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kernel-ark/include/asm-sh/page.h
Martin Schwidefsky 2f569afd9c 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>
2008-02-08 09:22:42 -08:00

182 lines
5.4 KiB
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#ifndef __ASM_SH_PAGE_H
#define __ASM_SH_PAGE_H
/*
* Copyright (C) 1999 Niibe Yutaka
*/
#include <linux/const.h>
/* PAGE_SHIFT determines the page size */
#if defined(CONFIG_PAGE_SIZE_4KB)
# define PAGE_SHIFT 12
#elif defined(CONFIG_PAGE_SIZE_8KB)
# define PAGE_SHIFT 13
#elif defined(CONFIG_PAGE_SIZE_64KB)
# define PAGE_SHIFT 16
#else
# error "Bogus kernel page size?"
#endif
#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#define PTE_MASK PAGE_MASK
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
#if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
#define HPAGE_SHIFT 16
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_256K)
#define HPAGE_SHIFT 18
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
#define HPAGE_SHIFT 20
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
#define HPAGE_SHIFT 22
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_64MB)
#define HPAGE_SHIFT 26
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_512MB)
#define HPAGE_SHIFT 29
#endif
#ifdef CONFIG_HUGETLB_PAGE
#define HPAGE_SIZE (1UL << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE-1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT-PAGE_SHIFT)
#endif
#ifndef __ASSEMBLY__
extern unsigned long shm_align_mask;
extern unsigned long max_low_pfn, min_low_pfn;
extern unsigned long memory_start, memory_end;
extern void clear_page(void *to);
extern void copy_page(void *to, void *from);
#if !defined(CONFIG_CACHE_OFF) && defined(CONFIG_MMU) && \
(defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB))
struct page;
struct vm_area_struct;
extern void clear_user_page(void *to, unsigned long address, struct page *page);
#ifdef CONFIG_CPU_SH4
extern void copy_user_highpage(struct page *to, struct page *from,
unsigned long vaddr, struct vm_area_struct *vma);
#define __HAVE_ARCH_COPY_USER_HIGHPAGE
#endif
#else
#define clear_user_page(page, vaddr, pg) clear_page(page)
#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)
#endif
/*
* These are used to make use of C type-checking..
*/
#ifdef CONFIG_X2TLB
typedef struct { unsigned long pte_low, pte_high; } pte_t;
typedef struct { unsigned long long pgprot; } pgprot_t;
typedef struct { unsigned long long pgd; } pgd_t;
#define pte_val(x) \
((x).pte_low | ((unsigned long long)(x).pte_high << 32))
#define __pte(x) \
({ pte_t __pte = {(x), ((unsigned long long)(x)) >> 32}; __pte; })
#elif defined(CONFIG_SUPERH32)
typedef struct { unsigned long pte_low; } pte_t;
typedef struct { unsigned long pgprot; } pgprot_t;
typedef struct { unsigned long pgd; } pgd_t;
#define pte_val(x) ((x).pte_low)
#define __pte(x) ((pte_t) { (x) } )
#else
typedef struct { unsigned long long pte_low; } pte_t;
typedef struct { unsigned long pgprot; } pgprot_t;
typedef struct { unsigned long pgd; } pgd_t;
#define pte_val(x) ((x).pte_low)
#define __pte(x) ((pte_t) { (x) } )
#endif
#define pgd_val(x) ((x).pgd)
#define pgprot_val(x) ((x).pgprot)
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
typedef struct page *pgtable_t;
#endif /* !__ASSEMBLY__ */
/*
* __MEMORY_START and SIZE are the physical addresses and size of RAM.
*/
#define __MEMORY_START CONFIG_MEMORY_START
#define __MEMORY_SIZE CONFIG_MEMORY_SIZE
/*
* PAGE_OFFSET is the virtual address of the start of kernel address
* space.
*/
#define PAGE_OFFSET CONFIG_PAGE_OFFSET
/*
* Virtual to physical RAM address translation.
*
* In 29 bit mode, the physical offset of RAM from address 0 is visible in
* the kernel virtual address space, and thus we don't have to take
* this into account when translating. However in 32 bit mode this offset
* is not visible (it is part of the PMB mapping) and so needs to be
* added or subtracted as required.
*/
#ifdef CONFIG_32BIT
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET+__MEMORY_START)
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET-__MEMORY_START))
#else
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
#endif
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
/*
* PFN = physical frame number (ie PFN 0 == physical address 0)
* PFN_START is the PFN of the first page of RAM. By defining this we
* don't have struct page entries for the portion of address space
* between physical address 0 and the start of RAM.
*/
#define PFN_START (__MEMORY_START >> PAGE_SHIFT)
#define ARCH_PFN_OFFSET (PFN_START)
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
#ifdef CONFIG_FLATMEM
#define pfn_valid(pfn) ((pfn) >= min_low_pfn && (pfn) < max_low_pfn)
#endif
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#include <asm-generic/memory_model.h>
#include <asm-generic/page.h>
/* vDSO support */
#ifdef CONFIG_VSYSCALL
#define __HAVE_ARCH_GATE_AREA
#endif
/*
* Some drivers need to perform DMA into kmalloc'ed buffers
* and so we have to increase the kmalloc minalign for this.
*/
#define ARCH_KMALLOC_MINALIGN L1_CACHE_BYTES
#ifdef CONFIG_SUPERH64
/*
* While BYTES_PER_WORD == 4 on the current sh64 ABI, GCC will still
* happily generate {ld/st}.q pairs, requiring us to have 8-byte
* alignment to avoid traps. The kmalloc alignment is gauranteed by
* virtue of L1_CACHE_BYTES, requiring this to only be special cased
* for slab caches.
*/
#define ARCH_SLAB_MINALIGN 8
#endif
#endif /* __ASM_SH_PAGE_H */
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