by Liu Hua

[permalink] [raw]

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

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 <[email protected]>" ?
>>
>> 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 <[email protected]>
>> ---
>> 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 <[email protected]>
>
>> -----------------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 <[email protected]>
>> ---
>> 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 <[email protected]>
>
>>
>>
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