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

From: [email-masked] (Liu hua)
Date: Sun, 13 Apr 2014 21:25:05 +0800

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 <[email-masked]>
> 
> 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 <[email-masked]>
> 

> .
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 <[email-masked]>
Signed-off-by: Liu Hua <[email-masked]>
---
 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