom consistent dma
> region. So the related variable and document should be removed
>
> Signed-off-by: Liu Hua <sdu.liu@huawei.com>

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   Documentation/arm/memory.txt  | 4 ----
>   arch/arm/include/asm/memory.h | 2 --
>   2 files changed, 6 deletions(-)
>
> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
> index 4bfb9ff..8a361c0 100644
> --- a/Documentation/arm/memory.txt
> +++ b/Documentation/arm/memory.txt
> @@ -44,10 +44,6 @@ fffe0000	fffe7fff	ITCM mapping area for platforms with
>   fff00000	fffdffff	Fixmap mapping region.  Addresses provided
>   				by fix_to_virt() will be located here.
>   
> -ffc00000	ffefffff	DMA memory mapping region.  Memory returned
> -				by the dma_alloc_xxx functions will be
> -				dynamically mapped here.
> -
>   ff000000	ffbfffff	Reserved for future expansion of DMA
>   				mapping region.
>   
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 02fa255..2b75146 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -83,8 +83,6 @@
>    */
>   #define IOREMAP_MAX_ORDER	24
>   
> -#define CONSISTENT_END		(0xffe00000UL)
> -
>   #else /* CONFIG_MMU */
>   
>   /*

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Nicolas Pitre]

On Fri, 11 Apr 2014, Liu Hua wrote:

> Because commit e9da6e9905e6 has remove custom consistent dma
> region. So the related variable and document should be removed
> 
> Signed-off-by: Liu Hua <sdu.liu@huawei.com>

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

Incidentally I sent an identical patch to RMK's patch system:

http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8023/1

Either version is fine with me.


Nicolas

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Nicolas Pitre]

On Fri, 11 Apr 2014, Nicolas Pitre wrote:

> On Fri, 11 Apr 2014, Liu Hua wrote:
> 
> > Because commit e9da6e9905e6 has remove custom consistent dma
> > region. So the related variable and document should be removed
> > 
> > Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> 
> Acked-by: Nicolas Pitre <nico@linaro.org>
> 
> Incidentally I sent an identical patch to RMK's patch system:
> 
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8023/1
> 
> Either version is fine with me.

Actually mine is slightly better as I also removed the entry covering 
0xff000000 to 0xffbfffff which is no longer used either.


Nicolas

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Liu hua]

Hi Nicolas,

Your version is better. you tell me this in the former letters.
So I am very sorry to forget to check that.

May be I should remake this second patch to fit your change. What do
you think about that patch?

Liu Hua

On 2014/4/12 11:12, Nicolas Pitre wrote:
> On Fri, 11 Apr 2014, Liu Hua wrote:
> 
>> Because commit e9da6e9905e6 has remove custom consistent dma
>> region. So the related variable and document should be removed
>>
>> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> 
> Acked-by: Nicolas Pitre <nico@linaro.org>
> 
> Incidentally I sent an identical patch to RMK's patch system:
> 
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8023/1
> 
> Either version is fine with me.
> 
> 
> Nicolas
> 
> 

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Nicolas Pitre]

On Sat, 12 Apr 2014, Liu hua wrote:

> Hi Nicolas,
> 
> Your version is better. you tell me this in the former letters.
> So I am very sorry to forget to check that.
> 
> May be I should remake this second patch to fit your change. What do
> you think about that patch?

You may simply drop your first patch and only keep the other two.


Nicolas

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Liu hua]

On 2014/4/12 22:32, Nicolas Pitre write:
> On Sat, 12 Apr 2014, Liu hua wrote:
> 
>> Hi Nicolas,
>>
>> Your version is better. you tell me this in the former letters.
>> So I am very sorry to forget to check that.
>>
>> May be I should remake this second patch to fit your change. What do
>> you think about that patch?
> 
> You may simply drop your first patch and only keep the other two.
> 
Sure. But your patch and my second one both change Document/arm/memory.txt.
I am afraid there will be conflicts when someone tests my patch before
yours getting into the mainline.

Maybe I can spilt the document-changing part to a new patch. And send it
after yours are in the mainline.

Liu Hua
> 
> Nicolas
> 
> 

[PATCH v2 1/2] ARM : DMA : remove useless information about DMA

[Nicolas Pitre]

On Sun, 13 Apr 2014, Liu hua wrote:

> On 2014/4/12 22:32, Nicolas Pitre write:
> > On Sat, 12 Apr 2014, Liu hua wrote:
> > 
> >> Hi Nicolas,
> >>
> >> Your version is better. you tell me this in the former letters.
> >> So I am very sorry to forget to check that.
> >>
> >> May be I should remake this second patch to fit your change. What do
> >> you think about that patch?
> > 
> > You may simply drop your first patch and only keep the other two.
> > 
> Sure. But your patch and my second one both change Document/arm/memory.txt.
> I am afraid there will be conflicts when someone tests my patch before
> yours getting into the mainline.

That's still an easy conflict to fix.  And it is likely that git will 
fix it automatically.


Nicolas

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

[Liu Hua]

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  |  4 ++--
 arch/arm/include/asm/highmem.h |  1 +
 arch/arm/mm/highmem.c          | 10 +++++-----
 arch/arm/mm/mm.h               |  7 +++++++
 arch/arm/mm/mmu.c              |  4 ++++
 mm/highmem.c                   |  1 +
 7 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
index 8a361c0..4bca737 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
+ffc00000	ffdfffff	Fixmap mapping region.  Addresses provided
 				by fix_to_virt() will be located here.
 
 ff000000	ffbfffff	Reserved for future expansion of DMA
diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index bbae919..014a70d 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -13,8 +13,8 @@
  * 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)
 
 #define FIX_KMAP_BEGIN		0
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 21b9e1b..9bc8988 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -69,14 +69,14 @@ 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 +95,7 @@ void __kunmap_atomic(void *kvaddr)
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
 		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
-		set_top_pte(vaddr, __pte(0));
+		set_fixmap_pte(idx, __pte(0));
 #else
 		(void) idx;  /* to kill a warning */
 #endif
@@ -119,9 +119,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + 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;
 }
diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
index 7ea641b..3460d73 100644
--- a/arch/arm/mm/mm.h
+++ b/arch/arm/mm/mm.h
@@ -1,6 +1,7 @@
 #ifdef CONFIG_MMU
 #include <linux/list.h>
 #include <linux/vmalloc.h>
+#include <asm/fixmap.h>
 
 /* the upper-most page table pointer */
 extern pmd_t *top_pmd;
@@ -25,6 +26,12 @@ static inline void set_top_pte(unsigned long va, pte_t pte)
 	local_flush_tlb_kernel_page(va);
 }
 
+static inline void set_fixmap_pte(int idx, pte_t pte)
+{
+	unsigned long vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+	set_pte_ext(fixmap_page_table + idx, pte, 0);
+	local_flush_tlb_kernel_page(vaddr);
+}
 static inline pte_t get_top_pte(unsigned long va)
 {
 	pte_t *ptep = pte_offset_kernel(top_pmd, va);
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
 }
 
diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70c..d0094ba 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -72,6 +72,7 @@ static unsigned int last_pkmap_nr;
 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
 
 pte_t * pkmap_page_table;
+pte_t *fixmap_page_table;
 
 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
 
-- 
1.9.0

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

[Nicolas Pitre]

On Fri, 11 Apr 2014, Liu Hua wrote:

> 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>

Comments below.

> ---
>  Documentation/arm/memory.txt   |  2 +-
>  arch/arm/include/asm/fixmap.h  |  4 ++--
>  arch/arm/include/asm/highmem.h |  1 +
>  arch/arm/mm/highmem.c          | 10 +++++-----
>  arch/arm/mm/mm.h               |  7 +++++++
>  arch/arm/mm/mmu.c              |  4 ++++
>  mm/highmem.c                   |  1 +
>  7 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
> index 8a361c0..4bca737 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
> +ffc00000	ffdfffff	Fixmap mapping region.  Addresses provided
>  				by fix_to_virt() will be located here.
>  
>  ff000000	ffbfffff	Reserved for future expansion of DMA
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index bbae919..014a70d 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -13,8 +13,8 @@
>   * 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)
>  
>  #define FIX_KMAP_BEGIN		0
> 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 21b9e1b..9bc8988 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -69,14 +69,14 @@ 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 +95,7 @@ void __kunmap_atomic(void *kvaddr)
>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> -		set_top_pte(vaddr, __pte(0));
> +		set_fixmap_pte(idx, __pte(0));
>  #else
>  		(void) idx;  /* to kill a warning */
>  #endif
> @@ -119,9 +119,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
>  	idx = type + KM_TYPE_NR * smp_processor_id();
>  	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + 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;
>  }
> diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
> index 7ea641b..3460d73 100644
> --- a/arch/arm/mm/mm.h
> +++ b/arch/arm/mm/mm.h
> @@ -1,6 +1,7 @@
>  #ifdef CONFIG_MMU
>  #include <linux/list.h>
>  #include <linux/vmalloc.h>
> +#include <asm/fixmap.h>
>  
>  /* the upper-most page table pointer */
>  extern pmd_t *top_pmd;
> @@ -25,6 +26,12 @@ static inline void set_top_pte(unsigned long va, pte_t pte)
>  	local_flush_tlb_kernel_page(va);
>  }
>  
> +static inline void set_fixmap_pte(int idx, pte_t pte)
> +{
> +	unsigned long vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
> +	set_pte_ext(fixmap_page_table + idx, pte, 0);
> +	local_flush_tlb_kernel_page(vaddr);
> +}

This has no other users than the code in highmem.c so it probably should 
live there.

Other than that...

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

>  static inline pte_t get_top_pte(unsigned long va)
>  {
>  	pte_t *ptep = pte_offset_kernel(top_pmd, va);
> 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
>  }
>  
> diff --git a/mm/highmem.c b/mm/highmem.c
> index b32b70c..d0094ba 100644
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -72,6 +72,7 @@ static unsigned int last_pkmap_nr;
>  static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
>  
>  pte_t * pkmap_page_table;
> +pte_t *fixmap_page_table;
>  
>  static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
>  
> -- 
> 1.9.0
> 

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

[Liu hua]

On 2014/4/12 11:26, Nicolas Pitre wrote:
> On Fri, 11 Apr 2014, Liu Hua wrote:
> 
>> 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>
> 
> Comments below.
> 
>> ---
>>  Documentation/arm/memory.txt   |  2 +-
>>  arch/arm/include/asm/fixmap.h  |  4 ++--
>>  arch/arm/include/asm/highmem.h |  1 +
>>  arch/arm/mm/highmem.c          | 10 +++++-----
>>  arch/arm/mm/mm.h               |  7 +++++++
>>  arch/arm/mm/mmu.c              |  4 ++++
>>  mm/highmem.c                   |  1 +
>>  7 files changed, 21 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt
>> index 8a361c0..4bca737 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
>> +ffc00000	ffdfffff	Fixmap mapping region.  Addresses provided
>>  				by fix_to_virt() will be located here.
>>  
>>  ff000000	ffbfffff	Reserved for future expansion of DMA
>> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
>> index bbae919..014a70d 100644
>> --- a/arch/arm/include/asm/fixmap.h
>> +++ b/arch/arm/include/asm/fixmap.h
>> @@ -13,8 +13,8 @@
>>   * 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)
>>  
>>  #define FIX_KMAP_BEGIN		0
>> 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 21b9e1b..9bc8988 100644
>> --- a/arch/arm/mm/highmem.c
>> +++ b/arch/arm/mm/highmem.c
>> @@ -69,14 +69,14 @@ 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 +95,7 @@ void __kunmap_atomic(void *kvaddr)
>>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>>  #ifdef CONFIG_DEBUG_HIGHMEM
>>  		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
>> -		set_top_pte(vaddr, __pte(0));
>> +		set_fixmap_pte(idx, __pte(0));
>>  #else
>>  		(void) idx;  /* to kill a warning */
>>  #endif
>> @@ -119,9 +119,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
>>  	idx = type + KM_TYPE_NR * smp_processor_id();
>>  	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + 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;
>>  }
>> diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
>> index 7ea641b..3460d73 100644
>> --- a/arch/arm/mm/mm.h
>> +++ b/arch/arm/mm/mm.h
>> @@ -1,6 +1,7 @@
>>  #ifdef CONFIG_MMU
>>  #include <linux/list.h>
>>  #include <linux/vmalloc.h>
>> +#include <asm/fixmap.h>
>>  
>>  /* the upper-most page table pointer */
>>  extern pmd_t *top_pmd;
>> @@ -25,6 +26,12 @@ static inline void set_top_pte(unsigned long va, pte_t pte)
>>  	local_flush_tlb_kernel_page(va);
>>  }
>>  
>> +static inline void set_fixmap_pte(int idx, pte_t pte)
>> +{
>> +	unsigned long vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>> +	set_pte_ext(fixmap_page_table + idx, pte, 0);
>> +	local_flush_tlb_kernel_page(vaddr);
>> +}
> 
> This has no other users than the code in highmem.c so it probably should 
> live there.
> 
> Other than that...
> 
> Acked-by: Nicolas Pitre <nico@linaro.org>
> 

> .
> 
Hi Nicolas.

Sure, your suggestion made my patch looks better. How about that :

Thanks,
Liu Hua
-------------------------------------------------

Changes from v2:
	moved new codes to highmem.c as more as possible.
	unchanged Document/arm/memory.txt.


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

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Liu Hua <sdu.liu@huawei.com>
---
 arch/arm/include/asm/fixmap.h  |  4 ++--
 arch/arm/include/asm/highmem.h |  1 +
 arch/arm/mm/highmem.c          | 28 ++++++++++++++++++++++------
 arch/arm/mm/mmu.c              |  4 ++++
 4 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index bbae919..014a70d 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -13,8 +13,8 @@
  * 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)

 #define FIX_KMAP_BEGIN		0
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 21b9e1b..fa97896 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -18,6 +18,22 @@
 #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(FIX_KMAP_BEGIN + 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);
+	idx -= FIX_KMAP_BEGIN;
+	return *(fixmap_page_table + idx);
+}
+
 void *kmap(struct page *page)
 {
 	might_sleep();
@@ -69,14 +85,14 @@ 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 +111,7 @@ void __kunmap_atomic(void *kvaddr)
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
 		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
-		set_top_pte(vaddr, __pte(0));
+		set_fixmap_pte(idx, __pte(0));
 #else
 		(void) idx;  /* to kill a warning */
 #endif
@@ -119,9 +135,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + 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 +149,5 @@ 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

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

[Nicolas Pitre]

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.


> -------------------------------------------------
> 
> Changes from v2:
> 	moved new codes to highmem.c as more as possible.
> 	unchanged Document/arm/memory.txt.
> 
> 
> 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
> 
> Acked-by: Nicolas Pitre <nico@linaro.org>
> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> ---
>  arch/arm/include/asm/fixmap.h  |  4 ++--
>  arch/arm/include/asm/highmem.h |  1 +
>  arch/arm/mm/highmem.c          | 28 ++++++++++++++++++++++------
>  arch/arm/mm/mmu.c              |  4 ++++
>  4 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index bbae919..014a70d 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -13,8 +13,8 @@
>   * 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)
> 
>  #define FIX_KMAP_BEGIN		0
> 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 21b9e1b..fa97896 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -18,6 +18,22 @@
>  #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(FIX_KMAP_BEGIN + 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);
> +	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.

> +}
> +
>  void *kmap(struct page *page)
>  {
>  	might_sleep();
> @@ -69,14 +85,14 @@ 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)));

This is therefore also wrong.  It should be
fixmap_page_table + idx + FIX_KMAP_BEGIN.

>  #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 +111,7 @@ void __kunmap_atomic(void *kvaddr)
>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> -		set_top_pte(vaddr, __pte(0));
> +		set_fixmap_pte(idx, __pte(0));
>  #else
>  		(void) idx;  /* to kill a warning */
>  #endif
> @@ -119,9 +135,9 @@ void *kmap_atomic_pfn(unsigned long pfn)
>  	idx = type + KM_TYPE_NR * smp_processor_id();
>  	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>  #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

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

[Liu hua]

? 2014/4/14 1:34, Nicolas Pitre ??:
> 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(-)

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.
+ *
+ */
+#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




-----------------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

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

[Nicolas Pitre]

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>

> 
> 

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

[Liu hua]

? 2014/4/14 21:50, Nicolas Pitre ??:
> 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

[PATCH v2 0/2] change ARM linux memory layout to support 32 CPUs

[Nicolas Pitre]

On Fri, 11 Apr 2014, Liu Hua wrote:

> Hi Nicolas or Russell,
> 
> This patch series change fixmap mapping region to suppport 32 CPUs.
> Because the "top_pmd" covers 0xfffe0000 - 0xffffffff(2M). And part 
> is used by vector table. So I move this region down to 0xffc00000
>  - 0xffdffff. 
> 
> 
> I have tested the patches on arma9(2 CPUs) and arma15(16 CPUs) platforms
> 
> BTW, As we know we can configure NR_CPUS up to 32. So we need 2048K 
> at most. But for ARM systems with less cpus, there is a waste 
> of virtual address. So should we change its size according to
> NR_CPUS, as what MIPS linux does ?

It is probably not worth the bother.  We lived with this area reserved 
for static DMA mapping while there was no longer any DMA mapped there 
for quite a while.



> 
> Changes from v1:
> ---------------
> - changed documentation for ARM linux memory layout.
> - moved fixmap mapping region, not just extended.
> 
> Liu Hua (2):
>   ARM : DMA : remove useless information about DMA
>   ARM : extend fixmap mapping region to support 32 CPUs
> 
>  Documentation/arm/memory.txt   |  8 ++------
>  arch/arm/include/asm/fixmap.h  |  4 ++--
>  arch/arm/include/asm/highmem.h |  1 +
>  arch/arm/include/asm/memory.h  |  2 --
>  arch/arm/mm/highmem.c          | 10 +++++-----
>  arch/arm/mm/mm.h               |  7 +++++++
>  arch/arm/mm/mmu.c              |  4 ++++
>  mm/highmem.c                   |  1 +
>  8 files changed, 22 insertions(+), 15 deletions(-)
> 
> -- 
> 1.9.0
>