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kernel-ark/include/asm-parisc/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

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#ifndef _PARISC_PAGE_H
#define _PARISC_PAGE_H
#include <linux/const.h>
#if defined(CONFIG_PARISC_PAGE_SIZE_4KB)
# define PAGE_SHIFT 12
#elif defined(CONFIG_PARISC_PAGE_SIZE_16KB)
# define PAGE_SHIFT 14
#elif defined(CONFIG_PARISC_PAGE_SIZE_64KB)
# define PAGE_SHIFT 16
#else
# error "unknown default kernel page size"
#endif
#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#ifndef __ASSEMBLY__
#include <asm/types.h>
#include <asm/cache.h>
#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
#define copy_page(to,from) copy_user_page_asm((void *)(to), (void *)(from))
struct page;
void copy_user_page_asm(void *to, void *from);
void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
struct page *pg);
void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
/*
* These are used to make use of C type-checking..
*/
#define STRICT_MM_TYPECHECKS
#ifdef STRICT_MM_TYPECHECKS
typedef struct { unsigned long pte;
#if !defined(CONFIG_64BIT)
unsigned long future_flags;
/* XXX: it's possible to remove future_flags and change BITS_PER_PTE_ENTRY
to 2, but then strangely the identical 32bit kernel boots on a
c3000(pa20), but not any longer on a 715(pa11).
Still investigating... HelgeD.
*/
#endif
} pte_t; /* either 32 or 64bit */
/* NOTE: even on 64 bits, these entries are __u32 because we allocate
* the pmd and pgd in ZONE_DMA (i.e. under 4GB) */
typedef struct { __u32 pmd; } pmd_t;
typedef struct { __u32 pgd; } pgd_t;
typedef struct { unsigned long pgprot; } pgprot_t;
#define pte_val(x) ((x).pte)
/* These do not work lvalues, so make sure we don't use them as such. */
#define pmd_val(x) ((x).pmd + 0)
#define pgd_val(x) ((x).pgd + 0)
#define pgprot_val(x) ((x).pgprot)
#define __pte(x) ((pte_t) { (x) } )
#define __pmd(x) ((pmd_t) { (x) } )
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
#define __pmd_val_set(x,n) (x).pmd = (n)
#define __pgd_val_set(x,n) (x).pgd = (n)
#else
/*
* .. while these make it easier on the compiler
*/
typedef unsigned long pte_t;
typedef __u32 pmd_t;
typedef __u32 pgd_t;
typedef unsigned long pgprot_t;
#define pte_val(x) (x)
#define pmd_val(x) (x)
#define pgd_val(x) (x)
#define pgprot_val(x) (x)
#define __pte(x) (x)
#define __pmd(x) (x)
#define __pgd(x) (x)
#define __pgprot(x) (x)
#define __pmd_val_set(x,n) (x) = (n)
#define __pgd_val_set(x,n) (x) = (n)
#endif /* STRICT_MM_TYPECHECKS */
typedef struct page *pgtable_t;
typedef struct __physmem_range {
unsigned long start_pfn;
unsigned long pages; /* PAGE_SIZE pages */
} physmem_range_t;
extern physmem_range_t pmem_ranges[];
extern int npmem_ranges;
#endif /* !__ASSEMBLY__ */
/* WARNING: The definitions below must match exactly to sizeof(pte_t)
* etc
*/
#ifdef CONFIG_64BIT
#define BITS_PER_PTE_ENTRY 3
#define BITS_PER_PMD_ENTRY 2
#define BITS_PER_PGD_ENTRY 2
#else
#define BITS_PER_PTE_ENTRY 3
#define BITS_PER_PMD_ENTRY 2
#define BITS_PER_PGD_ENTRY BITS_PER_PMD_ENTRY
#endif
#define PGD_ENTRY_SIZE (1UL << BITS_PER_PGD_ENTRY)
#define PMD_ENTRY_SIZE (1UL << BITS_PER_PMD_ENTRY)
#define PTE_ENTRY_SIZE (1UL << BITS_PER_PTE_ENTRY)
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
#define LINUX_GATEWAY_SPACE 0
/* This governs the relationship between virtual and physical addresses.
* If you alter it, make sure to take care of our various fixed mapping
* segments in fixmap.h */
#ifdef CONFIG_64BIT
#define __PAGE_OFFSET (0x40000000) /* 1GB */
#else
#define __PAGE_OFFSET (0x10000000) /* 256MB */
#endif
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
/* The size of the gateway page (we leave lots of room for expansion) */
#define GATEWAY_PAGE_SIZE 0x4000
/* The start of the actual kernel binary---used in vmlinux.lds.S
* Leave some space after __PAGE_OFFSET for detecting kernel null
* ptr derefs */
#define KERNEL_BINARY_TEXT_START (__PAGE_OFFSET + 0x100000)
/* These macros don't work for 64-bit C code -- don't allow in C at all */
#ifdef __ASSEMBLY__
# define PA(x) ((x)-__PAGE_OFFSET)
# define VA(x) ((x)+__PAGE_OFFSET)
#endif
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
#ifndef CONFIG_DISCONTIGMEM
#define pfn_valid(pfn) ((pfn) < max_mapnr)
#endif /* CONFIG_DISCONTIGMEM */
#ifdef CONFIG_HUGETLB_PAGE
#define HPAGE_SHIFT 22 /* 4MB (is this fixed?) */
#define HPAGE_SIZE ((1UL) << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
#endif
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
#define virt_to_page(kaddr) pfn_to_page(__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>
#endif /* _PARISC_PAGE_H */
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