pgtable.h

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/*
 *  include/asm-s390/pgtable.h
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Hartmut Penner ([e-mail])
 *               Ulrich Weigand ([e-mail])
 *               Martin Schwidefsky ([e-mail])
 *
 *  Derived from "include/asm-i386/pgtable.h"
 */

#ifndef _ASM_S390_PGTABLE_H
#define _ASM_S390_PGTABLE_H

/*
 * The Linux memory management assumes a three-level page table setup. For
 * s390 31 bit we "fold" the mid level into the top-level page table, so
 * that we physically have the same two-level page table as the s390 mmu
 * expects in 31 bit mode. For s390 64 bit we use three of the five levels
 * the hardware provides (region first and region second tables are not
 * used).
 *
 * The "pgd_xxx()" functions are trivial for a folded two-level
 * setup: the pgd is never bad, and a pmd always exists (as it's folded
 * into the pgd entry)
 *
 * This file contains the functions and defines necessary to modify and use
 * the S390 page table tree.
 */
#ifndef __ASSEMBLY__
#include <asm/bug.h>
#include <asm/processor.h>
#include <linux/threads.h>

struct vm_area_struct; /* forward declaration (include/linux/mm.h) */

extern pgd_t swapper_pg_dir[] __attribute__ ((aligned (4096)));
extern void paging_init(void);

/*
 * The S390 doesn't have any external MMU info: the kernel page
 * tables contain all the necessary information.
 */
#define update_mmu_cache(vma, address, pte)     do { } while (0)

/*
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
extern char empty_zero_page[PAGE_SIZE];
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
#endif /* !__ASSEMBLY__ */

/*
 * PMD_SHIFT determines the size of the area a second-level page
 * table can map
 * PGDIR_SHIFT determines what a third-level page table entry can map
 */
#ifndef __s390x__
# define PMD_SHIFT	22
# define PGDIR_SHIFT	22
#else /* __s390x__ */
# define PMD_SHIFT	21
# define PGDIR_SHIFT	31
#endif /* __s390x__ */

#define PMD_SIZE        (1UL << PMD_SHIFT)
#define PMD_MASK        (~(PMD_SIZE-1))
#define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
#define PGDIR_MASK      (~(PGDIR_SIZE-1))

/*
 * entries per page directory level: the S390 is two-level, so
 * we don't really have any PMD directory physically.
 * for S390 segment-table entries are combined to one PGD
 * that leads to 1024 pte per pgd
 */
#ifndef __s390x__
# define PTRS_PER_PTE    1024
# define PTRS_PER_PMD    1
# define PTRS_PER_PGD    512
#else /* __s390x__ */
# define PTRS_PER_PTE    512
# define PTRS_PER_PMD    1024
# define PTRS_PER_PGD    2048
#endif /* __s390x__ */

/*
 * pgd entries used up by user/kernel:
 */
#ifndef __s390x__
# define USER_PTRS_PER_PGD  512
# define USER_PGD_PTRS      512
# define KERNEL_PGD_PTRS    512
# define FIRST_USER_PGD_NR  0
#else /* __s390x__ */
# define USER_PTRS_PER_PGD  2048
# define USER_PGD_PTRS      2048
# define KERNEL_PGD_PTRS    2048
# define FIRST_USER_PGD_NR  0
#endif /* __s390x__ */

#define pte_ERROR(e) \
	printk("%s:%d: bad pte %p.\n", __FILE__, __LINE__, (void *) pte_val(e))
#define pmd_ERROR(e) \
	printk("%s:%d: bad pmd %p.\n", __FILE__, __LINE__, (void *) pmd_val(e))
#define pgd_ERROR(e) \
	printk("%s:%d: bad pgd %p.\n", __FILE__, __LINE__, (void *) pgd_val(e))

#ifndef __ASSEMBLY__
/*
 * Just any arbitrary offset to the start of the vmalloc VM area: the
 * current 8MB value just means that there will be a 8MB "hole" after the
 * physical memory until the kernel virtual memory starts.  That means that
 * any out-of-bounds memory accesses will hopefully be caught.
 * The vmalloc() routines leaves a hole of 4kB between each vmalloced
 * area for the same reason. ;)
 */
#define VMALLOC_OFFSET  (8*1024*1024)
#define VMALLOC_START   (((unsigned long) high_memory + VMALLOC_OFFSET) \
			 & ~(VMALLOC_OFFSET-1))
#ifndef __s390x__
# define VMALLOC_END     (0x7fffffffL)
#else /* __s390x__ */
# define VMALLOC_END     (0x40000000000L)
#endif /* __s390x__ */


/*
 * A 31 bit pagetable entry of S390 has following format:
 *  |   PFRA          |    |  OS  |
 * 0                   0IP0
 * 00000000001111111111222222222233
 * 01234567890123456789012345678901
 *
 * I Page-Invalid Bit:    Page is not available for address-translation
 * P Page-Protection Bit: Store access not possible for page
 *
 * A 31 bit segmenttable entry of S390 has following format:
 *  |   P-table origin      |  |PTL
 * 0                         IC
 * 00000000001111111111222222222233
 * 01234567890123456789012345678901
 *
 * I Segment-Invalid Bit:    Segment is not available for address-translation
 * C Common-Segment Bit:     Segment is not private (PoP 3-30)
 * PTL Page-Table-Length:    Page-table length (PTL+1*16 entries -> up to 256)
 *
 * The 31 bit segmenttable origin of S390 has following format:
 *
 *  |S-table origin   |     | STL |
 * X                   **GPS
 * 00000000001111111111222222222233
 * 01234567890123456789012345678901
 *
 * X Space-Switch event:
 * G Segment-Invalid Bit:     *
 * P Private-Space Bit:       Segment is not private (PoP 3-30)
 * S Storage-Alteration:
 * STL Segment-Table-Length:  Segment-table length (STL+1*16 entries -> up to 2048)
 *
 * A 64 bit pagetable entry of S390 has following format:
 * |                     PFRA                         |0IP0|  OS  |
 * 0000000000111111111122222222223333333333444444444455555555556666
 * 0123456789012345678901234567890123456789012345678901234567890123
 *
 * I Page-Invalid Bit:    Page is not available for address-translation
 * P Page-Protection Bit: Store access not possible for page
 *
 * A 64 bit segmenttable entry of S390 has following format:
 * |        P-table origin                              |      TT
 * 0000000000111111111122222222223333333333444444444455555555556666
 * 0123456789012345678901234567890123456789012345678901234567890123
 *
 * I Segment-Invalid Bit:    Segment is not available for address-translation
 * C Common-Segment Bit:     Segment is not private (PoP 3-30)
 * P Page-Protection Bit: Store access not possible for page
 * TT Type 00
 *
 * A 64 bit region table entry of S390 has following format:
 * |        S-table origin                             |   TF  TTTL
 * 0000000000111111111122222222223333333333444444444455555555556666
 * 0123456789012345678901234567890123456789012345678901234567890123
 *
 * I Segment-Invalid Bit:    Segment is not available for address-translation
 * TT Type 01
 * TF
 * TL Table lenght
 *
 * The 64 bit regiontable origin of S390 has following format:
 * |      region table origon                          |       DTTL
 * 0000000000111111111122222222223333333333444444444455555555556666
 * 0123456789012345678901234567890123456789012345678901234567890123
 *
 * X Space-Switch event:
 * G Segment-Invalid Bit:  
 * P Private-Space Bit:    
 * S Storage-Alteration:
 * R Real space
 * TL Table-Length:
 *
 * A storage key has the following format:
 * | ACC |F|R|C|0|
 *  0   3 4 5 6 7
 * ACC: access key
 * F  : fetch protection bit
 * R  : referenced bit
 * C  : changed bit
 */

/* Hardware bits in the page table entry */
#define _PAGE_RO        0x200          /* HW read-only                     */
#define _PAGE_INVALID   0x400          /* HW invalid                       */

/* Mask and four different kinds of invalid pages. */
#define _PAGE_INVALID_MASK	0x601
#define _PAGE_INVALID_EMPTY	0x400
#define _PAGE_INVALID_NONE	0x401
#define _PAGE_INVALID_SWAP	0x600
#define _PAGE_INVALID_FILE	0x601

#ifndef __s390x__

/* Bits in the segment table entry */
#define _PAGE_TABLE_LEN 0xf            /* only full page-tables            */
#define _PAGE_TABLE_COM 0x10           /* common page-table                */
#define _PAGE_TABLE_INV 0x20           /* invalid page-table               */
#define _SEG_PRESENT    0x001          /* Software (overlap with PTL)      */

/* Bits int the storage key */
#define _PAGE_CHANGED    0x02          /* HW changed bit                   */
#define _PAGE_REFERENCED 0x04          /* HW referenced bit                */

#define _USER_SEG_TABLE_LEN    0x7f    /* user-segment-table up to 2 GB    */
#define _KERNEL_SEG_TABLE_LEN  0x7f    /* kernel-segment-table up to 2 GB  */

/*
 * User and Kernel pagetables are identical
 */
#define _PAGE_TABLE	_PAGE_TABLE_LEN
#define _KERNPG_TABLE	_PAGE_TABLE_LEN

/*
 * The Kernel segment-tables includes the User segment-table
 */

#define _SEGMENT_TABLE	(_USER_SEG_TABLE_LEN|0x80000000|0x100)
#define _KERNSEG_TABLE	_KERNEL_SEG_TABLE_LEN

#define USER_STD_MASK	0x00000080UL

#else /* __s390x__ */

/* Bits in the segment table entry */
#define _PMD_ENTRY_INV   0x20          /* invalid segment table entry      */
#define _PMD_ENTRY       0x00        

/* Bits in the region third table entry */
#define _PGD_ENTRY_INV   0x20          /* invalid region table entry       */
#define _PGD_ENTRY       0x07

/*
 * User and kernel page directory
 */
#define _REGION_THIRD       0x4
#define _REGION_THIRD_LEN   0x3 
#define _REGION_TABLE       (_REGION_THIRD|_REGION_THIRD_LEN|0x40|0x100)
#define _KERN_REGION_TABLE  (_REGION_THIRD|_REGION_THIRD_LEN)

#define USER_STD_MASK           0x0000000000000080UL

/* Bits in the storage key */
#define _PAGE_CHANGED    0x02          /* HW changed bit                   */
#define _PAGE_REFERENCED 0x04          /* HW referenced bit                */

#endif /* __s390x__ */

/*
 * No mapping available
 */
#define PAGE_NONE_SHARED  __pgprot(_PAGE_INVALID_NONE)
#define PAGE_NONE_PRIVATE __pgprot(_PAGE_INVALID_NONE)
#define PAGE_RO_SHARED	  __pgprot(_PAGE_RO)
#define PAGE_RO_PRIVATE	  __pgprot(_PAGE_RO)
#define PAGE_COPY	  __pgprot(_PAGE_RO)
#define PAGE_SHARED	  __pgprot(0)
#define PAGE_KERNEL	  __pgprot(0)

/*
 * The S390 can't do page protection for execute, and considers that the
 * same are read. Also, write permissions imply read permissions. This is
 * the closest we can get..
 */
         /*xwr*/
#define __P000  PAGE_NONE_PRIVATE
#define __P001  PAGE_RO_PRIVATE
#define __P010  PAGE_COPY
#define __P011  PAGE_COPY
#define __P100  PAGE_RO_PRIVATE
#define __P101  PAGE_RO_PRIVATE
#define __P110  PAGE_COPY
#define __P111  PAGE_COPY

#define __S000  PAGE_NONE_SHARED
#define __S001  PAGE_RO_SHARED
#define __S010  PAGE_SHARED
#define __S011  PAGE_SHARED
#define __S100  PAGE_RO_SHARED
#define __S101  PAGE_RO_SHARED
#define __S110  PAGE_SHARED
#define __S111  PAGE_SHARED

/*
 * Certain architectures need to do special things when PTEs
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
extern inline void set_pte(pte_t *pteptr, pte_t pteval)
{
	*pteptr = pteval;
}

/*
 * pgd/pmd/pte query functions
 */
#ifndef __s390x__

extern inline int pgd_present(pgd_t pgd) { return 1; }
extern inline int pgd_none(pgd_t pgd)    { return 0; }
extern inline int pgd_bad(pgd_t pgd)     { return 0; }

extern inline int pmd_present(pmd_t pmd) { return pmd_val(pmd) & _SEG_PRESENT; }
extern inline int pmd_none(pmd_t pmd)    { return pmd_val(pmd) & _PAGE_TABLE_INV; }
extern inline int pmd_bad(pmd_t pmd)
{
	return (pmd_val(pmd) & (~PAGE_MASK & ~_PAGE_TABLE_INV)) != _PAGE_TABLE;
}

#else /* __s390x__ */

extern inline int pgd_present(pgd_t pgd)
{
	return (pgd_val(pgd) & ~PAGE_MASK) == _PGD_ENTRY;
}

extern inline int pgd_none(pgd_t pgd)
{
	return pgd_val(pgd) & _PGD_ENTRY_INV;
}

extern inline int pgd_bad(pgd_t pgd)
{
	return (pgd_val(pgd) & (~PAGE_MASK & ~_PGD_ENTRY_INV)) != _PGD_ENTRY;
}

extern inline int pmd_present(pmd_t pmd)
{
	return (pmd_val(pmd) & ~PAGE_MASK) == _PMD_ENTRY;
}

extern inline int pmd_none(pmd_t pmd)
{
	return pmd_val(pmd) & _PMD_ENTRY_INV;
}

extern inline int pmd_bad(pmd_t pmd)
{
	return (pmd_val(pmd) & (~PAGE_MASK & ~_PMD_ENTRY_INV)) != _PMD_ENTRY;
}

#endif /* __s390x__ */

extern inline int pte_none(pte_t pte)
{
	return (pte_val(pte) & _PAGE_INVALID_MASK) == _PAGE_INVALID_EMPTY;
}

extern inline int pte_present(pte_t pte)
{
	return !(pte_val(pte) & _PAGE_INVALID) ||
		(pte_val(pte) & _PAGE_INVALID_MASK) == _PAGE_INVALID_NONE;
}

extern inline int pte_file(pte_t pte)
{
	return (pte_val(pte) & _PAGE_INVALID_MASK) == _PAGE_INVALID_FILE;
}

#define pte_same(a,b)	(pte_val(a) == pte_val(b))

/*
 * query functions pte_write/pte_dirty/pte_young only work if
 * pte_present() is true. Undefined behaviour if not..
 */
extern inline int pte_write(pte_t pte)
{
	return (pte_val(pte) & _PAGE_RO) == 0;
}

extern inline int pte_dirty(pte_t pte)
{