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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2008-02-08 15:22:04 +0300
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 20:22:42 +0300
commit2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4 (patch)
tree23a31763887d9505e62e9d7cc8ec2fa4b86bd380 /include/asm-m68k
parent13214adf738abc92b0a00c0763fd3be79eebaa7c (diff)
downloadlinux-2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4.tar.xz
CONFIG_HIGHPTE vs. sub-page page tables.
Background: I've implemented 1K/2K page tables for s390. These sub-page page tables are required to properly support the s390 virtualization instruction with KVM. The SIE instruction requires that the page tables have 256 page table entries (pte) followed by 256 page status table entries (pgste). The pgstes are only required if the process is using the SIE instruction. The pgstes are updated by the hardware and by the hypervisor for a number of reasons, one of them is dirty and reference bit tracking. To avoid wasting memory the standard pte table allocation should return 1K/2K (31/64 bit) and 2K/4K if the process is using SIE. Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means the s390 version for pte_alloc_one cannot return a pointer to a struct page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one cannot return a pointer to a pte either, since that would require more than 32 bit for the return value of pte_alloc_one (and the pte * would not be accessible since its not kmapped). Solution: The only solution I found to this dilemma is a new typedef: a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a later patch. For everybody else it will be a (struct page *). The additional problem with the initialization of the ptl lock and the NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and a destructor pgtable_page_dtor. The page table allocation and free functions need to call these two whenever a page table page is allocated or freed. pmd_populate will get a pgtable_t instead of a struct page pointer. To get the pgtable_t back from a pmd entry that has been installed with pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page call in free_pte_range and apply_to_pte_range. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-m68k')
-rw-r--r--include/asm-m68k/motorola_pgalloc.h14
-rw-r--r--include/asm-m68k/page.h1
-rw-r--r--include/asm-m68k/sun3_pgalloc.h17
3 files changed, 21 insertions, 11 deletions
diff --git a/include/asm-m68k/motorola_pgalloc.h b/include/asm-m68k/motorola_pgalloc.h
index 500ec9b8b189..d08bf6261df8 100644
--- a/include/asm-m68k/motorola_pgalloc.h
+++ b/include/asm-m68k/motorola_pgalloc.h
@@ -7,7 +7,6 @@
extern pmd_t *get_pointer_table(void);
extern int free_pointer_table(pmd_t *);
-
static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
pte_t *pte;
@@ -28,7 +27,7 @@ static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
free_page((unsigned long) pte);
}
-static inline struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+static inline pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *page = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
pte_t *pte;
@@ -43,19 +42,21 @@ static inline struct page *pte_alloc_one(struct mm_struct *mm, unsigned long add
nocache_page(pte);
}
kunmap(pte);
-
+ pgtable_page_ctor(page);
return page;
}
-static inline void pte_free(struct mm_struct *mm, struct page *page)
+static inline void pte_free(struct mm_struct *mm, pgtable_t page)
{
+ pgtable_page_dtor(page);
cache_page(kmap(page));
kunmap(page);
__free_page(page);
}
-static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *page)
+static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t page)
{
+ pgtable_page_dtor(page);
cache_page(kmap(page));
kunmap(page);
__free_page(page);
@@ -94,10 +95,11 @@ static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *
pmd_set(pmd, pte);
}
-static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, struct page *page)
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page)
{
pmd_set(pmd, page_address(page));
}
+#define pmd_pgtable(pmd) pmd_page(pmd)
static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
{
diff --git a/include/asm-m68k/page.h b/include/asm-m68k/page.h
index 3f29e2a03a43..880c2cbff8a6 100644
--- a/include/asm-m68k/page.h
+++ b/include/asm-m68k/page.h
@@ -91,6 +91,7 @@ typedef struct { unsigned long pte; } pte_t;
typedef struct { unsigned long pmd[16]; } pmd_t;
typedef struct { unsigned long pgd; } pgd_t;
typedef struct { unsigned long pgprot; } pgprot_t;
+typedef struct page *pgtable_t;
#define pte_val(x) ((x).pte)
#define pmd_val(x) ((&x)->pmd[0])
diff --git a/include/asm-m68k/sun3_pgalloc.h b/include/asm-m68k/sun3_pgalloc.h
index a5a91e72714b..d4c83f143816 100644
--- a/include/asm-m68k/sun3_pgalloc.h
+++ b/include/asm-m68k/sun3_pgalloc.h
@@ -26,12 +26,17 @@ static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
free_page((unsigned long) pte);
}
-static inline void pte_free(struct mm_struct *mm, struct page *page)
+static inline void pte_free(struct mm_struct *mm, pgtable_t page)
{
+ pgtable_page_dtor(page);
__free_page(page);
}
-#define __pte_free_tlb(tlb,pte) tlb_remove_page((tlb),(pte))
+#define __pte_free_tlb(tlb,pte) \
+do { \
+ pgtable_page_dtor(pte); \
+ tlb_remove_page((tlb), pte); \
+} while (0)
static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
unsigned long address)
@@ -45,8 +50,8 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
return (pte_t *) (page);
}
-static inline struct page *pte_alloc_one(struct mm_struct *mm,
- unsigned long address)
+static inline pgtable_t pte_alloc_one(struct mm_struct *mm,
+ unsigned long address)
{
struct page *page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
@@ -54,6 +59,7 @@ static inline struct page *pte_alloc_one(struct mm_struct *mm,
return NULL;
clear_highpage(page);
+ pgtable_page_ctor(page);
return page;
}
@@ -63,10 +69,11 @@ static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *
pmd_val(*pmd) = __pa((unsigned long)pte);
}
-static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, struct page *page)
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page)
{
pmd_val(*pmd) = __pa((unsigned long)page_address(page));
}
+#define pmd_pgtable(pmd) pmd_page(pmd)
/*
* allocating and freeing a pmd is trivial: the 1-entry pmd is