Re: [PATCH v2 2/2] ARM : change fixmap mapping region to support 32 CPUs
From: Liu hua
Date: Mon Apr 14 2014 - 08:32:29 EST
ä 2014/4/14 1:34, Nicolas Pitre åé:
> 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@xxxxxxxxxx>" ?
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@xxxxxxxxxx>
---
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@xxxxxxxxxx>
---
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
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